GUIDANCE FOR CONDUCTING FACILITY IMPACT ASSESSMENT COMMONWEALTH OF MASSACHUSETTS
EXECUTIVE OFFICE OF ENVIRONMENTAL AFFAIRS
DEPARTMENT OF ENVIRONMENTAL PROTECTION
ONE WINTER STREET, BOSTON, MA 02108 617-292-5500
MITT ROMNEY STEPHEN R.PRITCHARD
Governor
Secretary
KERRY HEALEY ROBERT W.GOLLEDGE,Jr.
Lieutenant Governor Commissioner
Guidance for Conducting Facility Impact Assessment
for Solid Waste Facility Site Assignment
in Support of 310 CMR 16.00
Initial Publication: June 2001
Revised: March 22, 2006
Approved: qo"'W'm
Jhmes C. Colman
Assistant Commisioner
Bureau of Waste Prevention
This inforamahm is available in alternate format.Call Donald M.Gomes,ADA Coordinator at 617-556-1057.TDD Service-1-900-29&2207.
DEP on the World Wide Web http/Mv mass gov/dep
Printed on Recycled Paper
This document is intended to guide parties, MassDEP staff
and others in conducting or reviewing facility impact
assessments for solid waste facilities in compliance with 310
CMR 16. 00.
This document is intended solely as guidance. It does not
create any substantive or procedural rights and is not
enforceable by any party in any administrative proceeding within
the Commonwealth. This document summarizes the requirements of
310 CMR 16. 00 and provides guidance on approaches MassDEP
considers acceptable for meeting the general requirements for
conducting a facility impact assessment for solid waste
facilities as set forth in these regulations. Parties using
this guidance should be aware that there may be other acceptable
alternatives for achieving compliance with general regulatory
requirements.
Regulatory citations in this document should not be relied
upon as a complete list of the regulatory requirements related
to conducting a facility impact assessment pursuant to these
regulations. Parties conducting a facility impact assessment
for solid waste facility site assignment should consult 310 CMR
16. 00.
2
Table of Contents
ExecutiveSummary........................................................................................................................v
SECTION1: Introduction.............................................................................................................. 1
1.1 Applicability and Scope.....................................................................................................2
1.2 Accounting for Emissions from Other Faciliities.............................................................. 3
SECTION 2: Facility Assessment Screening Protocol..................................................................4
2.1 Best Management Practices............................................................................................... 7
2.2 Assessment Appropriate To Facility Type..................................................................... 13
2.2.1 Waste-Handling Facilities of Any Size..................................................................... 13
2.2.2 Small Landfills That Take in Less Than or Equal to 150 Tons Per Day.................. 14
2.2.3 New Landfills and Expansions That Take in Greater Than 150 Tons Per Day........ 14
SECTION 3: Qualitative Impact Assessment............................................................................. 15
SECTION 4: Quantitative Impact Assessment............................................................................ 17
4.1 Hazard Identification—Contaminants of Concern (COC).............................................. 17
4.1.1 Proposed Landfi I Is.................................................................................................... 20
4.1.1.1 Types of Landfills..................................................................................................20
4.1.1.1.1 COC in Landfill Gas from Municipal Solid Waste Facilities.......................21
Landfill Area Sources...................................................................................................21
Landfill Gas Constituents .........................................................................................21
AP-42 Chemicals................................................................................................... 22
OtherChemicals.................................................................................................... 22
SpecialWastes.......................................................................................................23
Landfill Point Sources..................................................................................................25
Stack Gas Constituents............................................................................................. 25
AP-42 Chemicals...................................................................................................26
Other Landfill Gas Chemicals............................................................................... 26
Secondary Pollutants from Stack Emissions.........................................................26
4.1.1.1.2 COC From Non-Municipal Solid Waste Landfills....................................... 26
AshLandfills................................................................................................................ 27
Unprocessed Construction and Demolition Landfills(C&D)......................................28
4.1.2 Emissions From Proposed Waste Handling Facilities..............................................28
4.1.3 Diesel Particulates..................................................................................................... 29
4.1.4 Toxicity Profiles........................................................................................................ 30
4. 2 Dose-Response Assessment............................................................................................ 30
4.2.1 Conversions from Dose............................................................................................. 32
4.2.2 Sources of Dose-Response Values............................................................................ 33
4.2.3 Dose-Response information for the AP-42 Chemicals............................................. 34
4.2.4 Relative Absorption Factors ..................................................................................... 35
4.3 Exposure Assessment...................................................................................................... 35
4.3.1 Screening Case Exposure Profile.............................................................................. 36
i
4.3.2 Refined Exposure Profile..........................................................................................36
4.3.3 Quantitative Estimates of Exposure.......................................................................... 37
4.3.3.1 Modeling Approach Used to Calculate Exposure Point Concentrations............... 38
4.3.3.1.1 Landfill Gas and Particulate Emissions........................................................39
4.3.3.1.1.1 Municipal Solid Waste Landfills...............................................................39
Area Sources (Uncontrolled Emissions)...................................................................39
Area Sources(Controlled Emissions)....................................................................... 39
Point Sources (Controlled Emissions)......................................................................40
Non-Municipal Solid Waste Landfills .........................................................................40
Area Sources (Uncontrolled Emissions)..................................................................40
4.3.3.1.2 Air Quality Impact Analysis Modeling Protocol..........................................40
Sourcedata...................................................................................................................40
ReceptorNetwork ........................................................................................................41
MeteorologicalData.....................................................................................................42
Atmospheric Dispersion Coefficients.......................................................................... 42
AirQuality Models.......................................................................................................42
4.3.3.1.3 Air Quality Impact Analyses Report.............................................................42
Averaging Times of Concern.......................................................................................42
Contents of Air Quality Impact Analysis Report.........................................................42
4.3.3.2 Calculation of Average Daily Exposure a...............................................................43
4.3.3.3 Inhalation of Particulate-Associated Contamination.............................................44
4.3.3.4 Calculation of the Lifetime Average Daily Exposure (LADE) or the Lifetime
AverageDaily Dose (LADD)............................................................................................. 45
4.4 Risk Characterization ......................................................................................................45
4.4.1 Non-cancer Risk........................................................................................................45
4.4.1.1 Screening Hazard Index..........................................................................................47
4.4.1.2 Health Endpoint-Specific Hazard Index (Multiple Chemicals) ............................47
4.4.2 Cancer Risk...............................................................................................................48
4.4.3 Available Tools......................................................................................................... 49
4.5 Uncertainty Analysis....................................................................................................... 49
4.6 Risk Management............................................................................................................ 50
SECTION 5: Water Resources.................................................................................................... 53
SECTION 6: Facility impact assessment Report Content and Submission Process ................... 54
6.1 Report Content................................................................................................................. 54
6.2 Submission of Proposed Facility impact assessment Protocol and Scoping Activities .. 55
6.3 Submission of a Facility impact assessment within Applicable Permit Applications..... 56
REFERENCES.............................................................................................................................. 59
APPENDIX A. Checklist for Facility impact assessment of Solid Waste Facilities
List of Tables
Table 1. Summary of Revised Siting Requirements/Criteria......................................................... 5
Table 2. MassDEP Approved BMPs for Landfills........................................................................ 9
Table 3. MassDEP Approved BMPs for Waste Handling Facilities........................................... 11
Table 4. Level 1 Qualitative Impact Assessment- Waste Handling Facilities............................ 16
Table 5. Level 1 Qualitative Impact Assessment - Small Landfills ............................................ 16
Table 6. List of Landfill AP-42 Chemicals.................................................................................. 19
Table 7. Toxicity Information for the AP-42 List of Chemicals .................................................24
List of Figures
Figure 1. MADEP Protocol for Selecting Level of Assessment.................................................... 6
Figure 2. Quantitative Assessment Review................................................................................. 52
iii
For further information, please contact:
• Solid Waste Regulations &BMPs: James Doucett, Bureau of Waste Prevention.
(James.Doucetta.state.ma.us) (617) 292-5868
• Risk Assessment: Carol Rowan West and Diane Manganaro, Office of Research &
Standards—(Carol.Rowan.West(a state.ma.us) (617) 292-5570;
(Diane.Manganaroastate.ma.usl (617) 556-1158
• Emissions and Dispersion Modeling: Stephen Dennis, Bureau of Waste Prevention
(Stenhen.Dennisa,,state.ma.usl (617) 292-5766
• Stationary Source Inventory Emissions System (SSEIS): Robert Boisselle,Bureau of
Waste Prevention (Robert Boisellea..state.ma.us) (617) 292-5609
• GIS Information: Brian Brodeur, Bureau of Planning and Policy
(Brlan.Brodellra,state.ma.us) (617) 574-6802
• Diesel Emission Controls, Tom Naderi, Bureau of Waste Prevention
(Soroosh.Naderi(a).state.ma.us) (617) 556-1124
• Groundwater Assessment Requirements: Contact the Solid Waste Program in your DEP
region.
iv
Executive Summary
Guidance for Conducting Facility Impact Assessment for Solid Waste
Facilities in Support of 310 CMR 16.00
Preface
This Facility impact assessment Guidance Document (hereafter referred to as the Guidance
Document) was developed to provide project proponents with information on!how_to-complete
facility-impact_assessments-for the Department`of_'Environmental Protec__tion (MassDEP) when
applying for site assignments-under`310 CMR 16.00. This guidance document revises and
supersedes MassDEP's previous guidance titled Interim Risk-Evaluation Guidance for Solid Waste
Facility Site Assignment and Permitting, issued in June 2001. Important revisions include:
• assessments are now required for site assignments only,not for permits;
• assessments are no longer required for ash landfills;
• references to hydrogen sulfide issues, specifically for facilities handling construction and
demolition debris materials;
• a section on recommended best management practices; and
• a provision that applicants address the full site-assigned project, rather than doing a phase by
phase assessment.
This Guidance Document applies to those applicants who are applying for a site assignment or
'major-modificationto a site assignment on or after June 8, 2001 (the effective date of the newly
revised Site Assignment Regulations at 310 CMR 16.00); and
The required assessment of the facility for purposes of site assignment may be conducted during the
MEPA process for projects requiring an environmental impact report. If that assessment is
complete and adequate, a second assessment will not be required in the site assignment process.
This Guidance Document does not apply to the following facilities or operations to which the solid
waste regulations do not apply or that are exempt from the site assignment:
a. Facilities and operations to which 310 CMR 16.00 does not apply as specified at
310 CMR 16.05(2).
b. Conditionally exempt recycling operations as specified at 310 CMR 16.05(3).
c. Conditionally exempt composting operations as specified at 310 CMR 16.05(4).
d. Other conditionally exempted operations as specified at 310 CMR 16.05(5).
e. Facilities that are not required to obtain a site assignment or permit pursuant to the
Determination of Need process specified at 310 CMR 16.05(6)-(l0)
f. Facilities under construction as of June 8, 2001 (the effective date of the newly revised
Site Assignment Regulations)
MassDEP uses this Guidance Document and the information provided by an applicant to determine
whether a site is suitable for a solid waste facility assuming that the facility meets all other
v
requirements of 310 CMR 16.00. It is therefore incumbent upon the applicant to demonstrate and
otherwise provide MassDEP with sufficient information so that MassDEP can determine whether or
not to issue a favorable site suitability report. if the applicant fails to provide sufficient information
as determined by MassDEP during its review of an application, then the application will be deemed
to be technically deficient. The applicant will then be provided with an opportunity to supplement
the information provided in the application.
When MassDEP reviews facility assessments and issues a report containing a finding that the site
fails to meet the site suitability criteria, MassDEP may entertain written requests for reconsideration
from the applicant stating the basis on which the reconsideration is requested. Such a request must
be filed within 14 days of the issuance of MassDEP's site suitability report(310 CMR 16.14).
Unless MassDEP reaffirms or revises this guidance document within three years of the date it is
issued,this guidance document will "sunset" and will no longer be applicable. Within two years of
the date it is issued, MassDEP intends to initiate a review of the guidance and seek input from its
Solid Waste Advisory Committee to determine whether the guidance should be maintained as is,
revised, or eliminated.
Introduction
This Guidance Document presents MassDEP's current methodology for determining the level of
assessment required for proposed solid waste facilities,provides guidance on the impact
assessment procedures to be used for proposals, and provides a description of MassDEP's risk
management approach.
Depending on features of the proposed facility such as its type and size, use of BMPs, and other
factors, each proposed facility should be evaluated under a Level I (qualitative impact
assessment) or Level 2 (quantitative impact assessment) approach. Figure 1 describes this
approach, which is designed to help ensure that the level of assessment for a proposed facility is
commensurate with the potential for risk from the facility. In general, small facilities that are
well controlled receive a lower level of assessment (Level 1 assessment) than large facilities with
the potential for greater impact (Level 2 assessment).
Vi
Figure 1. MassDEP Protocol for Selecting Level of Assessment
Impact Evaluation Flowchart
Assumes all other requirements are met
(310 CMR 16.00)
Level I
Qualitative Impact Evaluation
Is the facility a new landfill'or
landfill expansion>150 TPD v
Ino
A-Enhanced BMPs for dust&odor,and
planned use of low emission diesel equipment
for all equipment on site?
Yes to all: B_the capacity of the proposal Is less than 150 No to all
A,sand ie,A„Band
(if applicable)C tons/day? (if applicable)C
C-(for landfills<150 TPD). Assessment of
potential surface and groundwater contamination
and complete cleanup plan if needed?
No to A,Bor
(if applicable)C
A
Are there more
Positive Report \ no than
C/wo mitigation re uirements Evaluate' ; (5l1 TPY VOC ,r``
g q / from sources l iav els
;within-onemlle?l (aa5 yrµ�I dYl
Yes
Negative
Reporf'
1 r
Level 2 f$uantitative Evaluation with
Quantitative Impact Evaluation DEP Review Considerina the
Following:
•Emissions of Total VOCs from
facilities within one mile,If any,
Evalu\ •Facility-specific cancer and
noncancer nsks,
•The extent to which Enhanced
Was are proposed,
•Potential surface and groundwater
contamination and complete cleanup
plan,If needed.
GAVOPositive Report
mingahon requirements
"`Landfill”includes MSW,Residuals,and C&D
'- Evaluation includes factors listed in the Executive Summary,pge viii
'Evaluation includes factors listed in the Executive Summary,pal xi-xn
' Request for mconsrdenahon ofs negative finding on site sutebihry allowed(310 CMR 16 14)
vii
Proposed Level 1 and Level 2 assessments are reviewed by MassDEP following the steps
depicted in Figure 1. For Level 1 assessments, the factors considered that bear upon whether a
positive or negative site assignment report is issued by MassDEP include the following:
- facility type and size;
- extent to which BMPs are proposed;
- the type of land uses impacted by the facility;
- emissions-of�volatileorganic_compounds(VOCs)$omotherpoint.s_ources_within-the-area;A
- -specific particulate matter sources, such as other solid waste management facilitiesjunk-
,cyardp,auto salvage-shops; bus and truck depots, etc. within the area; and
- (for landfills/expansions less than 150 tons per day)a commitment to develop and implement
a cleanup plan for any surface water and groundwater contamination to comply with water
quality standards in applicable laws and regulations (plan must be approved by MassDEP
before the expansion is approved - See separate guidance titled Guidance for the Assessment
of Groundwater and Surface Water for Solid Waste Facility Site Assignment and Permitting).
Transfer stations,_construction_and'demoliiion-(C&D) processing tacihttes, and small landfills
are assessed using a Level 1 assessment.
Yom—---_--
The Level 2 assessment process is described below. It is based on the risk assessment
procedures established by the National Academy of Science, builds upon existing risk
assessment methods developed by the U.S Environmental Protection Agency (USEPA) (USEPA,
1989) and is similar to risk assessment methods used under the Massachusetts Contingency Plan
(MCP).'
The Level 2 quantitative impact assessment is used to assess potential human health impacts due
to inhalation of air contaminants from a proposed landfill that meets all of the facility and siting
requirements contained in the siting regulations (3 10 CMR 16.00). Emissions of certain toxic
pollutants (e.g., benzene, vinyl chloride, perch loroethylene, etc.) are included in the quantitative
assessment of potential risks from proposed solid waste facilities (i.e., new landfills and landfill
expansions over 150 tons a day). Total cancer and non-cancer risks associated with emissions of
toxics from the proposed facility are estimated under this protocol. Criteria pollutants (i.e.,
ozone, particulate matter, carbon monoxide, nitrogen oxides, sulfur dioxide, lead)will be
evaluated elsewhere in the siting and permitting processes to ensure compliance with National
Ambient Air Quality standards (which are federal standards that consider health impacts).
Potential groundwater impacts are not included in the quantitative risk assessment, because
MassDEP believes that future groundwater impacts from the proposed facilities will be
adequately controlled provided that facilities are constructed and operated in compliance with all
applicable regulations. To protect important water resources, MassDEP has prohibited the siting
of facilities in sensitive water resource areas. MassDEP has also modified the existing Site
Assignment Regulations for Solid Waste Facilities to require increased setback distances from all
water resources. This serves as a primary mechanism to prevent water impacts. In addition,
MassDEP requires BMPs for stormwater, leachate collection, and water monitoring requirements
' Over time and with anticipated stakeholder input,MassDEP has plans to review additional elements so that facility
impacts will be more fully addressed
viii
for landfills. As part of the permitting process, proposed landfills and proposed expansions of
landfills are also required to install double liners. In addition, for all proposed landfill
expansions (for both Level 1 and Level 2 assessments), MassDEP requires an assessment of
existing surface water and groundwater quality monitoring data for the existing facility.
Depending on the level of contamination, the applicant may be required to prepare and
implement a cleanup plan to achieve groundwater and surface water standards under the Solid
Waste and Waste Site Cleanup programs.
To protect air quality and public health, and to minimize nuisance conditions, MassDEP
encourages BMPs for dust and odors, and the use of low emission diesel equipment on-site'. In
addition, the revised regulations require increased setbacks of facilities from sensitive receptors,
including homes, schools, nursing homes, daycare centers, etc. which reduce potential inhalation
risks to individuals in proximity of the facility. MassDEP is not recommending an assessment of
mobile source emissions at this time, including those from on-site equipment,trucks carrying
waste to the facility and emissions from all other off-site traffic, in the Level 2 quantitative
impact assessment.
MassDEP is issuing separate guidance to address hydrogen sulfide emissions from landfills that
handle C&D materials. While this risk assessment guidance document references types of BMPs
that facilities should implement to reduce hydrogen sulfide emissions, this separate guidance
recommends more specific management and control strategies. Based on this guidance,
MassDEP may require additional assessment and/or controls at landfills where there is a
potential for hydrogen sulfide emissions.
The following sections present brief summaries of the steps that comprise a Level 2 quantitative
impact assessment.
STEP 1: Hazard Identification-Identification of Chemicals of Concern
Chemicals of concern (COC) from proposed landfills and their associated emission factors may
be determined from the USEPA Landfill Gas Emissions Model (USEPA 1998). This model
focuses on 47 COC (see Table 6 in the Guidance Document) with respect to emissions from
landfill sites and vents, whether they are controlled or uncontrolled. The list of 47 chemicals is
based on a USEPA publication, Compilation of AP-42 Emission Factors(USEPA 1997a) on
chemicals that have been found to be emitted from landfills based on national testing of landfill
emissions and from published documents. MassDEP has determined that all chemicals on this
list for which published toxicity values exist should be included in the quantitative risk
assessment. As toxicity data for the remaining chemicals become available,they will also be
included in future quantitative risk assessments. On a case-by-case basis, MassDEP will review
proposals from proponents wishing to evaluate and use other data (e.g., from similar landfills to
the one proposed)to establish alternate lists of COC and/or emission factors. In particular,
`On-site diesel equipment refers to equipment used at the facility and does not include diesel vehicles transporting
refuse into and out of the facility. At landfills,on-site diesel equipment could include equipment for excavating and
moving dirt,for covering and compacting operations,and on-site power production. At waste handling facilities,
on-site diesel equipment may include equipment that is used to move,consolidate and compact trash before it is
taken off site.
ix
MassDEP will consider capture rate data specified in existing MassDEP facility air permits.
Approval from MassDEP on the approach to be used should be sought prior to initiating such an
assessment.
If appropriate, project proponents should also address potential emissions and risks associated
with special wastes, for which a permit will be requested, that contain potential COC that are not
included on the list of 47 compounds and for which toxicity data exist. A special waste is only
required to be addressed in the quantitative risk assessment if that waste comprises greater than
fifty percent per year of the total waste taken in at that facility. In such cases, approval from
MassDEP should also be sought prior to identifying any additional COC and emission factors for
use in the quantitative risk assessment for those chemicals.
STEP 2: Dose Response Assessment
The project proponent should utilize the most current published toxicity values for the
chemicals of concern. Current values are listed by MassDEP in this Guidance Document3. These
toxicity values represent cancer slope factors and reference concentrations that have been published
by USEPA (e.g., Integrated Risk Information System) or others, as appropriate. These values are
updated from time to time by the organizations responsible for their development. The project
proponent is responsible for ensuring that the most current values are used in the quantitative risk
assessment.
STEP 3: Exposure Assessment
The project proponent should estimate potential exposures to chemicals of concern from the
proposed facility based on appropriate modeling (USEPA Guidance for Landfill Gas Emissions
Model)and other appropriate methods (e.g., dispersion models) that are specified by MassDEP
in this Guidance Document.
The inhalation exposure pathway is quantitatively addressed. The Guidance Document specifies
the modeling outputs, including for example, a peak annual average and long-term (30-year)
average air concentration for each toxic chemical at the property line and beyond.
As mentioned above, if a facility proponent prefers not to utilize the USEPA emission factors in
modeling facility emissions but wants to collect and/or use other information, such as monitoring
data from a similar existing facility, MassDEP review and approval of the proposed alternative is
required to ensure that it meets all appropriate requirements.
STEP 4: Risk Characterization
A quantitative risk assessment should be performed using the exposure estimates and the dose
response information, determined as noted above. The multi-chemical, single pathway
assessment should include an assessment of the total facility excess lifetime cancer risks and
chronic and sub-chronic non-cancer risks. The quantitative risk assessment should also include a
3 The project proponent should use toxicity data that are available at the time of the project assessment. Project
proponents are responsible for using the most up-to-date values in their assessments.
X
discussion of the uncertainties, such as those associated with the hazard identification, dose-
response, exposure assessment(including both modeling and exposure issues), and risk
characterization steps.
STEP 5: Risk Management
Results of the facility impact assessment will be compared to MassDEP's risk management
criteria, considering additional factors, as described below.
Risk Management Criteria for Level 2 Assessments
Absent other significant factors,the MCP risk management criteria(Excess Lifetime Cancer
Risk= 1-in-100,000, Hazard Index= 1) will be applicable to the results of a quantitative
assessment prepared for a Level 2 assessment. Additionally, proposed facilities that would pose
de minimis risks (ELCR less than one-in-one million and a Hazard Index less than 0.1)will be
generally approvable at any location. Where there are other significant emissions of VOCs in the
immediate area, more stringent risk management criteria may be appropriate as discussed further
below.
Additional Risk Management Considerations
The following additional factors will be considered by MassDEP when evaluating the
appropriateness of a location for a proposed landfill and for permitting expansions of existing
landfills:
• The aggregate emissions and associated potential risks, as described by the combination of
the following two factors:
I. the risk posed by the facility itself(quantitative estimations of the Total Facility
Hazard Index and Excess Lifetime Cancer Risk); and
2. the emissions of pollutants that can impact public health from nearby facilities
(evaluated using an indicator, total VOC emissions from all point sources within 1
mile, unless otherwise determined by MassDEP, as listed in MassDEP's
database 4, including existing waste facilities at the proposed location). The use of
this indicator is predicated on the assumption that the higher the emissions of
VOCs from adjacent air point sources registered in MassDEP's database,the
higher the potential risk in the community affected by these facilities. The facility
proponent may choose to conduct multiple facility source modeling and
quantitative risk assessment of the adjacent sources to provide a refined estimate
of overall risk.
4 Stationary Source Emissions Inventory System
s The facility proponent should consult with MADEP prior to initiating such work. Such an analysis could be part of
the initial proposal,prior to a requirement for mitigation,prior to the issuance of a negative site suitability report,or
as part of a request for reconsideration.
xi
• A commitment to develop and implement a cleanup plan for any surface water and
groundwater contamination to comply with water quality standards in applicable laws and
regulations (plan must be approved by MassDEP before the expansion is approved), if the
proposed facility is an expansion of a landfill.
• Other factors affecting environmental conditions in the area, such as possible
mitigation/offset measures offered by the proponent, expected future change to emissions
from facilities in the area,the type of land uses impacted by the facility; specific particulate
matter sources within the area, such as solid waste management facilities,junk yards, auto
salvage shops, bus and truck depots, etc.; and the environmental impacts of not constructing
the facility.
• Uncertainty of the available data.
Assuming that all other requirements are met, MassDEP would issue a positive site suitability
report if the risk management criteria are clearly met, suggest mitigation measures if the results
are near the proposed limits, or issue a negative determination, require changes to the proposal or
require mitigation measures if one or more of the criteria are exceeded. Mitigation options may
include enhanced controls on emission sources at the site and/or off-site mitigation.
Figure 2 graphically depicts MassDEP's approach to evaluating quantitative information that has
been developed for the Guidance Document. The darkly shaded area to the right of the figure
represents those facilities with an estimated total facility Excess Lifetime Cancer Risk greater
than one-in-one hundred thousand or an estimated total facility Hazard Index greater than one.
Outside that darkly shaded area, the facility itself poses an acceptable risk. In this latter case, the
facility site can be approved unless emissions from adjacent air point sources are high. In that
case, additional mitigation or additional assessment may be needed.
Figure 2.
Quantitative Evaluation Review
Facility
Risk Estimates L
�< 1x10 6 < 1x10-5 > 1x10 5�- ELCR, and
< 0.1 < 1 > 1 HI-----
Emissions
j From 0 —------ - — '-------
Adjacent
Air Point j
Sources
�
tons/ r- -----
( Yr) - High --- - - --- � -I-------- ---1
Xii
Tools Available
MassDEP has developed a spreadsheet to assist in conducting a quantitative risk assessment for
landfills. This spreadsheet addresses the default lists of chemicals suggested in this document. It
may be accessed at the MassDEP home page at httr)://ww-,v.mass.eov/der). For proposed
facilities for which special wastes should be evaluated or which otherwise need to consider
additional chemicals,the risks from these chemicals should be calculated separately and added to
the risk determined using the spreadsheet.
This guidance document identifies the minimum components that the impact assessment
report should include, explains how the impact report fits into the site assignment process and
identifies specific submission requirements.
xiii
SECTION 1: Introduction
In June 2001, the Massachusetts Department of Environmental Protection (MassDEP)
adopted revisions to the Site Assignment Regulations (3 10 CMR 16.00) which govern the siting
of solid waste facilities in Massachusetts. In particular, 310 CMR 16.40 establishes the criteria
and decision-making process MassDEP shall utilize in determining whether a site is suitable for
a proposed solid waste management facility.
In October, 2001, the MassDEP Commissioner convened a Science Panel to review the
Interim Guidance Document(June 8, 2001 Interim Guidance) and to provide recommendations
for the assessment of cumulative impacts. The Science Panel report
(htto://www.mass.eov/deo/bwo/dswm/dswmr)ubs.htm#swac) recommended no clear next steps.
As a result, no major changes to the impact assessment guidance are being made as part of this
update. The main focus of this updated document is clarification of the previous Interim
Guidance, including additional guidance on water resources assessment.
MassDEP is committed to ensuring that solid waste facilities are located and designed to
minimize impacts to public health and the environment. Requirements for siting or expanding
solid waste facilities or expansions call for enhanced measures to address potential facility-
related impacts to the public. These measures include increases in required setback distances of
the facility to sensitive receptors or resources, requirements to prevent water impacts, and
qualitative or quantitative impact assessments, as determined by the size and characteristics of
the proposed facility and its surrounding area. In addition,MassDEP is encouraging Best
Management Practices(BMPs) for dust and odors, and the use of low emission diesel equipment
for all on-site diesel equipment.
The revised solid waste site assignment regulations incorporate a systematic review
process that evaluates the potential impacts of a proposed facility or expansion on public health.
The level of assessment reflects the potential for risk from the proposed facility. The assessment
should be based on the types and amount of wastes the facility proposes to handle. Small, well-
controlled facilities receive a lower level of assessment than large facilities with the potential for
greater impact. In addition to assessing site suitability based on facility-specific considerations,
the revised regulations also take into consideration the impacts of existing sources of pollution or
contamination in the surrounding area.
To protect=air=quality,_public health-and to-minimize nuisance conditions, M_assDEPV
;encourages all proposed solid waste management facilitieses eo incorporate Best IVManagemerl�
Practices (BMPs`) to control dust and odors in their proposal srIn addition, MassDEP encourages
'facility operators to equip=or retrofit all-equipment-on-site with-low emission-diesef-technology�
MassDEP believes that-use ofsuch-6MPs should greatly reduce fugitive particulate and other
emissions and odors. MassDEP also requires=increased-setback=distances of facilities from
sensitive receptors including4iomes; schools, nursing homes, daycare centers, etc. to reduce
potential risks to individuals living or working in the proximity of a solid waste facility. For
larger landfills, a quantitative impact assessment should be conducted to assess facility-specific
cancer and non-cancer risks associated with emissions of gaseous pollutants. In addition, for all
I
proposed facility types or expansions, total potential emissions of volatile organic compounds
(VOCs), determined using the MassDEP Stationary Source Emissions and Inventory System
(SSEIS)database, should be evaluated as an indicator of industrial activity and/or the potential
for emissions in the area that may cause or contribute to adverse impacts related to landfill gases.
To protect water resources, MassDEP requires increased-setback-distances_from
groundwater and surface-waters3 In addition, MassDEP requires that proposed landfills install
double liners with leak detection and leachate collection devices and perform periodic water
monitoring. As part of the facility impact assessment,proponents should evaluate potential
groundwater and surface water impacts at landfills applying for expansions in either Level 1 or
Level 2 assessments. MassDEP considers an approved plan for the remediation of any
groundwater or surface water as a condition of the expansion permit approval. As part of the
requirements for site assignment and permitting of landfills, MassDEP requires that a
commitment be made to develop and implement a cleanup plan (approved by MassDEP) for any
surface water and groundwater contamination to comply with water quality standards in
applicable laws and regulations.
This Guidance Document for Solid Waste Facilities(hereafter referred to as the Guidance
Document) is intended to be used by anyone seeking site assignment under 310 CMR 16.00. It
summarizes the decision criteria to be used to determine whether and how a facility impact
assessment should be conducted as part of a solid waste management facility siting application.
The various components of the assessment process are defined and discussed as they pertain to
solid waste management facilities.
Unless MassDEP reaffirms or revises this guidance document within three years
of the date it is issued, this guidance document will "sunset" and will no longer be
applicable. Within two years of the date it is issued, MassDEP intends to initiate a
review of the guidance and seek input from its Solid Waste Advisory Committee to
determine whether the guidance should be maintained as is, revised, or eliminated.
1.1 Applicability and Scope
Definition
A solid waste management facility is defined as"an established site or works, and other
appurtenances thereto,which is, has been or will be used for the handling, storage,transfer,
processing, treatment or disposal of solid waste including all land, structures and improvements
which are directly related to solid waste activities". The Guidance Document addresses two
general categories of facilities: landfills that process and dispose of refuse on-site and handling
facilities that take in the waste and transfer it elsewhere. "Landfills" include municipal solid
waste landfills, C&D landfills, and residuals landfills(such as ash.) Examples ofhandling)l
facilities-include-transfer stations, C&D processing facilities and mixed-waste composting
facilities. Those facilities that are exempt from the site assignment process under 310 CMR
16.05 are also exempt from Facility input assessment requirements. Many types of facilities may
6 Potential emissions are defined as those that might be generated if a facility were to operate at a maximum rate
continuously.
2
include both on-site disposal and waste-processing components. For facilities taking in multiple
types of waste, the predominant waste generally dictates the level of assessment required by
MassDEP. However, proponents of facilities that handle multiple wastes and proponents of
multiple types of facilities at the same site should consult with MassDEP prior to proceeding
with the assessment process. if the type of solid waste facility proposed does not fall into one of
the categories identified by MassDEP, proponents should also consult with MassDEP prior to
proceeding with the assessment process.
1.2 Accounting for Emissions from Other Facilities
While the Site Assignment Regulations in the past have addressed the cumulative impact
of multiple solid waste disposal facilities greater than or equal to 300 tons per day in a
municipality, they have not considered the impacts from other solid and non-solid waste sources
in the area surrounding the proposed facility or expansion. The revised-regulations-addresslhes
(issue-of whether-the generation of,pollution_or contamination-from the=proposed facility ori
expansion,-taking-into'considerafion-the=existing-sources;will-have-a negative-impact on-publicz�
Ehealft The assessment of cumulative impact is still a young science and there are many areas of
uncertainty inherent in the process. MassDEP is committed to moving towards more
comprehensive methodologies as they are developed.
MassDEP's current approach for evaluating the impacts of proposed solid waste facilities
takes into consideration the emissions from existing sources using information on total emissions
of air toxics (i.e., total volatile organic compounds (VOCs)) from the MassDEP Stationary
Source Emissions and Inventory System (SSEIS) database. The SSEIS database contains
emissions information for VOCs emitted from both major and minor point sources. The SSEIS
database contains a list of registered facilities, along with emission information for "potential",
"actual" and"permitted"facility emissions. Potential emissions represent maximum emissions
that might be generated if a facility were to operate at a maximum rate continuously. Actual
emissions reflect emissions that have occurred based on the facility's actual operating schedule.
Permitted emissions include any MassDEP-imposed emissions restrictions for that facility. For
calculating total emissions, total potential emissions of VOCs in tons per year (TPY) from all
sources registered in the MassDEP SSEIS database within one mile of the perimeter of the
proposed facility or expansion, unless determined otherwise by MassDEP, should be compiled
by the project proponent. information on total potential emissions is evaluated together with
other quantitative and/or qualitative information about the facility, using MassDEP's risk
management considerations and criteria as discussed elsewhere in this guidance, to make a
decision about site suitability.
MassDEP chose to use total VOC emissions data as described above for this protocol for
the following reasons: VOCs are an indicator of industrial activity as well as an indicator of
emissions in the area that could potentially be associated with adverse impacts related to specific
landfill gases. SSEIS information represents the best database for this information, given that
Massachusetts tracks emissions of VOCs as precursors to ozone due to Massachusetts' non-
attainment status for ozone. The VOC emissions information in this database is believed to be
the most representative indicator of total point source emissions currently available. Thell
assumption-inherent-in-the-use-of this-indicator-is that-the--higher-the-emissions-are-fro_m_adiacent3
air point sources;the-higheris-the-potential=rrisk-inthe—community-affected-by=these-facilities.
3
On a case-by-case basis, prior to requiring additional mitigation or issuing a negative site
suitability report, MassDEP may allow multi-facility source modeling and quantitative risk
assessment of adjacent sources to be used to more fully evaluate overall impacts.
SECTION 2: Facility Assessment Screening Protocol
The level of assessment that MassDEP requires for a proposed siting application is
determined by a number of parameters related to the proposed facility and its surroundings.
Figure 1 outlines the systematic protocol for determining the level of assessment an applicant
should use to determine whether a siting request may be approved. The protocol involves two
levels of assessment, including a Level 1 - Qualitative Impact Assessment and a Level 2—
Quantitative Impact Assessment.
MassDEP believes that emissions from large landfills may produce ambient air levels of
these pollutants of potential concern to the general public. For this reason, applications to site
larger landfills or expansions should include an assessment of potential air impacts in a
quantitative risk assessment. MassDEP believes that gaseous emissions from very small and
well-controlled landfills, which meet all applicable facility and siting criteria in the solid waste
regulations (Table 1), are likely to be low. Thus, a qualitative assessment of emissions from very
small landfills is deemed by MassDEP to be a sufficient basis for assessing their potential
impacts.
Proposed landfill expansions and new landfills that meet the criteria summarized in
Figure I should undergo quantitative impact assessments. Landfill expansions differ from new
landfills in that they may offer the opportunity to obtain site-specific information on ambient air
emissions via on-site monitoring of the existing landfill that is seeking to expand. Such
information may serve as a supplement to the LandGem model (USEPA, 1998) suite of COC and
their associated emission factors. Proponents of new landfills may also use data from a similar
landfill subject to prior approval by MassDEP. For expansion requests,the quantitative risk
assessment should address the full site assigned project. For new facility requests, the entire
facility should be addressed. When monitoring data are available as a basis for determining
exposure point concentrations, a conservative approach should be used to conduct the risk
assessment. The list of AP-42 COC should always be included in the assessment although this
list may be supplemented with additional chemicals as indicated by monitoring results. In
addition, the higher of the monitored concentration or concentration derived from an AP-42
emission factor should be used to conduct the quantitative assessment. Concentrations of VOCs
emitted from decaying waste fall along a lognormal gas production curve, and vary significantly
over the decaying process, influenced by the age of the waste and the particular set of
environmental conditions characterizing the landfill. Since it is very difficult to determine at
what point along the gas production curve a set of monitoring results may have been derived,
MassDEP's policy regarding this issue is to use the higher concentration as an estimate of a
worst-case concentration. Waste-handling facilities differ from landfills in that the waste is
transitory and therefore is present at the facility for only a short period of time. Gaseous
'The facility proponent should consult with MassDEP prior to initiating such work. Such an analysis could be part
of the initial proposal,prior to a requirement for mitigation,prior to the issuance of a negative site suitability report,
or as part of a request for reconsideration.
4
emissions are much lower than they are at landfills where refuse is buried on-site and
decomposes over a period of years. As a result,particulate emissions associated with the transfer
and transport of refuse as well as emissions from on-site diesel equipment is of the most concern
at these facilities. For this reason, MassDEP encourages implementation of BMPs and the use of
low emission equipment on-site at these facilities to address fugitive dust and diesel emissions.
MassDEP believes that use of BMPs will greatly reduce emissions of concern at these facilities.
Table 1. Summary of Revised Siting
Requirements/Criteria
310 CMR 16.40
Applicable and relevant state and federal standards, criteria, guidelines or
allowable limits in written health policies 2 n
[3 10 CMR 16.40(1)2.1
I
Groundwater Protection restrictions (Zone 11's IWPA's, etc...)
X310 CMR 40.40(3)(a), (c), (d)l 1�1�) !�
Setbacks from residences, schools,preschools, agricultural land, etc...
(310 CMR 16.40(3)(a)(c)(d)1
I I
Assessment of traffic congestion, safety, vehicle emissions
[3 10 CMR 16.40(4)(6)1
I I
Wildlife Habitat, ACEC, Wetlands Protection Act
[3 10 CMR 16.40(4)(c)(d)1
I
Air Quality Impacts: [3 10 CMR 16.40(4)(c)(e)l
I I
Nuisance Conditions: [3 10 CMR 16.40(4)(c)(f)l
5
Figure 1. MassDEP Protocol for Selecting Level of Assessment
Impact Evaluation Flowchart
Assumes all other requirements are met
(310 CMR 16.00)
Level I
Qualitative Impact Evaluation
Is the facility a new landfill'or „e.
landfill expansion>150 TPD 9
Ino
A-Enhanced BMPs for dust 8 odor,and
planned use of low emission diesel equipment
for all equipment on saep
Yes to all: No
all
A,a and _ B-We capacity of the proposal is less than 150 a A„B and
(If appllci a C tons/day? (R appbcable)C
C-tor landfills e150 TPD) Assessment of
potential surface and groundwater wntammahon
and complete deanup plan If needed?
No to A,Bor
(If applicable)C
.r
Are there more
Positive Report a no than
whvo mitigation ments 4 Evaluate ation require50 TPV VOC
from sources
within one mile?
yes
Negative
Report'
.r
Level 2 Quantitative Evaluation with
Quantitative I mpact Evaluation DEP Review Considering the
Following:
•Emissions of Total VOCs from
facilities within one mile,if any,
Evaluates •Facility-specific cancer and
nommncer nsks,
•The extent to which Enhanced
i are proposed;
•Potential surface and groundwater
contamination and complete cleanup
plan,if needed
Positive Report
(.MO mitigation requirements
"'Landfill”acludes MSW,Residuals,and C&D
' Eraluagon mcludes factors listed m the Executive Swmnary,pg.vui
'Evaluation includes factors listed in the Executive Summary,pat,xi-xn.
' Request for reconsideration of negative finding on site su ibibty allowed(3 10 CMR 16 14)
6
JT-he_database-on-emissions=from waste.facilities_other than•landflls-is-limited: Detailed
information on the types and concentrations of compounds emitted from waste-handling
facilities has not been collected and compiled as it has been for landfills. The level of
uncertainty introduced by these data limitations and the modeling and assessment processes
would likely render a quantitative impact assessment of these facilities impractical given the
current level of knowledge. As additional emissions data are collected on these facilities and
modeling and assessment methodologies improve,MassDEP may determine in the future that
quantitative assessment should be conducted for these facilities as well.
In addition to qualitative and quantitative assessments for determining site suitability, a
facility may be subject to periodic or ongoing monitoring requirements on a case-by-case basis.
The details of these requirements, if any, will be specified in the facility permit. Other
requirements of the solid waste regulations as well as of the USEPA federal Clean Air Act (e.g.,
the assessment of criteria pollutant impacts from the facility) are not addressed in the Guidance.
However, an assessment of facility emissions relative to National Ambient Air Quality Standards
(NAAQS) will be done elsewhere in the siting and permitting processes(see Table 1).
To summarize;a_qualita`tive-impactassessmenfis'req-ired-for new`waste-processing
,facilities or-expansions and smaller landfills or—eexpansionsin-less than-150 tons p&O
cday of refuses Waste handling Facilities include-transfer_statibn and C&D processing facilities.
Small landfills include municipal solid waste, C&D, and residuals landfills or expansions that
take in less than 150 tons per day of refuse. i§ifing_requests-for-these facilities will-be_
evaluated
6a'sed ontheacceptability-if p'roposed-BMP's-(see TiblEs—land 3);proposed-refuse-capacity
VOCemission`s-from-other-major_an--d_minor-point-sources-within-onemile-ofthe-facility. Please
note that MassDEP is issuing guidance for addressing hydrogen sulfide emissions from landfills,
especially from landfills that accept C&D waste, fines, or residuals. While MassDEP does not
currently require a quantitative risk assessment for small landfills, MassDEP may require
additional assessment and/or controls at these landfills where there is a potential for hydrogen
sulfide emissions. Quantitative Risk Assessments should be conducted for large landfills or
expansions. In this context, a large"landfill" is defined as a municipal solid waste, C&D, or
residuals landfill that takes in more than 150 tons per day of waste. Additional qualitative
facility-specific or site-related information may be considered on a case-specific basis to make a
final determination on site suitability.
2.1 Best Management Practices
-MassDEP_-expects-that=facilities-will implement Best ManagementTractices=(BMPsyin7
o
,e-design—and operation-of a-proposed-new-solid-waste-management-facility-or-expansion-tom
�reduee_ormitigate-potential impacts-forspecific areas-ot-concein:7 these areas of concern �
include: groundwater protection; surface water protection; air quality-protection-(noises
`dust/particulates,hydrogen-sulfide and-other emissions,and-odor-);fire protection; and
insect/rodent control. In the context of this guidance, a-BMP-is_a.preventive-technologyor
mere-thatis implemented=to_limit_potential-impacts by-facilities-and-to address_public_health,
and nuisance—concerns?A facility applicant should provide a listing and discussion of proposed
BMPs that address these areas of concern.
1f
7
The extent to which an applicant proposes BMPs and the BMPs' purported effectiveness' in
reducing or mitigating potential impacts will be important factors in the MassDEP decision-
making process regarding the adequacy of a facility's impact assessment report. For example,
particulate emissions from solid waste management facilities are difficult to estimate using
existing information and methods. Yet they are one of the primary pollutants of concern for
many facilities, especially those conducting a Level 1-qualitative impact assessment. The
implementation of BMPs and the use of low-emission equipment on site can effectively control
emissions of particulates from facilities,thus reducing the need for a quantitative assessment of
impacts, especially for facilities initially conducting Level 1 assessments. Facility proponents
should implement appropriate BMPs to minimize fugitive dust emissions, hydrogen sulfide
emissions, odors and diesel emissions to meet the Air Quality Regulation.
Fael Il ty-proponents-should;identify-BMPs_that-are_applicable_to the-operations-ofthe_facility-and,
that-will--minimize facilityimpacts to`the maximum-practicable eztenC Tables 2 and 3 contain a
list of MassDEP-approved BMPs. However,these BMPs are given only as suggestions for
applicants' consideration. Other methods not listed will be considered by MassDEP provided
that they adequately control the environmental issue of concern. Specific BMP requirements
will be established in the applicant's facility permit. MassDEP may require reporting on the
effective implementation of BMPs as a permit condition.
8 To evaluate the effectiveness of BMPs,MassDEP may require a facility,as part of it s permit, conduct ambient air monitoring
for particulates and other substances of concern during facility operation.
'See for example 310 CMR 7.01:General Regulation to Prevent Air Pollution:
(1) No person owning,leasing,or controlling the operation of any air contamination source shall willfully,
negligently,or through failure to provide necessary equipment or to take necessary precautions,permit any
emission from said air contamination source or sources of such quantities of air contaminants which will cause,by
themselves or in conjunction with other air contaminants,a condition of air pollution
8
Table 2. MassDEP Approved BMPs for Landfills
(MSW Landfills,Ash Landfills,and C&D Landfills)
Areas of Concern for Potential Risk
a0A e°j�oo oag�ti
Quo`
MADEP Approved BMPs C�� 5J P` -SP `cye
IActive Face Of Landfill:
Using alternative daily cover materials that reduce
dust,odors,and vermin to a greater degree than
standard soil type materials(these would include X X X
manufactured products such as Posi-Shell, polymer
modified foams,tarpaulins, etc.)
Maintain as small an active face as possible x X X
When using C&D fines or residuals as cover or
grading and shaping material, mix with soil X
When using C&D fines or residuals as cover or
grading and shaping material, ensure that the X
processing facility has a program in place to
separate gypsum materials prior to processing
Diesel Emission Controls:
Il Replacing old diesel equipment with new, lower X
emission diesel equipment
Using electrically powered motors X
' Retrofitting ninety percent(90%)of all 1997 and
older diesel engines used wholly or partially on site X
for more than 10 hours per week
Replacing diesel powered equipment with
compressed natural gas, liquid natural gas or liquid X
petroleum gas equipment
For off-road engines, using only cleaner on-road X
diesel fuel
For on-road engines, using only cleaner ultra low X
sulfur diesel fuel
fMinimizing idling of equipment by turning off engines
i
when not in use(includes employee training and X
signaqe)
]Access Roads and Parking Areas:
�! Ensuring paved surfaces X X X
j Street sweeping as necessary X X X
Using dust suppressants on unpaved surfaces X
where necessary(CaCl2,water)
Interim Landfill Gas Collection and Control in Active
Cell of Landfill:
Using temporary flares or other gas collection X X
systems
9
(continued)
Table 2. MassDEP Approved BMPs for Landfills
(MSW Landfills,Ash Landfills,and C&D Landfills)
Areas of Concern for Potential Risk
� o a
ocao�a`oJ�\`� Q`oag4ti.c J�oaeo
MADEP Approved BMPs Geo yJ� P` Q��� Nrye
Water Quality Controls:
Collecting water runoff from paved areas x x
Using oil/water separators x x
Using above ground leachate storage tanks X x
Ensuring available potable water source for
immediate use in case of fire or other emergency at x
the facility
Storm Water/Erosion Controls:
Implementing applicable storm water regulations
and guidance by the Bureau of Resource Protection x x
Using vegetation,wood chips, erosion control mats
or other means to minimize erosion from the site x X
Wheel washing in an area using secondary x x x
containment measures
1Other:
Providing documentation that facility owners/operators
have received formal training and have been certified
as a landfill operator(certification can be received x X x x x
through national professorial programs)
Establishinq an odor complaint response plan
* Retrofit devices should include only California Air Resources Board(CAR B),US Environmental Protection Agency(EPA),
or New England States for Coordinated Air Use Management(NESCAUM)certified retrofit devices.
10
Table 3. MassDEP Approved BMPs for Waste Handling Facilities
(Transfer Station;C&D Processing Facilities,and Other Waste Handling.Facilities) f
Areas of Concern for Potential Risk j
a`a� aSec " .0 aeca
MADEP Approved BMPs
G�oJ yJra Pit �``Q `cyeo
For Any Waste Handling Facilitv:
Diesel Emission Controls:
Replacing old diesel equipment with new, lower x
emission diesel equipment
f Using electrically powered motors X
Retrofitting ninety percent(90%)of all 1997 and
older diesel engines used wholly or partially on site X
r more than 10 hours per week
Replacing diesel powered equipment with
compressed natural gas, liquid natural gas or liquid X
petroleum gas equipment
1 For off-road engines, using only cleaner on-road x
1 diesel fuel
'For on-road engines, using only cleaner ultra low x
sulfur diesel fuel
(Minimizing idling of equipment by turning off engines
f when not in use(includes employee training and X
signage)
f Access Road and Parking Areas
Ensuring paved surfaces for access roads, X X X
handling areas
,1/' Street Sweeping as necessary X x X
Conveyor Systems:
Using completely enclosed conveyor belts for
materials that may blow around or result in dust X
nuisances
Stockpile or Storage Areas:
Storing materials in a building or 3-sided covered x x X X
storage bunkers
Street sweeping as necessary X X x
Ensuring paved surfaces X X X
Ill Using-water misting systems X X
Water Quality Controls:
I� Ensuring available potable water source for
immediate use in case of fire or other emergency X
at the facility
Using oil/water separators x
Using secondary containment around storage x x
areas and truck washing areas
11
(continued)
Table 3. MassDEP Approved BMPs for Waste Handling Facilities
ffransfer_S_tations,C&D Processing Facilities,and Other Waste Handling Facilities)
Areas of Concern for Potential Risk
a`e� �a�yc a`� e`.`0 oaec�
MADEP Approved BMPs c oe �q roti JQ`
J a �� Q c
lFor Any Waste Handling Facility.,
Storm Water/Erosion Controls:
Implementing applicable stormwater regulations
and guidance by the Bureau of Resource X X
Protection
Using vegetation,wood chips, erosion control mats
or other means to minimize erosion from the site X X
uWheel washing in an area using secondary X X X
containment measures
For Small Compactor Unit-Type Transfer Stations:
Using a 3-sided shed roof over the hopper into
which waste is dumped to control litter and keep X X
rain from entering waste
For Large Transfer Stations, C&D Processing Faciliti-s, ani'Other Waste Handl ng Facilities:
General BMPs
Fully enclosed building and waste handling areas X X X X X
Using automatic doors and secondary enclosures
(hanging plastic"curtains")at doors X
Using a negative air pressure system that includes X
fans and filters
i Requiring that all waste deliveries entering or X X X X
i exiting the facility be covered
1 Using sealed containers for delivery of potential
odiferous materials(e.g.,food waste, processed X X
I organic wastes,sludges)
Sealing and screening opening which may allow X
insects and rodents to enter the building
Using a water misting system within the waste X x
unloading areas
Noise Controls:
Noise survey before and after construction X
Installing noise attenuation plantings or structures
(includes installing screening/barriers such as
trees, berms, or walls around the facility to block
and absorb facility noise. The installation of X
vegetative barriers such as trees can also help
absorb and disperse potential odors from the
facility.)
Using wing walls and concrete structures, rather
than metal structures,to help block noise X
12
(continued)
Table 3. MassDEP Approved BMPs for Waste Handling Facilities
(Transfer_Stations;C&D Processing Facilities,and Other Waste Handling Facilities)
Areas of Concern for Potential Risk
wee ties c1 R, mew
MADEP Approved BMPs oa.a °�a °a;`
v a
For Larqe Transfer Stations, C&D Processinq Faciliti is,and Other Waste Handl na Facilities:
!Q Noise Controls:
(l Using controls on exhaust equipment X
Orienting transfer building openings away from X
receptors
[� Using enclosures for loud equipment X
11 Air Pollution:
Using enhanced air pollution controls when dust
and odors cannot be adequately contained through X
other measures as determined by DEP
Using a biofilter X
* Retrofit devices should include only California Air Resources Board(CARB),US Environmental Protection Agency(EPA),
or New England States for Coordinated Air Use Management(NESCAUM)certified retrofit devices.
2.2 Assessment Appropriate To Facility Type
Facilities fulfilling the criteria for a Level 1 assessment should conduct a qualitative
impact assessment. Facilities fulfilling the criteria for a Level 2 assessment should conduct a
quantitative impact assessment. All facilities must initially meet all facility and siting criteria in
accordance with the Site Assignment Regulations(310 CMR 16.00) (see Table 1) before
conducting an impact assessment. Facilities requiring Level 1 and Level 2 assessments are
discussed in more detail below.
2.2.1 Waste-Handling Facilities of Any Size
All facilities that handle/process waste and dispose of it off-site are encouraged to
implement BMPs as discussed above prior to conducting an impact assessment. If a facility10
has in place both acceptable BMPs for dust and odors and a plan to use low-emission diesel
equipment on site, and the capacity of the proposed facility or expansion is less than 150 tons per
day, MassDEP would likely issue a positive site suitability report without additional
investigation and mitigation.
If either of the conditions described above are not met (i.e., if_t�lity-has a pip ed�
capacity-greater than 150 tons per-day-or does notcommit_011fe-use ofBMPs);MassDEP wills
evaluate`the proposal and-make a final-site suitabiility=determination as-specified_in-tlie-�
`Qualitative Impact Assessment Section 3.�7
10 Provided that the facility will meet all applicable regulatory requirements.
13
If the facility does not propose use of BMPs including the use of low-emission diesel
equipment on site and the capacity of the proposed facility or expansion is greater than 150 tons
per day, the applicant should compile information from the SSEIS database on emissions from
VOC sources within one mile of the facility perimeter as an indicator of industrial activity in the
area. For proposed expansions, VOC totals should include emissions from the existing solid
waste facilities registered in SSEIS within one mile of the facility being expanded. If total
potential VOC emissions within a one-mile radius exceed 50 tons per year, MassDEP will likely
issue a negative site suitability report. If total potential VOC emissions do not exceed 50 tons
per year, MassDEP will base its site suitability decision on other facility-specific and site-related
factors as specified in the Qualitative Impact Assessment section (Section 3 below).
2.2.2 Small Landfills That Take in Less Than or Equal to 150 Tons Per Day
Small landfills or expansions proposing to take in less than or equal to 150 tons per day
do not need to conduct a Level 2 quantitative impact assessment. Such facilities will be
evaluated largely in terms of the extent to which BMPs are proposed. If a proposed small
landfill (that will meet all applicable regulatory requirements) commits to use BMPs for dust and
odors as well as low-emission diesel equipment for on-site equipment to be used at the new
facility or expansion and this proposal is acceptable to MassDEP, MassDEP would grant that
facility a positive site suitability report.
If BMPs and the use of low-emission diesel equipment are not proposed for the facility,
MassDEP will base its site suitability decisions on those factors specified in the Qualitative
Impact Assessment section (Section 3).
2.2.3 New Landfills and Expansions That Take in Greater Than 150 Tons Per Day
All applications for landfills that take in greater than 150 tons per day of refuse should
conduct a Level 2 quantitative impact assessment as part of the application process. The results
of the quantitative impact assessment, including estimated facility-specific cancer and non-
cancer risks from air emissions, will be considered in the context of total SSEIS VOC emissions
from all point sources located within one mile of the perimeter of the proposed facility, unless
determined otherwise by MassDEP. (VOC totals should include emissions from the existing
solid waste facilities registered in SSEIS within one mile of the landfill being expanded.)
MassDEP guidance for conducting a quantitative impact assessment is contained in Section 4 of
this document.
MassDEP will evaluate this information in accordance with its quantitative risk
management criteria specified in Section 4.6 of this document. Specifically, MassDEP will
consider the totality of the information, including the acceptability of any proposed BMPs and
SSEIS VOC emissions information.
14
SECTION 3: Qualitative Impact Assessment
MassDEP uses information on the type and capacity of the proposed facility,the extent of
proposed use of BMPs, and VOC emissions information from facilities within one mile of the
proposed facility to categorize proposals regarding level of assessment.
As the approach specified in Figure 1 indicates, for facilities requiring a Level 1
assessment, there are scenarios for which a site suitability determination can be clearly made
based on this information alone. For example, if a waste-handling facility has a capacity less
than 150 tons per day and proposes BMPs that are acceptable to MassDEP (i.e., ones that will
effectively control emissions and resulting impacts) MassDEP will likely issue a positive site
suitability report for the facility. If a waste-handling facility has a capacity greater than 150 tons
per day, does not propose to use BMPs and is in an area where VOC emissions from adjacent
facilities are greater than 50 tons per year, MassDEP may issue a negative site suitability report.
This determination is based on the premise that additional emissions from a large facility in an
area that already has significant emission sources could present an unacceptable additional public
health burden to the surrounding community (however,the facility proponent may request a
reconsideration of the negative finding).
There are a number of assessment scenarios under a Level 1 qualitative impact
assessment that are not as clear-cut with regard to making a site suitability decision. In these
cases, MassDEP evaluates the totality of the above information in the context of additional
facility-specific and site-related factors. Tables 4 and 5 summarize the factors MassDEP will
consider in qualitative impact assessments for making site suitability decisions. The factors may
include but are not limited to:
•the extent to which BMPs are proposed;
•the type of land uses impacted by the facility;
•emissions of volatile organic compounds from other sources within the area; and
•particulate matter sources, such as solid waste management facilities,junk yards, auto
salvage shops, bus and truck depots, etc. within the area.
For landfills with a capacity of less than 150 tons per day,the facility proponent should
evaluate groundwater and surface water quality relative to water quality standards in applicable
laws and regulations. If indicated by the assessment, the proponent must commit to develop and
implement a cleanup plan to achieve compliance with these standards. See Appendix B—
Guidance for the Assessment of Groundwater and Surface Water for Solid Waste Facility Site
Assignment and Permitting in Support of 310 CMR 16.00 & 19.000.
15
Table 4. Level 1 Qualitative Impact Assessment -Waste Handling Facilities
For the following facilities (new or expansion):
• Rran'sfer"stations
• C&D Processing facilities
Size Has the applicant What are emissions from MassDEP's likely
proposed BMPs? adjacent sources? response will be:
Yes Not Required Positive Report
< 150 tons/day No < 50 TPY VOCs Evaluate: +/-Report
No > 50 TPY VOCs Evaluate: +/- Report
Yes < 50 TPY VOCs Evaluate: +/-Report
=>LL150=tons/day Yes > 50 TPY VOCs Evaluate: +/- Report
No < 50 TPY VOCs Evaluate+/- Report
No > 50 TPY VOCs Negative Report
Table 5. Level 1 Qualitative Impact Assessment - Small Landfills
For the followina facilities (new or expansion) <150 TPD:
• MSW landfills
• Residuals (e.g. ash, special wastes) landfills
• C&D landfills
Has the Do adjacent Do other solid Results of Water MassDEP's likely
applicant sources need to waste facilities Resources response will be:
proposed be considered? need to be Assessment'
BMPs? considered?
Yes No,Not Consideration Adequate Positive Report
Necessary Not Necessary
Inadequate Negative Report
Yes, Amount of Yes, Amount of Adequate Evaluate: +/- Report
No VOCs Emitted VOCs Emitted
Inadequate Negative Report
'Assessment includes the water assessment and any applicable cleanup plan.
16
SECTION 4: Quantitative Impact Assessment
The Level 2 quantitative impact assessment protocol described in this document is
designed to produce quantitative estimates of risk for a proposed landfill orzexpansionor both
non-cancer and cancer effects. The methodology outlined below follows the risk assessment
procedures of the National Academy of Science and builds upon existing risk assessment
methods that MassDEP has established for assessment of contaminated sites as governed by the
Massachusetts Contingency Plan (MCP), 310 CMR 40.0000.
The risk assessment process consists of five steps. These include Hazard Identification,
Dose-Response Assessment, Exposure Assessment, Risk Characterization and Uncertainty
Analysis.
Hazard Identification determines whether a substance causes adverse effects and
identifies those effects. A list of chemicals that are known to be or proposed to be emitted from
a facility, along with their associated health effects, is compiled. Chemicals that are known or
suspected to pose adverse health effects are identified as Contaminants of Concern (COC).
The Dose-Response Assessment describes the relationship between the level of exposure
and the likelihood and severity of the adverse effects of the COC. Available toxicity values from
USEPA or other sources are identified which quantify the concentrations or doses of chemicals
associated with particular non-cancer or cancer endpoints.
The Exposure Assessment identifies potential routes of exposure,the populations
exposed,the frequency, duration and extent of exposure to the COC, and quantitative estimates
of exposure.
The Risk Characterization combines information from the first three steps to estimate
the magnitude of the non-cancer and cancer health risks associated with exposure to the
chemicals. The results of the quantitative risk assessment are compared to the risk management
criteria established by MassDEP.
The Uncertainty Analysis identifies the uncertainty and variability inherent in the risk
assessment due to the limitations in data quality and quantity and discusses the variability in the
range of responses associated with the human population.
It is important to remember that risk estimates generated in the risk assessment are not
precise measures of absolute risks. Rather, risk assessment is a tool, a method of providing
valuable information regarding potential risks to public health. The risk assessment process
outlined above is discussed in more detail below.
4.1 Hazard Identification—Contaminants of Concern (COC)
In the Hazard Identification step of a risk assessment, a preliminary list of chemicals that
are likely to be emitted from the proposed facility under study is compiled. Information obtained
from the solid waste literature addressing the type of facility under study as well as facility-
specific air monitoring studies or modeling exercises are used to develop a list of COC.
17
The assessment will be based on the type of wastes that the facility will handle. The
hazards associated with each chemical that has been selected as a COC should be described as
well in the form of toxicity profiles. This information is used to identify the nature of adverse
health effects associated with exposure to particular contaminants (Section 4.1.4) and whether
the adverse health effect is likely to occur in humans.
MassDEP provides a default list of COC in this Guidance Document for municipal solid
waste landfills, for which the quantitative risk assessment should include, at a minimum,the
subset of AP-42 chemicals, as identified in Table 6 of this document. If the municipal solid waste
landfill proposes to take in special wastes in an amount greater than fifty percent of the total
yearly waste tonnage taken in by that facility, then MassDEP should be contacted to discuss
inclusion of additional chemicals.
For ash and C&D landfills a quantitative risk assessment of potential air emissions is not
needed. At ash landfills, MassDEP has determined that fugitive particulates associated with
disposal activities are the emissions of most concern at these facilities and can be controlled by
implementing BMPs pertaining to that type of facility. The results of an air monitoring study
showed that entrainment to air of fugitive particles from ash is negligible if that ash is maintained
at a high moisture content and if BMPs for dust control are implemented and maintained during
generation and disposal activities of ash'1. For C&D landfills, fugitive particulates can be
similarly addressed by implementing and maintaining BMPs for dust control. In addition to
particulate emissions, landfills that accept C&D waste, fines, or residuals may need to address
hydrogen sulfide emissions.
Identification of COC for the various types of solid waste management facilities is
discussed in the following sections.
"Quantitative Impact Assessment(Risk Assessment)Supplemental Information Request"for the Ward Hill Neck
Landfill in Haverhill,Camp,Dresser&McKee,October 2002.
18
Table 6. List of Landfill AP-42 Chemicals
1,1,1-Trichloroethane(HAP) Carbonyl Sulfide(HAPNOC) Flumotrichloromethane(VOC)
1,1,2,2-Tetrachloroethane Chlorobenzene(HAPNOC) Hexane(HAPNOC)
(HAP/VOC)
1,1,2-Trichloroethane(HAPNOC) Chlorodifluoromethane(VOC) Hydrogen Sulfide
1,1-Dichloroethane(HAPNOC) Chloroethane(HAPNOC) Mercury (HAP)
1,1-Dichloroethene(HAPNOC) Chloroform(HAP/VOC) Methyl Ethyl Ketone(HAPNOC)
1,2-Dichloroethane(HAP/VOC) Chloromethane(HAPNOC) Methyl IsobutyI Ketone(HAPNOC)
1,2-Dichloropropane(HAPNOC) Dichlorobenzene(VOC/HAP for Methyl Mercaptan(VOC)
1,4-isomer)
2-Propanol(VOC) Dichlorodifluoromethane(VOC) Pentane(VOC)
Acetone Dichlorofluoromethane(VOC) Perchloroethylene(HAPNOC)
Acrylonitrile(HAPNOC) Dichloromethane(HAP) Propane(VOC)
Benzene(HAP/VOC) Dimethyl Sulfide(VOC) Toluene(HAPNOC)
Bromodichloromethane(VOC) Ethane Trichloroethene(HAP/VOC)
Butane(VOC) Ethanol(VOC) t-1,2-Dichloroethene
Carbon Disulfide(HAP/VOC) Ethylbenzene(HAPNOC) Vinyl chloride(HAP/VOC)
+Carbon Monoxide Ethyl Mercaptan(VOC) Xylene(HAP/VOC)
Carbon Tetrachloride(HAPNOC) Ethylene Dibromide(HAPNOC)
+This compound should be evaluated under 310 CMR 16.00.
19
4.1.1 Proposed Landfills
A site assignment request for a proposed landfill (greater than 150 tons per day) can
represent either a totally new siting request or a request for an expansion to an existing facility.
Both types of requests require that a quantitative impact assessment be conducted as part of the
application for a site suitability determination or permit. A proposed expansion may have the
advantage of use of emissions monitoring at the existing part of the facility to help identify
potential COC in the proposed expansion, an option for which MassDEP approval is needed.
However, given that the types of chemicals emitted from a landfill may differ depending on the
stage of the decomposition process, emissions data from an existing landfill should not form the
sole basis for identifying COC. While the results of such monitoring could be useful in terms of
identifying compounds that may be unique to that landfill, it should not be assumed that these
results are completely representative of the future emissions from the proposed expansion. An
existing landfill is further along in the decomposition process than is the expansion and the
landfill gas constituents released at that time are a function of the type of refuse that it has
received over time as well as the rate and stage of biodegradation. The proposed expansion area
may possibly receive a different mix of refuse, either by design or as a result of changes in the
consumer waste stream over time. However, given the fact that an expansion may receive a
waste stream somewhat similar to the existing landfill and that it shares the same geological and
climatological characteristics, it is likely that at least some of the landfill gas constituents may be
the same.
As discussed above, the risk assessment for municipal solid waste landfills should, at a
minimum, include the list of AP-42 COC provided in this document pertinent to that type of
landfill. In addition, a facility that takes in a special waste or wastes in an amount greater than
fifty percent of the total annual waste tonnage taken in by that facility, should consider any
additional potential emissions associated with the special waste. In such cases,the proponent
should,with MassDEP approval, identify any additional COC beyond the MassDEP list. Prior
MassDEP approval is also needed for all proposed protocols for identifying COC at non-
municipal solid waste landfills.
Emissions from landfills to the ambient air may occur as both area sources and point
sources. Landfill gas generated over the surface of the entire landfill as a result of
decomposition is considered an area source. Point sources include landfill flares or stacks in
which collected landfill gas is directly emitted or undergoes combustion. An uncontrolled
landfill is only characterized by area sources. The following sections summarize the various
types of landfill emissions and provide guidance on the selection of COC for both area and point
emission sources.
4.1.1.1 Types of Landfills
As discussed in Section 2.2.3, all large landfills and expansions with a capacity to receive
greater than 150 tons per day of refuse should conduct a quantitative impact assessment as part
of the application process for a site suitability request or a permit to construct if expanding into a
previously site assigned parcel of land for which a quantitative impact assessment was not done.
The types of landfills covered by this assessment include municipal solid waste (MSW) facilities,
20
C&D facilities, and facilities that take in special wastes in an amount exceeding fifty percent of
the total waste taken in by that facility.
Landfill gas emissions from on-site disposal of these wastes will occur for many years
after closure of the landfill. The USEPA has developed a model that allows for the temporal
characterization of landfill gas emissions from MSW facilities. MassDEP's recommended
approach for modeling and assessing landfill gas emissions is addressed below.
Non-municipal waste facilities are less general and accept a specific type of waste. For
example, residuals facilities may accept municipal solid waste incinerator ash and C&D landfills
may accept construction and demolition waste. MassDEP believes that one of the emissions of
concern from non-MSW facilities is fugitive particulates generated during transport and
processing of these wastes. The characterization of fugitive particulate emissions from landfills
is limited, although total emission generation and modeling methods do exist. MassDEP will
entertain proposals on a case-by-case basis for chemically characterizing, modeling and
assessing fugitive particulate emissions and potential health risks from landfills. Additional
discussion on the recommended protocol for these proposals is addressed below. In addition to
particulate emissions, landfills that accept C&D waste, fines,or residuals may need to address
hydrogen sulfide emissions.
4.1.1.1.1 COC in Landfill Gas from Municipal Solid Waste Facilities
Landfill Area Sources
Landfill Gas Constituents
Landfill gas is generated as a by-product of the anaerobic biodegradation of refuse in
landfills. The predominant landfill gases include methane and carbon dioxide, with much
smaller amounts of non-methane organic compounds (NMOC). As methane and carbon dioxide
are released from decaying refuse,these gases pass through the landfill, sweeping NMOC and
other air pollutants present in the refuse to the surface.
NMOC include volatile organic compounds and other air pollutants. USEPA defines air
pollutants as compounds found in landfill gas or emitted with landfill gas, some of which are
listed as air pollutants under Section 112 of the Clean Air Act.
Reduced sulfur compounds represent the sulfur-containing fraction of landfill gas.
Although these compounds comprise a relatively small fraction of landfill gas, because of their
characteristic odors, they are often the most evident components. Reduced sulfur compounds are
a common reason for odor complaints from the public.
USEPA has concluded that a number of compounds found in landfill gas cause, or
contribute significantly,to air pollution that may reasonably be anticipated to endanger public
health or welfare. Some NMOCs are known to have carcinogenic or non-carcinogenic health
effects. Methane is of concern primarily because of its explosive potential and as a greenhouse
gas that contributes to global warming. Public welfare concerns include the odor nuisance from
certain landfill gas constituents such as sulfur compounds, and the concern for migration of
21
methane,producing the potential for explosions or fire. It is assumed that landfill gas can be
emitted anywhere in the landfill and, as such, is considered to be an area source (USEPA, 1998).
AP-42 Chemicals
The list of chemicals commonly referred to as the "AP-42 chemicals" was developed by
USEPA. This list identifies a number of air pollutants expected to be emitted from landfills
based on test data USEPA compiled in a document entitled Compilation of Air Pollutant
Emission Factors, AP-42(USEPA, 1997a). This information was collected by USEPA in an
extensive search of the literature, electronic databases, and USEPA resources, including
municipal solid waste landfill testing reports. The data were then reviewed and reduced to
produce the AP-42 list, a list of 47 chemicals found to be emitted from landfills. The list of AP-
42 compounds is in Table 6 of this document. USEPA incorporated this same list of AP-42
chemicals into the Landfill Gas Emissions Model (LandGEM). LandGEM models the emission
rates of the 47 chemicals of concern with respect to the landfill site and/or from controlled and
uncontrolled vents. MassDEP has reviewed the list of AP-42 chemicals and has identified
sufficient toxicity information to evaluate quantitatively all but a handful of the chemicals(Table
7). One criteria pollutant on this list, carbon monoxide, is evaluated elsewhere under 310 CMR
16.00 and is not addressed in the risk assessment. As additional toxicity data for the chemicals
without currently published values become available,they should also be included in quantitative
risk assessments.
The AP-42 chemicals represent a good starting point for predicting and evaluating
potential emissions from a facility that is still in the design phase. MassDEP considers the AP-
42 chemicals as the most comprehensive database on landfill gas emissions currently available in
the landfill literature. Therefore, all quantitative risk assessments done in support of a landfill
site assignment request should, at a minimum, consider the list of AP-42 chemicals as COC. If a
proponent prefers to use facility-specific monitoring data to characterize emissions at the facility
being evaluated, the proponent may do so. However, this information should only be used to
supplement the list of AP-42, not delete from it.
In the case of landfills that also accept special waste(i.e., a waste for which a special
waste permit is needed) in an amount greater than fifty percent of its total annual waste intake,
the proponent should evaluate the potential of the special waste to result in emissions of
additional chemicals other than those on the AP-42 list. MassDEP review and approval of such
assessments is required. See section on"Special Wastes" below.
Other Chemicals
MassDEP will entertain proposals on a case-by-case basis for identifying additional
COC, including for example, based on collecting monitoring data from a similar facility. For
landfill expansion requests, such a proposal could include monitoring at the existing landfill
assuming it receives the same waste stream.
It should be noted that since landfill emissions are also a function of the stage of
decomposition,this parameter should also be addressed when identifying COC. As discussed
22
previously in this document, since it is very difficult to determine at what point along a gas
production curve a set of monitoring data may have been derived, MassDEP's policy regarding
this issue is that, at a minimum,the list of AP-42 COC should be used along with, for each
chemical,the higher of the AP-42 concentration or the monitored concentration as an estimate of
a worst-case concentration. The list of COC can be supplemented with additional chemicals but
chemicals should not be deleted from the list.
The USEPA has established a number of promulgated test methods for measuring air
emissions which can be found on the internet at the Technology Transfer Network (TTN)
Emission Measurement Center(EMC) of USEPA's website at
http://www.epa.gov/ttnemeOl/promgate.html. Monitoring plans submitted by the applicant
should be comprehensive and include a protocol for identifying tentatively identified compounds
(TICS) as well a quality assurance/quality control (QA/QC) plan.
Special Wastes
A special waste or combination of special wastes should be addressed in a quantitative
risk assessment if that waste comprises greater than fifty percent per year of the total waste taken
in at a facility. If the percentage of special waste is equal to or below fifty percent of the total
yearly waste tonnage,then a quantitative assessment of emissions from the special waste is not
required. However,the proponent must comply with all existing MassDEP regulations and
permit requirements governing special wastes as provided for in 310 CMR 19.000. In addition,
the proponent should document their yearly projection of special waste tonnage and describe
how this quantitative estimate is determined. If the percentage of a particular waste is projected
to be greater than fifty percent at any time during a facility's lifetime, then the potential
emissions from special wastes should be included in the risk assessment. In such situations, the
list of AP-42 COC identified for inclusion in the quantitative risk assessment for a landfill siting
or permitting request should be supplemented with additional chemicals predicted to be emitted
based on the special wastes of concern. All such chemicals for which toxicity data exist should
be included in the impact assessment.
As discussed above, quantitative information on potential emissions can be obtained in
several ways. Applicants may be required to identify from the peer-reviewed literature
additional COC, subject to MassDEP approval, predicted to be released from special wastes.
These data should be obtained from reputable emissions studies conducted at similar facilities.
Information about the chemical and physical properties of the special wastes as they relate to the
decomposition process can also be used.
Alternatively, as discussed in the previous section, MassDEP will entertain proposals on
a case-by-case basis for identifying additional chemicals based on collecting monitoring data
from a similar facility taking in the same type of special wastes. For landfill expansion requests,
such a proposal could include monitoring at the existing landfill assuming it processes the
particular special waste of concern.
23
Table 7. Toxicity Information for the AP-42 List of Chemicals
Toxicity Information
SubChronic Chronic Inhalation
(Always check for updated toxicity information) Reference Reference Unit Risk
Concentration Concentration Value USEPA
RfC RfC URinh Cancer
Chemical CAS mq/m3 ref mq/m3 ref(ug/m3)-7 Classification rt.
1,1,1-Trichloroethane(methyl chloroform) 71-55-6 1.00E+01 2b 5.20E+00 3a D
1,1,2,2-Tetrachloroethane 79-34-5 2 8011+00 10 9.30E-02 3a 5.80E-05 C 1
1,1,2-Trichloroethane 79-00-5 7.40E-02 6 7.40E-02 3a 1 60E-05 C 1
1,1-Dichloroethane(ethylidene dichloride) 75-34-3 5.00E+00 2 5 OOE-01 2 1.60E-06 C 5
1,1-Dichloroethene(vinylidene chloride) 75-35-4 8.10E-02 10 2.00E-01 1 C
1,2-Dichloroethane(ethylene dichloride) 107-06-2 5.50E-02 6 5.50E-02 3a 2.60E-05 B2 1
1,2-Dichloropropane(propylene dichloride) 78-87-5 1.30E-02 2 4 OOE-03 1 1.90E-05 B2 31:
2-Propanol(isopropyl alcohol) 67-63-0
Acetone 67-64-1 3.10E+01 10 8.00E-01 3a D
Acrylonitrile 107-13-1 2 OOE-03 6 2 OOE-03 1 6 80E-05 Bt 1
Benzene 71-43-2 3.20E-02 4 9.00E-03 3a 7.80E-06 A 1
Bromodichloromethane 75-27-4
Butane 106-97-8 4.50E+00 6 9.50E-01 11
Carbon disulfide 75-15-0 7.00E-01 2 7.00E-01 1 NA
Carbon monoxide
Carbon tetrachloride 56-23-5 4 30E-01 6 4.30E-01 3a 1.50E-05 B2 1
Carbonyl sulfide 463-58-1 5.00E-04 6 5.00E-04 3a
Chlorobenzene 108-90-7 2.00E-01 21b 6.00E-02 7 D
Chlorodifluoromethane 75-45-6 5.00E+01 6 500E+01 1
Chloroethane(ethyl chloride) 75-00-3 1.00E+p1 2 1.00E+01 1
Chloroform 67-66-3 6.60E-01 6 6.60E-01 3a 2.30E-05 B2 1
Chloromethane(methyl chloride) 74-87-3 4.20E-01 10 3 OOE-01 7 1 80E-06 C 2
Dichlorobenzene(tox data for para)- 106-46-7 1.20E+00 10 8.00E-01 1 6 90E-06 C 2e
Dichlorodifluoromethane 75-71-8 2.00E+00 2 2.00E-01 2
Dichlorofluoromethane 75-43-4
Dichloromethane(methylene chloride) 75-09-2 3 00E+00 2 3.00E+00 2 4 70E-07 B2 1
Dimethyl sulfide(methyl sulfide) 75-18-3
Ethane 74-84-0 4.50E+00 6 9 50E-01 11
Ethanol 64-17-5 2 50E-01 6 2 50E-01 3a
Ethylbenzene 10041-4 1.00E+00 2b 1.00E+00 1 D
Ethyl mercaptan(ethanethiol) 75-08-1
Ethylene dibromide(dibromoethane) 106-93-4 2.00E-03 2 2.00E-04 2 2.20E-04 B2 1
Fluorotrichloromethane 75-69-4 7.00E+00 2 7.00E-01 2
Hexane 110-54-3 2.00E-01 2 2.00E-01 1
Hydrogen sulfide 7783--06-4 1.00E-02 2 1.00E-03 1 NA
Mercury,total(tox data for elemental) 7439-97-6 3 00E-04 2 3 OOE-04 1 D
Methyl ethyl ketone 78-93-3 1 00E+00 2 1 00E+00 1 D
Methyl isobutyl ketone 108-10-1 8 OOE-01 2 8.00E-02 2 NA
Methyl mercaptan 74-93-1 2.50E-03 6 2 OOE-03 9 NA
Pentane 109-66-0 2.00E-01 6 2 OOE-01 8
Perchloroethylene 127-18-4 4.60E+00 6 4.60E+00 3a 5 50E-05 NA 31:
Propane 74-98-6 2.00E-01 6 9.50E-01 11
Toluene 108-88-3 4.00E-01 21b 4.00E-01 1
Trichloroethylene 79-01-6 5.50E-01 10 1.80E-01 3 1.70E-06 NA 2t
t-1,2-Dichloroethene 156-60-5 8 t0E-01 10 1 10E+00 3a NA
Vinyl chloride 75-01-4 1 OOE-01 6 1 OOE-01 1 8.80E-06 A 1
Xylenes(m-,o-,p-) 1330-20-7 3.10E+00 10 6 OOE-02 3a D
References for Table 7
1. USEPA Integrated Risk Information System(IRIS)
2. USEPA Health Effects Assessment Summary Tables(HEAST)
2.a Converted from the oral slope factor listed in HEAST
2.b Withdrawn from HEAST pending EPA review
3.a MassDEP-Back-calculated from the MassDEP Threshold Effects Exposure Limits
3.b MassDEP- From the Chemical Health Effects Assessment Methodology and the Method to Derive
24
Allowable Ambient Limits(CHEM/AAL)
4 MassDEP—Calculated Value
5. California EPA
6. This chronic value should be used to evaluate subchronic exposures in the absence of a subchronic RfC.
7. Provisional value,USEPA National Center for Environmental Assessment
8. Toxicity values for hexane are used to evaluate this alkane.
9. US EPA Risk Assessment Information System(RAIS)
10. Agency for Toxic Substances and Disease Registry(ATSDR)
11. Calculated using the MassDEP CHEM/AAL process from the NIOSH occupational limit for butane. This value
should also be used to evaluate ethane and propane.
Landfill Point Sources
Stack Gas Constituents
Gas collection systems can be either active or passive. Active systems employ pressure
gradient using mechanical blowers or compressors whereas passive systems rely on the natural
pressure gradients created as landfill gas builds up to mobilize the landfill gas. The design of
collection systems varies with landfill characteristics and operation. Some involve installation of
probes at the landfill perimeter, although the probes are generally installed directly within the
refuse-containing area. In general, active systems are more efficient in collecting gas than are
passive systems. Reported gas collection system efficiencies range from 60%to 85%, with an
average of 75% most commonly assumed(USEPA, 1997d).
Control treatment of the collected gas can be done using either a combustion technology
or a purification technique. Combustion technologies generally involve either flares, in which
collected gas is destroyed via burning, or an energy recovery technique in which energy
generated in the destruction of the gas is collected via gas turbines, boiler to steam turbines or
internal combustion engines. Purification techniques generally involve use of adsorption,
absorption and membrane techniques to remove water, carbon dioxide and NMOCs.
Flares use an open combustion process and represent point emission sources within a
landfill. Flares may be open or enclosed. Enclosed flare systems can better control the quality
of combustion by regulating temperature, residence time of components in the combustion zone,
turbulent mixing within the combustion zone and the amount of oxygen available for
combustion. A well-operating flare has a control efficiency of 90-99% for NMOC, 91-99% for
halogenated species and 38-99% for non-halogenated species (USEPA, 1997d).
Based on the fact that collection and combustion of landfill gas is not one hundred
percent efficient, constituents of landfill gas are still expected to be released from landfills with
collection and treatment systems. These emissions can result from uncollected gas or non-
combusted gas from control devices. In addition to landfill gas constituents, the flaring process
produces secondary pollutants that are released at the stack. Secondary pollutants typically
released from landfill flares include nitrogen oxides, carbon monoxide and particulate matter.
Other pollutants may also be released, depending on the waste stream within that landfill. For
example, when chlorinated compounds are combusted in control equipment, hydrogen chloride
emissions are formed.
25
AP-42 Chemicals
As discussed above, although the total amount of landfill gas constituents is expected to
decrease substantially with the use of collection and treatment systems, these chemicals are still
expected to be released in controlled landfills. Thus, even for a controlled facility, all
quantitative risk assessments done in support of a landfill expansion request should, at a
minimum, include the list of AP-42 chemicals as COC or a MassDEP approved alternative list of
COC's. See the section above on area sources for additional information on the AP-42
chemicals and options for identifying a list of COC at landfills.
Other Landfill Gas Chemicals
As discussed above, since chemicals emitted in landfill gas are a function of the waste
stream received, it is possible that additional chemicals which are not on the AP-42 list may be
emitted in the collected landfill gas, especially in the case of facilities that accept non-traditional
wastes or special wastes. As stated above, even for a controlled facility, predicted emissions
from such wastes, if they comprise greater than fifty percent of the total annual waste intake for
that facility, should be included as COC. See above section on area sources for additional
information on options for establishing COC for special wastes at landfills.
Secondary Pollutants from Stack Emissions
MassDEP may require on a case-by-case basis the identification of additional COC (e.g.,
hydrogen chloride) in stack emissions. These data may include well-conducted landfill flare
emissions studies from the literature conducted at facilities accepting a similar waste stream.
Additional stack gas constituents may also be predicted by analyzing the waste stream for that
facility along with information on the chemical and physical properties of the chemicals
predicted to be generated in landfill gas. Principles of combustion chemistry can be used to
predict the combustion by-products generated upon flaring.
Alternatively, MassDEP may require on a case-by-case basis the identification of
secondary COC based on collecting monitoring data from a similar facility. For requests
involving landfill expansions at facilities with collection and treatment systems, such a proposal
could include monitoring at the existing stack assuming the expansion will receive the same
waste stream as the existing landfill. Information on USEPA promulgated test methods for
measuring air emissions for a number of parameters can be found on the internet at the
Technology Transfer Network(TTN) Emission Measurement Center (EMC) of USEPA's
website at http://www.epa.gov/ttnemeOl/promgate.htmi. Monitoring plans submitted by the
applicant should be comprehensive and include a quality assurance/quality control (QA/QC)
plan.
4.1.1.2 COC From Non-Municipal Solid Waste Landfills
For ash landfills and C&D landfills, MassDEP has determined that the emissions of most
concern are fugitive particulates generated during transport and processing of these wastes, as
well as hydrogen sulfide for C&D landfills. Particulates of health concern include those with a
diameter less than 10 µm (PM 10, PM2.5), in particular those fess than 2.5 µm (PM2.5).
26
Toxicologically, it is the very small particulates that, once inhaled, can penetrate deep into the
lung where they are not easily eliminated by the lung's clearance mechanism and can thus persist
to do more damage. At each of these facilities, MassDEP believes that particulate emissions can
be adequately controlled through use of facility-specific BMPs that address fugitive dust control.
MassDEP is issuing guidance on addressing hydrogen sulfide emissions that will include
recommendations on establishing monitoring systems, developing response plans, and facility
operations and design.
Ash Landfills
Ash, and in particular, fly ash, consists of very fine particulates. For this reason,
MassDEP had been concerned in the past about potential emissions of fugitive particulates from
ash transport and disposal activities at landfills. Studies that look at the potential for entrainment
into air of fugitive particles at ash landfills are limited. As a conservative approach, MassDEP
therefore historically required that the potential emissions and resulting risks due to fugitive
emissions from landfills be estimated and evaluated using the AP-42 approach. The AP-42
approach was used to generate an estimate of a dust emission rate to which percent metal
composition data(measured in facility-specific ash) was applied to estimate metal concentrations
in that ash.
MassDEP found that the assessments conducted using the AP-42 approach typically
yielded very low estimates of risk, generally in the de minimis range. In the course of
conducting these assessments,MassDEP also learned more about the ash-generation process and
the nature of ash. Based on the required BMPs for ash, the ash-generating process typically
yields a product of high moisture content. Ash is produced as the end product of the burning of
organic materials (e.g., most typically, municipal solid waste, coal, etc.). Bottom ash is created
when the residue from combustion falls into a water bath that cools the residue,thus saturating
the bottom ash stream with water. Fly ash is typically mixed with water to increase its moisture
content. Ash is hygroscopic and once dry forms a fairly rigid structure that does not easily break
down into particles small enough to become airborne.
The preponderance of evidence demonstrates that ash disposal does not result in any
significant entrainment of ash dust. In 2002, a field monitoring study (AMEC, 2002) was
performed at the Ward Neck Landfill Expansion in Haverhill, Massachusetts for Covanta
Haverhill Associates (hereafter referred to as the "Covanta report")to measure concentrations of
fugitive emissions that might be associated with ash disposal activities. This investigation was
undertaken by the proponents of this facility to address their contention that ash emissions
associated with disposal activities were negligible and that the exposure assessment would be
zero in a quantitative risk assessment. Both upwind and downwind concentrations of respirable
particulates (PM 10) were measured at this facility during ash disposal activities. It was found
that downwind PM10 concentrations were slightly (although statistically significant) higher than
upwind concentrations. However, additional observations strongly indicated increases in
downwind PM10 were due to diesel exhaust from on-site equipment rather than from
entrainment of ash. The observations included: PMI 0 concentrations were higher downwind
during dry dumping runs (i.e., empty trucks simulating ash dumping); there were no significant
differences between upwind and downwind metal concentrations during ash dumping activities.
27
Given that the moisture content of ash is the characteristic that prevents entrainment, protection
against future dust generation after water has been added is assured because it is extremely
difficult for ash to dry out.
jBased on experiences to date and on the results of the=Covanta study__,_MassDEP--
concludes that_entrainment to air of fugitive particles from ash is negligible=ifthat-a h
maintained at a high moisture content(i e; greater,than_18%_water content) during-generation 7
Ad disposal activities./
Thus, if proper BMPs that address fugitive dust control are implemented at a facility,
there should be no need for an assessment of fugitive dust in a quantitative risk assessment. In
addition, also based on findings of the Covanta study, BMPs should be put into place at facilities
to retrofit existing on-site vehicles with diesel control technology and to limit idling times.
Construction and Demolition Landfills(C&D)
No chemical-specific, quantitative risk assessment is required for C&D landfills at this
time. Fugitive particulates from C&D landfills are addressed in the assessment of the criteria
pollutant PMI 0 that is required to be done elsewhere in the siting and permitting processes. As
discussed above for ash landfills, MassDEP believes that fugitive emissions from C&D facilities
may be adequately controlled by implementing BMPs that address control of fugitive dust.
However, MassDEP is issuing guidance to address hydrogen sulfide emissions from landfills that
handle C&D waste, fines, or residuals. Based on this guidance, MassDEP may require additional
controls or assessment for landfills that handle C&D waste, fines, or residuals.
4.1.2 Emissions From Proposed Waste Handling Facilities
Generally waste handling facilities should be characterized by a Level 1 assessment and
emissions should_le=adequatel-y-controI IR_b BMP-?Waste handling facilities are those in
which refuse is collected, processed and transported off-site. Facilities may either handle
municipal trash such as municipal waste transfer stations, or they may specialize in a particular
sector of the waste stream. Examples of more specialized waste handling facilities include
construction and demolition facilities and facilities that recycle landscaping wastes. Often,these
facilities exist because there is a market for materials recovered or recycled from the waste
stream. Usually, these facilities are able to recover portions of the waste stream to be shipped
off-site for reuse or recycling and the unrecoverable portion is transported off-site to another
facility for disposal. The residence time of most wastes at waste handling facilities is transitory,
since the waste enters the facility, is processed and is then shipped off-site.
The types of emissions generatedfromthese facilities vary greatfy depending on-the.
nature of-the-refuse-p%c-essed,Mize-d waste co'ilecte`d`inmunicipal transfer stations is-similar in
composition to municipal refuse that is landfilled. If these wastes were stored at the facility for
an extended period of time during which the decomposition process could progress, the gases
generated might be similar to those found at landfills. Since this is not the case and because of
the transitory nature of the wastes passing through such facilities, MassDEP considers the
28
c_oncefti at waste
�MtSS� p ocessng-known as fugitive partic lates?lines as those area emissions generated_during
cSz
CpA p, Fugitive particulates that are generated and dispersed at a facility during day-to-day
J�tk` 1a 5 operations may-b-e emitted-in=conjunction with the-loadiW-and-unloading-of refuse,_packing=and,,
k,e,P compacting=operationsand=other activities'-especi'ally.in_wi'ndy,-'dry=conditions? However,waste
�01 handling facilities are not characterized by the fugitive dust associated with excavation,packing
and landfill covering operations that are typical of landfills. Thus, emissions-of fugitive
particulates in-a-well=controlled_waste_handling-facility-are=expected=to-berelatively_low?
MassDEP's protocol for evaluating site suitability of solid waste facilities encourages all
facilities to install measures to controldusts=utiliiingBest-Management=P-ng (BMP§).
MassDEP expects that use of BMPs for dust control will address and significantly limit the
emission of fugitive dusts from waste processing facilities.
4.1.3 'Diesel=Particulates
Diesel exhaust generated from=heavy,truck-equipment=and=engines_used_at-solid=waste
facilities contain large-quantities of particulates-and-nitrogen oxides-(NOx) as=wel(as other
pollutants including=hydrocarbons-and-several=gases. In general, although diesel engines are
more efficient than their gasoline-powered counterparts, current regulations allow them to emit
far more pollutants.
0 Dieselparticulates=and-N07-at=solid waste management faeilities-may-be-emitted=from
.- m_ _-_ y
on-site eg-..wpmenAN
t as wel-- 1 as from vehicles fransporting retuse mto and out the facility. At
landfills, heavy truck diesel equipment is used for excavating and moving dirt, for landfill
covering and compacting operations as well as for waste transport. rAt_waste-h-andling_facilities,
dieseI-equip ment i;-us—ed=to move;consolidate and-compact trash before it`is`trucked or railed),
(off-site-Diesel transport vehicles,which are used to haul refuse into and out of the facility will
emit diesel particulates and NOx during the relatively brief time they are visiting the facility.
cHoweyer,=the numbero£trucks visiting-a facility in any one=day-will-influen ee theproportion'of2-
,diesel=pollutants=contributed=from=truck-Traffic which could be=quite-significant, depending on the
facility. On the other hand,there maybe many fewer pieces of h avy-duty diesel=equipment-on
site-and=these=may operate=at`a facility for hours ata ttime;constantly emitting-diesel pollutants
Such equipment may even operate in enclosed facilities, resulting in substantial, localized
exposure to workers.
Diesel-particulates are very-fine,-mostofwhich=are=characterized=by-a=particle-diameter
less-thann2.5=µm andtherefore have the-capacity-to be-inhaled=deep-into-the-lungs,=where they9
<�1 'a� can have-advers-eeff-ectsi Particulates produce eye and nose irritation and aggravate respiratory
LtU� problems, including asthma. In addition,very fine particulates have been found to contribute to
9� an increased risk of premature death.4Diesel=engines=release=particulates-directly_-into-the-air,
emit—nitrogen oxides a'nd sulfur oxides;which-then transform into-`secondary'-'=partieulates-in-theme
atmosphere.'
�( p NOx-lowers-resistance ooerspiratory=infections=and=aggavates=symptoms associated-with
a casthma and-bronchitis' In addition,NO, contributes to the formation of ozone(03), which
irritates the respiratory system causing coughing and choking and reduced lung capacity.
29
To limit diesel emissions from proposed solid waste facilities, MassDEP strongly
encourages that_a11=on-site transport_equipment-used-on-all new-and-axpanded=landfills and-new
and expanded waste handling facilities�be=retrofitted=with=diesel-contro_l_-technology. Such
retrofitting will significantly reduce on-site diesel emissions.
4.1.4 Toxicity Profiles
The descriptions of the potential health effects associated with each contaminant are
typically provided in a Toxicity Profile. Toxicity Profiles serve several purposes. They provide
a summary of the potential adverse human health effects that may be associated with exposure to
a particular contaminant and they contain references for the dose-response assessment. The
information in Toxicity Profiles may also be used to group chemicals by health endpoint and
mechanism of toxicity in order to fine-tune risk estimates. In addition,toxicity profiles also
serve as reference material for non-toxicologists who want to understand the potential health
impacts associated with contaminants.
The scope and level of detail of a Toxicity Profile will vary depending upon the nature
and quantity of information available for a particular chemical. For many substances,
toxicological information is readily available from many sources, and repetition of that
information in great detail in the Toxicity Profile is not necessary. For the purpose of the AP-42
chemicals evaluated in the quantitative risk assessment, a short descriptive summary of the
known health effects associated with the chemicals of interest and the basis for any existing
standards or guidelines would be sufficient. This information can be presented in the form of a
table or brief text. At a minimum,the profile should summarize known chronic systemic
toxicity, developmental/reproductive toxicity, genotoxicity and carcinogenicity. If additional
chemicals have been identified, a more in-depth toxicological profile should be provided which
also includes a profile of the toxicokinetics, human and animal mechanisms of toxicity,
structure-activity relationships and interaction with other chemicals, as appropriate. In preparing
the toxicity profile, the risk assessor should rely on credible,peer-reviewed sources of
information such as controlled, epidemiologic investigations, clinical trials, experimental animal
studies, metabolic and pharmacokinetic experiments, in vitro studies and structure-activity
studies. All references should be provided to document the sources of information used to
prepare the toxicity profile.
4.2 Dose-Response Assessment
The Dose-Response Assessment involves a compilation of toxicity information on the
health effects of the COC. This information is obtained from human epidemiological or animal
toxicology studies in the published literature. Dose-response information for a large number of
compounds is represented in toxicity values published by the USEPA and other government
agencies. Toxicity values are chemical- and route-specific values obtained from epidemiological
or animal toxicity studies that have been adjusted to be applicable to chronic or subchronic
exposures of the general population, including sensitive individuals. These types of values,
which include non-threshold inhalation toxicity values and cancer unit risk values are generally
used in health risk assessment to estimate the type and magnitude of risk associated with
exposure to chemicals.
30
Toxicologically, there is believed to be an exposure level of a compound below which
adverse health effects do not occur. Theoretically, health effects are only possible once that
particular level of exposure or threshold is exceeded. Such a level is referred to as a threshold
dose. In theory, the threshold dose would be safe for all receptors who might be exposed at that
level. A brief summary of key toxicity values for use in quantitative impact assessments for
proposed facilities is described below. MassDEP recommends assessment methods based on
standard USEPA toxicity values and equations.
A threshold dose or exposure can be administered as an acute, subchronic or chronic
exposure. Acute exposure is typically assumed to be up to 24 hours in duration (quantitative
assessment of acute exposure is not required at this time). Subchronic exposures for humans
refer to exposures up to seven years in duration, while a chronic time period is greater than seven
years. Both subchronic and chronic exposures should be evaluated in the risk assessment for all
chemicals in order to assess all relevant exposure scenarios. Subchronic and chronic
subthreshold values should be used to evaluate subchronic and chronic exposures, respectively.
Non-Cancer
For the inhalation pathway, a subthreshold exposure for chronic exposures is
represented by a Reference Concentration (RfC) (in units of mg/m3). The RfC is the
inhalation exposure concentration (with uncertainty spanning perhaps an order of
magnitude or greater) to which daily exposure of a human population, including sensitive
populations, is likely to be free of appreciable effects. Methods for development of
inhalation reference concentrations are detailed by USEPA.
For the ingestion pathway, a Reference Dose(RfD) represents a subthreshold oral
dose for chronic exposures (in units of mg/kg/day). The RfD is the dose (with
uncertainty spanning perhaps an order of magnitude or greater) to which daily exposure
of a human population, including sensitive subgroups, is likely to be free of appreciable
effects during a lifetime. Methods for development of R1Ds are similar to those used to
develop RfCs. RfDs may be used to evaluate inhalation exposures of particulate-
associated contaminants, typically evaluated in terms of dose rather than concentration.
Additional discussion of the use of RfDs is found in the Exposure Assessment section of
this document.
Cancer
Unlike threshold effects, with non-threshold effects it is assumed that every
concentration or level of a compound, no matter how small, produces some effect.
Carcinogenicity and mutagenicity are examples of non-threshold effects.
The dose-response assessment for carcinogens assumes that there is no threshold
dose for carcinogenicity, or in other words, that there is no dose of a carcinogenic
substance (other than no exposure)that is associated with zero risk. USEPA evaluates
available toxicity data and assigns the chemical to a weight-of-evidence class.
For inhalation exposures,the ability of a chemical to increase the incidence of
cancer in a target population is typically described by the cancer unit risk(UR) factor.
31
The Unit Risk is the upper 95% Confidence Limit of the mean incremental lifetime
cancer risk estimated to result from lifetime exposure to a compound if it is in the air at a
concentration of 1 µg/m3. A Unit Risk is expressed as risk per concentration in air,
typically given in units of (ltg/m3)-1. Unit Risk values are issued from a number of
different sources (See Section 4.2.2). Unit Risk values are multiplied by the
concentration (in µg/m3) of a compound in air to derive a unitless cancer risk estimate.
For the ingestion pathway, the measure of carcinogenic potency is described by a
Cancer Slope Factor(CSF). CSFs are also issued from a number of different sources
(See Section 4.2.2). The CSF for a chemical is calculated using mathematical
extrapolation models, commonly the linear multistage model, from the dose-response
curve of a toxicological study. The largest possible linear slope (within the 95%
Confidence Limit) of this curve is estimated at low extrapolated doses. Although for
some chemicals, human epidemiologic data are the basis of an estimate of the
carcinogenic potency, the most common basis of these values is an animal study. The
CSF is expressed as risk per unit dose, and is typically given in units of
(mg/kg/day)-1. Use of the slope factor assumes that the calculated dose received is
expressed as a lifetime average. CSFs are multiplied by the ingested dose(in mg/kg/day)
of a compound to derive a unitless cancer risk estimate. CSFs may be used to evaluate
inhalation exposures of particulate-associated contaminants,typically evaluated in terms
of dose rather than concentration. Additional discussion on the use of the CSF is found
in the Exposure Assessment section of this document.
The dose-response assessment describes the observed effects in humans and/or laboratory
animals associated with particular exposures or doses of the chemicals of concern. This
information is obtained from published literature describing epidemiological or toxicological
studies involving the particular chemical. For most chemicals included as COC in a solid waste
facility impact assessment, the dose-response information needed to conduct a risk assessment
may be found in secondary sources published by the USEPA or other government agencies, as
described below.
The dose-response relationships for each COC should be identified in the risk assessment
report. This information is later coupled with knowledge of the nature and magnitude of
potential exposures to characterize risk.
The dose-response information used for risk assessment may be divided into three major
categories:
• Toxicity information associated with threshold(non-carcinogenic) health effects
• Toxicity information concerning carcinogenicity, either from human epidemiologic data
or from laboratory studies
• The Relative Absorption Factors (RAFs) used to relate the toxicity information
identified from the literature to the exposure pathway of concern at the proposed site
under investigation.
4.2.1 Conversions from Dose
32
In the absence of RfCs or Unit Risk values, an oral Reference Dose or Slope Factor may
be used to estimate risk by converting the Reference Dose to a Reference Concentration and the
Slope Factor to a Unit Risk if it is appropriate to do so based on toxicological considerations.
4.2.2 Sources of Dose-Response Values
There are a number of different sources of both subthreshold and non-threshold toxicity
criteria. When selecting toxicity information for use in quantitative risk assessment, the project
proponent should ensure that the information is appropriate for the assessment being conducted
and that it is up-to-date. Note that sources differ in the frequency at which they are updated and
level of review they receive.
Both threshold and non-threshold toxicity criteria are available from a variety of sources.
These include(listed in general order of preference, although case-by-case exceptions may
apply):
• Integrated Risk Information System (IRIS)database - This database contains values that
represent a consensus judgment of the USEPA Carcinogen Risk Assessment Verification
`Cy Endeavor(CRAVE), which is composed of scientists from various USEPA offices and the
Office of Research and Development. It is the preferred source of toxicity information. The
' tP IRIS database is updated monthly and is available on the Internet. IRIS contains both chronic
�� inhalation RfCs and RfDs, and unit risk factors. (http://www.epa.gov)
• Health Effects Assessment Summary Tables (HEAST) - HEAST contains values that have
received some form of review by USEPA,but have not been verified and are considered
provisional. HEAST is prepared by USEPA's Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH. HEAST can be
obtained by contacting the National Technical Information Service(NTIS) Subscriptions
Department. HEAST contains both chronic RfCs and RIDS and unit risk factors.
• Other Sources
non-cancer:
- Allowable Threshold Concentration (ATC) - The "Allowable Threshold
Concentrations" are similar to the USEPA inhalation RfCs in intent but they are
derived by ORS using a modified version of the methodology used by ORS to
develop Threshold Effects Exposure Limits (TELs) (MassDEP, 1990), an ambient air
exposure guideline based on consideration of threshold-type health effects, developed
for MassDEP's air toxics program. The ATC values are equal to five times the TEL
values since they do not include a program-specific safety factor of 20%to account
for multi-media exposure.
- Other Toxicity Values developed by MassDEP/ORS - ORS develops chronic and
subchronic RfC-equivalent and RfD-equivalent values for some compounds for
which no values are available in IRIS or HEAST. These values are based on
available toxicological data and standard USEPA approaches for developing
33
reference concentrations and reference doses for threshold effects. The list of
chemicals includes a number of carcinogens for which USEPA has not derived non-
cancer toxicity values. These values can be accessed through the MassDEP web site
at httD://www.mass.2ov/deD.
- Agency for Toxic Substances and Disease Registry(ATSDR) - ATSDR produces
Toxicological Profiles for hundreds of hazardous substances. In the toxicological
profiles, ATSDR develops Minimal Risk Level (MRLs) for threshold effects of some
chemicals. These values are updated when the profiles are revised, if appropriate.
An MRL is defined as an estimate of the daily human exposure to a substance that is
likely to be free of appreciable risk of adverse non-cancer effects over a specified
duration of exposure. MRLs are derived using the modified risk assessment
methodology the USEPA uses to derive reference concentrations for lifetime
exposure.
- Calculation of a dose-response value using toxicity information from the
literature-Dose-response values may be derived by a qualified risk assessor or
toxicologist if none of the above sources provide a toxicity value, or if more recent,
credible and relevant data becomes available. USEPA approaches to the development
of RfCs are described in Interim Methods for Development of Inhalation Reference
Concentrations. The review and approval by MassDEP of such proposed values
would depend upon the justification and documentation provided to support it.
cancer:
- Toxicity Values Developed by MassDEP/ORS - The Office of Research and
Standards may develop unit risks for chemicals for which no values are available in
IRIS or HEAST. When available,these values can be accessed through MassDEP's
website at httD://www.mass.aov/deD.
- California Environmental Protection Agency(Cal/EPA) - Cal/EPA's Office of
Environmental Health Hazard Assessment(OEHHA), Department of Pesticide
Regulation (DPR) and Department of Toxic Substances Control (DTSC) develop or
approve cancer potency factors for use in risk assessments and as the basis for
regulatory action. A list of available cancer potency factors is revised semiannually
and can be obtained from OEHHA's Hazardous Waste Toxicology Section.
4.2.3 Dose-Response Information for the AP-42 Chemicals
MassDEP has compiled a list of dose-response information for the AP-42 chemicals. These
include chronic inhalation RfCs or RfC-equivalents and inhalation cancer unit risk values. These
values are contained Table 7.
34
4.2.4. Relative Absorption Factors
The Relative Absorption Factor(RAF) is used to account for differences in the
absorption of a COC under assumed exposure conditions (exposure route and matrix) relative to
the absorption of the COC under the experimental conditions upon which the dose-response
value is based. It is used to adjust the calculated exposure in terms of exposure route and
medium of exposure relative to the exposure route and medium of exposure of the chemical
under experimental conditions.
In the case of inhalation criteria and inhalation exposures, the RfCs and inhalation URs
are typically derived based on inhalation toxicology studies. In such a case, the route and
medium of exposure would be the same as the route and medium of the study from which the
toxicity information was obtained. There are cases, however, in which the RfC and/or unit risk
have been derived based on studies using an exposure route/medium other than inhalation. In
these cases, an RAF should be used to account for these differences.
To estimate an RAF,two factors should be identified:
• the absorption efficiency for the chemical via the route and medium of exposure being
evaluated for the proposed facility, and
• the absorption efficiency for the route and medium of exposure in the experimental study
which is the basis of the dose-response value for the chemical in question.
Thus, the RAF adjusts the dose (or exposure) estimates based on these two absorption
efficiencies. The RAF is calculated as follows:
RAF—
Absorption EfGenCyS/IE rouleimedmm of exposure
Absorption Ef cieneysrvDr ro„I..med,.of exposure
The basis for all toxicity values used to conduct a risk assessment should be reviewed to
ensure that differences in absorption efficiency have been accounted for.
4.3 Exposure Assessment
The exposure assessment is a critical component of the risk assessment process as it
describes the contact between the contamination and the people who are potentially affected by it.
The exposure assessment should allow for the assessment of risks posed by the solid waste facility
to receptors in the surrounding area(i.e.,modeling domain, see Section 4.3.3.1.2.). Both current
and identified future uses of the surrounding area should be considered. For example, if a facility is
located adjacent to an undeveloped tract of land that is zoned for residential development,the future
use of this area as a residential neighborhood should be considered as part of the exposure
assessment.
For the purpose of evaluating facility-specific risk under the Site Assignment Regulations
(3 10 CMR 16.00) only exposure to COC via inhalation of ambient air should be assessed
quantitatively in a risk assessment. This exposure involves inhalation of emissions from the facility.
As described earlier,potential exposures via groundwater are addressed by the
35
implementation of a series of measures to prevent contamination of groundwater and subsequent
exposure to the human population.
The exposure assessment generally includes two components: the exposure profile and
quantitative estimates of exposure. The exposure profile describes the exposures that may occur to
human receptors in the area surrounding the facility. The quantification of exposure translates the
narrative exposure profile into an exposure equation resulting in a numerical estimate of exposure.
These numerical estimates are subsequently used in the calculation of health risks.
A screening exposure profile should initially be used to evaluate the impact of a proposed
new facility or expansion. This profile should assume continuous exposure to landfill emissions by
a receptor situated at the maximum point of impact at or beyond the property line. If health risks
estimated from such a scenario exceed risk management criteria,then the applicant may, on a case-
by-case basis,develop a more refined exposure profile that incorporates site-specific exposure
parameters. A refined exposure profile and associated assessment should, however,be protective
for all receptors who are assumed to be impacted by emissions from the proposed facility.
Potential exposures to COC from the proposed facility should be based on emissions and
dispersion modeling as discussed in Section 4.3.3.1.
4.3.1 Screening Case Exposure Profile
The screening case exposure profile assumes that a receptor is situated at the maximum
point of impact at or beyond the property line continuously,twenty-four hours per day, seven days
per week for thirty years 12, breathing air containing the modeled exposure point concentrations.
The screening exposure profile conservatively assumes that a receptor never leaves the area of
maximum impact for thirty years. If non-cancer and cancer risks calculated based on this exposure
profile meet risk management criteria,then the development of a more refined exposure profile,
based on more realistic exposure estimates, is not necessary as further refinements will only
decrease risk estimates further. However, if estimated screening risks exceed risk management
criteria,then a more realistic exposure profile(e.g.,reflecting time the receptor spends away from
home,at school,at work,etc.) should be developed as discussed below.
4.3.2 Refined Exposure Profile
The refined exposure profile should contain a narrative description of how exposure takes
place in the area surrounding the facility being evaluated. The exposure profile assists the risk
assessor in identifying the appropriate frequency and duration of exposure to which human
receptors are exposed via inhalation to concentrations of COC in air.
Potentially exposed human receptors in the area surrounding the facility will generally
comprise a diverse group that lives(or may in the future live) in the area surrounding the facility.
For the purposes of the risk characterization these residents should be further divided into
subpopulations based upon gender and age if those factors are indicative of a higher exposure
"The thirty-year annual average exposure,which represents a chronic period of time,is adopted for the LADE
assessment based on work done by USEPA that identifies this value as the 95"percentile estimate of the time that
most people will spend living at one residence(EPA, 1997b)
36
potential. Young children,women of childbearing age and the elderly are often chosen as receptors
of concern in residential locations because of these factors. At industrial locations, adults may be
the most susceptible receptors. However,this may not be the case if,for example,there is a daycare
center on the premises. Identification of the most sensitive subpopulations should be done on a
case-by-case basis. Thus,to adequately evaluate these residents,the risk assessor may conclude that
all other subpopulations in the area would be subject to lower exposures and risks than those
calculated. Note,though,that while the receptors are described in terms of"subpopulations" or
"subgroups",the product of the risk assessment is still an estimate of the risk that applies to the
protection of an individual within that group. The quantitative risk assessment focuses on
individual risk not population risk.
A detailed exposure profile may be developed for what is believed to be the most highly
exposed receptor in the surrounding area accompanied by the conclusion that lesser exposed
receptors will also be protected. How often the exposures occur along with the length of these
exposures should be addressed. The exposure profile should address the facts, data,assumptions
and inferences about how exposures take place. Professional judgment is necessary,especially for
proposed new facilities for which there is no actual facility-specific information on operations.
Since these factors determine the magnitude of exposure (and thus the magnitude of the risk posed
by the proposed facility), it is important that there be a clear description and summary of this
information. The exposure profiles allow anyone concerned about the facility to read and
understand what was considered in the risk characterization.
The information that is used to develop an exposure profile for a facility should be obtained
via a compilation of data on the facility's proposed operation as well as on the composition and
distribution of the population in the area surrounding it. Relevant information on the proposed
facility and the surrounding area would include:
o the address and location of the proposed facility
o a detailed map of the proposed facility and surrounding area
o a description of the land uses at and surrounding the proposed facility
o a listing of other major point emission sources in the area regulated by
MassDEP (i.e., from SSEIS)
o identification of potentially sensitive populations in the surrounding area(e.g.,
daycare centers, nursing homes, etc.)
Some of this information may be available through the Massachusetts Geographic Information
System (MASS-GIS), which provides color plots or digital data. For a full listing of available
data, contact MassDEP GIS at (617) 574-6802 or Brian.Brodeurastate.ma.us.
4.3.3 Quantitative Estimates of Exposure
Once the screening and/or refined exposure profiles have been developed, the potential
exposures experienced by the receptors of concern from the proposed facility are quantified
using emission and dispersion modeling as described in Section 4.3.3.1. The outputs of the
modeling include the maximum annual average and the 30-year annual average estimates of
COC concentrations at the maximum point of impact in the surrounding population beyond the
property line and at the property line.
37
If the proponent chooses to do facility-specific monitoring, the results of this
investigation should be used to replace only those default AP-42 concentrations that are lower in
magnitude than monitored concentrations. As discussed in Section 2 of this document, a
conservative approach should be used in the risk assessment in which the highest of the
monitored concentration or concentration derived from an AP-42 emission factor is used in the
assessment. Concentrations of VOCs emitted from decaying waste fall along a lognormal gas
production curve and vary significantly over the decaying process, influenced by the age of the
waste and the particular set of environmental conditions characterizing the landfill. Since it is
very difficult to determine at what point along the gas production curve a data set may have been
derived, MassDEP's policy regarding this issue is to use the higher concentration as an estimate
of a worst-case concentration.
The several different time estimates of modeled exposure are necessary in order to
evaluate all relevant exposure scenarios. A chronic exposure for humans is typically described as
a period of time greater than seven years in duration. A subchronic human exposure is described
as a period of time from three months to seven years. For chemicals that are carcinogenic, a
lifetime average daily exposure(LADE) should be calculated. The thirty-year annual average
exposure,which represents a chronic period of time, is adopted for the LADE assessment based
on work done by USEPA that identifies this value as the 95`h percentile estimate of the time that
most people will spend living at one residence (USEPA, 1989).
4.3.3.1 Modeling Approach Used to Calculate Exposure Point Concentrations
The USEPA Landfill Gas Emissions Model (LandGEM) can be used for estimating
emissions of methane, carbon dioxide and non-methane organic compounds from municipal
solid waste (MSW) landfills. The model can be run using site-specific data or, if site-specific
data are unavailable, using default values. Information on the LandGEM model can be found in
User's Manual -Landfill Gas Emissions Model (USEPA, 1998).
Fugitive dust emissions from landfill operations due to filling, capping, waste
transportation, and wind erosion can be estimated with EPA AP-42 emission equations. Toxic
compounds in ash disposed in a landfill should be determined using an approved MassDEP ash
sampling and analysis program.
After air pollution emission estimates have been quantified, USEPA air quality dispersion
models can be used to estimate air pollution concentrations in the vicinity of the landfill.
Estimates of ambient air quality concentrations should be based on air quality models contained
in Supplement C to the Guidelines on Air Quality Models (Revised), EPA Publication No. EPA-
450/2-78-027R-C or other state-of the-art modeling procedures approved by MassDEP.
The Guidance Document will not address the modeling protocol for estimating levels of
NAAQS air pollutants. The potential impacts of criteria pollutants will not be addressed in the
facility impact assessment but are addressed elsewhere in the siting and permitting process.
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4.3.3.1.1 Landfill Gas and Particulate Emissions
USEPA has concluded that many compounds found in landfill gas may endanger public
health if left uncontrolled. Fugitive dust associated with landfill operations may cause or
contribute to a condition of air pollution. Emission rates of landfill gas compounds and fugitive
particulate matter should be estimated using models and procedures approved by MassDEP.
4.3.3.1.1.1 Municipal Solid Waste Landfills
Municipal solid waste (MSW)produces emissions by three mechanisms: volatilization,
chemical reaction, and biological decomposition of solid or liquid compounds into other
chemical species. Volatilization is affected by the partial pressure of the constituent,
concentration of the constituent at the liquid air interface, temperature, and confining pressure.
Chemical reactions are also affected by temperature as well as waste composition, moisture
content, and the practice of separate disposal areas for different waste types. Factors affecting
biological decomposition include nutrient and oxygen availability, refuse composition, age of
landfill moisture content, temperature, acidity, and waste that is toxic to bacteria.
Area Sources (Uncontrolled Emissions)
Uncontrolled area source emission estimates can be determined for individual
landfills using USEPA's Landfill Gas Emissions Model (LandGEM). This theoretical
first-order kinetic model can be accessed from the EPA's Office of Air Quality and
Planning, Technology Transfer Network(OAQPS-TTN)website. The model can be
run using site-specific data. In the absence of site-specific emissions information,
MassDEP recommends using LandGEM with the USEPA AP-42 default values.
LandGEM provides emission estimates after the first year of refuse is in place and
provides annual estimates out to 200 years. Refuse data in Mg/year (million grams per
year) should be input into the model for each active year of operation—typically, a 4 to
7 year period of time.
If required, fugitive dust emissions from landfill operations due to filling,
capping, waste transportation, and wind erosion can be estimated with USEPA AP-
42 emission factors. Toxic compounds in any ash disposed of in a landfill should
be determined using an approved MassDEP ash sampling and analysis program.
Area Sources(Controlled Emissions)
Emissions from landfills are typically controlled by installing a gas collection
system and combusting the collected gas through the use of internal combustion
engines, flares, or turbines. To estimate landfill area source emissions after closure,
USEPA recommends using a 75% collection efficiency if site-specific collection
efficiencies are not available. During the period of time that the landfill is still active,
landfill gas capture efficiency should be assumed to be 0%. Gas collection systems do
not generally operate well before closure because it is too easy for air to enter the
system. If applicants have an existing air permit that specifies a gas capture rate,
39
MassDEP will rely on that data. Absent that type of documented data, MassDEP will
rely on the above default assumptions.
Point Sources (Controlled Emissions)
Collected landfill gas emissions are typically controlled by combusting the
collected gas through the use of internal combustion engines, flares, or turbines. The
AP-42 emission factor tables can be used to estimate the destruction efficiencies of the
control systems used to destroy NMOC compounds in collected landfill gas (typically
98%or more).
Non-Municipal Solid Waste Landfills
Non-municipal solid waste facilities generally accept a specific form of waste.
Examples are ash landfills and C&D landfill sites. Typical emissions of concern are
fugitive particulate matter generated during processing and transportation of such
wastes, and for C&D landfills, hydrogen sulfide emissions.
Area Sources (Uncontrolled Emissions)
If required, fugitive dust emissions from landfill operations due to filling,
capping, waste transportation, and wind erosion can be estimated with AP-42 emission
factors, or other state-of-the-art procedures approved by MassDEP. MassDEP may
request case-by-case estimates of fugitive dust emission rates and other COC based
upon a review of the literature.
4.3.3.1.2 Air Quality Impact Analysis Modeling Protocol
Listed below are the recommended contents of an air quality analysis modeling
protocol. Applicants should meet with MassDEP staff to discuss the proposed contents
of an air quality modeling protocol before submitting the protocol to MassDEP for
review and approval. All estimates of ambient air quality concentrations should be
based on air quality dispersion models and other requirements specified in Supplement
C to the Guidelines on Air Quality Models (Revised), USEPA Publication No. EPA-
450/2-78-027R-C, or other state-of the-art modeling techniques with technical merit as
approved by MassDEP.
For ash landfills, the proponent should discuss with MassDEP an assessment
plan and the potential need for any interactive modeling of sources with similar
emissions. The results of this discussion should be incorporated into the modeling
protocol.
Source Data
Facility Description: A description of the proposed landfill or proposed landfill
expansion under review should be provided, including site plans and appropriate
40
topographic maps. Yearly trash acceptance rates (out to the year of cell closure) and
geographic areas to be filled (out to the year of cell closure) should be identified.
Operating Schedules: Daily and weekly operating schedules should be described,
including truckloads of waste, fill and cover operations and any emission mitigation
activities.
Landfill Emission Rates: Landfill gas emission rates in grams per year for methane,
NMOC, carbon dioxide and the list of AP-42 compounds should be estimated using
USEPA's LandGEM model. MassDEP will accept other emission estimation
techniques if they have technical merit and reflect state-of-the-art emission estimation
procedures. Refuse data Mg/year should be input into the model for each active year of
operation out to closure (typically 4 to 7 years). After closure, assume that 75% of the
landfill gas emissions predicted by the LandGEM model will be collected and burned,
unless site-specific collection efficiencies are available. During the time a landfill is
still active, landfill capture efficiency should be assumed to be 0% due to the fact that
before closure it is too easy for air to enter the system and thus the system does not
operate well. Landfill yearly emission rates should be calculated for a 30 period of time,
including the years of active filling, usually a 4 to 7 year period of time.
Stack Emission Rates: Metric stack parameters and emission rates for all stacks,
flares and vents associated with the landfill gas collection system should be provided.
Stack data should include height above ground, stack diameter, stack exit velocity,
stack temperature and stack emission rates in grams per second for the AP-42 list of
COC. The AP-42 emission factor tables can be used to estimate the destruction
efficiencies of the control systems used to destroy the COC in collected landfill gas
(typically 98%or more).
Receptor Network
Grid: A Cartesian receptor grid should be designed for the modeling analysis,
centered on the approximate center of the proposed landfill expansion area. The
network should be of sufficient detail to ensure that maximum air quality
concentrations at or beyond the property line will be determined. Receptor rows and
columns should be spaced 50 meters apart. The network should be 2 kilometers on a
side, unless there is a need to more accurately determine air quality impacts at more
distant receptor areas of concern.
Discrete Receptors: Receptor coordinates for other sensitive receptors should also be
obtained (nearby residences, schools,parks). The principal purpose of discrete receptor
placement is to ensure that maximum air quality concentrations are determined at all
locations where the public has access.
Elevations: Receptor elevations should be obtained from USGS 1:25,000 3 in contour
electronic data and/or by inspection of applicable USGS maps.
41
Meteoroloeical Data
Five years of hourly meteorological data should be employed for the modeling
analysis. The data should be reasonably representative of the area where the landfill is
located. USEPA recommends using a 5 year data set whenever possible in order to
account for year-to-year variability in wind speed and direction patterns.
Atmospheric Dispersion Coefficients
A description of the land use within 3 kilometers of the proposed site (Auers
technique) should be provided in order to determine if urban or rural dispersion
coefficients should be employed. A field visit with MassDEP staff may be required to
ensure appropriate land use determinations.
Air Oualitv Models
Estimates of ambient air quality concentrations should be based on the air quality
models contained in Supplement C to the Guidelines on Air Quality Models (Revised),
USEPA Publication No. EPA-450/2-78-027R-C or other state-of the-art modeling
approved by MassDEP. Model options and settings should be specified and justified.
MassDEP recommends using USEPA's ISC3 model for estimating long-term air
quality impacts from point and area source emissions associated with landfill emissions.
The ISC3 model can be accessed from the USEPA's Office of Air Quality and
Planning, Technology Transfer Network website httD://www.eDa.Qov/ttn/scram/.
4.3.3.1.3 Air Quality Impact Analyses Report
Air quality impacts of emissions from landfills and /or landfill expansions should be
determined following an air quality modeling protocol approved by MassDEP. All
input and output files for all modeling runs should be retained for review by MassDEP.
Averaeine Times of Concern
Air quality impacts at each receptor point in the receptor network should be
determined for each of the AP-42 compounds. Maximum 1 year and maximum 30-
year impacts for each gas should be presented for the maximum off-site location. In
addition, maximum 1-year and maximum 30-year impacts for each landfill gas should
be noted for all locations where the public has access.
Contents of Air Oualitv Impact Analvsis Report
Modeling results should be presented and discussed in an air quality impact
analysis report. The report should be submitted to MassDEP for review, and should
document and describe all data and procedures used in the modeling analysis (source
42
configuration, emission calculations, point and area source model input data, air quality
model options and settings, receptor network, meteorological data, and predicted air
quality concentrations). A review of this information may indicate that additional
modeling analysis is required to ensure that maximum air quality impact levels and
locations have been identified.
4.3.3.2 Calculation of Average Daily Exposures;,
The toxicity information generally used to evaluate the risk of harm to health
associated with inhalation exposures, Reference Concentrations and Unit Risk values,
are air concentrations. These values are intended to be used in combination with
Average Daily Exposures (and Lifetime Average Daily Exposures for carcinogens)
expressed as applied concentrations. RfCs are typically used when evaluating gaseous
inhalation exposures.
Gaseous air contaminants may be inhaled by the receptor of concern located in
the vicinity of the facility emissions. The Average Daily Exposure to the contaminated
air(ADEau) is dependent upon the frequency and duration of the assumed exposures.
The result of this calculation should be an estimate of applied concentration. Note that
the equation is a simple adjustment of the exposure point concentration to account for
the amount of time the receptor spends in the area with contaminated air.
[COC Ja„ * EF * EP * C
ADEo„— AP
Where:
ADE,;,= Average Daily Exposure to a contaminant in air (dimensions: mass/volume;
typical units: mg/m3)
(COC]a,,=Exposure point concentration of COC in the air at the Exposure Point during the
period of exposure (dimensions: mass/volume;typical units: gg/m3).
EF= Exposure Frequency, or the number of exposure events during the exposure
period divided by the time of the exposure (dimensions: time/time; typical
units: hours/day, days/week)
EP= Duration of the exposure period (dimensions: time;typical units: years)
Al?= Averaging Period(dimension: time; typical units: years)
C= Appropriate units conversion factor(s) (e.g., 10-3 mg/gg, 1 week/? days)
For receptors assumed to be exposed constantly during the period of exposure (such as
for many residential exposures), the Average Daily Exposure would be equal to the Exposure
Point Concentration. Separate ADEa,r estimates should be based on the modeled maximum
annual average(for the assessment of subchronic exposure) and the thirty-year average (for
chronic exposures) exposure point concentrations, as discussed in Section 4.3.3.
43
4.3.3.3 Inhalation of Particulate-Associated Contamination
When evaluating particulate inhalation exposures, an Average Daily Dose rather than an
Average Daily Concentration is calculated. (The equations for calculating each of these values
are given below.) Airborne particulates (fugitive dust) may carry COC to receptors, resulting in
particulate-related inhalation exposures. The RfC and unit risk should still be used to estimate
risk in such a case by converting the RfC to an RfD and the unit risk to a slope factor.
For airborne chemicals that act at the point of contact(e.g., the lungs) when inhaled,the
Average Daily Exposure of these chemicals calculated in the manner described above would be
used in combination with an RfC or unit risk to estimate potential risks. Under such conditions,
the ADDparticulate inhalation would not be calculated.
An Average Daily Dose due to the inhalation of particulate-associated chemicals
(ADDpartwulate inhalation)may be calculated as:
[RP]a„ *[COC]P,,,,,r„ro,, * VR * RAF * EF * EP * C
ADDS.,, uro,e, Hary — BW * AP
Where:
ADDpHrtieulate inhalation= Average Daily Dose of a contaminant through the inhalation of
particulates. (dimensions: mass/mass*time; typical units:
mg/kg*day)
[RP]air= Exposure point concentration of respirable particulates(i.e.,PM10) in the air at
the Exposure Point during the exposure event.(dimensions: mass/volume;
typical units: ltg/m3)
[COC]parnanlate= Exposure point concentration of COC in the particulate material at the
Exposure Point during the period of exposure (dimensions: mass/volume;
typical units: mg/kg)
VR= Ventilation (inhalation) rate for the receptor of concern during the period of
exposure. (dimensions: volume/time; typical units: m3/hour)
RAF= Relative Absorption Factor(unitless)
EF= Exposure Frequency, or the number of exposure events during the exposure
period divided by the time of the exposure (dimensions: time/time; typical
units: hours/day, days/week)
EP= Duration of the exposure period(dimensions: time;typical units: years)
BW= Body weight of the receptor of concern during the averaging period (dimension:
mass;typical units: kg)
AP= Averaging Period(dimension: time; typical units: years)
C= Appropriate units conversion factor(s) (e.g., 10-6 kg/mg, 1 week/? days)
The equation below, for calculating the ADD,nhp can also be used to convert between an
exposure concentration (ADEa,t) and a dose (ADDinhp)•
44
4.3.3.4 Calculation of the Lifetime Average Daily Exposure(LADE) or the Lifetime
Average Daily Dose(LADD)
In order to be consistent with the toxicity values used to estimate cancer risk, the Lifetime
Average Daily Exposure (LADE) or Lifetime Average Daily Dose (LADD) should be used.
These values are calculated assuming that the chronic exposure to COC is averaged over a
lifetime. For the purposes of quantitative risk assessment, a chronic thirty-year exposure to
landfill gas is assumed and averaged over an assumed lifetime of 70 years. Thus, in the above
equations (in Sections 4.3.3.2 and 4.3.3.3),the exposure period (EP) should be designated as 30
years and the averaging period (AP) as 70 years.
4.4 Risk Characterization
Risk Characterization is the final step in the risk assessment process. In this step, the
results of the Hazard Identification, Dose-Response Assessment and Exposure Assessment are
integrated to yield quantitative measures of cancer and non-cancer risk. The Risk
Characterization can be thought of as providing a link between risk assessment and risk
management because it presents the numerical estimates of risk posed by the proposed facility in
a context that can be used easily by risk managers to make a siting decision.
A critical component in the presentation of risk estimates is the discussion of major
assumptions, scientific judgments and uncertainties inherent in the numerical risk estimates. The
importance of this component cannot be overstated. The discussion of uncertainties should place
the numerical estimates of risk and hazard in the overall context of what is known about the
proposed facility and surrounding area and what is uncertain. The numerical risk estimates
should never be interpreted as a characterization of absolute risk but should always be interpreted
in the context of the uncertainties.
Inhalation risk estimates for each chemical should be combined (summed)to yield total
cancer and non-cancer risks considering all chemicals for the receptor evaluated. These total
risks should then be compared with specific risk management criteria as defined in Section 4.6.
A discussion of the methods for characterizing cancer and non-cancer risks and a
discussion of the interpretation of Risk Characterization results within the context of the Solid
Waste Facility Siting Regulations is provided below. This section also describes how
uncertainties in the risk assessment should be addressed.
4.4.1 Non-cancer Risk
The measure used to describe the potential for non-carcinogenic health effects is the
Hazard Quotient(HQ). For a given chemical, the HQ is the ratio of a receptor's exposure level
(or dose) for a single chemical to the "acceptable"(or allowable) exposure level for that
chemical. For exposure to multiple chemicals, the chemical-specific Hazard Quotients may be
summed to calculate a Hazard Index (HI).
Hazard Index=HQ1 +HQz +HQ3 +...+HQ„
45
A Hazard Index of 1.0 or less indicates that adverse health effects from the exposures
under assessment are unlikely. When the Hl is less than or equal to 1.0, the conclusion is that the
proposed facility poses an acceptable risk of harm to human health.
A HI of greater than 1.0 indicates that non-cancer health effects could occur, and cannot
be ruled out. It does not mean that non-cancer effects will occur. Uncertainty inherent in most
toxicity benchmark values precludes identifying a specific dose above which adverse effects are
likely and below which effects are unlikely. Accordingly, the probability of an effect cannot be
quantified from a HI. For anv one chemical. it is always true that the likelihood of an effect
increases as the exposure level (and therefore the HI) increases.
The uncertainty inherent in toxicity benchmark values for different chemicals differs both
qualitatively and quantitatively. Therefore, for different substances,the probability of an effect
increases at different rates. For example, a HI of 20 for one substance may indicate a very high
probability of an effect, but may represent only a moderate probability of an effect for another
chemical.
In interpreting the HQ or HI, one should consider the appropriateness of the exposure
assumptions and the basis of the toxicity information used to develop the toxicity benchmark
values. As a general rule,the greater the HI is above 1.0, the greater the level of concern.
In its most general form,the Hazard Quotient associated with a chemical via inhalation is
calculated as:
HQ= ADE " or,for dose equations: HQ= ADD`"
Where:
HQ= The Hazard Quotient associated with exposure to the chemical via
inhalation
RIC= The Reference Concentration or substitute toxicity value identified for the
chemical of concern for chronic exposure (in mg/m3).
RID = The oral Reference Dose or appropriate substitute toxicity value identified
for the chemical of concern. (in mg/kg/day).
ADEa,,= The estimated Average Daily Exposure of the chemical via the specified
exposure route. (in mg/m).
ADDe,,= The estimated Average Daily Dose of the chemical via the specified
exposure route. (in mg/kg/day).
As mentioned previously,total non-cancer risks should be calculated for each facility.
The HI accounts for inhalation exposures that a receptor may receive from multiple chemicals
emitted from the proposed facility and represents the non-carcinogenic impact of that facility to
receptors.
46
The documentation of the Risk Characterization should clearly present all mathematical
equations used to calculate total non-cancer risks for inhalation.
4.4.1.1 Screening Hazard Index
Initially, the risk assessor should calculate a Screenitte Hazard Index for a given receptor
by totaling all the individual chemical-specific HQs calculated as described above. A HI
calculated in this way will provide a conservative 13 estimate of the true HI because it treats as
additive, different toxic effects from multiple chemicals acting on different organ systems by
different mechanisms of action. In fact, in a true HI,the only endpoints that should be treated as
additive are those that produce adverse effects on the same organ system by the same
mechanism. Thus, the screening Hi will provide a conservative estimate of the actual HI
because it reflects the sum of toxicities for multiple chemicals, regardless of the chemical's
health endpoint, target organ or mechanism of action.
There may be multiple adverse health effects associated with exposure to a given
chemical and it is the most sensitive adverse health effect observed in the scientific data which
typically drives estimation of the Reference Concentration and other toxicity benchmarks. Thus,
for a given group of chemicals, Reference Concentrations may be based on different toxic effects
on different organ systems by different mechanisms of action.
The screening HI should be compared with the total non-cancer risk limit, which is a HI
equal to 1.0. If the screening HI is less than 1.0, then no additional effort is needed to
characterize non-cancer risks. However, if the screening Hi exceeds 1.0,the risk assessor may
then group together chemicals with similar toxic effects and mechanisms of action and calculate
a separate HI for each group.
Separate HIs should be calculated for different exposure periods, both subchronic and
chronic.
4.4.1.2 Health Endpoint-Specific Hazard Index (Multiple Chemicals)
The procedure for segregating His by effect and mechanism of action is not simple and
should be performed by a toxicologist. If the segregation is done improperly, an underestimate
of the true hazard could result. Segregation of HIs requires identification of the major health
endpoints of each chemical, including effects observed at higher doses than the critical effect on
which the toxicity value is based. This is because the critical effect for one chemical may not be
relevant for other chemicals and doses of other chemicals may not be additive for that effect. On
the other hand, additive impacts could be important for other health endpoints that are only
expected at higher doses.
"Current USEPA methodology is based on additivity of risk. It is acknowledged however that there is an inherent
uncertainty in the assumption that the addition of risks is a conservative approach. Actual risks may be over-
estimated if this assumption is correct or they may be underestimated since possible synergistic effects are not
addressed.
47
Major effect categories that should be considered in segregating chemicals include
neurotoxicity, developmental toxicity, reproductive toxicity and immunotoxicity. Adverse
effects also should be categorized by target organ (i.e., hepatic, renal, respiratory, cardiovascular,
gastrointestinal, hematological, musculoskeletal and dermal/ocular).
Once chemicals have been categorized,total inhalation hazard indices (for subchronic
and chronic toxicity) for chemicals with similar health endpoints and mechanisms of toxicity
should be calculated by summing the chemical-specific HQs calculated for each of these
chemicals. Each HI should be compared with MassDEP risk management criteria for siting solid
waste facilities as presented in Section 4.6.
4.4.2 Cancer Risk
The potential for carcinogenic (i.e., non-threshold) health effects is characterized as the
Excess Lifetime Cancer Risk(ELCR). The ELCR represents the incremental probability of an
individual developing cancer over a lifetime as a result of exposure to the potential carcinogen.
For a given chemical, the estimated ELCR is the product of the receptor's quantified exposure
and a measure of carcinogenic potency. The typical measure of carcinogenic potency for
inhalation is the USEPA Unit Risk (UR) value.
In its basic form,the ELCR associated with exposure to a given chemical via a particular
exposure pathway is estimated as follows:
ELCR=LADE,„ x UR or, for dose equations: ELCR=LADD,,, xSF
Where:
ELCR= The Excess Lifetime Cancer Risk associated with exposure to the chemical via
inhalation.
LADE,,= The Lifetime Average Daily Exposure to the chemical in air. In µg/rn .
LADDw,= The Lifetime Average Daily Dose of the chemical in air. In mg/kg-d.
UR= The Unit Risk for the particular chemical of concern. In(µg/m )-I.
SF = The Cancer Slope Factor identified for the chemical, for the inhalation
exposure pathway. In (mg/kg*d)-l.
The Lifetime Average Daily Exposure (LADE,,,) (and the LADDa,,) is calculated from
the Exposure Point Concentration using exposure assumptions identified for the receptor being
evaluated. The Exposure Assessment Section of this Guidance describes the process for
calculating the receptor's LADEa,r. The selection of Unit Risk values is discussed in greater
detail in the Dose-Response Section.
Total inhalation cancer risks should be calculated, including all Class A and B
carcinogens (i.e., chemicals classified by USEPA as being known human carcinogens and
probable human carcinogens). In addition, for those Class C carcinogens (i.e., those classified
by USEPA as being possible human carcinogens) for which unit risk factors exist, inhalation
cancer risks should also be calculated and included in the total ELCR. For those Class C
carcinogens for which the available toxicity data are insufficient to quantify cancer risks, the
48
potential carcinogenic effects of these substances should be discussed qualitatively in the
uncertainty section of the risk assessment. As discussed previously, all carcinogens for which
MassDEP has provided unit risk information in Table 7 should be evaluated at a minimum.
The total ELCR for inhalation represents the total carcinogenic impact that the proposed
facility has on a particular receptor. The total ELCR accounts for exposures that a receptor may
receive from multiple chemicals via inhalation.
As shown by the following equation,the Total Facility ELCR can be calculated by summing
all of the chemical-specific inhalation ELCRs calculated as described above.
Total Facility ELCR =E ELCR he.,.,-sP,,,,,
The total ELCR should be compared with MassDEP risk management criteria for siting
solid waste facilities as presented in Section 4.6.
The documentation of the Risk Characterization should clearly present all mathematical
equations used to calculate Total Facility Cancer Risks.
4.4.3 Available Tools
MassDEP has developed a spreadsheet for conducting a quantitative risk assessment for
municipal solid waste landfills. This spreadsheet addresses the default list of COC suggested in
this document. It may be accessed at the MassDEP web site at httD://www.mass.gov/den. For
certain proposed landfills or expansions that need to consider additional chemicals (e.g., such as
for a facility that takes in greater than fifty percent of a particular special waste), the risks from
these chemicals should be calculated separately and added to the risk determined using the
spreadsheet.
4.5 Uncertainty Analysis
The Uncertainty Analysis is an important component of the Risk Characterization. A
Risk Characterization is not considered complete unless an Uncertainty Analysis that identifies
and discuses the uncertainties in the risk assessment is included. The Uncertainty Analysis
should contain a narrative section that places the numerical risk estimates in the overall context
about what is known and what is not known about the proposed facility or expansion and in the
context of decisions that MassDEP will make about potential mitigation.
The dose-response and exposure assessment guidance presented in this document are
intended to provide a consistent framework for evaluating potential site impacts. However,the
numerical risk estimates calculated using this guidance, or for that matter any risk assessment
methodology, should not be interpreted as precise estimates of the risk of harm to health. Due to
fundamental limitations in the available science and practical limitations in the extent to which
data can be obtained and analyzed, all facility impact assessments, whether of a quantitative or
qualitative nature, require the exercise of scientific and professional judgment. These limitations
introduce a variety of uncertainties into the process, some of which may lead to overestimations,
49
and some to underestimations, of actual risk. Because of this an Uncertainty Analysis section
should be included in all risk assessments completed using this guidance.
The types and sources of uncertainty in the risk assessment that should be discussed in
the Uncertainty Analysis include, but are not limited to:
• identification of facility-related contaminants of concern;
• The use of modeling to develop emissions and Exposure Point Concentration
estimates;
• Interpretation of qualitative and quantitative toxicological data used to develop cancer
and non-cancer toxicity values;
• Development of Exposure Profile(s) and selection of exposure assumptions used in
dose calculations.
Although the Uncertainty Analysis may be a qualitative assessment of uncertainties
affecting the risk estimates,the risk assessor should attempt to describe the magnitude and
direction of effect that a particular area of uncertainty is likely to have on the numerical risk
estimates.
4.6 Risk Management
The risk management criteria that MassDEP uses to make a decision on site suitability for
Level 2 assessments are based on two parameters, including facility-specific risks and emissions
of VOCs from other point sources in the area. MassDEP has integrated these factors in a matrix
considering the risk posed by the facility itself and the risk posed by nearby facilities.
The facility-specific risk is estimated using quantitative risk assessment as described in
this document and is represented as estimated Total Facility Hazard Index (HI) and Excess
Lifetime Cancer Risk(ELCR). Absent any other significant factors,the risk management
criteria that MassDEP has established for the Massachusetts Contingency Plan (MCP) should
apply to a proposed facility. These criteria include a facility HI of one (1) and an ELCR of one
in one hundred thousand (1 x 10-5)14.
Proposed facilities that pose a de minimis risk are generally approvable at any location.
A de minimis risk is generally considered an insignificant risk. A de minimis risk is defined as a
Total Facility ELCR of one in one—million (1 x 10-6) and a Total Facility HI of 0.1. Where a
facility exceeds de minimis risk and there are other significant emissions of VOCs in the
immediate area, more stringent risk management criteria may be appropriate.
The risk posed by other facilities in the area is qualitatively evaluated using a sum of total VOC
emissions from air point sources15 within a mile of the proposed facility, unless otherwise
determined by MassDEP. The quantification of cancer and non-cancer risk posed by these
14 These are the same risk management criteria that apply to exposures associated with the post-closure,off-site
migration of COC(including landfill gas emissions)from Solid Waste Management Facilities pursuant to the
"Adequately Regulated"provisions of the MCP(310CMR 40.0114)
15 As listed in MADEP's Stationary Source Emissions inventory System database
50
emissions is not required. As discussed in Section 1.2, use of this indicator assumes that the
higher the emissions are from adjacent air point sources, the higher is the potential risk in the
community affected by these facilities. Total VOC emissions should be compiled from the
MassDEP SSEIS database from all point sources registered in the database that are within one
mile of the proposed facility's perimeter, unless determined otherwise by MassDEP. This total
should also include emissions from all existing point solid waste facilities at the proposed
location. The facility proponent may choose to conduct multiple facility source modeling and
quantitative risk assessment of the adjacent sources to provide a refined estimate of overall
risk 16.
Facility specific and emissions of total VOCs from point sources in the area are evaluated within
the context of a number of other criteria including other factors affecting environmental
conditions in the community, uncertainty of the available quantitative data and the status of any
commitment to clean up any surface and groundwater contamination to comply with applicable
laws and regulations if the plan is a proposed landfill expansion. (A remediation plan must be
approved by MassDEP before the expansion is approved.). Other factors affecting the
community's environmental conditions might include possible mitigation/offset measures
offered by the proponent, expected future change to emissions from facilities in the area, types of
land uses, and specific particulate matter sources such as solid waste management facilities, junk
yards, auto salvage shops, bus and truck depots, etc., and the environmental impacts of not
constructing the facility.
Figure 2, entitled"Quantitative Assessment Review" illustrates MassDEP's risk
management approach for evaluating quantitative information that has been developed using the
protocol described in this document. The darkly shaded area below represents those facilities
with an estimated Excess Lifetime Cancer Risk(ELCR) greater than one in one hundred
thousand or an estimated Hazard Index greater than one. Outside the darkly shaded area,the
facility itself poses an acceptable risk. The facility site may be approved unless emissions from
adjacent air point sources are high. In that case, additional mitigation may be required.
16 The facility proponent should consult with MADEP prior to initiating such work. Such an analysis could be part
of the initial proposal,prior to a requirement for mitigation,prior to the issuance of a negative site suitability report,
or as part of a request for reconsideration.
51
Figure 2.
Quantitative Evaluation Review
1 Facility Risk Estimates I
< 1x10 < 1x10 S > 1x10 s 1 'ELCR and
— I . ..<0.1 < 1 > 1 U --
ssions
From 0
Adjacent ___--
Air Point
Sources
tons/yr)
High
In general,MassDEP would likely issue a positive site suitability report if the risk
management criteria are clearly met, suggest mitigation measures if the results are near the proposed
limits,or require changes to the proposal or mitigation measures if one or more of the criteria are
exceeded. Mitigation options may include controls on emission sources at the site and/or off-site
mitigation.
MassDEP's assessment will be based on site-specific factors. Where the combination of
factors indicates that the location may not be suitable for the proposed facility,the burden of proof
is on the applicant to overcome the presumption that the facility would result in unacceptable
environmental and public health impacts.
52
SECTION 5: Water Resources
Proponents of landfill expansion projects must evaluate the impacts of the existing
facility on groundwater and surface water. Where an existing facility has affected groundwater
or surface water, the risk of harm to public health and the environment from the contamination
must be characterized, and a plan for remediation developed if necessary for compliance with
appropriate water quality standards. MassDEP will review plans for assessment and remediation
in conjunction with its review of applications to construct landfill expansions, and will establish
permit conditions requiring implementation of remedial action plans where necessary.
MassDEP has published a separate guidance document titled Guidance for the
Assessment of Groundwater and Surface Water for Solid Waste Facility Site Assignment and
Permitting in Support of 310 CMR 16.00& 19.000, which provides more extensive guidance on
what groundwater and surface water assessments should cover. This guidance includes a
discussion of important considerations that should be addressed regarding the assessment of
water resources around an existing or expanded solid waste facility. The overlap between the
MCP (3 10 CMR 40.0000)and site assignment (3 10 CMR 16.00) is discussed with regard to
water resources, including the MCP "adequately regulated"provision. This guidance specifies
the performance standards that should be met for the assessment of water quality. In addition, it
also includes checklists to assist in identifying the components of the water assessment.
53
SECTION 6: Facility Impact Assessment Report Content and
Submission Process
This section addresses the minimum types and amounts of information that should be
submitted in a timely fashion in support of a Level I or Level 11 assessment. The Facility impact
assessment submitted in support of a decision for site suitability or authorization to construct
permit should provide a comprehensive picture of the risks associated with the proposed facility
in accordance with this Guidance Document.
Appendix A of this document contains a checklist, entitled "Checklist for Facility impact
assessment of Solid Waste Facilities", that summarizes the minimum descriptive and technical
components that the Facility impact assessment should include. This checklist may be used for
planning an optional Scope of Work or in preparing the report within the applicable permit
application process. A discussion of report content is provided in Section 6.1. The provision for
submitting an optional Scope of Work is discussed in Section 6.2. The timing and requirements
of the overall permit application process are discussed in Section 6.3.
6.1 Report Content
The facility impact assessment report should include the descriptive and technical
information described below. The report should include an overview that includes a basic
description of the site and of the proposed facility/expansion. Important components of the
overview should include:
• the purpose of the assessment(i.e., is it for a new site assignment or a modification of an
existing one);
• the proposed development schedule(if there are multiple stages);
• historical and current use of the site;
• a description of the location (including an address) of the proposed facility;
• important topographical and meteorological features of the area and/or the facility itself;
• a description of best management practices (BMPs)that will be incorporated in the
design and operation of the facility;
• a map of the facility and its surroundings (indicating the permitted area of the proposed
landfill or expansion), including:
o the location of any receptors;
o amount and types of waste to be disposed;
o the proposed capacity of the facility; and
o ajustification for the selected method of assessment(i.e., Level I or Level II).
The report should next describe the basic components of the qualitative or quantitative
assessment. For a Level I qualitative assessment, the report should provide information on
facility size, best management practices (BMPs)proposed for the facility and information on
emissions from adjacent sources, preferably within the context of the information presented in
the overview.
For a Level II quantitative assessment, the following additional information should be
submitted:
54
• an overview of the general modeling approach -The name and reference information
for the emissions and dispersion models to be used should be included in this
information.
• a description of modeling inputs and assumptions - This information should include
appropriate documentation as to the source of these factors, including the source of
meteorological data used for modeling;
• basic risk assessment components—This information should include the list of
Chemicals of Concern (COC), along with the basis upon which the list was compiled,the
list and sources of dose-response information, a description of risk assessment exposure
assumptions and adjustments made to exposure point concentrations, a description of
equations used to calculate non-cancer and cancer risks and a description of the
uncertainties inherent in the modeling and risk assessment calculations;
• a summary of tons per year VOCs emitted from adjacent facilities within a mile of
the solid waste facility—This information should include a brief description of the
facilities identified and the types of VOCs they generate. The printout from SSEIS
should be included in the report. For a landfill expansion, the quantification of facility-
related VOC emissions should also include an estimate of total VOCs generated from the
existing portion of the solid waste facility as available from SSEIS.
• a description of current and proposed BMPs at both the existing portion of the
facility, if applicable, and the new or expanded area - This information should include
a description of all BMPs currently in place at the existing facility, a description of the
landfill double liner system that will be installed at the new or expanded portion of the
facility, as well as a description of all BMPs to be installed.
Finally, for any landfill for which an expansion is proposed, the report must include an
assessment of the impacts of the existing facility on groundwater and surface water. See Section
5 and Appendix B for guidance on conducting this assessment and determining whether remedial
action is needed. Appropriate documentation as specified in this Appendix should be submitted
to support the assessment of groundwater and surface water resources.
6.2 Submission of Proposed Facility impact assessment Protocol and Scoping Activities
For facilities that take in a large amount of non-traditional or special wastes or in cases in
which the default modeling and/or impact assessment approaches presented in the Guidance
Document are inappropriate,the facility assessment report may be preceded by an optional scope of
work (SOW) or report protocol A SOW may be submitted by a facility applicant for MassDEP
review and feedback. The facility applicant should submit one (1) copy of the SOW directly to the
appropriate regional office, and two (2) copies of the SOW to MassDEP-Boston, at the following
address:
55
Massachusetts Department of Environmental Protection
Bureau of Waste Prevention
Attn.: FIA Review
One Winter Street—8th Floor
Boston, Massachusetts 02108
The applicant should contact the appropriate MassDEP regional office to discuss the
applicant's project and determine whether a SOW review is necessary. MassDEP will review a
draft SOW if necessary and provide either written comments and/or hold a scoping session to
discuss comments with the applicant. The appropriate regional office will schedule and coordinate
any necessary scoping session. In addition, the appropriate regional office will coordinate all
communication to MassDEP-Boston regarding any review of a proposed SOW.
The SOW may describe the planned content of the report, or details pertaining to other
aspects of the assessment including, for example, landfill gas sampling and analysis protocol,
modeling methodologies, proposed changes to default methods or data sources or other
alternative assessment approaches. After the protocol has been reviewed, the proponent may
prepare the final facility impact assessment report, guided by the decisions made in the SOW.
The SOW should be submitted well in advance of the beginning of the affected permit review
period (including both the administrative and technical review periods)to allow time to
coordinate the preparation of the impact assessment report with all other required permit
application submittals.
6.3 Submission of a Facility impact assessment within Applicable Permit Applications
Permit applicants must comply with the permit submittal requirements governing the
specific solid waste management facility permit being requested (e.g., 310 CMR 16.04(b) for a
Site Suitability Report. In addition to the submittal requirements stated in 310 CMR 16.00,the
applicant should submit one (1) copy of the permit transmittal form along with three(3) copies
of the complete impact assessment report, including all supporting documentation,to
MassDEP's Boston office at:
Massachusetts Department of Environmental Protection
Bureau of Waste Prevention
Attn.: Facility impact assessment (FIA)Review
One Winter Street—8th Floor
Boston, Massachusetts 02108
Increasingly, the Massachusetts Environmental Protection Act(MEPA) has required
either the facility impact assessment or at the very least, a discussion of the applicant's proposed
plans to proceed with such an assessment as required in 310 CMR 16.00. MassDEP encourages
a facility impact assessment during the MEPA process. The performance of an impact
assessment during the MEPA process allows the facility applicant additional time to conduct the
assessment and to receive comments from MassDEP prior to MassDEP's review of the impact
assessment report during permit application review. If the applicant conducts a facility impact
assessment during the MEPA process, the applicant should submit one (1) copy of the
56
Environmental Notification Form and any subsequent Environmental Impact Report(including
any subsequent Supplemental and Final Impact Reports)to the appropriate MassDEP regional
office and three (3) copies of the facility impact assessment to MassDEP's Boston office at:
Massachusetts Department of Environmental Protection
Bureau of Waste Prevention
Attn.: Facility Impact Assessment(FIA)Review
One Winter Street—8th Floor
Boston, Massachusetts 02108
If an applicant has completed a facility impact assessment for the proposed facility for
MEPA, the applicant should resubmit one (1) copy of the impact assessment to the appropriate
MassDEP regional office and three (3)copies to MassDEP's Boston office (at the above
address), including all relevant appendices cited in the impact assessment, all public and MEPA
comments received with respect to the impact assessment, and documentation of MEPA's
acceptance of the facility impact assessment(this may be in the form of MEPA's final comments
and Project Certification). MassDEP will review impact assessment reports submitted as part of
site assignment applications of solid waste facility permit applications. If MassDEP identifies
deficiencies in the report, MassDEP will provide comments to the facility applicant.
For Site Suitability Permit Applications(3 10 CMR 16.00):
1. During the initial 40 days of the Review Period, MassDEP may require the
applicant to respond to any comments it has received from the local board of
health and other interested persons pursuant to 310 CMR 16.11 (3) (a).
2. The Applicant may modify its impact assessment within the initial 40 days of
the Review Period in accordance with 310 CMR 16.11 (3) (a-b)Application
Response and Modification.
3. If MassDEP determines that the deficiencies are significant in accordance
with 310 CMR 16.11 (5) MassDEP may require the applicant to provide
additional information. At the point of MassDEP's request for additional
information the applicant may:
a. Submit the information and be subject to 310 CMR 16.11 (3)(b)(c)
modification of application regulations
b. Formally withdraw the site suitability application until such time as a
complete application, including a complete facility impact assessment,
may be submitted; or
c. Let MassDEP continue its review of the unmodified application.
MassDEP reserves the right to rescind any approval of a facility impact assessment if
significant information is received in the future regarding the scientific integrity of the
information in the impact assessment report. In addition, MassDEP will require all BMPs and
mitigation activities proposed by the applicant to be implemented as a condition of the applicable
facility permit. Failure to implement BMPs and other approved commitments would constitute a
violation of the facility permit and may result in enforcement actions.
57
58
References
Massachusetts Department of Environmental Protection (MassDEP). July, 1988. Ash Sampling
and Analysis Guidance. SWM-9-7/88 (as further clarified in 7/97 MassDEP communications to
facility operators).
Massachusetts Department of Environmental Protection. (MassDEP). July, 1995. Guidance for
Disposal Site Risk Characterization—in Support of the Massachusetts Contingency Plan. Bureau of
Waste Site Cleanup and Office of Research and Standards.
United States Environmental Protection Agency(USEPA). December, 1989. Risk Assessment
Guidance for Superfund (volume 1)—Human Health Assessment Manual (Part A)—Interim Final.
Office of Emergency and Remedial Response.
United States Environmental Protection Agency (USEPA). 1997a. Compilation of Air Pollutant
Emission Factors,AP-42. 5`h ed. Supplement C. Office of Air Quality Planning and Standards.
Research Triangle Park,NC.
United States Environmental Protection Agency (USEPA). 1997b. Exposure Factors Handbook.
National Center for Environmental Assessment
United States Environmental Protection Agency (USEPA). 1997c. Health Effects Assessment
Summary Tables(HEAST). Solid Waste and Emergency Response. FY 1997 Update.
United States Environmental Protection Agency(USEPA). 1997d. Emission Factor
Documentation for AP-42 Section 2.4—Municipal Solid Waste Landfills—Revised.
United States Environmental Protection Agency(USEPA). February, 1998. User's Manual—
Landfill Gas Emissions Model. Air Pollution Prevention and Control Division; Control Technology
Center; and Office of Research and Development.
United States Environmental Protection Agency (USEPA). 2001. Integrated Risk Information
System(IRIS)database. httD://www.eoa.aov/neisDam3/iris/subst/index.htmi.
59
APPENDIX A
Checklist for Facility impact assessment
of Solid Waste Facilities
I
Checklist for Facility impact assessment of Solid Waste Facilities
For All Level 1 and Level 2 Assessments
Facilitv Based Imnaet Assessment (FIA) Submissions:
Scope of Work(SOW) >>(See Section 6.2)
❑ Submit one (1) copy of the proposed SOW to the appropriate MassDEP regional office
❑ Submit two (2) copies of the proposed SOW to MassDEP - Boston office
FIA Assessment Performed During MEPA >>(See Section 6.3)
❑ Submit one (1) copy of the ENF and subsequent EIR(including any subsequent SEIR and
FEIR) to the appropriate MassDEP regional office
❑ Submit three (3) copies of the FIA assessment(including all relevant appendices cited in
the FIA assessment)to MassDEP—Boston office
❑ If submitting an FIA assessment performed during MEPA within a formal Site
Assignment or Solid Waste Facility Permit, submit:
■ One (1) copy of the FIA Assessment to the appropriate MassDEP regional
Office
• Three (3) copies of the FIA Assessment to MassDEP—Boston office
• All relevant appendices cited in the FIA assessment
■ All comments received regarding the impact assessment from all
interested parties and MEPA
• Documentation of MEPA's acceptance of the FIA assessment
General FIA Assessment >>(See Section 6.3)
❑ Submit one (1) copy of the FIA Assessment to the appropriate MassDEP regional Office
❑ Submit three (3) copies of the FIA Assessment to MassDEP—Boston office
All Submissions to MassDEP—Boston should be directed to:
Massachusetts Department of Environmental Protection
Bureau of Waste Prevention
Attn.: FIA Review
One Winter Street— 8th Floor
Boston, Massachusetts 02108
Acronyms:
SOW—Scope of Work SEIR—Supplemental Environmental Impact Report
ENE—Environmental Notification Form FEIR—Final Environmental Impact Report
FIR—Environmental Impact Report FIA—Facility impact assessment
2
Descriptive Information: >>(See Section 6.1)
❑ Description of proposed facility/expansion, potentially exposed receptors and
surrounding land uses within one mile
❑ Purpose of assessment
❑ Information on historical/current use of site
❑ Description and address of proposed facility/expansion
❑ Pertinent site-related information (e.g., topography, meteorology, etc.)
❑ Proposed capacity of the facility in tons per day
❑ Description of development schedule
❑ Level of impact assessment (i.e., Level 1 or Level 2) with justification for selection
❑ Map of the proposed facility/expansion and surroundings
❑ location of receptors indicated
❑ map of permitted area of the proposed facility
Industrial Emissions from Adjacent Sources >>(See Section 1.2)
❑ Description and quantification of total facility-related VOC emissions within one mile of
the facility provided(from SSEIS database)
❑ Printout from SSEIS
❑ For a facility expansion,total VOC estimate from SSEIS for the existing facility
Best Management Practices >>(See Section 2.1)
❑ Detailed assessment of the proposed facility with respect to the major"areas of concern"
❑ Proposal of specific BMPs to be implemented by the facility and a detailed discussion
regarding their ability to reduce potential impacts in relation to the major"areas of
concern"
For All Landfills
Water Resources Assessment: >>(See Section 5.0 and Appendix B)
❑ Description of cleanup plan to achieve groundwater and surface water standards under
the Solid Waste and MCP programs(if applicable). (See Section 5 and separate
MassDEP guidance titled Guidance for the Assessment of Groundwater and Surface
Water for Solid Waste Facility Site Assignment and Permitting in Support of 310 CMR
16.00& 19.000.)
A-3
For Level 2 Assessments—Ouantitative Assessment
Hazard Identification >>(See Section 4.1)
❑ Chemicals of Concern (COC) identified
❑ For a MSW landfill, AP-42 chemicals
❑ Exceptions to AP-42 list(based on monitoring and/or literature information)
explained and MassDEP approval obtained before risk assessment undertaken
❑ Based on nature of waste proposed to be handled by the facility (e.g., special wastes;
other) additional COC proposed and approved by MassDEP (if applicable)
❑ Toxicity profiles for each COC
Dose-Response Assessment >>(See Section 4.2)
❑ Dose-response information (including source and/or values) identified for each COC in
the risk assessment
❑ Use of the toxicity information for the AP-42 chemicals
❑ Source of and/or dose-response values proposed and approved by MassDEP for other
COC
Exposure Assessment >>(See Section 4.3)
❑ Screening case exposure profile and/or refined exposure profile developed
❑ Name of emissions model used
❑ Name of dispersion model
❑ Receptor network defined and (for refined exposure profile) sensitive receptors
identified/included
❑ Modeling inputs defined
❑ Modeling outputs defined
❑ Risk assessment exposure assumptions defined and explained (including source of data)
❑ Description of approach used to calculate exposure point concentrations
Risk Characterization >>(See Section 4.4)
❑ Description of approach used to calculate non-cancer and cancer risks
❑ Statement as to whether the MassDEP-developed spreadsheet was used in conducting the
risk
Uncertainty Analysis >>(See Section 4.5)
❑ Description and quantification of facility-related VOC emissions from SSEIS database
A-4
Page 1 of 1
Joanne Scott +
From: Carrigan, John (DEP) [John.Carrigan@state.ma.us]
Sent: Monday, June 09, 2008 10:15 PM
To: Joanne Scott
Subject: facility Impact Guidance "
Attachments: FacilityAssGuideSiteAssignment2006.pdf
Joanne:
Attached is the Department's guidance for conducting Facility Impact Assessments under 310 CMR 16.000.
Note for facilities other than landfills such as, transfer stations the Department determined that qualitative risk
assessments including,the collection of monitoring data assessment provided the facility operation included
appropriate Best Management Practices. Table 3 on page 11 of the attached document identifies the BMPs the
Department believes are appropriate in general for facilities such as the proposed Salem Transfer Station. Note
that with regards to the issue of doors the BMPs provide for the use of mechanical doors in combination with
plastic hanging strips. The closing of mechanical doors is generally a requirement at facilities such as C&D
processing facilities where grinding is occurring.
JohnC
John A. Carrigan, Chief
Solid Waste Management Section
Bureau of Waste Prevention
Northeast Regional Office Massachusetts Department of Environmental Protection
2058 Lowell Street
Wilmington, MA 01887
Phone: (978) 694-3299
Fax: (978)694-3499
For Intra-Agency Discussion Only
1
6/10/2008
COMMONWEALTH OF MASSACHUSETTS
EXECUTIVE OFFICE OF ENVIRONMENTAL AFFAIRS
DEPARTMENT OF ENVIRONMENTAL PROTECTION
ONE WINTER STREET, BOSTON, MA 02108 617-292-5500
MITT ROMNEY STEPHEN R.PRITCHARD
Governor
Secretary
KERRY HEALEY ROBERT W.GOLLEDGE,Jr.
Lieutenant Governor
Commissioner
Guidance for Conducting Facility Impact Assessment
for Solid Waste Facility Site Assignment
in Support of 310 CMR 16.00
Initial Publication: June 2001
Revised: March 22, 2006
Approved: Qvvv�m
Imes C. Colman
Assistant Commisioner
Bureau of Waste Prevention
This information is available in alternate format Call Donald M.Gomes,ADA Coordinator at 617-556-1057.TDD Service-1-800-298-2207.
DEP on the World Wide Web hftp//�.mass.gov/dep
.mass.gov/dep
�, Printed on Recycled Paper
This document is intended to guide parties, MassDEP staff
and others in conducting or reviewing facility impact
assessments for solid waste facilities in compliance with 310
CMR 16. 00.
This document is intended solely as, guidance. It does not
create any substantive or procedural rights and is not
enforceable by any party in any administrative proceeding within
the Commonwealth. This document summarizes the requirements of
310 CMR 16. 00 and provides guidance on approaches MassDEP
considers acceptable for meeting the general requirements for
conducting a facility impact assessment for solid waste
facilities as set forth in these regulations. Parties using
this guidance should be aware that there may be other acceptable
alternatives for achieving compliance with general regulatory
requirements.
Regulatory citations in this document should not be relied
upon as a complete list of the regulatory requirements related
to conducting a facility impact assessment pursuant to these
regulations. Parties conducting a facility impact assessment
for solid waste facility site assignment should consult 310 CMR
16. 00.
2
Table of Contents
ExecutiveSummary........................................................................................................................v
SECTION1: Introduction.............................................................................................................. 1
1.1 Applicability and Scope.....................................................................................................2
1.2 Accounting for Emissions from Other Faciliities.............................................................. 3
SECTION 2: Facility Assessment Screening Protocol..................................................................4
2.1 Best Management Practices...............................................................................................7
2.2 Assessment Appropriate To Facility Type..................................................................... 13
2.2.1 Waste-Handling Facilities of Any Size..................................................................... 13
2.2.2 Small Landfills That Take in Less Than or Equal to 150 Tons Per Day.................. 14
2.2.3 New Landfills and Expansions That Take in Greater Than 150 Tons Per Da}......... 14
SECTION 3: Qualitative Impact Assessment............................................................................. 15
SECTION 4: Quantitative Impact Assessment............................................................................ 17
4.1 Hazard Identification—Contaminants of Concern (COC).............................................. 17
4.1.1 Proposed Landfills....................................................................................................20
4.1.1.1 Types of Landfills.................................................................................................. 20
4.1.1.1.1 COC in Landfill Gas from Municipal Solid Waste Facilities.......................21
Landfill Area Sources...................................................................................................21
Landfill Gas Constituents .........................................................................................21
AP-42 Chemicals................................................................................................... 22
OtherChemicals....................................................................................................22
SpecialWastes.......................................................................................................23
LandfillPoint Sources.................................................................................................. 25
StackGas Constituents ............................................................................................. 25
AP-42 Chemicals................................................................................................... 26
Other Landfill Gas Chemicals...............................................................................26
Secondary Pollutants from Stack Emissions.........................................................26
4.1.1.1.2 COC From Non-Municipal Solid Waste Landfills.......................................26
AshLandfills................................................................................................................27
Unprocessed Construction and Demolition Landfills (C&D)......................................28
4.1.2 Emissions From Proposed Waste Handling Facilities..............................................28
4.1.3 Diesel Particulates..................................................................................................... 29
4.1.4 Toxicity Profiles........................................................................................................ 30
4. 2 Dose-Response Assessment............................................................................................ 30
4.2.1 Conversions from Dose............................................................................................. 32
4.2.2 Sources of Dose-Response Values............................................................................ 33
4.2.3 Dose-Response Information for the AP-42 Chemicals............................................. 34
4.2.4 Relative Absorption Factors ..................................................................................... 35
4.3 Exposure Assessment...................................................................................................... 35
4.3.1 Screening Case Exposure Profile.............................................................................. 36
4.3.2 Refined Exposure Profile.......................................................................................... 36
4.3.3 Quantitative Estimates of Exposure.......................................................................... 37
4.3.3.1 Modeling Approach Used to Calculate Exposure Point Concentrations............... 38
4.3.3.1.1 Landfill Gas and Particulate Emissions........................................................ 39
4.3.3.1.1.1 Municipal Solid Waste Landfills............................................................... 39
Area Sources (Uncontrolled Emissions)................................................................... 39
Area Sources (Controlled Emissions)....................................................................... 39
Point Sources(Controlled Emissions)......................................................................40
Non-Municipal Solid Waste Landfills.........................................................................40
Area Sources (Uncontrolled Emissions)..................................................................40
4.3.3.1.2 Air Quality Impact Analysis Modeling Protocol..........................................40
Sourcedata...................................................................................................................40
ReceptorNetwork ........................................................................................................41
MeteorologicalData.....................................................................................................42
Atmospheric Dispersion Coefficients..........................................................................42
AirQuality Models.......................................................................................................42
4.3.3.1.3 Air Quality Impact Analyses Report.............................................................42
Averaging Times of Concern.......................................................................................42
Contents of Air Quality Impact Analysis Report.........................................................42
4.3.3.2 Calculation of Average Daily Exposures,r.............................................................43
4.3.3.3 Inhalation of Particulate-Associated Contamination.............................................44
4.3.3.4 Calculation of the Lifetime Average Daily Exposure (LADE) or the Lifetime
Average Daily Dose(LADD).............................................................................................45
4.4 Risk Characterization ...................................................................................................... 45
4.4.1 Non-cancer Risk........................................................................................................45
4.4.1.1 Screening Hazard Index..........................................................................................47
4.4.1.2 Health Endpoint-Specific Hazard Index (Multiple Chemicals) ............................47
4.4.2 Cancer Risk............................................................................................................... 48
4.4.3 Available Tools.........................................................................................................49
4.5 Uncertainty Analysis.......................................................................................................49
4.6 Risk Management............................................................................................................ 50
SECTION 5: Water Resources.................................................................................................... 53
SECTION 6: Facility impact assessment Report Content and Submission Process ................... 54
6.1 Report Content................................................................................................................. 54
6.2 Submission of Proposed Facility impact assessment Protocol and Scoping Activities .. 55
6.3 Submission of a Facility impact assessment within Applicable Permit Applications..... 56
REFERENCES.............................................................................................................................. 59
APPENDIX A. Checklist for Facility impact assessment of Solid Waste Facilities
ii
List of Tables
Table 1. Summary of Revised Siting Requirements/Criteria......................................................... 5
Table 2. MassDEP Approved BMPs for Landfills........................................................................ 9
Table 3. MassDEP Approved BMPs for Waste Handling Facilities........................................... 11
Table 4. Level 1 Qualitative Impact Assessment - Waste Handling Facilities............................ 16
Table 5. Level 1 Qualitative Impact Assessment- Small Landfills ............................................ 16
Table 6. List of Landfill AP-42 Chemicals.................................................................................. 19
Table 7. Toxicity Information for the AP-42 List of Chemicals.................................................24
List of Figures
Figure 1. MADEP Protocol for Selecting Level of Assessment.................................................... 6
Figure 2. Quantitative Assessment Review................................................................................. 52
iii
For further information, please contact:
• Solid Waste Regulations &BMPs: James Doucett, Bureau of Waste Prevention.
(James.Doucett(a,,state.ma.us) (617) 292-5868
• Risk Assessment: Carol Rowan West and Diane Manganaro, Office of Research &
Standards—(Carol.Rowan.West(a),state.ma.us) (617) 292-5570;
(Diane.Maneanaroa,state.ma.us) (617) 556-1158
• Emissions and Dispersion Modeling: Stephen Dennis, Bureau of Waste Prevention
(Steohen.Dennis a.state.ma.us) (617) 292-5766
• Stationary Source Inventory Emissions System (SSEIS): Robert Boisselle, Bureau of
Waste Prevention (Robert Boiselle(a�,state.ma.us) (617) 292-5609
• GIS Information: Brian Brodeur, Bureau of Planning and Policy
(Brian.Brodeur(astate.ma.us) (617) 574-6802
• Diesel Emission Controls, Tom Naderi, Bureau of Waste Prevention
(Soroosh.Naderi(a-).state.ma.us) (617) 556-1124
• Groundwater Assessment Requirements: Contact the Solid Waste Program in your DEP
region.
iv
Executive Summary
Guidance for Conducting Facility Impact Assessment for Solid Waste
Facilities in Support of 310 CMR 16.00
Preface
This Facility impact assessment Guidance Document (hereafter referred to as the Guidance
Document) was developed to provide project proponents with information on how to complete
facility impact assessments for the Department of Environmental Protection (MassDEP) when
applying for site assignments under 310 CMR 16.00. This guidance document revises and
supersedes MassDEP's previous guidance titled Interim Risk-Evaluation Guidance for Solid Waste
Facility Site Assignment and Permitting, issued in June 2001. Important revisions include:
• assessments are now required for site assignments only, not for permits;
• assessments are no longer required for ash landfills;
• references to hydrogen sulfide issues, specifically for facilities handling construction and
demolition debris materials;
• a section on recommended best management practices; and
• a provision that applicants address the full site-assigned project, rather than doing a phase by
phase assessment.
This Guidance Document applies to those applicants who are applying for a site assignment or
major modification to a site assignment on or after June 8, 2001 (the effective date of the newly
revised Site Assignment Regulations at 310 CMR 16.00);and
The required assessment of the facility for purposes of site assignment may be conducted during the
MEPA process for projects requiring an environmental impact report. If that assessment is
complete and adequate,a second assessment will not be required in the site assignment process.
This Guidance Document does not apply to the following facilities or operations to which the solid
waste regulations do not apply or that are exempt from the site assignment:
a. Facilities and operations to which 310 CMR 16.00 does not apply as specified at
310 CMR 16.05(2).
b. Conditionally exempt recycling operations as specified at 310 CMR 16.05(3).
c. Conditionally exempt composting operations as specified at 310 CMR 16.05(4).
d. Other conditionally exempted operations as specified at 310 CMR 16.05(5).
e. Facilities that are not required to obtain a site assignment or permit pursuant to the
Determination of Need process specified at 310 CMR 16.05(6)-(10)
f. Facilities under construction as of June 8,2001 (the effective date of the newly revised
Site Assignment Regulations)
MassDEP uses this Guidance Document and the information provided by an applicant to determine
whether a site is suitable for a solid waste facility assuming that the facility meets all other
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requirements of 310 CMR 16.00. It is therefore incumbent upon the applicant to demonstrate and
otherwise provide MassDEP with sufficient information so that MassDEP can determine whether or
not to issue a favorable site suitability report. If the applicant fails to provide sufficient information
as determined by MassDEP during its review of an application,then the application will be deemed
to be technically deficient. The applicant will then be provided with an opportunity to supplement
the information provided in the application.
When MassDEP reviews facility assessments and issues a report containing a finding that the site
fails to meet the site suitability criteria,MassDEP may entertain written requests for reconsideration
from the applicant stating the basis on which the reconsideration is requested. Such a request must
be filed within 14 days of the issuance of MassDEP's site suitability report(310 CMR 16.14).
Unless MassDEP reaffirms or revises this guidance document within three years of the date it is
issued,this guidance document will "sunset"and will no longer be applicable. Within two years of
the date it is issued,MassDEP intends to initiate a review of the guidance and seek input from its
Solid Waste Advisory Committee to determine whether the guidance should be maintained as is,
revised, or eliminated.
Introduction
This Guidance Document presents MassDEP's current methodology for determining the level of
assessment required for proposed solid waste facilities, provides guidance on the impact
assessment procedures to be used for proposals, and provides a description of MassDEP's risk
management approach.
Depending on features of the proposed facility such as its type and size, use of BMPs, and other
factors, each proposed facility should be evaluated under a Level 1 (qualitative impact
assessment) or Level 2 (quantitative impact assessment) approach. Figure 1 describes this
approach, which is designed to help ensure that the level of assessment for a proposed facility is
commensurate with the potential for risk from the facility. In general, small facilities that are
well controlled receive a lower level of assessment(Level l assessment)than large facilities with
the potential for greater impact (Level 2 assessment).
Vi
Figure 1. MassDEP Protocol for Selectine Level of Assessment
Impact Evaluation Flowchart
Assumes all other requirements are met
(310 CMR 16.00)
Lc,cl I
Qualitative Impact Evaluation
Is the facility a new landfill'or „a.
landfill expansion>150 TPD 9�-
1na
A-Enhanced BMPs for dust 8 odor,and
planned use of low emission diesel equipment
for all equipment on site?
Yes tom: Noto all
A,B ane _ B-the capacity of the proposal is less than 150
tonS/da — ie,A„aand
pf
app licable)C Y Id applicablelC
C-(for landfills<1 50 TPD). Assessment of
potential surface and groundwater contamination
and complete cleanup plan if needed?
No to A,B or
(If applicable)C
r
- --- Are there more
Positive Report _ no than
w/wo mitigation requirements Evaluate' 50 TPY VOC
from sources
---- within one mile?
yes
CNegabve
Report'
Y f
Level 2 Quantitative Evaluation with
Quantitative Impact Evaluation DEP Review Considerina the
Following:
•Emissions of Total VOCs from
facilities within one mile,if any,
Evaluates 4 •Facility-specific cancer and
noncancer risks,
•The extent to which Enhanced
Was are proposed,
•Potential surface and groundwater
contamination and complete deanup
plan,If needed.
Positive Report 1
(./.a
mitigauon requirements/
"`Landfill'includes MSW,Residuals,and C&D
' E'raluanon includes factors listed m the Executive Summary,a,vin
Evaluation includes factors listed at the Executive Summary,pag xi-au
' Request for reconsideration of negative finding on site suability allowed(3 10 CMR 16 14)
v11
Proposed Level 1 and Level 2 assessments are reviewed by MassDEP following the steps
depicted in Figure 1. For Level 1 assessments,the factors considered that bear upon whether a
positive or negative site assignment report is issued by MassDEP include the following:
- facility type and size;
- extent to which BMPs are proposed;
- the type of land uses impacted by the facility;
- emissions of volatile organic compounds (VOCs) from other point sources within the area;
- -specific particulate matter sources, such as other solid waste management facilities,junk
yards, auto salvage shops, bus and truck depots, etc. within the area; and
- (for landfills/expansions less than 150 tons per day) a commitment to develop and implement
a cleanup plan for any surface water and groundwater contamination to comply with water
quality standards in applicable laws and regulations (plan must be approved by MassDEP
before the expansion is approved- See separate guidance titled Guidance for the Assessment
of Groundwater and Surface Water for Solid Waste Facility Site Assignment and Permitting).
Transfer stations, construction and demolition (C&D) processing facilities, and small landfills
are assessed using a Level 1 assessment.
The Level 2 assessment process is described below. It is based on the risk assessment
procedures established by the National Academy of Science, builds upon existing risk
assessment methods developed by the U.S Environmental Protection Agency (USEPA) (USEPA,
1989) and is similar to risk assessment methods used under the Massachusetts Contingency Plan
(MCP).
The Level 2 quantitative impact assessment is used to assess potential human health impacts due
to inhalation of air contaminants from a proposed landfill that meets all of the facility and siting
requirements contained in the siting regulations (3 10 CMR 16.00). Emissions of certain toxic
pollutants (e.g., benzene, vinyl chloride, perchloroethylene, etc.) are included in the quantitative
assessment of potential risks from proposed solid waste facilities (i.e., new landfills and landfill
expansions over 150 tons a day). Total cancer and non-cancer risks associated with emissions of
toxics from the proposed facility are estimated under this protocol. Criteria pollutants (i.e.,
ozone,particulate matter, carbon monoxide, nitrogen oxides, sulfur dioxide, lead) will be
evaluated elsewhere in the siting and permitting processes to ensure compliance with National
Ambient Air Quality standards (which are federal standards that consider health impacts).
Potential groundwater impacts are not included in the quantitative risk assessment, because
MassDEP believes that future groundwater impacts from the proposed facilities will be
adequately controlled provided that facilities are constructed and operated in compliance with all
applicable regulations. To protect important water resources, MassDEP has prohibited the siting
of facilities in sensitive water resource areas. MassDEP has also modified the existing Site
Assignment Regulations for Solid Waste Facilities to require increased setback distances from all
water resources. This serves as a primary mechanism to prevent water impacts. In addition,
MassDEP requires BMPs for stormwater, leachate collection, and water monitoring requirements
' Over time and with anticipated stakeholder input,MassDEP has plans to review additional elements so that facility
impacts will be more fully addressed
viii
for landfills. As part of the permitting process,proposed landfills and proposed expansions of
landfills are also required to install double liners. In addition, for all proposed landfill
expansions (for both Level 1 and Level 2 assessments), MassDEP requires an assessment of
existing surface water and groundwater quality monitoring data for the existing facility.
Depending on the level of contamination, the applicant may be required to prepare and
implement a cleanup plan to achieve groundwater and surface water standards under the Solid
Waste and Waste Site Cleanup programs.
To protect air quality and public health, and to minimize nuisance conditions, MassDEP
encourages BMPs for dust and odors, and the use of low emission diesel equipment on-site'. In
addition,the revised regulations require increased setbacks of facilities from sensitive receptors,
including homes, schools, nursing homes, daycare centers, etc. which reduce potential inhalation
risks to individuals in proximity of the facility. MassDEP is not recommending an assessment of
mobile source emissions at this time, including those from on-site equipment, trucks carrying
waste to the facility and emissions from all other off-site traffic, in the Level 2 quantitative
impact assessment.
MassDEP is issuing separate guidance to address hydrogen sulfide emissions from landfills that
handle C&D materials. While this risk assessment guidance document references types of BMPs
that facilities should implement to reduce hydrogen sulfide emissions, this separate guidance
recommends more specific management and control strategies. Based on this guidance,
MassDEP may require additional assessment and/or controls at landfills where there is a
potential for hydrogen sulfide emissions.
The following sections present brief summaries of the steps that comprise a Level 2 quantitative
impact assessment.
STEP 1: Hazard Identification -Identification of Chemicals of Concern
Chemicals of concern (COC) from proposed landfills and their associated emission factors may
be determined from the USEPA Landfill Gas Emissions Model (USEPA 1998). This model
focuses on 47 COC (see Table 6 in the Guidance Document) with respect to emissions from
landfill sites and vents, whether they are controlled or uncontrolled. The list of 47 chemicals is
based on a USEPA publication, Compilation of AP-42 Emission Factors (USEPA 1997a) on
chemicals that have been found to be emitted from landfills based on national testing of landfill
emissions and from published documents. MassDEP has determined that all chemicals on this
list for which published toxicity values exist should be included in the quantitative risk
assessment. As toxicity data for the remaining chemicals become available,they will also be
included in future quantitative risk assessments. On a case-by-case basis, MassDEP will review
proposals from proponents wishing to evaluate and use other data(e.g., from similar landfills to
the one proposed) to establish alternate lists of COC and/or emission factors. In particular,
z On-site diesel equipment refers to equipment used at the facility and does not include diesel vehicles transporting
refuse into and out of the facility. At landfills,on-site diesel equipment could include equipment for excavating and
moving dirt,for covering and compacting operations,and on-site power production. At waste handling facilities,
on-site diesel equipment may include equipment that is used to move,consolidate and compact trash before it is
taken off site.
ix
MassDEP will consider capture rate data specified in existing MassDEP facility air permits.
Approval from MassDEP on the approach to be used should be sought prior to initiating such an
assessment.
If appropriate, project proponents should also address potential emissions and risks associated
with special wastes, for which a permit will be requested, that contain potential COC that are not
included on the list of 47 compounds and for which toxicity data exist. A special waste is only
required to be addressed in the quantitative risk assessment if that waste comprises greater than
fifty percent per year of the total waste taken in at that facility. In such cases, approval from
MassDEP should also be sought prior to identifying any additional COC and emission factors for
use in the quantitative risk assessment for those chemicals.
STEP 2: Dose Response Assessment
The project proponent should utilize the most current published toxicity values for the
chemicals of concern. Current values are listed by MassDEP in this Guidance Document 3. These
toxicity values represent cancer slope factors and reference concentrations that have been published
by USEPA (e.g., Integrated Risk Information System) or others, as appropriate. These values are
updated from time to time by the organizations responsible for their development. The project
proponent is responsible for ensuring that the most current values are used in the quantitative risk
assessment.
STEP 3: Exposure Assessment
The project proponent should estimate potential exposures to chemicals of concern from the
proposed facility based on appropriate modeling (USEPA Guidance for Landfill Gas Emissions
Model)and other appropriate methods(e.g., dispersion models)that are specified by MassDEP
in this Guidance Document.
The inhalation exposure pathway is quantitatively addressed. The Guidance Document specifies
the modeling outputs, including for example, a peak annual average and long-term (30-year)
average air concentration for each toxic chemical at the property line and beyond.
As mentioned above, if a facility proponent prefers not to utilize the USEPA emission factors in
modeling facility emissions but wants to collect and/or use other information, such as monitoring
data from a similar existing facility, MassDEP review and approval of the proposed alternative is
required to ensure that it meets all appropriate requirements.
STEP 4: Risk Characterization
A quantitative risk assessment should be performed using the exposure estimates and the dose
response information, determined as noted above. The multi-chemical, single pathway
assessment should include an assessment of the total facility excess lifetime cancer risks and
chronic and sub-chronic non-cancer risks. The quantitative risk assessment should also include a
3 The project proponent should use toxicity data that are available at the time of the project assessment. Project
proponents are responsible for using the most up-to-date values in their assessments.
x
discussion of the uncertainties, such as those associated with the hazard identification, dose-
response, exposure assessment(including both modeling and exposure issues), and risk
characterization steps.
STEP 5: Risk Management
Results of the facility impact assessment will be compared to MassDEP's risk management
criteria, considering additional factors, as described below.
Risk Management Criteria for Level 2 Assessments
Absent other significant factors,the MCP risk management criteria(Excess Lifetime Cancer
Risk= 1-in-100,000, Hazard Index= 1) will be applicable to the results of a quantitative
assessment prepared for a Level 2 assessment. Additionally,proposed facilities that would pose
de minimis risks (ELCR less than one-in-one million and a Hazard Index less than 0.1)will be
generally approvable at any location. Where there are other significant emissions of VOCs in the
immediate area, more stringent risk management criteria may be appropriate as discussed further
below.
Additional Risk Management Considerations
The following additional factors will be considered by MassDEP when evaluating the
appropriateness of a location for a proposed landfill and for permitting expansions of existing
landfills:
• The aggregate emissions and associated potential risks, as described by the combination of
the following two factors:
1. the risk posed by the facility itself(quantitative estimations of the Total Facility
Hazard Index and Excess Lifetime Cancer Risk); and
2. the emissions of pollutants that can impact public health from nearby facilities
(evaluated using an indicator,total VOC emissions from all point sources within 1
mile, unless otherwise determined by MassDEP, as listed in MassDEP's
database 4, including existing waste facilities at the proposed location). The use of
this indicator is predicated on the assumption that the higher the emissions of
VOCs from adjacent air point sources registered in MassDEP's database, the
higher the potential risk in the community affected by these facilities. The facility
proponent may choose to conduct multiple facility source modeling and
quantitative risk assessment of the adjacent sources to provide a refined estimate
of overall risk.
°Stationary Source Emissions Inventory System
s The facility proponent should consult with MADEP prior to initiating such work. Such an analysis could be part of
the initial proposal,prior to a requirement for mitigation,prior to the issuance of a negative site suitability report,or
as part of a request for reconsideration.
xi
• A commitment to develop and implement a cleanup plan for any surface water and
groundwater contamination to comply with water quality standards in applicable laws and
regulations(plan must be approved by MassDEP before the expansion is approved), if the
proposed facility is an expansion of a landfill.
• Other factors affecting environmental conditions in the area, such as possible
mitigation/offset measures offered by the proponent, expected future change to emissions
from facilities in the area, the type of land uses impacted by the facility; specific particulate
matter sources within the area, such as solid waste management facilities,junk yards, auto
salvage shops, bus and truck depots, etc.; and the environmental impacts of not constructing
the facility.
• Uncertainty of the available data.
Assuming that all other requirements are met,MassDEP would issue a positive site suitability
report if the risk management criteria are clearly met, suggest mitigation measures if the results
are near the proposed limits, or issue a negative determination, require changes to the proposal or
require mitigation measures if one or more of the criteria are exceeded. Mitigation options may
include enhanced controls on emission sources at the site and/or off-site mitigation.
Figure 2 graphically depicts MassDEP's approach to evaluating quantitative information that has
been developed for the Guidance Document. The darkly shaded area to the right of the figure
represents those facilities with an estimated total facility Excess Lifetime Cancer Risk greater
than one-in-one hundred thousand or an estimated total facility Hazard Index greater than one.
Outside that darkly shaded area, the facility itself poses an acceptable risk. In this latter case, the
facility site can be approved unless emissions from adjacent air point sources are high. In that
case, additional mitigation or additional assessment may be needed.
Figure 2.
Quantitative Evaluation Review
TFactlit_Risk Estimates
-- ---
< 1x10 T < 1x10-5 T^> 1x10'3 �- ELCR, and
{ ff
- — -- -_I <0.1 < I 1 > 1 I=HI -
Emissions
From 0
Adjacent
-- --- -�
Air Point
Sources
----- -- - - - — - -+ -
i
-(tons/yr) - -
High
xii
Tools Available
MassDEP has developed a spreadsheet to assist in conducting a quantitative risk assessment for
landfills. This spreadsheet addresses the default lists of chemicals suggested in this document. It
may be accessed at the MassDEP home page at htto://www.mass.vov/den. For proposed
facilities for which special wastes should be evaluated or which otherwise need to consider
additional chemicals,the risks from these chemicals should be calculated separately and added to
the risk determined using the spreadsheet.
This guidance document identifies the minimum components that the impact assessment
report should include, explains how the impact report fits into the site assignment process and
identifies specific submission requirements.
xiii
SECTION 1: Introduction
In June 2001, the Massachusetts Department of Environmental Protection (MassDEP)
adopted revisions to the Site Assignment Regulations (3 10 CMR 16.00)which govern the siting
of solid waste facilities in Massachusetts. In particular, 310 CMR 16.40 establishes the criteria
and decision-making process MassDEP shall utilize in determining whether a site is suitable for
a proposed solid waste management facility.
In October, 2001,the MassDEP Commissioner convened a Science Panel to review the
Interim Guidance Document (June 8, 2001 Interim Guidance) and to provide recommendations
for the assessment of cumulative impacts. The Science Panel report
(htto://www.mass.Pov/deo/bwn/dswm/dswmDubs.htm#swac)recommended no clear next steps.
As a result, no major changes to the impact assessment guidance are being made as part of this
update. The main focus of this updated document is clarification of the previous Interim
Guidance, including additional guidance on water resources assessment.
MassDEP is committed to ensuring that solid waste facilities are located and designed to
minimize impacts to public health and the environment. Requirements for siting or expanding
solid waste facilities or expansions call for enhanced measures to address potential facility-
related impacts to the public. These measures include increases in required setback distances of
the facility to sensitive receptors or resources, requirements to prevent water impacts, and
qualitative or quantitative impact assessments, as determined by the size and characteristics of
the proposed facility and its surrounding area. In addition, MassDEP is encouraging Best
Management Practices (BMPs) for dust and odors, and the use of low emission diesel equipment
for all on-site diesel equipment.
The revised solid waste site assignment regulations incorporate a systematic review
process that evaluates the potential impacts of a proposed facility or expansion on public health.
The level of assessment reflects the potential for risk from the proposed facility. The assessment
should be based on the types and amount of wastes the facility proposes to handle. Small, well-
controlled facilities receive a lower level of assessment than large facilities with the potential for
greater impact. In addition to assessing site suitability based on facility-specific considerations,
the revised regulations also take into consideration the impacts of existing sources of pollution or
contamination in the surrounding area.
To protect air quality, public health and to minimize nuisance conditions, MassDEP
encourages all proposed solid waste management facilities to incorporate Best Management
Practices(BMPs) to control dust and odors in their proposals. In addition,MassDEP encourages
facility operators to equip or retrofit all equipment on site with low emission diesel technology.
MassDEP believes that use of such BMPs should greatly reduce fugitive particulate and other
emissions and odors. MassDEP also requires increased setback distances of facilities from
sensitive receptors including homes, schools, nursing homes, daycare centers, etc. to reduce
potential risks to individuals living or working in the proximity of a solid waste facility. For
larger landfills, a quantitative impact assessment should be conducted to assess facility-specific
cancer and non-cancer risks associated with emissions of gaseous pollutants. In addition, for all
1
proposed facility types or expansions,total potential emissions of volatile organic compounds
(VOCs), determined using the MassDEP Stationary Source Emissions and Inventory System
(SSEIS) database, should be evaluated as an indicator of industrial activity and/or the potential
for emissions in the area that may cause or contribute to adverse impacts related to landfill gases.
To protect water resources, MassDEP requires increased setback distances from
groundwater and surface waters. In addition, MassDEP requires that proposed landfills install
double liners with leak detection and leachate collection devices and perform periodic water
monitoring. As part of the facility impact assessment, proponents should evaluate potential
groundwater and surface water impacts at landfills applying for expansions in either Level 1 or
Level 2 assessments. MassDEP considers an approved plan for the remediation of any
groundwater or surface water as a condition of the expansion permit approval. As part of the
requirements for site assignment and permitting of landfills, MassDEP requires that a
commitment be made to develop and implement a cleanup plan (approved by MassDEP) for any
surface water and groundwater contamination to comply with water quality standards in
applicable laws and regulations.
This Guidance Document for Solid Waste Facilities (hereafter referred to as the Guidance
Document) is intended to be used by anyone seeking site assignment under 310 CMR 16.00. It
summarizes the decision criteria to be used to determine whether and how a facility impact
assessment should be conducted as part of a solid waste management facility siting application.
The various components of the assessment process are defined and discussed as they pertain to
solid waste management facilities.
Unless MassDEP reaffirms or revises this guidance document within three years
of the date it is issued, this guidance document will "sunset' and will no longer be
applicable. Within two years of the date it is issued, MassDEP intends to initiate a
review of the guidance and seek input from its Solid Waste Advisory Committee to
determine whether the guidance should be maintained as is, revised, or eliminated.
1.1 Applicability and Scope
Definition
A solid waste management facility is defined as"an established site or works, and other
appurtenances thereto, which is, has been or will be used for the handling, storage, transfer,
processing,treatment or disposal of solid waste including all land, structures and improvements
which are directly related to solid waste activities". The Guidance Document addresses two
general categories of facilities: landfills that process and dispose of refuse on-site and handling
facilities that take in the waste and transfer it elsewhere. "Landfills" include municipal solid
waste landfills, C&D landfills, and residuals landfills (such as ash.) Examples of handling
facilities include transfer stations, C&D processing facilities and mixed-waste composting
facilities. Those facilities that are exempt from the site assignment process under 310 CMR
16.05 are also exempt from Facility input assessment requirements. Many types of facilities may
b Potential emissions are defined as those that might be generated if a facility were to operate at a maximum rate
continuously.
2
include both on-site disposal and waste-processing components. For facilities taking in multiple
types of waste, the predominant waste generally dictates the level of assessment required by
MassDEP. However, proponents of facilities that handle multiple wastes and proponents of
multiple types of facilities at the same site should consult with MassDEP prior to proceeding
with the assessment process. If the type of solid waste facility proposed does not fall into one of
the categories identified by MassDEP, proponents should also consult with MassDEP prior to
proceeding with the assessment process.
1.2 Accounting for Emissions from Other Facilities
While the Site Assignment Regulations in the past have addressed the cumulative impact
of multiple solid waste disposal facilities greater than or equal to 300 tons per day in a
municipality, they have not considered the impacts from other solid and non-solid waste sources
in the area surrounding the proposed facility or expansion. The revised regulations address the
issue of whether the generation of pollution or contamination from the proposed facility or
expansion,taking into consideration the existing sources, will have a negative impact on public
health. The assessment of cumulative impact is still a young science and there are many areas of
uncertainty inherent in the process. MassDEP is committed to moving towards more
comprehensive methodologies as they are developed.
MassDEP's current approach for evaluating the impacts of proposed solid waste facilities
takes into consideration the emissions from existing sources using information on total emissions
of air toxics (i.e.,total volatile organic compounds (VOCs)) from the MassDEP Stationary
Source Emissions and Inventory System (SSEIS) database. The SSEIS database contains
emissions information for VOCs emitted from both major and minor point sources. The SSEIS
database contains a list of registered facilities, along with emission information for "potential",
"actual"and"permitted" facility emissions. Potential emissions represent maximum emissions
that might be generated if a facility were to operate at a maximum rate continuously. Actual
emissions reflect emissions that have occurred based on the facility's actual operating schedule.
Permitted emissions include any MassDEP-imposed emissions restrictions for that facility. For
calculating total emissions, total potential emissions of VOCs in tons per year(TPY) from all
sources registered in the MassDEP SSEIS database within one mile of the perimeter of the
proposed facility or expansion, unless determined otherwise by MassDEP, should be compiled
by the project proponent. Information on total potential emissions is evaluated together with
other quantitative and/or qualitative information about the facility, using MassDEP's risk
management considerations and criteria as discussed elsewhere in this guidance,to make a
decision about site suitability.
MassDEP chose to use total VOC emissions data as described above for this protocol for
the following reasons: VOCs are an indicator of industrial activity as well as an indicator of
emissions in the area that could potentially be associated with adverse impacts related to specific
landfill gases. SSEIS information represents the best database for this information, given that
Massachusetts tracks emissions of VOCs as precursors to ozone due to Massachusetts' non-
attainment status for ozone. The VOC emissions information in this database is believed to be
the most representative indicator of total point source emissions currently available. The
assumption inherent in the use of this indicator is that the higher the emissions are from adjacent
air point sources,the higher is the potential risk in the community affected by these facilities.
3
On a case-by-case basis, prior to requiring additional mitigation or issuing a negative site
suitability report, MassDEP may allow multi-facility source modeling and quantitative risk
assessment of adjacent sources to be used to more fully evaluate overall impacts.
SECTION 2: Facility Assessment Screening Protocol
The level of assessment that MassDEP requires for a proposed siting application is
determined by a number of parameters related to the proposed facility and its surroundings.
Figure 1 outlines the systematic protocol for determining the level of assessment an applicant
should use to determine whether a siting request may be approved. The protocol involves two
levels of assessment, including a Level 1 - Qualitative Impact Assessment and a Level 2—
Quantitative Impact Assessment.
MassDEP believes that emissions from large landfills may produce ambient air levels of
these pollutants of potential concern to the general public. For this reason, applications to site
larger landfills or expansions should include an assessment of potential air impacts in a
quantitative risk assessment. MassDEP believes that gaseous emissions from very small and
well-controlled landfills,which meet all applicable facility and siting criteria in the solid waste
regulations (Table 1), are likely to be low. Thus, a qualitative assessment of emissions from very
small landfills is deemed by MassDEP to be a sufficient basis for assessing their potential
impacts.
Proposed landfill expansions and new landfills that meet the criteria summarized in
Figure 1 should undergo quantitative impact assessments. Landfill expansions differ from new
landfills in that they may offer the opportunity to obtain site-specific information on ambient air
emissions via on-site monitoring of the existing landfill that is seeking to expand. Such
information may serve as a supplement to the LandGem model (USEPA, 1998) suite of COC and
their associated emission factors. Proponents of new landfills may also use data from a similar
landfill subject to prior approval by MassDEP. For expansion requests, the quantitative risk
assessment should address the full site assigned project. For new facility requests,the entire
facility should be addressed. When monitoring data are available as a basis for determining
exposure point concentrations, a conservative approach should be used to conduct the risk
assessment. The list of AP-42 COC should always be included in the assessment although this
list may be supplemented with additional chemicals as indicated by monitoring results. In
addition, the higher of the monitored concentration or concentration derived from an AP-42
emission factor should be used to conduct the quantitative assessment. Concentrations of VOCs
emitted from decaying waste fall along a lognormal gas production curve, and vary significantly
over the decaying process, influenced by the age of the waste and the particular set of
environmental conditions characterizing the landfill. Since it is very difficult to determine at
what point along the gas production curve a set of monitoring results may have been derived,
MassDEP's policy regarding this issue is to use the higher concentration as an estimate of a
worst-case concentration. Waste-handling facilities differ from landfills in that the waste is
transitory and therefore is present at the facility for only a short period of time. Gaseous
r The facility proponent should consult with MassDEP prior to initiating such work. Such an analysis could be part
of the initial proposal,prior to a requirement for mitigation,prior to the issuance of a negative site suitability report,
or as part of a request for reconsideration.
4
emissions are much lower than they are at landfills where refuse is buried on-site and
decomposes over a period of years. As a result,particulate emissions associated with the transfer
and transport of refuse as well as emissions from on-site diesel equipment is of the most concern
at these facilities. For this reason, MassDEP encourages implementation of BMPs and the use of
low emission equipment on-site at these facilities to address fugitive dust and diesel emissions.
MassDEP believes that use of BMPs will greatly reduce emissions of concern at these facilities.
Table 1. Summary of Revised Siting
Requirements/Criteria
310 CMR 16.40
Applicable and relevant state and federal standards, criteria, guidelines or
allowable limits in written health policies
[3 10 CMR 16.40(1)2.1
I I
Groundwater Protection restrictions(Zone II's IWPA's, etc...)
[3 10 CMR 40.40(3)(a), (c), (d))
I
Setbacks from residences, schools,preschools, agricultural land, etc...
[3 10 CMR 16.40(3)(a)(c)(d))
I I
Assessment of traffic congestion, safety, vehicle emissions
[3 10 CMR 16.40(4)(b))
I I
Wildlife Habitat, ACEC, Wetlands Protection Act
[3 10 CMR 16.40(4)(c)(d))
I I
Air Quality Impacts: [3 10 CMR 16.40(4)(c)(e)]
I I
Nuisance Conditions: [3 10 CMR 16.40(4)(c)(f))
5
Figure 1. MassDEP Protocol for Selecting Level of Assessment
Impact Evaluation Flowchart
Assumes all other requirements are met
(310 CMR 16.00)
Level 1
Qualitative Impact Evaluatian
Is the facility a new landfill'or „e.
landfill expansion>150 TPD o
Ino
A-Enhanced Mass for dust&odor,and
planned use of low emission diesel equipment
for all equipment on site?
Vto�(: — B NN
A,B end t
A, - e capacity of the proposal is less than 150 a oA„oBalland
(ifapplicable)C tons/day? (if apphcable)C
C-(for landfills e150 TPD) Assessmentof
potential surface and groundwater contamination
and complete cleanup plan if needed?
TNegative
,r
- Are there more
Positive Report no than
w/coo mlbgation regmrements 50 TPY VOC
from sources
within one mlle�
yea
Y F
Level 2 Quantitative Evaluation with
Quantitative Impact Evaluation DEP Review Considering the
Following:
•Emissions of Total VOCs from
facilities within one mile,if any,
Evaluate' •Facility-specific cancer and
noncancef nsks;
•The extent to which Enhanced
BMPs are proposed:
•Potential surface and groundwater
contamination and complete cleanup
plan,d needed.
Positive Report
wAvo mitigation requirements
"`Landfill”includes MSW,Residuals,and C&D
' Evaluation includes factors listed in the Executive Summary,Pge vin
'Eveluahoa includes factors listed in the Execuhve Summary,pag xi-xu
' Request for reconsideration of negative finding on site suab lity allowed(310 C61R 16 10).
6
The database on emissions from waste facilities other than landfills is limited. Detailed
information on the types and concentrations of compounds emitted from waste-handling
facilities has not been collected and compiled as it has been for landfills. The level of
uncertainty introduced by these data limitations and the modeling and assessment processes
would likely render a quantitative impact assessment of these facilities impractical given the
current level of knowledge. As additional emissions data are collected on these facilities and
modeling and assessment methodologies improve, MassDEP may determine in the future that
quantitative assessment should be conducted for these facilities as well.
In addition to qualitative and quantitative assessments for determining site suitability, a
facility may be subject to periodic or ongoing monitoring requirements on a case-by-case basis.
The details of these requirements, if any, will be specified in the facility permit. Other
requirements of the solid waste regulations as well as of the USEPA federal Clean Air Act(e.g.,
the assessment of criteria pollutant impacts from the facility) are not addressed in the Guidance.
However, an assessment of facility emissions relative to National Ambient Air Quality Standards
(NAAQS)will be done elsewhere in the siting and permitting processes (see Table 1).
To summarize, a qualitative impact assessment is required for new waste-processing
facilities or expansions and smaller landfills or expansions which take in less than 150 tons per
day of refuse. Waste handling facilities include transfer stations and C&D processing facilities.
Small landfills include municipal solid waste, C&D, and residuals landfills or expansions that
take in less than 150 tons per day of refuse. Siting requests for these facilities will be evaluated
based on the acceptability of proposed BMPs (see Tables 2 and 3), proposed refuse capacity, and
VOC emissions from other major and minor point sources within one mile of the facility. Please
note that MassDEP is issuing guidance for addressing hydrogen sulfide emissions from landfills,
especially from landfills that accept C&D waste, fines, or residuals. While MassDEP does not
currently require a quantitative risk assessment for small landfills, MassDEP may require
additional assessment and/or controls at these landfills where there is a potential for hydrogen
sulfide emissions. Quantitative Risk Assessments should be conducted for large landfills or
expansions. In this context, a large "landfill" is defined as a municipal solid waste, C&D, or
residuals landfill that takes in more than 150 tons per day of waste. Additional qualitative
facility-specific or site-related information may be considered on a case-specific basis to make a
final determination on site suitability.
2.1 Best Management Practices
MassDEP expects that facilities will implement Best Management Practices (BMPs) in
the design and operation of a proposed new solid waste management facility or expansion to
reduce or mitigate potential impacts for specific areas of concern. These areas of concern
include: groundwater protection; surface water protection; air quality protection (noise,
dust/particulates, hydrogen sulfide and other emissions, and odor); fire protection; and
insect/rodent control. In the context of this guidance, a BMP is a preventive technology or
measure that is implemented to limit potential impacts by facilities and to address public health
and nuisance concerns. A facility applicant should provide a listing and discussion of proposed
BMPs that address these areas of concern.
7
The extent to which an applicant proposes BMPs and the BMPs' purported effectiveness' in
reducing or mitigating potential impacts will be important factors in the MassDEP decision-
making process regarding the adequacy of a facility's impact assessment report. For example,
particulate emissions from solid waste management facilities are difficult to estimate using
existing information and methods. Yet they are one of the primary pollutants of concern for
many facilities, especially those conducting a Level 1-qualitative impact assessment. The
implementation of BMPs and the use of low-emission equipment on site can effectively control
emissions of particulates from facilities, thus reducing the need for a quantitative assessment of
impacts, esR&ially for facilities initially conducting Level 1 assessments. Facility proponents
should implement appropriate BMPs to minimize fugitive dust emissions, hydrogen sulfide
emissions, odors and diesel emissions to meet the Air Quality Regulation.
Facility proponents should identify BMPs that are applicable to the operations of the facility and
that will minimize facility impacts to the maximum practicable extent. Tables 2 and 3 contain a
list of MassDEP-approved BMPs. However,these BMPs are given only as suggestions for
applicants' consideration. Other methods not listed will be considered by MassDEP provided
that they adequately control the environmental issue of concern. Specific BMP requirements
will be established in the applicant's facility permit. MassDEP may require reporting on the
effective implementation of BMPs as a permit condition.
a To evaluate the effectiveness of BMPs,MassDEP may require a facility,as part of it s permit, conduct ambient air monitoring
for particulates and other substances of concern during facility operation.
'See for example 310 CMR 7.01:General Regulation to Prevent Air Pollution:
(1) No person owning,leasing,or controlling the operation of any air contamination source shall willfully,
negligently,or through failure to provide necessary equipment or to take necessary precautions,permit any
emission from said air contamination source or sources of such quantities of air contaminants which will cause,by
themselves or in conjunction with other air contaminants,a condition of air pollution.
8
Table 2. MassDEP Approved BMPs for Landfills
(MSW Landfills,Ash Landfills,and C&D Landfills)
I Areas of Concern for Potential Risk
0%7 e4``oo oagc�
oJc �J 'dO4 Q�o�
MADEP Approved BMPs G� `R; P QAC¢ °y
(Active Face Of Landfill:
Using alternative daily cover materials that reduce
dust, odors, and vermin to a greater degree than
standard soil type materials(these would include X X x
manufactured products such as Posi-Shell, polymer
modified foams,tarpaulins, etc.)
Maintain as small an active face as possible X X X
When using C&D fines or residuals as cover or
X
grading and shaping material, mix with soil
When using C&D fines or residuals as cover or
grading and shaping material, ensure that the X
processing facility has a program in place to
separate gypsum materials prior to processing
Diesel Emission Controls:
Replacing old diesel equipment with new, lower X
emission diesel equipment
Using electrically powered motors X
Retrofitting ninety percent(90%)of all 1997 and
older diesel engines used wholly or partially on site X
for more than 10 hours per week
Replacing diesel powered equipment with
compressed natural gas, liquid natural gas or liquid X
petroleum gas equipment
For off-road engines, using only cleaner on-road X
diesel fuel
For on-road engines, using only cleaner ultra low X
sulfur diesel fuel
Minimizing idling of equipment by turning off engines
when not in use(includes employee training and X
signage)
(Access Roads and Parking Areas:
Ensuring paved surfaces X X X
Street sweeping as necessary X X X
Using dust suppressants on unpaved surfaces
where necessary(CaCl2,water) X
Interim Landfill Gas Collection and Control in Active
Cell of Landfill:
Using temporary flares or other gas collection X X
systems
9
(continued)
Table 2. MassDEP Approved BMPs for Landfills
(MSW Landfills,Ash Landfills,and C&D Landfills)
Areas of Concern for Potential Risk
0 oa6pa
oJca j`aoe '`Oo Q�oti e4JQ-
MADEP Approved BMPs
lWater Quality Controls:
Collecting water runoff from paved areas x x
Using oil/water separators x x
Using above ground leachate storage tanks x x
Ensuring available potable water source for
immediate use in case of fire or other emergency at x
the facility
Storm Water/Erosion Controls:
Implementing applicable storm water regulations
and guidance by the Bureau of Resource Protection X x
Using vegetation,wood chips, erosion control mats
or other means to minimize erosion from the site x x
Wheel washing in an area using secondary x x x
containment measures
Other:
Providing documentation that facility owners/operators
have received formal training and have been certified
as a landfill operator(certification can be received x x x x x
through national professorial programs)
Establishinq an odor complaint response plan
* Retrofit devices should include only California Air Resources Board(CARB),US Environmental Protection Agency(EPA),
or New England States for Coordinated Air Use Management(NESCAUM)certified retrofit devices.
10
Table 3. MassDEP Approved BMPs for Waste Handling Facilities
(Transfer Stations,C&D Processing Facilities,and Other Waste Handlinijacilities)
Areas of Concern for Potential Risk
a�a� avec `.� �`°o
4agcti
MADEP Approved BMPs ¢ Ja tie o
o° ao `0 Quo o�Q
�ForAnv Waste Handling Facilitv:
IDiesel Emission Controls:
Replacing old diesel equipment with new, lower x
emission diesel equipment
Using electrically powered motors x
Retrofif ing ninety percent(90%)of all 1997 and
older diesel engines used wholly or partially on site x
r more than 10 hours per week
Replacing diesel powered equipment with
compressed natural gas, liquid natural gas or liquid x
petroleum gas equipment
For off-road engines, using only cleaner on-road x
diesel fuel
For on-road engines, using only cleaner ultra low x
sulfur diesel fuel
Minimizing idling of equipment by turning off engines
when not in use(includes employee training and x
signage)
Access Road and Parking Areas
Ensuring paved surfaces for access roads, x x x
handling areas
Street Sweeping as necessary x x x
Conveyor Systems:
Using completely enclosed conveyor belts for
materials that may blow around or result in dust x
nuisances
Stockpile or Storage Areas:
Storing materials in a building or 3-sided covered x x x x
storage bunkers
Street sweeping as necessary x x x
Ensuring paved surfaces x x x
Using water misting systems x x
Water Quality Controls:
Ensuring available potable water source for
immediate use in case of fire or other emergency x
at the facility
Using oil/water separators X
Using secondary containment around storage x x
areas and truck washinq areas
11
(continued)
Table 3. MassDEP Approved BMPs for Waste Handling Facilities
(Transfer Stations,C&D Processing Facilities,and Other Waste Handling Facilities)
Areas of Concern for Potential Risk
w r1 v�°o 00,
MADEP Approved BMPs Jc y yG 1 Jy" Q`otyc a
CP
0
For Any Waste Handling Facility.
Storm Water/Erosion Controls:
Implementing applicable stormwater regulations
and guidance by the Bureau of Resource X X
Protection
Using vegetation,wood chips,erosion control mats
or other means to minimize erosion from the site X X
Wheel washing in an area using secondary X X X
containment measures
For Small Compactor Unit-Type Transfer Stations: _
Using a 3-sided shed roof over the hopper into
which waste is dumped to control litter and keep X X
rain from entering waste
For Large Transfer Stations, C&D Processinq Faciliti s,and Other Waste Handl no Facilities:
General BMPs I
Fully enclosed building and waste handling areas X X X x x li
Using automatic doors and secondary enclosures
(hanging plastic"curtains")at doors X
Using a negative air pressure system that includes X
fans and filters
Requiring that all waste deliveries entering or X X X X
exiting the facility be covered
Using sealed containers for delivery of potential
odiferous materials(e.g.,food waste, processed X X
organic wastes, sludges) _
Sealing and screening opening which may allow X
insects and rodents to enter the building
Using a water misting system within the waste X X
unloading areas
Noise Controls:
Noise survey before and after construction X
Installing noise attenuation plantings or structures
(includes installing screening/barriers such as
trees, berms, or walls around the facility to block
and absorb facility noise The installation of X
vegetative barriers such as trees can also help
absorb and disperse potential odors from the
facility.)
Using wing walls and concrete structures, rather
than metal structures,to help block noise X
12
(continued)
Table 3. MassDEP Approved BMPs for Waste Handling Facilities
(Transfer Stations,C&D Processing Facilities,and Other Waste Handling Facilities)
f Areas of Concern for Potential Risk
bei" Net cl
MADEP Approved BMPs a4 le o4 °tee°ve Q°a
Geo yJb p� Q`se `ee
IFor Large Transfer Stations, C&D Processing Facilities,and Other Waste Handling Facilities:
I Noise Controls:
Using controls on exhaust equipment X
Orienting transfer building openings away from X
receptors
Using enclosures for loud equipment X
I Air Pollution:
Using enhanced air pollution controls when dust
and odors cannot be adequately contained through X
other measures as determined by DEP
Using a biofilter X
* Retrofit devices should include only California Air Resources Board(CARB),US Environmental Protection Agency(EPA),
or New England States for Coordinated Air Use Management(NESCAUM)certified retrofit devices.
2.2 Assessment Appropriate To Facility Type
Facilities fulfilling the criteria for a Level 1 assessment should conduct a qualitative
impact assessment. Facilities fulfilling the criteria for a Level 2 assessment should conduct a
quantitative impact assessment. All facilities must initially meet all facility and siting criteria in
accordance with the Site Assignment Regulations(310 CMR 16.00) (see Table 1) before
conducting an impact assessment. Facilities requiring Level 1 and Level 2 assessments are
discussed in more detail below.
2.2.1 Waste-Handling Facilities of Any Size
All facilities that handle/process waste and dispose of it off-site are encouraged to
implement BMPs as discussed above prior to conducting an impact assessment. If a facility10
has in place both acceptable BMPs for dust and odors and a plan to use low-emission diesel
equipment on site, and the capacity of the proposed facility or expansion is less than 150 tons per
day, MassDEP would likely issue a positive site suitability report without additional
investigation and mitigation.
If either of the conditions described above are not met (i.e., if the facility has a proposed
capacity greater than 150 tons per day or does not commit to the use of BMPs), MassDEP will
evaluate the proposal and make a final site suitability determination as specified in the
Qualitative Impact Assessment, Section 3.
10 Provided that the facility will meet all applicable regulatory requirements.
13
If the facility does not propose use of BMPs including the use of low-emission diesel
equipment on site and the capacity of the proposed facility or expansion is greater than 150 tons
per day,the applicant should compile information from the SSEIS database on emissions from
VOC sources within one mile of the facility perimeter as an indicator of industrial activity in the
area. For proposed expansions, VOC totals should include emissions from the existing solid
waste facilities registered in SSEIS within one mile of the facility being expanded. If total
potential VOC emissions within a one-mile radius exceed 50 tons per year, MassDEP will likely
issue a negative site suitability report. If total potential VOC emissions do not exceed 50 tons
per year, MassDEP will base its site suitability decision on other facility-specific and site-related
factors as specified in the Qualitative Impact Assessment section (Section 3 below).
2.2.2 Small Landfills That Take in Less Than or Equal to 150 Tons Per Day
Small landfills or expansions proposing to take in less than or equal to 150 tons per day
do not need to conduct a Level 2 quantitative impact assessment. Such facilities will be
evaluated largely in terms of the extent to which BMPs are proposed. If a proposed small
landfill (that will meet all applicable regulatory requirements) commits to use BMPs for dust and
odors as well as low-emission diesel equipment for on-site equipment to be used at the new
facility or expansion and this proposal is acceptable to MassDEP, MassDEP would grant that
facility a positive site suitability report.
If BMPs and the use of low-emission diesel equipment are not proposed for the facility,
MassDEP will base its site suitability decisions on those factors specified in the Qualitative
Impact Assessment section (Section 3).
2.2.3 New Landfills and Expansions That Take in Greater Than 150 Tons Per Day
All applications for landfills that take in greater than 150 tons per day of refuse should
conduct a Level 2 quantitative impact assessment as part of the application process. The results
of the quantitative impact assessment, including estimated facility-specific cancer and non-
cancer risks from air emissions, will be considered in the context of total SSEIS VOC emissions
from all point sources located within one mile of the perimeter of the proposed facility, unless
determined otherwise by MassDEP. (VOC totals should include emissions from the existing
solid waste facilities registered in SSEIS within one mile of the landfill being expanded.)
MassDEP guidance for conducting a quantitative impact assessment is contained in Section 4 of
this document.
MassDEP will evaluate this information in accordance with its quantitative risk
management criteria specified in Section 4.6 of this document. Specifically, MassDEP will
consider the totality of the information, including the acceptability of any proposed BMPs and
SSEIS VOC emissions information.
14
SECTION 3: Qualitative Impact Assessment
MassDEP uses information on the type and capacity of the proposed facility,the extent of
proposed use of BMPs, and VOC emissions information from facilities within one mile of the
proposed facility to categorize proposals regarding level of assessment.
As the approach specified in Figure 1 indicates, for facilities requiring a Level 1
assessment,there are scenarios for which a site suitability determination can be clearly made
based on this information alone. For example, if a waste-handling facility has a capacity less
than 150 tons per day and proposes BMPs that are acceptable to MassDEP (i.e., ones that will
effectively control emissions and resulting impacts)MassDEP will likely issue a positive site
suitability report for the facility. If a waste-handling facility has a capacity greater than 150 tons
per day, does not propose to use BMPs and is in an area where VOC emissions from adjacent
facilities are greater than 50 tons per year, MassDEP may issue a negative site suitability report.
This determination is based on the premise that additional emissions from a large facility in an
area that already has significant emission sources could present an unacceptable additional public
health burden to the surrounding community (however,the facility proponent may request a
reconsideration of the negative finding).
There are a number of assessment scenarios under a Level 1 qualitative impact
assessment that are not as clear-cut with regard to making a site suitability decision. In these
cases, MassDEP evaluates the totality of the above information in the context of additional
facility-specific and site-related factors. Tables 4 and 5 summarize the factors MassDEP will
consider in qualitative impact assessments for making site suitability decisions. The factors may
include but are not limited to:
•the extent to which BMPs are proposed;
•the type of land uses impacted by the facility;
•emissions of volatile organic compounds from other sources within the area; and
*particulate matter sources, such as solid waste management facilities,junk yards, auto
salvage shops, bus and truck depots, etc. within the area.
For landfills with a capacity of less than 150 tons per day, the facility proponent should
evaluate groundwater and surface water quality relative to water quality standards in applicable
laws and regulations. If indicated by the assessment,the proponent must commit to develop and
implement a cleanup plan to achieve compliance with these standards. See Appendix B—
Guidance for the Assessment of Groundwater and Surface Water for Solid Waste Facility Site
Assignment and Permitting in Support of 310 CMR 16.00 & 19.000.
15
Table 4. Level 1 Qualitative Impact Assessment -Waste Handling Facilities
For the followina facilities (new or expansion): '
• Transfer stations
• C&D Processing facilities
Size Has the applicant What are emissions from MassDEP's likely
proposed BMPs? adjacent sources? response will be:
Yes Not Required Positive Report
< 150 tons/day No < 50 TPY VOCs Evaluate: +/-Report
No > 50 TPY VOCs Evaluate: +/-Report
Yes < 50 TPY VOCs Evaluate: +/- Report
> 150 tons/day Yes > 50 TPY VOCs Evaluate: +/- Report
No < 50 TPY VOCs Evaluate+/-Report
No > 50 TPY VOCs Negative Report
Table 5. Level 1 Qualitative Impact Assessment - Small Landfills
For the following facilities (new or exgansion) <150 TPD:
• MSW landfills
• Residuals(e.g. ash,special wastes) landfills
• C&D landfills
Has the Do adjacent Do other solid Results of Water MassDEP's likely
applicant sources need to waste facilities Resources response will be:
proposed be considered? need to be Assessment
BMPs? considered?
Yes No,Not Consideration Adequate Positive Report
Necessary Not Necessary
Inadequate Negative Report
Yes, Amount of Yes, Amount of Adequate Evaluate: +/-Report
No VOCs Emitted VOCs Emitted
Inadequate Negative Report
Assessment includes the water assessment and any applicable cleanup plan.
16
SECTION 4: Quantitative Impact Assessment
The Level 2 quantitative impact assessment protocol described in this document is
designed to produce quantitative estimates of risk for a proposed landfill or expansion for both
non-cancer and cancer effects. The methodology outlined below follows the risk assessment
procedures of the National Academy of Science and builds upon existing risk assessment
methods that MassDEP has established for assessment of contaminated sites as governed by the
Massachusetts Contingency Plan (MCP), 310 CMR 40.0000.
The risk assessment process consists of five steps. These include Hazard Identification,
Dose-Response Assessment, Exposure Assessment, Risk Characterization and Uncertainty
Analysis.
Hazard Identification determines whether a substance causes adverse effects and
identifies those effects. A list of chemicals that are known to be or proposed to be emitted from
a facility, along with their associated health effects, is compiled. Chemicals that are known or
suspected to pose adverse health effects are identified as Contaminants of Concern (COC).
The Dose-Response Assessment describes the relationship between the level of exposure
and the likelihood and severity of the adverse effects of the COC. Available toxicity values from
USEPA or other sources are identified which quantify the concentrations or doses of chemicals
associated with particular non-cancer or cancer endpoints.
The Exposure Assessment identifies potential routes of exposure, the populations
exposed, the frequency, duration and extent of exposure to the COC, and quantitative estimates
of exposure.
The Risk Characterization combines information from the first three steps to estimate
the magnitude of the non-cancer and cancer health risks associated with exposure to the
chemicals. The results of the quantitative risk assessment are compared to the risk management
criteria established by MassDEP.
The Uncertainty Analysis identifies the uncertainty and variability inherent in the risk
assessment due to the limitations in data quality and quantity and discusses the variability in the
range of responses associated with the human population.
It is important to remember that risk estimates generated in the risk assessment are not
precise measures of absolute risks. Rather, risk assessment is a tool, a method of providing
valuable information regarding potential risks to public health. The risk assessment process
outlined above is discussed in more detail below.
4.1 Hazard Identification—Contaminants of Concern (COC)
In the Hazard Identification step of a risk assessment, a preliminary list of chemicals that
are likely to be emitted from the proposed facility under study is compiled. Information obtained
from the solid waste literature addressing the type of facility under study as well as facility-
specific air monitoring studies or modeling exercises are used to develop a list of COC.
17
The assessment will be based on the type of wastes that the facility will handle. The
hazards associated with each chemical that has been selected as a COC should be described as
well in the form of toxicity profiles. This information is used to identify the nature of adverse
health effects associated with exposure to particular contaminants (Section 4.1.4) and whether
the adverse health effect is likely to occur in humans.
MassDEP provides a default list of COC in this Guidance Document for municipal solid
waste landfills, for which the quantitative risk assessment should include, at a minimum,the
subset of AP-42 chemicals, as identified in Table 6 of this document. If the municipal solid waste
landfill proposes to take in special wastes in an amount greater than fifty percent of the total
yearly waste tonnage taken in by that facility, then MassDEP should be contacted to discuss
inclusion of additional chemicals.
For ash and C&D landfills a quantitative risk assessment of potential air emissions is not
needed. At ash landfills, MassDEP has determined that fugitive particulates associated with
disposal activities are the emissions of most concern at these facilities and can be controlled by
implementing BMPs pertaining to that type of facility. The results of an air monitoring study
showed that entrainment to air of fugitive particles from ash is negligible if that ash is maintained
at a high moisture content and if BMPs for dust control are implemented and maintained during
generation and disposal activities of ashy'. For C&D landfills, fugitive particulates can be
similarly addressed by implementing and maintaining BMPs for dust control. In addition to
particulate emissions, landfills that accept C&D waste, fines, or residuals may need to address
hydrogen sulfide emissions.
Identification of COC for the various types of solid waste management facilities is
discussed in the following sections.
�� "Quantitative Impact Assessment(Risk Assessment)Supplemental Information Request'for the Ward Hill Neck
Landfill in Haverhill,Camp,Dresser&McKee,October 2002.
18
Table 6. List of Landfill AP-42 Chemicals
1,1,1-Trichloroethane(HAP) Carbonyl Sulfide(HAP/VOC) Fluorotrichloromethane(VOC)
1,1,2,2-Tetrachloroethane Chlorobenzene(HAPNOC) Hexane(HAPNOC)
(HAPNOC)
1,1,2-Trichloroethane(HAPNOC) Chlorodifluoromethane(VOC) Hydrogen Sulfide
1,1-Dichloroethane(HAP/VOC) Chloroethane(HAP/VOC) Mercury (HAP)
1,1-Dichloroethene(HAPNOC) Chloroform(HAP/VOC) Methyl Ethyl Ketone(HAPNOC)
1,2-Dichloroethane(HAPNOC) Chloromethane(HAP/VOC) Methyl IsobutyI Ketone(HAPNOC)
1,2-Dichloropropane(HAPNOC) Dichlorobenzene(VOC/HAP for Methyl Mercaptan(VOC)
1,4-isomer)
2-Propanol(VOC) Dichlorodifluoromethane(VOC) Pentane(VOC)
Acetone Dichlorofluoromethane(VOC) Perchloroethylene(HAPNOC)
Acrylonitrile(HAPNOC) Dichloromethane(HAP) Propane(VOC)
Benzene(HAP/VOC) Dimethyl Sulfide(VOC) Toluene(HAPNOC)
Bromodichloromethane(VOC) Ethane Trichloroethene(HAP/VOC)
Butane(VOC) Ethanol(VOC) t-1,2-Dichloroethene
Carbon Disulfide(HAP/VOC) Ethylbenzene(HAP/VOC) Vinyl chloride(HAP/VOC)
+Carbon Monoxide Ethyl Mercaptan(VOC) Xylene(HAPNOC)
Carbon Tetrachloride(HAPNOC) Ethylene Dibromide(HAPNOC)
+This compound should be evaluated under 310 CMR 16.00.
19
4.1.1 Proposed Landfills
A site assignment request for a proposed landfill (greater than 150 tons per day) can
represent either a totally new siting request or a request for an expansion to an existing facility.
Both types of requests require that a quantitative impact assessment be conducted as part of the
application for a site suitability determination or permit. A proposed expansion may have the
advantage of use of emissions monitoring at the existing part of the facility to help identify
potential COC in the proposed expansion, an option for which MassDEP approval is needed.
However, given that the types of chemicals emitted from a landfill may differ depending on the
stage of the decomposition process, emissions data from an existing landfill should not form the
sole basis for identifying COC. While the results of such monitoring could be useful in terms of
identifying compounds that may be unique to that landfill, it should not be assumed that these
results are completely representative of the future emissions from the proposed expansion. An
existing landfill is further along in the decomposition process than is the expansion and the
landfill gas constituents released at that time are a function of the type of refuse that it has
received over time as well as the rate and stage of biodegradation. The proposed expansion area
may possibly receive a different mix of refuse, either by design or as a result of changes in the
consumer waste stream over time. However, given the fact that an expansion may receive a
waste stream somewhat similar to the existing landfill and that it shares the same geological and
climatological characteristics, it is likely that at least some of the landfill gas constituents may be
the same.
As discussed above, the risk assessment for municipal solid waste landfills should, at a
minimum, include the list of AP-42 COC provided in this document pertinent to that type of
landfill. In addition, a facility that takes in a special waste or wastes in an amount greater than
fifty percent of the total annual waste tonnage taken in by that facility, should consider any
additional potential emissions associated with the special waste. In such cases, the proponent
should, with MassDEP approval, identify any additional COC beyond the MassDEP list. Prior
MassDEP approval is also needed for all proposed protocols for identifying COC at non-
municipal solid waste landfills.
Emissions from landfills to the ambient air may occur as both area sources and point
sources. Landfill gas generated over the surface of the entire landfill as a result of
decomposition is considered an area source. Point sources include landfill flares or stacks in
which collected landfill gas is directly emitted or undergoes combustion. An uncontrolled
landfill is only characterized by area sources. The following sections summarize the various
types of landfill emissions and provide guidance on the selection of COC for both area and point
emission sources.
4.1.1.1 Types of Landfills
As discussed in Section 2.2.3, all large landfills and expansions with a capacity to receive
greater than 150 tons per day of refuse should conduct a quantitative impact assessment as part
of the application process for a site suitability request or a permit to construct if expanding into a
previously site assigned parcel of land for which a quantitative impact assessment was not done.
The types of landfills covered by this assessment include municipal solid waste (MSW) facilities,
20
C&D facilities, and facilities that take in special wastes in an amount exceeding fifty percent of
the total waste taken in by that facility.
Landfill gas emissions from on-site disposal of these wastes will occur for many years
after closure of the landfill. The USEPA has developed a model that allows for the temporal
characterization of landfill gas emissions from MSW facilities. MassDEP's recommended
approach for modeling and assessing landfill gas emissions is addressed below.
Non-municipal waste facilities are less general and accept a specific type of waste. For
example, residuals facilities may accept municipal solid waste incinerator ash and C&D landfills
may accept construction and demolition waste. MassDEP believes that one of the emissions of
concern from non-MSW facilities is fugitive particulates generated during transport and
processing of these wastes. The characterization of fugitive particulate emissions from landfills
is limited, although total emission generation and modeling methods do exist. MassDEP will
entertain proposals on a case-by-case basis for chemically characterizing, modeling and
assessing fugitive particulate emissions and potential health risks from landfills. Additional
discussion on the recommended protocol for these proposals is addressed below. In addition to
particulate emissions, landfills that accept C&D waste, fines, or residuals may need to address
hydrogen sulfide emissions.
4.1.1.1.1 COC in Landfill Gas from Municipal Solid Waste Facilities
Landfill Area Sources
Landfill Gas Constituents
Landfill gas is generated as a by-product of the anaerobic biodegradation of refuse in
landfills. The predominant landfill gases include methane and carbon dioxide, with much
smaller amounts of non-methane organic compounds (NMOC). As methane and carbon dioxide
are released from decaying refuse, these gases pass through the landfill, sweeping NMOC and
other air pollutants present in the refuse to the surface.
NMOC include volatile organic compounds and other air pollutants. USEPA defines air
pollutants as compounds found in landfill gas or emitted with landfill gas, some of which are
listed as air pollutants under Section 112 of the Clean Air Act.
Reduced sulfur compounds represent the sulfur-containing fraction of landfill gas.
Although these compounds comprise a relatively small fraction of landfill gas, because of their
characteristic odors, they are often the most evident components. Reduced sulfur compounds are
a common reason for odor complaints from the public.
USEPA has concluded that a number of compounds found in landfill gas cause, or
contribute significantly, to air pollution that may reasonably be anticipated to endanger public
health or welfare. Some NMOCs are known to have carcinogenic or non-carcinogenic health
effects. Methane is of concern primarily because of its explosive potential and as a greenhouse
gas that contributes to global warming. Public welfare concerns include the odor nuisance from
certain landfill gas constituents such as sulfur compounds, and the concern for migration of
21
methane, producing the potential for explosions or fire. It is assumed that landfill gas can be
emitted anywhere in the landfill and, as such, is considered to be an area source (USEPA, 1998).
AP-42 Chemicals
The list of chemicals commonly referred to as the"AP-42 chemicals"was developed by
USEPA. This list identifies a number of air pollutants expected to be emitted from landfills
based on test data USEPA compiled in a document entitled Compilation of Air Pollutant
Emission Factors, AP-42 (USEPA, 1997a). This information was collected by USEPA in an
extensive search of the literature, electronic databases, and USEPA resources, including
municipal solid waste landfill testing reports. The data were then reviewed and reduced to
produce the AP-42 list, a list of 47 chemicals found to be emitted from landfills. The list of AP-
42 compounds is in Table 6 of this document. USEPA incorporated this same list of AP-42
chemicals into the Landfill Gas Emissions Model (LandGEM). LandGEM models the emission
rates of the 47 chemicals of concern with respect to the landfill site and/or from controlled and
uncontrolled vents. MassDEP has reviewed the list of AP-42 chemicals and has identified
sufficient toxicity information to evaluate quantitatively all but a handful of the chemicals (Table
7). One criteria pollutant on this list, carbon monoxide, is evaluated elsewhere under 310 CMR
16.00 and is not addressed in the risk assessment. As additional toxicity data for the chemicals
without currently published values become available,they should also be included in quantitative
risk assessments.
The AP-42 chemicals represent a good starting point for predicting and evaluating
potential emissions from a facility that is still in the design phase. MassDEP considers the AP-
42 chemicals as the most comprehensive database on landfill gas emissions currently available in
the landfill literature. Therefore, all quantitative risk assessments done in support of a landfill
site assignment request should, at a minimum, consider the list of AP-42 chemicals as COC. If a
proponent prefers to use facility-specific monitoring data to characterize emissions at the facility
being evaluated,the proponent may do so. However, this information should only be used to
supplement the list of AP-42, not delete from it.
In the case of landfills that also accept special waste (i.e., a waste for which a special
waste permit is needed) in an amount greater than fifty percent of its total annual waste intake,
the proponent should evaluate the potential of the special waste to result in emissions of
additional chemicals other than those on the AP-42 list. MassDEP review and approval of such
assessments is required. See section on "Special Wastes" below.
Other Chemicals
MassDEP will entertain proposals on a case-by-case basis for identifying additional
COC, including for example, based on collecting monitoring data from a similar facility. For
landfill expansion requests, such a proposal could include monitoring at the existing landfill
assuming it receives the same waste stream.
It should be noted that since landfill emissions are also a function of the stage of
decomposition,this parameter should also be addressed when identifying COC. As discussed
22
previously in this document, since it is very difficult to determine at what point along a gas
production curve a set of monitoring data may have been derived, MassDEP's policy regarding
this issue is that, at a minimum, the list of AP-42 COC should be used along with, for each
chemical,the higher of the AP-42 concentration or the monitored concentration as an estimate of
a worst-case concentration. The list of COC can be supplemented with additional chemicals but
chemicals should not be deleted from the list.
The USEPA has established a number of promulgated test methods for measuring air
emissions which can be found on the internet at the Technology Transfer Network (TTN)
Emission Measurement Center(EMC) of USEPA's website at
http://www.epa.gov/ttnemc0l/promgate.html. Monitoring plans submitted by the applicant
should be comprehensive and include a protocol for identifying tentatively identified compounds
(TICS) as well a quality assurance/quality control (QA/QC)plan.
Special Wastes
A special waste or combination of special wastes should be addressed in a quantitative
risk assessment if that waste comprises greater than fifty percent per year of the total waste taken
in at a facility. If the percentage of special waste is equal to or below fifty percent of the total
yearly waste tonnage, then a quantitative assessment of emissions from the special waste is not
required. However, the proponent must comply with all existing MassDEP regulations and
permit requirements governing special wastes as provided for in 310 CMR 19.000. In addition,
the proponent should document their yearly projection of special waste tonnage and describe
how this quantitative estimate is determined. If the percentage of a particular waste is projected
to be greater than fifty percent at any time during a facility's lifetime,then the potential
emissions from special wastes should be included in the risk assessment. In such situations,the
list of AP-42 COC identified for inclusion in the quantitative risk assessment for a landfill siting
or permitting request should be supplemented with additional chemicals predicted to be emitted
based on the special wastes of concern. All such chemicals for which toxicity data exist should
be included in the impact assessment.
As discussed above, quantitative information on potential emissions can be obtained in
several ways. Applicants may be required to identify from the peer-reviewed literature
additional COC, subject to MassDEP approval, predicted to be released from special wastes.
These data should be obtained from reputable emissions studies conducted at similar facilities.
Information about the chemical and physical properties of the special wastes as they relate to the
decomposition process can also be used.
Alternatively, as discussed in the previous section, MassDEP will entertain proposals on
a case-by-case basis for identifying additional chemicals based on collecting monitoring data
from a similar facility taking in the same type of special wastes. For landfill expansion requests,
such a proposal could include monitoring at the existing landfill assuming it processes the
particular special waste of concern.
23
Table 7. Toxicity Information for the AP-42 List of Chemicals
Toxicity Information
SubChronic Chronic Inhalation
(Always check for updated toxicity information) Reference Reference Unit Risk
Concentration Concentration Value USEPA
RfC RfC URinh Cancer
Chemical CAS mg./m3 ref mq/m3 ref(u9/m3)-1 Classification re
1,1,1-Trichloroethane(methyl chloroform) 71-55-6 1.00E+01 2b 520E+00 3a D
1,1,2,2-Tetrachloroethane 79-34-5 2.80E+00 10 930E-02 3a 5.80E-05 C 1
1,1,2-Trichloroethane 79-00-5 7.40E-02 6 740E-02 3a 160E-05 C 1
1,1-Dichloroethane(ethylidene dichloride) 75-34-3 5.00E+00 2 5.00E-01 2 1 60E-06 C 5
1,1-Dichloroethene(vinylidene chloride) 75-35-4 8.10E-02 10 200E-01 1 C
1,2-Dichloroethane(ethylene dichloride) 107-06-2 5.50E-02 6 5 50E-02 3a 2.60E-05 B2 1
1,2-Dichloropropane(propylene dichloride) 78-87-5 1.30E-02 2 4.00E-03 1 1.90E-05 B2 3t
2-Propanol(isopropyl alcohol) 67-63-0
Acetone 67-64-1 310E+01 10 8.00E-01 3a D
Acrylonitrile 107-13-1 2.00E-03 6 2.00E-03 1 6.80E-05 31 1
Benzene 71-43-2 3.20E-02 4 9.00E-03 3a 7.80E-06 A 1
Bromodichloromethane 75-27-4
Butane 106-97-8 4 50E+00 6 9 50E-01 11
Carbon disulfide 75-15-0 7 OOE-01 2 7 OOE-01 1 NA
Carbon monoxide
Carbon tetrachloride 56-23-5 4.30E-01 6 4.30E-01 3a 1.50E-05 B2 1
Carbonyl sulfide 463-58-1 5.00E-04 6 5.00E-04 3a
Chlorobenzene 108-90-7 2 OOE-01 2b 6.00E-02 7 D
Chlorodifluoromethane 75-45-6 5.00E+01 6 5.00E+01 1
Chloroethane(ethyl chloride) 75-00-3 1.00E+01 2 1 00E+01 1
Chloroform 67-66-3 6.60E-01 6 6.60E-01 3a 2 30E-05 B2 i
Chloromethane(methyl chloride) 74-87-3 4.20E-01 10 3.00E-01 7 1.80E-06 C 2
Dichlorobenzene(tox data for para)- 10646-7 1.20E+00 10 8.00E-01 1 6.90E-06 C 2e
Dichlorodifluoromethane 75-71-8 200E+00 2 2.00E-01 2
Dichlorofluoromethane 7543-4
Dichloromethane(methylene chloride) 75-09-2 3.00E+00 2 3.00E+00 2 4.70E-07 B2 1
Dimethyl sulfide(methyl sulfide) 75-18-3
Ethane 74-84-0 4 50E+00 6 9 50E-01 11
Ethanol 64-17-5 2 50E-01 6 2 50E-01 3a
Ethylbenzene 10041-4 1.00E+00 2b 1.00E+00 1 D
Ethyl mercaptan(ethanethiol) 75-08-1
Ethylene dibromide(dibromoethane) 106-93-4 2 OOE-03 2 2.00E-04 2 2 20E-04 B2 1
Fluorotrichloromethane 75-69-4 7.00E+00 2 7.00E-01 2
Hexane 110-54-3 2.00E-01 2 2.00E-01 1
Hydrogen sulfide 7783--06-4 1.00E-02 2 1 OOE-03 1 NA
Mercury,total(tox data for elemental) 7439-97-6 3.00E-04 2 3 OOE-04 1 D
Methyl ethyl ketone 78-93-3 1 00E+00 2 1 00E+00 1 D
Methyl isobutyl ketone 108-10-1 8 OOE-01 2 8 OOE-02 2 NA
Methyl mercaptan 74-93-1 2 50E-03 6 2 OOE-03 9 NA
Pentane 109-66-0 2 OOE-01 6 2 OOE-01 8
Perchloroethylene 127-184 4.60E+00 6 4.60E+00 3a 5.50E-05 NA 3t
Propane 74-98-6 2.00E-01 6 9.50E-01 11
Toluene 108-88-3 4.00E-01 21b 4.00E-01 1
Trichloroethylene 79-01-6 5.50E-01 10 1.80E-01 3 1.70E-06 NA 2t
t-12-Dichloroethene 156-60-5 8.10E-01 10 110E+00 3a NA
Vinyl chlonde 75-01-4 1.00E-01 6 1.00E-01 1 8.80E-06 A 1
Xylenes(m-,o-,p-) 1330-20-7 3.10E+00 10 6.00E-02 3a D
References for Table 7
1. USEPA Integrated Risk Information System(IRIS)
2. USEPA Health Effects Assessment Summary Tables(HEAST)
2a Converted from the oral slope factor listed in HEAST
2 b Withdrawn from HEAST pending EPA review
3.a MassDEP-Back-calculated from the MassDEP Threshold Effects Exposure Limits
3.b MassDEP- From the Chemical Health Effects Assessment Methodology and the Method to Derive
24
Allowable Ambient Limits(CHEM/AAL)
4 MassDEP—Calculated Value
5. California EPA
6 This chronic value should be used to evaluate subchronic exposures in the absence of a subchronic RfC.
7. Provisional value,USEPA National Center for Environmental Assessment
8. Toxicity values for hexane are used to evaluate this alkane.
9. US EPA Risk Assessment Information System(RAIS)
10. Agency for Toxic Substances and Disease Registry(ATSDR)
11 Calculated using the MassDEP CHEM/AAL process from the NIOSH occupational limit for butane. This value
should also be used to evaluate ethane and propane.
Landfill Point Sources
Stack Gas Constituents
Gas collection systems can be either active or passive. Active systems employ pressure
gradient using mechanical blowers or compressors whereas passive systems rely on the natural
pressure gradients created as landfill gas builds up to mobilize the landfill gas. The design of
collection systems varies with landfill characteristics and operation. Some involve installation of
probes at the landfill perimeter, although the probes are generally installed directly within the
refuse-containing area. In general, active systems are more efficient in collecting gas than are
passive systems. Reported gas collection system efficiencies range from 60%to 85%, with an
average of 75%most commonly assumed (USEPA, 1997d).
Control treatment of the collected gas can be done using either a combustion technology
or a purification technique. Combustion technologies generally involve either flares, in which
collected gas is destroyed via burning, or an energy recovery technique in which energy
generated in the destruction of the gas is collected via gas turbines, boiler to steam turbines or
internal combustion engines. Purification techniques generally involve use of adsorption,
absorption and membrane techniques to remove water, carbon dioxide and NMOCs.
Flares use an open combustion process and represent point emission sources within a
landfill. Flares may be open or enclosed. Enclosed flare systems can better control the quality
of combustion by regulating temperature, residence time of components in the combustion zone,
turbulent mixing within the combustion zone and the amount of oxygen available for
combustion. A well-operating flare has a control efficiency of 90-99% for NMOC, 91-99% for
halogenated species and 38-99% for non-halogenated species (USEPA, 1997d).
Based on the fact that collection and combustion of landfill gas is not one hundred
percent efficient, constituents of landfill gas are still expected to be released from landfills with
collection and treatment systems. These emissions can result from uncollected gas or non-
combusted gas from control devices. In addition to landfill gas constituents,the flaring process
produces secondary pollutants that are released at the stack. Secondary pollutants typically
released from landfill flares include nitrogen oxides, carbon monoxide and particulate matter.
Other pollutants may also be released, depending on the waste stream within that landfill. For
example, when chlorinated compounds are combusted in control equipment, hydrogen chloride
emissions are formed.
25
AP-42 Chemicals
As discussed above, although the total amount of landfill gas constituents is expected to
decrease substantially with the use of collection and treatment systems, these chemicals are still
expected to be released in controlled landfills. Thus, even for a controlled facility, all
quantitative risk assessments done in support of a landfill expansion request should, at a
minimum, include the list of AP-42 chemicals as COC or a MassDEP approved alternative list of
COC's. See the section above on area sources for additional information on the AP-42
chemicals and options for identifying a list of COC at landfills.
Other Landfill Gas Chemicals
As discussed above, since chemicals emitted in landfill gas are a function of the waste
stream received, it is possible that additional chemicals which are not on the AP-42 list may be
emitted in the collected landfill gas, especially in the case of facilities that accept non-traditional
wastes or special wastes. As stated above, even for a controlled facility,predicted emissions
from such wastes, if they comprise greater than fifty percent of the total annual waste intake for
that facility, should be included as COC. See above section on area sources for additional
information on options for establishing COC for special wastes at landfills.
Secondary Pollutants from Stack Emissions
MassDEP may require on a case-by-case basis the identification of additional COC (e.g.,
hydrogen chloride) in stack emissions. These data may include well-conducted landfill flare
emissions studies from the literature conducted at facilities accepting a similar waste stream.
Additional stack gas constituents may also be predicted by analyzing the waste stream for that
facility along with information on the chemical and physical properties of the chemicals
predicted to be generated in landfill gas. Principles of combustion chemistry can be used to
predict the combustion by-products generated upon flaring.
Alternatively, MassDEP may require on a case-by-case basis the identification of
secondary COC based on collecting monitoring data from a similar facility. For requests
involving landfill expansions at facilities with collection and treatment systems, such a proposal
could include monitoring at the existing stack assuming the expansion will receive the same
waste stream as the existing landfill. Information on USEPA promulgated test methods for
measuring air emissions for a number of parameters can be found on the internet at the
Technology Transfer Network(TTN)Emission Measurement Center (EMC) of USEPA's
websiteathttp://www.epa.gov/ttnemcOl/promgate.html. Monitoring plans submitted by the
applicant should be comprehensive and include a quality assurance/quality control (QA/QC)
plan.
4.1.1.2 COC From Non-Municipal Solid Waste Landfills
For ash landfills and C&D landfills, MassDEP has determined that the emissions of most
concern are fugitive particulates generated during transport and processing of these wastes, as
well as hydrogen sulfide for C&D landfills. Particulates of health concern include those with a
diameter less than 10 gm (PMI 0, PM2.5), in particular those less than 2.5 µm (PM2.5).
26
Toxicologically, it is the very small particulates that, once inhaled, can penetrate deep into the
lung where they are not easily eliminated by the lung's clearance mechanism and can thus persist
to do more damage. At each of these facilities, MassDEP believes that particulate emissions can
be adequately controlled through use of facility-specific BMPs that address fugitive dust control.
MassDEP is issuing guidance on addressing hydrogen sulfide emissions that will include
recommendations on establishing monitoring systems, developing response plans, and facility
operations and design.
Ash Landfills
Ash, and in particular, fly ash, consists of very fine particulates. For this reason,
MassDEP had been concerned in the past about potential emissions of fugitive particulates from
ash transport and disposal activities at landfills. Studies that look at the potential for entrainment
into air of fugitive particles at ash landfills are limited. As a conservative approach, MassDEP
therefore historically required that the potential emissions and resulting risks due to fugitive
emissions from landfills be estimated and evaluated using the AP-42 approach. The AP-42
approach was used to generate an estimate of a dust emission rate to which percent metal
composition data(measured in facility-specific ash) was applied to estimate metal concentrations
in that ash.
MassDEP found that the assessments conducted using the AP-42 approach typically
yielded very low estimates of risk, generally in the de minimis range. In the course of
conducting these assessments, MassDEP also learned more about the ash-generation process and
the nature of ash. Based on the required BMPs for ash, the ash-generating process typically
yields a product of high moisture content. Ash is produced as the end product of the burning of
organic materials (e.g., most typically, municipal solid waste, coal, etc.). Bottom ash is created
when the residue from combustion falls into a water bath that cools the residue, thus saturating
the bottom ash stream with water. Fly ash is typically mixed with water to increase its moisture
content. Ash is hygroscopic and once dry forms a fairly rigid structure that does not easily break
down into particles small enough to become airborne.
The preponderance of evidence demonstrates that ash disposal does not result in any
significant entrainment of ash dust. In 2002, a Feld monitoring study (AMEC, 2002)was
performed at the Ward Neck Landfill Expansion in Haverhill, Massachusetts for Covanta
Haverhill Associates (hereafter referred to as the"Covanta report")to measure concentrations of
fugitive emissions that might be associated with ash disposal activities. This investigation was
undertaken by the proponents of this facility to address their contention that ash emissions
associated with disposal activities were negligible and that the exposure assessment would be
zero in a quantitative risk assessment. Both upwind and downwind concentrations of respirable
particulates (PM 10) were measured at this facility during ash disposal activities. It was found
that downwind PM 10 concentrations were slightly (although statistically significant) higher than
upwind concentrations. However, additional observations strongly indicated increases in
downwind PM10 were due to diesel exhaust from on-site equipment rather than from
entrainment of ash. The observations included: PM10 concentrations were higher downwind
during dry dumping runs (i.e., empty trucks simulating ash dumping); there were no significant
differences between upwind and downwind metal concentrations during ash dumping activities.
27
Given that the moisture content of ash is the characteristic that prevents entrainment, protection
against future dust generation after water has been added is assured because it is extremely
difficult for ash to dry out.
Based on experiences to date and on the results of the Covanta study, MassDEP
concludes that entrainment to air of fugitive particles from ash is negligible if that ash is
maintained at a high moisture content(i.e., greater than 18%water content) during generation
and disposal activities.
Thus, if proper BMPs that address fugitive dust control are implemented at a facility,
there should be no need for an assessment of fugitive dust in a quantitative risk assessment. In
addition, also based on findings of the Covanta study, BMPs should be put into place at facilities
to retrofit existing on-site vehicles with diesel control technology and to limit idling times.
Construction and Demolition Landfills(C&D)
No chemical-specific, quantitative risk assessment is required for C&D landfills at this
time. Fugitive particulates from C&D landfills are addressed in the assessment of the criteria
pollutant PMI 0 that is required to be done elsewhere in the siting and permitting processes. As
discussed above for ash landfills, MassDEP believes that fugitive emissions from C&D facilities
may be adequately controlled by implementing BMPs that address control of fugitive dust.
However, MassDEP is issuing guidance to address hydrogen sulfide emissions from landfills that
handle C&D waste, fines, or residuals. Based on this guidance, MassDEP may require additional
controls or assessment for landfills that handle C&D waste, fines, or residuals.
4.1.2 Emissions From Proposed Waste Handling Facilities
Generally waste handling facilities should be characterized by a Level 1 assessment and
emissions should be adequately controlled by BMPs. Waste handling facilities are those in
which refuse is collected, processed and transported off-site. Facilities may either handle
municipal trash such as municipal waste transfer stations, or they may specialize in a particular
sector of the waste stream. Examples of more specialized waste handling facilities include
construction and demolition facilities and facilities that recycle landscaping wastes. Often, these
facilities exist because there is a market for materials recovered or recycled from the waste
stream. Usually, these facilities are able to recover portions of the waste stream to be shipped
off-site for reuse or recycling and the unrecoverable portion is transported off-site to another
facility for disposal. The residence time of most wastes at waste handling facilities is transitory,
since the waste enters the facility, is processed and is then shipped off-site.
The types of emissions generated from these facilities vary greatly depending on the
nature of the refuse processed. Mixed waste collected in municipal transfer stations is similar in
composition to municipal refuse that is landfilled. If these wastes were stored at the facility for
an extended period of time during which the decomposition process could progress, the gases
generated might be similar to those found at landfills. Since this is not the case and because of
the transitory nature of the wastes passing through such facilities, MassDEP considers the
28
emissions of concern at waste handling facilities as those area emissions generated during
processing, known as fugitive particulates.
tEugitive particulatesthat are generated and dispersed at a facility during day-to-day
operations may be emitted in conjunction with the loading and unloading of refuse, packing and
compacting operations, and other activities, especially in windy, dry conditions. However, waste
handling facilities are not characterized by the fugitive dust associated with excavation, packing
and landfill covering operations that are typical of landfills. Thus, emissions of fugitive
particulates in a well-controlled waste handling facility are expected to be relatively low.
MassDEP's protocol for evaluating site suitability of solid wastefacilities encourages all
facilities to install measures to control dusts utilizing Best Management Practices (BMPs).
MassDEP expects thatuse'ofBMPs for dust control=will=address-and=significantly limiNhe
emission'of fugitivedusts-fro-m waste processing-facilities.
4.1.3 Diesel Particulates
Diesel exhaust generated from heavy truck equipment and engines used at solid waste
facilities contain large quantities of particulates and nitrogen oxides (NO,) as well as other
pollutants including hydrocarbons and several gases. In general, although diesel engines are
more efficient than their gasoline-powered counterparts, current regulations allow them to emit
far more pollutants.
Diesel particulates=and NOx at-solid waste management=facilities-may-be emitted from
on=site equipmentas-well=asTrom vehicles-transporting refuse-into:and=out=of-the=facility: At
landfills, heavy truck diesel equipment is used for excavating and moving dirt, for landfill
covering and compacting operations as well as for waste transport. At waste handling facilities,
diesel equipment is used to move, consolidate and compact trash before it is trucked or railed
off-site. Diesel transport vehicles, which are used to haul refuse into and out of the facility will
emit diesel particulates and NO,during the relatively brief time they are visiting the facility.
However, the number of trucks visiting a facility in any one day will influence the proportion of
diesel pollutants contributed from truck traffic which could be quite significant, depending on the
facility. On the other hand,there may be many fewer pieces of heavy duty diesel equipment on
site and these may operate at a facility for hours at a time, constantly emitting diesel pollutants.
Such equipment may even operate in enclosed facilities, resulting in substantial, localized
exposure to workers.
,Diesel-particulates_arevery,fin-e,most_o£whichare_characterized-by=a=particle=diameter
gess than-2:5 µm and tfierefor'e have the capacityto b'e inhaled=deep into the-lungs;where they
can-have adverse effe-Up Particulates produce eye and nose irritation and aggravate respiratory
problems, including asthma. In addition,very fine particulates have been found to contribute to
an increased risk of premature death. Diesel engines release particulates directly into the air,
emit nitrogen oxides and sulfur oxides, which then transform into "secondary"particulates in the
atmosphere.
NO, lowers resistance to respiratory infections and aggravates symptoms associated with
asthma and bronchitis. In addition,NO, contributes to the formation of ozone (03), which
irritates the respiratory system causing coughing and choking and reduced lung capacity.
29
To limit diesel emissions from proposed solid waste facilities, MassDEP strongly
encourages that all on-site transport equipment used on all new and expanded landfills and new
and expanded waste handling facilities be retrofitted with diesel control technology. Such
retrofitting-will-significantly,reduce on-site diesel-emissions.
�— —------r
4.1.4 Toxicity Profiles
The descriptions of the potential health effects associated with each contaminant are
typically provided in a Toxicity Profile. Toxicity Profiles serve several purposes. They provide
a summary of the potential adverse human health effects that may be associated with exposure to
a particular contaminant and they contain references for the dose-response assessment. The
information in Toxicity Profiles may also be used to group chemicals by health endpoint and
mechanism of toxicity in order to fine-tune risk estimates. In addition,toxicity profiles also
serve as reference material for non-toxicologists who want to understand the potential health
impacts associated with contaminants.
The scope and level of detail of a Toxicity Profile will vary depending upon the nature
and quantity of information available for a particular chemical. For many substances,
toxicological information is readily available from many sources, and repetition of that
information in great detail in the Toxicity Profile is not necessary. For the purpose of the AP-42
chemicals evaluated in the quantitative risk assessment, a short descriptive summary of the
known health effects associated with the chemicals of interest and the basis for any existing
standards or guidelines would be sufficient. This information can be presented in the form of a
table or brief text. Ata minimum',-the profile—should-surnmarize-known-chronic-systemic
toxicity,developmental/reproductive toxicity;genotoxicity and=carcinogenicity,. If additional
chemicals have been identified, a more in-depth toxicological profile should be provided which
also includes a profile of the toxicokinetics, human and animal mechanisms of toxicity,
structure-activity relationships and interaction with other chemicals, as appropriate. In preparing
the toxicity profile, the risk assessor should rely on credible,peer-reviewed sources of
information such as controlled, epidemiologic investigations, clinical trials, experimental animal
studies, metabolic and pharmacokinetic experiments, in vitro studies and structure-activity
studies. All references should be provided to document the sources of information used to
prepare the toxicity profile.
4.2 Dose-Response Assessment
The Dose-Response Assessment involves a compilation of toxicity information on the
health effects of the COC. This information is obtained from human epidemiological or animal
toxicology studies in the published literature. Dose-response information for a large number of
compounds is represented in toxicity values published by the USEPA and other government
agencies. Toxicity values are chemical- and route-specific values obtained from epidemiological
or animal toxicity studies that have been adjusted to be applicable to chronic or subchronic
exposures of the general population, including sensitive individuals. These types of values,
which include non-threshold inhalation toxicity values and cancer unit risk values are generally
used in health risk assessment to estimate the type and magnitude of risk associated with
exposure to chemicals.
30
Toxicologically, there is believed to be an exposure level of a compound below which
adverse health effects do not occur. Theoretically, health effects are only possible once that
particular level of exposure or threshold is exceeded. Such a level is referred to as a threshold
dose. In theory, the threshold dose would be safe for all receptors who might be exposed at that
level. A brief summary of key toxicity values for use in quantitative impact assessments for
proposed facilities is described below. MassDEP recommends assessment methods based on
standard USEPA toxicity values and equations.
A threshold dose or exposure can be administered as an acute, subchronic or chronic
exposure. Acute exposure is typically assumed to be up to 24 hours in duration (quantitative
assessment of acute exposure is not required at this time). Subchronic exposures for humans
refer to exposures up to seven years in duration, while a chronic time period is greater than seven
years. Both subchronic and chronic exposures should be evaluated in the risk assessment for all
chemicals in order to assess all relevant exposure scenarios. Subchronic and chronic
subthreshold values should be used to evaluate subchronic and chronic exposures, respectively.
Non-Cancer
For the inhalation pathway, a subthreshold exposure for chronic exposures is
represented by a Reference Concentration (RIC) (in units of mg/m3). The RfC is the
inhalation exposure concentration (with uncertainty spanning perhaps an order of
magnitude or greater) to which daily exposure of a human population, including sensitive
populations, is likely to be free of appreciable effects. Methods for development of
inhalation reference concentrations are detailed by USEPA.
For the ingestion pathway, a Reference Dose(RID)represents a subthreshold oral
dose for chronic exposures (in units of mg/kg/day). The RID is the dose (with
uncertainty spanning perhaps an order of magnitude or greater) to which daily exposure
of a human population, including sensitive subgroups, is likely to be free of appreciable
effects during a lifetime. Methods for development of RlDs are similar to those used to
develop RfCs. RfDs may be used to evaluate inhalation exposures of particulate-
associated contaminants, typically evaluated in terms of dose rather than concentration.
Additional discussion of the use of RfDs is found in the Exposure Assessment section of
this document.
Cancer
Unlike threshold effects, with non-threshold effects it is assumed that every
concentration or level of a compound, no matter how small, produces some effect.
Carcinogenicity and mutagenicity are examples of non-threshold effects.
The dose-response assessment for carcinogens assumes that there is no threshold
dose for carcinogenicity, or in other words, that there is no dose of a carcinogenic
substance (other than no exposure)that is associated with zero risk. USEPA evaluates
available toxicity data and assigns the chemical to a weight-of-evidence class.
For inhalation exposures,the ability of a chemical to increase the incidence of
cancer in a target population is typically described by the cancer unit risk(UR) factor.
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The Unit Risk is the upper 95% Confidence Limit of the mean incremental lifetime
cancer risk estimated to result from lifetime exposure to a compound if it is in the air at a
concentration of 1 µg/m3. A Unit Risk is expressed as risk per concentration in air,
typically given in units of (gg/m3)-1. Unit Risk values are issued from a number of
different sources (See Section 4.2.2). Unit Risk values are multiplied by the
concentration (in gg/m3) of a compound in air to derive a unitless cancer risk estimate.
For the ingestion pathway, the measure of carcinogenic potency is described by a
Cancer Slope Factor(CSF). CSFs are also issued from a number of different sources
(See Section 4.2.2). The CSF for a chemical is calculated using mathematical
extrapolation models, commonly the linear multistage model, from the dose-response
curve of a toxicological study. The largest possible linear slope (within the 95%
Confidence Limit) of this curve is estimated at low extrapolated doses. Although for
some chemicals, human epidemiologic data are the basis of an estimate of the
carcinogenic potency, the most common basis of these values is an animal study. The
CSF is expressed as risk per unit dose, and is typically given in units of
(mg/kg/day)-l. Use of the slope factor assumes that the calculated dose received is
expressed as a lifetime average. CSFs are multiplied by the ingested dose (in mg/kg/day)
of a compound to derive a unitless cancer risk estimate. CSFs may be used to evaluate
inhalation exposures of particulate-associated contaminants, typically evaluated in terms
of dose rather than concentration. Additional discussion on the use of the CSF is found
in the Exposure Assessment section of this document.
The dose-response assessment describes the observed effects in humans and/or laboratory
animals associated with particular exposures or doses of the chemicals of concern. This
information is obtained from published literature describing epidemiological or toxicological
studies involving the particular chemical. For most chemicals included as COC in a solid waste
facility impact assessment,the dose-response information needed to conduct a risk assessment
may be found in secondary sources published by the USEPA or other government agencies, as
described below.
The dose-response relationships for each COC should be identified in the risk assessment
report. This information is later coupled with knowledge of the nature and magnitude of
potential exposures to characterize risk.
The dose-response information used for risk assessment may be divided into three major
categories:
• Toxicity information associated with threshold (non-carcinogenic) health effects
• Toxicity information concerning carcinogenicity, either from human epidemiologic data
or from laboratory studies
• The Relative Absorption Factors (RAFs) used to relate the toxicity information
identified from the literature to the exposure pathway of concern at the proposed site
under investigation.
4.2.1 Conversions from Dose
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In the absence of RfCs or Unit Risk values, an oral Reference Dose or Slope Factor may
be used to estimate risk by converting the Reference Dose to a Reference Concentration and the
Slope Factor to a Unit Risk if it is appropriate to do so based on toxicological considerations.
4.2.2 Sources of Dose-Response Values
There are a number of different sources of both subthreshold and non-threshold toxicity
criteria. When selecting toxicity information for use in quantitative risk assessment,the project
proponent should ensure that the information is appropriate for the assessment being conducted
and that it is up-to-date. Note that sources differ in the frequency at which they are updated and
level of review they receive.
Both threshold and non-threshold toxicity criteria are available from a variety of sources.
These include (listed in general order of preference, although case-by-case exceptions may
apply):
• Integrated Risk Information System (IRIS) database - This database contains values that
represent a consensus judgment of the USEPA Carcinogen Risk Assessment Verification
Endeavor (CRAVE), which is composed of scientists from various USEPA offices and the
Office of Research and Development. It is the preferred source of toxicity information. The
IRIS database is updated monthly and is available on the Internet. IRIS contains both chronic
inhalation RfCs and RfDs, and unit risk factors. (http://www.epa.gov)
• Health Effects Assessment Summary Tables (HEAST) - HEAST contains values that have
received some form of review by USEPA, but have not been verified and are considered
provisional. HEAST is prepared by USEPA's Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH. HEAST can be
obtained by contacting the National Technical Information Service (NTIS) Subscriptions
Department. HEAST contains both chronic RfCs and RfDs and unit risk factors.
• Other Sources
non-cancer:
- Allowable Threshold Concentration (ATC) - The "Allowable Threshold
Concentrations" are similar to the USEPA inhalation RfCs in intent but they are
derived by ORS using a modified version of the methodology used by ORS to
develop Threshold Effects Exposure Limits (TELs) (MassDEP, 1990), an ambient air
exposure guideline based on consideration of threshold-type health effects, developed
for MassDEP's air toxics program. The ATC values are equal to five times the TEL
values since they do not include a program-specific safety factor of 20%to account
for multi-media exposure.
- Other Toxicity Values developed by MassDEP/ORS - ORS develops chronic and
subchronic RFC-equivalent and RfD-equivalent values for some compounds for
which no values are available in IRIS or HEAST. These values are based on
available toxicological data and standard USEPA approaches for developing
33
reference concentrations and reference doses for threshold effects. The list of
chemicals includes a number of carcinogens for which USEPA has not derived non-
cancer toxicity values. These values can be accessed through the MassDEP web site
at htto://www.mass.eov/den.
Agency for Toxic Substances and Disease Registry (ATSDR) - ATSDR produces
Toxicological Profiles for hundreds of hazardous substances. In the toxicological
profiles, ATSDR develops Minimal Risk Level (MRLs) for threshold effects of some
chemicals. These values are updated when the profiles are revised, if appropriate.
An MRL is defined as an estimate of the daily human exposure to a substance that is
likely to be free of appreciable risk of adverse non-cancer effects over a specified
duration of exposure. MRLs are derived using the modified risk assessment
methodology the USEPA uses to derive reference concentrations for lifetime
exposure.
Calculation of a dose-response value using toxicity information from the
literature - Dose-response values may be derived by a qualified risk assessor or
toxicologist if none of the above sources provide a toxicity value, or if more recent,
credible and relevant data becomes available. USEPA approaches to the development
of RfCs are described in Interim Methods for Development of Inhalation Reference
Concentrations. The review and approval by MassDEP of such proposed values
would depend upon the justification and documentation provided to support it.
cancer:
- Toxicity Values Developed by MassDEP/ORS - The Office of Research and
Standards may develop unit risks for chemicals for which no values are available in
IRIS or HEAST. When available, these values can be accessed through MassDEP's
website at htto://www.mass.Qov/den.
- California Environmental Protection Agency(Cal/EPA) - Cal/EPA's Office of
Environmental Health Hazard Assessment (OEHHA), Department of Pesticide
Regulation (DPR) and Department of Toxic Substances Control (DTSC)develop or
approve cancer potency factors for use in risk assessments and as the basis for
regulatory action. A list of available cancer potency factors is revised semiannually
and can be obtained from OEHHA's Hazardous Waste Toxicology Section.
4.2.3 Dose-Response Information for the AP-42 Chemicals
MassDEP has compiled a list of dose-response information for the AP-42 chemicals. These
include chronic inhalation RfCs or RfC-equivalents and inhalation cancer unit risk values. These
values are contained Table 7.
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4.2.4. Relative Absorption Factors
The Relative Absorption Factor(RAF) is used to account for differences in the
absorption of a COC under assumed exposure conditions(exposure route and matrix) relative to
the absorption of the COC under the experimental conditions upon which the dose-response
value is based. It is used to adjust the calculated exposure in terms of exposure route and
medium of exposure relative to the exposure route and medium of exposure of the chemical
under experimental conditions.
In the case of inhalation criteria and inhalation exposures, the RfCs and inhalation URs
are typically derived based on inhalation toxicology studies. In such a case, the route and
medium of exposure would be the same as the route and medium of the study from which the
toxicity information was obtained. There are cases, however, in which the RfC and/or unit risk
have been derived based on studies using an exposure route/medium other than inhalation. In
these cases, an RAF should be used to account for these differences.
To estimate an RAF,two factors should be identified:
• the absorption efficiency for the chemical via the route and medium of exposure being
evaluated for the proposed facility, and
• the absorption efficiency for the route and medium of exposure in the experimental study
which is the basis of the dose-response value for the chemical in question.
Thus, the RAF adjusts the dose (or exposure) estimates based on these two absorption
efficiencies. The RAF is calculated as follows:
Absorption Efficiencys, .L route:med,um of expo>ure
RAF—
Absorption Efficiencys7.uDr rourelmec,um of exposure
The basis for all toxicity values used to conduct a risk assessment should be reviewed to
ensure that differences in absorption efficiency have been accounted for.
4.3 Exposure Assessment
The exposure assessment is a critical component of the risk assessment process as it
describes the contact between the contamination and the people who are potentially affected by it.
The exposure assessment should allow for the assessment of risks posed by the solid waste facility
to receptors in the surrounding area(i.e.,modeling domain, see Section 4.3.3.1.2.). Both current
and identified future uses of the surrounding area should be considered. For example, if a facility is
located adjacent to an undeveloped tract of land that is zoned for residential development,the future
use of this area as a residential neighborhood should be considered as part of the exposure
assessment.
For the purpose of evaluating facility-specific risk under the Site Assignment Regulations
(310 CMR 16.00)only exposure to COC via inhalation of ambient air should be assessed
quantitatively in a risk assessment. This exposure involves inhalation of emissions from the facility.
As described earlier,potential exposures via groundwater are addressed by the
35
implementation of a series of measures to prevent contamination of groundwater and subsequent
exposure to the human population.
The exposure assessment generally includes two components: the exposure profile and
quantitative estimates of exposure. The exposure profile describes the exposures that may occur to
human receptors in the area surrounding the facility. The quantification of exposure translates the
narrative exposure profile into an exposure equation resulting in a numerical estimate of exposure.
These numerical estimates are subsequently used in the calculation of health risks.
A screening exposure profile should initially be used to evaluate the impact of a proposed
new facility or expansion. This profile should assume continuous exposure to landfill emissions by
a receptor situated at the maximum point of impact at or beyond the property line. If health risks
estimated from such a scenario exceed risk management criteria,then the applicant may,on a case-
by-case basis,develop a more refined exposure profile that incorporates site-specific exposure
parameters. A refined exposure profile and associated assessment should, however,be protective
for all receptors who are assumed to be impacted by emissions from the proposed facility.
Potential exposures to COC from the proposed facility should be based on emissions and
dispersion modeling as discussed in Section 4.3.3.1.
4.3.1 Screening Case Exposure Profile
The screening case exposure profile assumes that a receptor is situated at the maximum
point of impact at or beyond the property line continuously,twenty-four hours per day, seven days
per week for thirty years 12, breathing air containing the modeled exposure point concentrations.
The screening exposure profile conservatively assumes that a receptor never leaves the area of
maximum impact for thirty years. If non-cancer and cancer risks calculated based on this exposure
profile meet risk management criteria,then the development of a more refined exposure profile,
based on more realistic exposure estimates, is not necessary as further refinements will only
decrease risk estimates further. However, if estimated screening risks exceed risk management
criteria,then a more realistic exposure profile(e.g.,reflecting time the receptor spends away from
home, at school, at work,etc.) should be developed as discussed below.
4.3.2 Refined Exposure Profile
The refined exposure profile should contain a narrative description of how exposure takes
place in the area surrounding the facility being evaluated. The exposure profile assists the risk
assessor in identifying the appropriate frequency and duration of exposure to which human
receptors are exposed via inhalation to concentrations of COC in air.
Potentially exposed human receptors in the area surrounding the facility will generally
comprise a diverse group that lives(or may in the future live) in the area surrounding the facility.
For the purposes of the risk characterization these residents should be further divided into
subpopulations based upon gender and age if those factors are indicative of a higher exposure
"The thirty-year annual average exposure,which represents a chronic period of time,is adopted for the LADE
assessment based on work done by USEPA that identifies this value as the 95`h percentile estimate of the time that
most people will spend living at one residence(EPA, 1997b)
36
potential. Young children, women of childbearing age and the elderly are often chosen as receptors
of concern in residential locations because of these factors. At industrial locations, adults may be
the most susceptible receptors. However,this may not be the case if, for example,there is a daycare
center on the premises. Identification of the most sensitive subpopulations should be done on a
case-by-case basis. Thus,to adequately evaluate these residents,the risk assessor may conclude that
all other subpopulations in the area would be subject to lower exposures and risks than those
calculated. Note,though,that while the receptors are described in terms of"subpopulations"or
"subgroups",the product of the risk assessment is still an estimate of the risk that applies to the
protection of an individual within that group. The quantitative risk assessment focuses on
individual risk not population risk.
A detailed exposure profile may be developed for what is believed to be the most highly
exposed receptor in the surrounding area accompanied by the conclusion that lesser exposed
receptors will also be protected. How often the exposures occur along with the length of these
exposures should be addressed. The exposure profile should address the facts, data, assumptions
and inferences about how exposures take place. Professional judgment is necessary,especially for
proposed new facilities for which there is no actual facility-specific information on operations.
Since these factors determine the magnitude of exposure(and thus the magnitude of the risk posed
by the proposed facility), it is important that there be a clear description and summary of this
information. The exposure profiles allow anyone concerned about the facility to read and
understand what was considered in the risk characterization.
The information that is used to develop an exposure profile for a facility should be obtained
via a compilation of data on the facility's proposed operation as well as on the composition and
distribution of the population in the area surrounding it. Relevant information on the proposed
facility and the surrounding area would include:
o the address and location of the proposed facility
o a detailed map of the proposed facility and surrounding area
o a description of the land uses at and surrounding the proposed facility
o a listing of other major point emission sources in the area regulated by
MassDEP (i.e., from SSEIS)
o identification of potentially sensitive populations in the surrounding area(e.g.,
daycare centers, nursing homes, etc.)
Some of this information may be available through the Massachusetts Geographic Information
System (MASS-GIS), which provides color plots or digital data. For a full listing of available
data, contact MassDEP GIS at(617) 574-6802 or Brian.Brodeurastate.ma.us.
4.3.3 Quantitative Estimates of Exposure
Once the screening and/or refined exposure profiles have been developed,the potential
exposures experienced by the receptors of concern from the proposed facility are quantified
using emission and dispersion modeling as described in Section 4.3.3.1. The outputs of the
modeling include the maximum annual average and the 30-year annual average estimates of
COC concentrations at the maximum point of impact in the surrounding population beyond the
property line and at the property line.
37
If the proponent chooses to do facility-specific monitoring, the results of this
investigation should be used to replace only those default AP-42 concentrations that are lower in
magnitude than monitored concentrations. As discussed in Section 2 of this document, a
conservative approach should be used in the risk assessment in which the highest of the
monitored concentration or concentration derived from an AP-42 emission factor is used in the
assessment. Concentrations of VOCs emitted from decaying waste fall along a lognormal gas
production curve and vary significantly over the decaying process, influenced by the age of the
waste and the particular set of environmental conditions characterizing the landfill. Since it is
very difficult to determine at what point along the gas production curve a data set may have been
derived, MassDEP's policy regarding this issue is to use the higher concentration as an estimate
of a worst-case concentration.
The several different time estimates of modeled exposure are necessary in order to
evaluate all relevant exposure scenarios. A chronic exposure for humans is typically described as
a period of time greater than seven years in duration. A subchronic human exposure is described
as a period of time from three months to seven years. For chemicals that are carcinogenic, a
lifetime average daily exposure (LADE) should be calculated. The thirty-year annual average
exposure, which represents a chronic period of time, is adopted for the LADE assessment based
on work done by USEPA that identifies this value as the 95`h percentile estimate of the time that
most people will spend living at one residence(USEPA, 1989).
4.3.3.1 Modeling Approach Used to Calculate Exposure Point Concentrations
The USEPA Landfill Gas Emissions Model (LandGEM) can be used for estimating
emissions of methane, carbon dioxide and non-methane organic compounds from municipal
solid waste (MSW) landfills. The model can be run using site-specific data or, if site-specific
data are unavailable, using default values. Information on the LandGEM model can be found in
User's Manual - Landfill Gas Emissions Model (USEPA, 1998).
Fugitive dust emissions from landfill operations due to filling, capping, waste
transportation, and wind erosion can be estimated with EPA AP-42 emission equations. Toxic
compounds in ash disposed in a landfill should be determined using an approved MassDEP ash
sampling and analysis program.
After air pollution emission estimates have been quantified, USEPA air quality dispersion
models can be used to estimate air pollution concentrations in the vicinity of the landfill.
Estimates of ambient air quality concentrations should be based on air quality models contained
in Supplement C to the Guidelines on Air Quality Models (Revised), EPA Publication No. EPA-
450/2-78-027R-C or other state-of the-art modeling procedures approved by MassDEP.
The Guidance Document will not address the modeling protocol for estimating levels of
NAAQS air pollutants. The potential impacts of criteria pollutants will not be addressed in the
facility impact assessment but are addressed elsewhere in the siting and permitting process.
38
4.3.3.1.1 Landfill Gas and Particulate Emissions
USEPA has concluded that many compounds found in landfill gas may endanger public
health if left uncontrolled. Fugitive dust associated with landfill operations may cause or
contribute to a condition of air pollution. Emission rates of landfill gas compounds and fugitive
particulate matter should be estimated using models and procedures approved by MassDEP.
4.3.3.1.1.1 Municipal Solid Waste Landfills
Municipal solid waste (MSW) produces emissions by three mechanisms: volatilization,
chemical reaction, and biological decomposition of solid or liquid compounds into other
chemical species. Volatilization is affected by the partial pressure of the constituent,
concentration of the constituent at the liquid air interface, temperature, and confining pressure.
Chemical reactions are also affected by temperature as well as waste composition, moisture
content, and the practice of separate disposal areas for different waste types. Factors affecting
biological decomposition include nutrient and oxygen availability, refuse composition, age of
landfill moisture content, temperature. acidity, and waste that is toxic to bacteria.
Area Sources(Uncontrolled Emissions)
Uncontrolled area source emission estimates can be determined for individual
landfills using USEPA's Landfill Gas Emissions Model (LandGEM). This theoretical
first-order kinetic model can be accessed from the EPA's Office of Air Quality and
Planning, Technology Transfer Network (OAQPS-TTN) website. The model can be
run using site-specific data. In the absence of site-specific emissions information,
MassDEP recommends using LandGEM with the USEPA AP-42 default values.
LandGEM provides emission estimates after the first year of refuse is in place and
provides annual estimates out to 200 years. Refuse data in Mg/year (million grams per
year) should be input into the model for each active year of operation—typically, a 4 to
7 year period of time.
If required, fugitive dust emissions from landfill operations due to filling,
capping, waste transportation, and wind erosion can be estimated with USEPA AP-
42 emission factors. Toxic compounds in any ash disposed of in a landfill should
be determined using an approved MassDEP ash sampling and analysis program.
Area Sources(Controlled Emissions)
Emissions from landfills are typically controlled by installing a gas collection
system and combusting the collected gas through the use of internal combustion
engines, flares, or turbines. To estimate landfill area source emissions after closure,
USEPA recommends using a 75%collection efficiency if site-specific collection
efficiencies are not available. During the period of time that the landfill is still active,
landfill gas capture efficiency should be assumed to be 0%. Gas collection systems do
not generally operate well before closure because it is too easy for air to enter the
system. If applicants have an existing air permit that specifies a gas capture rate,
39
MassDEP will rely on that data. Absent that type of documented data, MassDEP will
rely on the above default assumptions.
Point Sources (Controlled Emissions)
Collected landfill gas emissions are typically controlled by combusting the
collected gas through the use of internal combustion engines, flares, or turbines. The
AP-42 emission factor tables can be used to estimate the destruction efficiencies of the
control systems used to destroy NMOC compounds in collected landfill gas(typically
98% or more).
Non-Municinal Solid Waste Landfills
Non-municipal solid waste facilities generally accept a specific form of waste.
Examples are ash landfills and C&D landfill sites. Typical emissions of concern are
fugitive particulate matter generated during processing and transportation of such
wastes, and for C&D landfills, hydrogen sulfide emissions.
Area Sources (Uncontrolled Emissions)
If required, fugitive dust emissions from landfill operations due to filling,
capping, waste transportation, and wind erosion can be estimated with AP-42 emission
factors, or other state-of-the-art procedures approved by MassDEP. MassDEP may
request case-by-case estimates of fugitive dust emission rates and other COC based
upon a review of the literature.
4.3.3.1.2 Air Quality Impact Analysis Modeling Protocol
Listed below are the recommended contents of an air quality analysis modeling
protocol. Applicants should meet with MassDEP staff to discuss the proposed contents
of an air quality modeling protocol before submitting the protocol to MassDEP for
review and approval. All estimates of ambient air quality concentrations should be
based on air quality dispersion models and other requirements specified in Supplement
C to the Guidelines on Air Quality Models (Revised), USEPA Publication No. EPA-
450/2-78-027R-C, or other state-of the-art modeling techniques with technical merit as
approved by MassDEP.
For ash landfills, the proponent should discuss with MassDEP an assessment
plan and the potential need for any interactive modeling of sources with similar
emissions. The results of this discussion should be incorporated into the modeling
protocol.
Source Data
Facility Description: A description of the proposed landfill or proposed landfill
expansion under review should be provided, including site plans and appropriate
40
topographic maps. Yearly trash acceptance rates (out to the year of cell closure) and
geographic areas to be filled (out to the year of cell closure) should be identified.
Operating Schedules: Daily and weekly operating schedules should be described,
including truckloads of waste, fill and cover operations and any emission mitigation
activities.
Landfill Emission Rates: Landfill gas emission rates in grams per year for methane,
NMOC, carbon dioxide and the list of AP-42 compounds should be estimated using
USEPA's LandGEM model. MassDEP will accept other emission estimation
techniques if they have technical merit and reflect state-of-the-art emission estimation
procedures. Refuse data Mg/year should be input into the model for each active year of
operation out to closure (typically 4 to 7 years). After closure, assume that 75%of the
landfill gas emissions predicted by the LandGEM model will be collected and burned,
unless site-specific collection efficiencies are available. During the time a landfill is
still active, landfill capture efficiency should be assumed to be 0% due to the fact that
before closure it is too easy for air to enter the system and thus the system does not
operate well. Landfill yearly emission rates should be calculated for a 30 period of time,
including the years of active filling, usually a 4 to 7 year period of time.
Stack Emission Rates: Metric stack parameters and emission rates for all stacks,
flares and vents associated with the landfill gas collection system should be provided.
Stack data should include height above ground, stack diameter, stack exit velocity,
stack temperature and stack emission rates in grams per second for the AP-42 list of
COC. The AP-42 emission factor tables can be used to estimate the destruction
efficiencies of the control systems used to destroy the COC in collected landfill gas
(typically 98% or more).
Receptor Network
Grid: A Cartesian receptor grid should be designed for the modeling analysis,
centered on the approximate center of the proposed landfill expansion area. The
network should be of sufficient detail to ensure that maximum air quality
concentrations at or beyond the property line will be determined. Receptor rows and
columns should be spaced 50 meters apart. The network should be 2 kilometers on a
side, unless there is a need to more accurately determine air quality impacts at more
distant receptor areas of concern.
Discrete Receptors: Receptor coordinates for other sensitive receptors should also be
obtained (nearby residences, schools, parks). The principal purpose of discrete receptor
placement is to ensure that maximum air quality concentrations are determined at all
locations where the public has access.
Elevations: Receptor elevations should be obtained from USGS 1:25,000 3 in contour
electronic data and/or by inspection of applicable USGS maps.
41
Meteorological Data
Five years of hourly meteorological data should be employed for the modeling
analysis. The data should be reasonably representative of the area where the landfill is
located. USEPA recommends using a 5 year data set whenever possible in order to
account for year-to-year variability in wind speed and direction patterns.
Atmospheric Dispersion Coefficients
A description of the land use within 3 kilometers of the proposed site (Auers
technique) should be provided in order to determine if urban or rural dispersion
coefficients should be employed. A field visit with MassDEP staff may be required to
ensure appropriate land use determinations.
Air Oualitv Models
Estimates of ambient air quality concentrations should be based on the air quality
models contained in Supplement C to the Guidelines on Air Quality Models (Revised),
USEPA Publication No. EPA-450/2-78-027R-C or other state-of the-art modeling
approved by MassDEP. Model options and settings should be specified and justified.
MassDEP recommends using USEPA's ISC3 model for estimating long-term air
quality impacts from point and area source emissions associated with landfill emissions.
The ISC3 model can be accessed from the USEPA's Office of Air Quality and
Planning, Technology Transfer Network website httn://www.ena.aov/ttn/scram/.
4.3.3.1.3 Air Quality Impact Analyses Report
Air quality impacts of emissions from landfills and/or landfill expansions should be
determined following an air quality modeling protocol approved by MassDEP. All
input and output files for all modeling runs should be retained for review by MassDEP.
Averaging Times of Concern
Air quality impacts at each receptor point in the receptor network should be
determined for each of the AP-42 compounds. Maximum 1 year and maximum 30-
year impacts for each gas should be presented for the maximum off-site location. In
addition, maximum 1-year and maximum 30-year impacts for each landfill gas should
be noted for all locations where the public has access.
Contents of Air Oualitv Impact Analvsis Report
Modeling results should be presented and discussed in an air quality impact
analysis report. The report should be submitted to MassDEP for review, and should
document and describe all data and procedures used in the modeling analysis (source
42
configuration, emission calculations,point and area source model input data, air quality
model options and settings, receptor network, meteorological data, and predicted air
quality concentrations). A review of this information may indicate that additional
modeling analysis is required to ensure that maximum air quality impact levels and
locations have been identified.
4.3.3.2 Calculation of Average Daily Exposure,;,
The toxicity information generally used to evaluate the risk of harm to health
associated with inhalation exposures, Reference Concentrations and Unit Risk values,
are air concentrations. These values are intended to be used in combination with
Average Daily Exposures (and Lifetime Average Daily Exposures for carcinogens)
expressed as applied concentrations. RfCs are typically used when evaluating gaseous
inhalation exposures.
Gaseous air contaminants may be inhaled by the receptor of concern located in
the vicinity of the facility emissions. The Average Daily Exposure to the contaminated
air(ADE,;,) is dependent upon the frequency and duration of the assumed exposures.
The result of this calculation should be an estimate of applied concentration. Note that
the equation is a simple adjustment of the exposure point concentration to account for
the amount of time the receptor spends in the area with contaminated air.
[COC J,,,, * EF * EP * C
ADEo„— AP
Where:
ADEai,= Average Daily Exposure to a contaminant in air (dimensions: mass/volume;
typical units: mg/m3)
[COC]air=Exposure point concentration of COC in the air at the Exposure Point during the
period of exposure(dimensions: mass/volume;typical units: µg/m3).
EF= Exposure Frequency, or the number of exposure events during the exposure
period divided by the time of the exposure (dimensions: time/time; typical
units: hours/day, days/week)
EP= Duration of the exposure period (dimensions:time; typical units: years)
AP= Averaging Period(dimension:time;typical units: years)
C= Appropriate units conversion factor(s) (e.g., 10-3 Mg/Pg, 1 week/?days)
For receptors assumed to be exposed constantly during the period of exposure (such as
for many residential exposures), the Average Daily Exposure would be equal to the Exposure
Point Concentration. Separate ADEa„estimates should be based on the modeled maximum
annual average (for the assessment of subchronic exposure) and the thirty-year average (for
chronic exposures) exposure point concentrations, as discussed in Section 4.3.3.
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4.3.3.3 Inhalation of Particulate-Associated Contamination
When evaluating particulate inhalation exposures, an Average Daily Dose rather than an
Average Daily Concentration is calculated. (The equations for calculating each of these values
are given below.) Airborne particulates (fugitive dust) may carry COC to receptors, resulting in
particulate-related inhalation exposures. The RfC and unit risk should still be used to estimate
risk in such a case by converting the RfC to an RfD and the unit risk to a slope factor.
For airborne chemicals that act at the point of contact (e.g., the lungs) when inhaled, the
Average Daily Exposure of these chemicals calculated in the manner described above would be
used in combination with an RfC or unit risk to estimate potential risks. Under such conditions,
the ADDpart,culate inhalation would not be calculated.
An Average Daily Dose due to the inhalation of particulate-associated chemicals
(ADDparticulate inhalation) may be calculated as:
[RP]o„ *[COC JP.r11CL1O1e * VR * RAF * EF * EP * C
ADDo„«aia,e,inhalation— BW * AP
Where:
ADDpaet;culate inhalation= Average Daily Dose of a contaminant through the inhalation of
particulates. (dimensions: mass/mass*time; typical units:
mg/kg*day)
[RP]air= Exposure point concentration of respirable particulates(i.e.,PM10) in the air at
the Exposure Point during the exposure event. (dimensions: mass/volume;
typical units: µg/m)
[COC]p=cniate= Exposure point concentration of COC in the particulate material at the
Exposure Point during the period of exposure (dimensions: mass/volume;
typical units: mg/kg)
VR= Ventilation (inhalation) rate for the receptor of concern during the period of
exposure. (dimensions: volume/time;typical units: m3/hour)
RAF= Relative Absorption Factor(unitless)
EF= Exposure Frequency, or the number of exposure events during the exposure
period divided by the time of the exposure (dimensions: time/time; typical
units: hours/day, days/week)
EP= Duration of the exposure period (dimensions: time; typical units: years)
BW= Body weight of the receptor of concern during the averaging period (dimension:
mass; typical units: kg)
AP= Averaging Period(dimension: time;typical units: years)
C= Appropriate units conversion factor(s) (e.g., 10-6 kg/mg, 1 week/? days)
The equation below, for calculating the ADD,nhp can also be used to convert between an
exposure concentration (ADEan) and a dose (ADD,nhp)•
44
4.3.3.4 Calculation of the Lifetime Average Daily Exposure (LADE) or the Lifetime
Average Daily Dose(LADD)
In order to be consistent with the toxicity values used to estimate cancer risk,the Lifetime
Average Daily Exposure (LADE) or Lifetime Average Daily Dose (LADD) should be used.
These values are calculated assuming that the chronic exposure to COC is averaged over a
lifetime. For the purposes of quantitative risk assessment, a chronic thirty-year exposure to
landfill gas is assumed and averaged over an assumed lifetime of 70 years. Thus, in the above
equations (in Sections 4.3.3.2 and 4.3.3.3),the exposure period (EP) should be designated as 30
years and the averaging period (AP) as 70 years.
4.4 Risk Characterization
Risk Characterization is the final step in the risk assessment process. In this step, the
results of the Hazard Identification, Dose-Response Assessment and Exposure Assessment are
integrated to yield quantitative measures of cancer and non-cancer risk. The Risk
Characterization can be thought of as providing a link between risk assessment and risk
management because it presents the numerical estimates of risk posed by the proposed facility in
a context that can be used easily by risk managers to make a siting decision.
A critical component in the presentation of risk estimates is the discussion of major
assumptions, scientific judgments and uncertainties inherent in the numerical risk estimates. The
importance of this component cannot be overstated. The discussion of uncertainties should place
the numerical estimates of risk and hazard in the overall context of what is known about the
proposed facility and surrounding area and what is uncertain. The numerical risk estimates
should never be interpreted as a characterization of absolute risk but should always be interpreted
in the context of the uncertainties.
Inhalation risk estimates for each chemical should be combined(summed)to yield total
cancer and non-cancer risks considering all chemicals for the receptor evaluated. These total
risks should then be compared with specific risk management criteria as defined in Section 4.6.
A discussion of the methods for characterizing cancer and non-cancer risks and a
discussion of the interpretation of Risk Characterization results within the context of the Solid
Waste Facility Siting Regulations is provided below. This section also describes how
uncertainties in the risk assessment should be addressed.
4.4.1 Non-cancer Risk
The measure used to describe the potential for non-carcinogenic health effects is the
Hazard Quotient(HQ). For a given chemical, the HQ is the ratio of a receptor's exposure level
(or dose) for a single chemical to the "acceptable"(or allowable) exposure level for that
chemical. For exposure to multiple chemicals, the chemical-specific Hazard Quotients may be
summed to calculate a Hazard Index (HI).
Hazard Index= HQ1 +HQz +HQ3 +...+HQ,
45
A Hazard Index of 1.0 or less indicates that adverse health effects from the exposures
under assessment are unlikely. When the HI is less than or equal to 1.0, the conclusion is that the
proposed facility poses an acceptable risk of harm to human health.
A HI of greater than 1.0 indicates that non-cancer health effects could occur, and cannot
be ruled out. It does not mean that non-cancer effects will occur. Uncertainty inherent in most
toxicity benchmark values precludes identifying a specific dose above which adverse effects are
likely and below which effects are unlikely. Accordingly,the probability of an effect cannot be
quantified from a Hl. For anv one chemical. it is always true that the likelihood of an effect
increases as the exposure level (and therefore the HI) increases.
The uncertainty inherent in toxicity benchmark values for different chemicals differs both
qualitatively and quantitatively. Therefore, for different substances, the probability of an effect
increases at different rates. For example, a HI of 20 for one substance may indicate a very high
probability of an effect, but may represent only a moderate probability of an effect for another
chemical.
In interpreting the HQ or HI, one should consider the appropriateness of the exposure
assumptions and the basis of the toxicity information used to develop the toxicity benchmark
values. As a general rule, the greater the HI is above 1.0, the greater the level of concern.
In its most general form,the Hazard Quotient associated with a chemical via inhalation is
calculated as:
HQ= A�°" or, for dose equations: HQ= DD."
Where:
HQ= The Hazard Quotient associated with exposure to the chemical via
inhalation
RIC= The Reference Concentration or substitute toxicity value identified for the
chemical of concern for chronic exposure (in mg/m3).
RID = The oral Reference Dose or appropriate substitute toxicity value identified
for the chemical of concern. (in mg/kg/day).
ADEa,,= The estimated Average Daily Exposure of the chemical via the specified
exposure route. (in mg/m3).
ADDa,,= The estimated Average Daily Dose of the chemical via the specified
exposure route. (in mg/kg/day).
As mentioned previously, total non-cancer risks should be calculated for each facility.
The HI accounts for inhalation exposures that a receptor may receive from multiple chemicals
emitted from the proposed facility and represents the non-carcinogenic impact of that facility to
receptors.
46
The documentation of the Risk Characterization should clearly present all mathematical
equations used to calculate total non-cancer risks for inhalation.
4.4.1.1 Screening Hazard Index
Initially, the risk assessor should calculate a Screening Hazard Index for a given receptor
by totaling all the individual chemical-specific HT calculated as described above. A HI
calculated in this way will provide a conservative estimate of the true HI because it treats as
additive, different toxic effects from multiple chemicals acting on different organ systems by
different mechanisms of action. In fact, in a true HI, the only endpoints that should be treated as
additive are those that produce adverse effects on the same organ system by the same
mechanism. Thus, the screening HI will provide a conservative estimate of the actual HI
because it reflects the sum of toxicities for multiple chemicals, regardless of the chemical's
health endpoint,target organ or mechanism of action.
There may be multiple adverse health effects associated with exposure to a given
chemical and it is the most sensitive adverse health effect observed in the scientific data which
typically drives estimation of the Reference Concentration and other toxicity benchmarks. Thus,
for a given group of chemicals, Reference Concentrations may be based on different toxic effects
on different organ systems by different mechanisms of action.
The screening HI should be compared with the total non-cancer risk limit, which is a HI
equal to 1.0. If the screening HI is less than 1.0, then no additional effort is needed to
characterize non-cancer risks. However, if the screening HI exceeds 1.0, the risk assessor may
then group together chemicals with similar toxic effects and mechanisms of action and calculate
a separate HI for each group.
Separate HIs should be calculated for different exposure periods, both subchronic and
chronic.
4.4.1.2 Health Endpoint-Specific Hazard Index (Multiple Chemicals)
The procedure for segregating HIs by effect and mechanism of action is not simple and
should be performed by a toxicologist. If the segregation is done improperly, an underestimate
of the true hazard could result. Segregation of HIs requires identification of the major health
endpoints of each chemical, including effects observed at higher doses than the critical effect on
which the toxicity value is based. This is because the critical effect for one chemical may not be
relevant for other chemicals and doses of other chemicals may not be additive for that effect. On
the other hand, additive impacts could be important for other health endpoints that are only
expected at higher doses.
i3 Current USEPA methodology is based on additivity of risk. It is acknowledged however that there is an inherent
uncertainty in the assumption that the addition of risks is a conservative approach. Actual risks may be over-
estimated if this assumption is correct or they may be underestimated since possible synergistic effects are not
addressed.
47
Major effect categories that should be considered in segregating chemicals include
neurotoxicity, developmental toxicity,reproductive toxicity and immunotoxicity. Adverse
effects also should be categorized by target organ (i.e., hepatic, renal, respiratory, cardiovascular,
gastrointestinal, hematological, musculoskeletal and dermal/ocular).
Once chemicals have been categorized, total inhalation hazard indices(for subchronic
and chronic toxicity) for chemicals with similar health endpoints and mechanisms of toxicity
should be calculated by summing the chemical-specific HQs calculated for each of these
chemicals. Each HI should be compared with MassDEP risk management criteria for siting solid
waste facilities as presented in Section 4.6.
4.4.2 Cancer Risk
The potential for carcinogenic (i.e., non-threshold) health effects is characterized as the
Excess Lifetime Cancer Risk(ELCR). The ELCR represents the incremental probability of an
individual developing cancer over a lifetime as a result of exposure to the potential carcinogen.
For a given chemical, the estimated ELCR is the product of the receptor's quantified exposure
and a measure of carcinogenic potency. The typical measure of carcinogenic potency for
inhalation is the USEPA Unit Risk(UR)value.
In its basic form,the ELCR associated with exposure to a given chemical via a particular
exposure pathway is estimated as follows:
ELCR=LADE,„ x UR or, for dose equations: ELCR=LADD,„ xSF
Where:
ELCR= The Excess Lifetime Cancer Risk associated with exposure to the chemical via
inhalation.
LADE.r= The Lifetime Average Daily Exposure to the chemical in air. In µg/m3.
LADD,,,= The Lifetime Average Daily Dose of the chemical in air. In mg/kg-d.
UR— The Unit Risk for the particular chemical of concern. In (pg/m )- .
SF = The Cancer Slope Factor identified for the chemical, for the inhalation
exposure pathway. In (mg/kg*d)-l.
The Lifetime Average Daily Exposure (LADEa,r) (and the LADD,,r) is calculated from
the Exposure Point Concentration using exposure assumptions identified for the receptor being
evaluated. The Exposure Assessment Section of this Guidance describes the process for
calculating the receptor's LADEw. The selection of Unit Risk values is discussed in greater
detail in the Dose-Response Section.
Total inhalation cancer risks should be calculated, including all Class A and B
carcinogens (i.e., chemicals classified by USEPA as being known human carcinogens and
probable human carcinogens). In addition, for those Class C carcinogens (i.e., those classified
by USEPA as being possible human carcinogens) for which unit risk factors exist, inhalation
cancer risks should also be calculated and included in the total ELCR. For those Class C
carcinogens for which the available toxicity data are insufficient to quantify cancer risks, the
48
potential carcinogenic effects of these substances should be discussed qualitatively in the
uncertainty section of the risk assessment. As discussed previously, all carcinogens for which
MassDEP has provided unit risk information in Table 7 should be evaluated at a minimum.
The total ELCR for inhalation represents the total carcinogenic impact that the proposed
facility has on a particular receptor. The total ELCR accounts for exposures that a receptor may
receive from multiple chemicals via inhalation.
As shown by the following equation,the Total Facility ELCR can be calculated by summing
all of the chemical-specific inhalation ELCRs calculated as described above.
Total Facility ELCR =E ELCR,h,.,.I-,Fr,f,
The total ELCR should be compared with MassDEP risk management criteria for siting
solid waste facilities as presented in Section 4.6.
The documentation of the Risk Characterization should clearly present all mathematical
equations used to calculate Total Facility Cancer Risks.
4.4.3 Available Tools
MassDEP has developed a spreadsheet for conducting a quantitative risk assessment for
municipal solid waste landfills. This spreadsheet addresses the default list of COC suggested in
this document. It may be accessed at the MassDEP web site at httn://www.mass.2ov/den. For
certain proposed landfills or expansions that need to consider additional chemicals (e.g., such as
for a facility that takes in greater than fifty percent of a particular special waste), the risks from
these chemicals should be calculated separately and added to the risk determined using the
spreadsheet.
4.5 Uncertainty Analysis
The Uncertainty Analysis is an important component of the Risk Characterization. A
Risk Characterization is not considered complete unless an Uncertainty Analysis that identifies
and discuses the uncertainties in the risk assessment is included. The Uncertainty Analysis
should contain a narrative section that places the numerical risk estimates in the overall context
about what is known and what is not known about the proposed facility or expansion and in the
context of decisions that MassDEP will make about potential mitigation.
The dose-response and exposure assessment guidance presented in this document are
intended to provide a consistent framework for evaluating potential site impacts. However, the
numerical risk estimates calculated using this guidance, or for that matter any risk assessment
methodology, should not be interpreted as precise estimates of the risk of harm to health. Due to
fundamental limitations in the available science and practical limitations in the extent to which
data can be obtained and analyzed, all facility impact assessments,whether of a quantitative or
qualitative nature, require the exercise of scientific and professional judgment. These limitations
introduce a variety of uncertainties into the process, some of which may lead to overestimations,
49
and some to underestimations, of actual risk. Because of this an Uncertainty Analysis section
should be included in all risk assessments completed using this guidance.
The types and sources of uncertainty in the risk assessment that should be discussed in
the Uncertainty Analysis include, but are not limited to:
• Identification of facility-related contaminants of concern;
• The use of modeling to develop emissions and Exposure Point Concentration
estimates;
• Interpretation of qualitative and quantitative toxicological data used to develop cancer
and non-cancer toxicity values;
• Development of Exposure Profile(s) and selection of exposure assumptions used in
dose calculations.
Although the Uncertainty Analysis may be a qualitative assessment of uncertainties
affecting the risk estimates, the risk assessor should attempt to describe the magnitude and
direction of effect that a particular area of uncertainty is likely to have on the numerical risk
estimates.
4.6 Risk Management
The risk management criteria that MassDEP uses to make a decision on site suitability for
Level 2 assessments are based on two parameters, including facility-specific risks and emissions
of VOCs from other point sources in the area. MassDEP has integrated these factors in a matrix
considering the risk posed by the facility itself and the risk posed by nearby facilities.
The facility-specific risk is estimated using quantitative risk assessment as described in
this document and is represented as estimated Total Facility Hazard Index (Hl)and Excess
Lifetime Cancer Risk (ELCR). Absent any other significant factors, the risk management
criteria that MassDEP has established for the Massachusetts Contingency Plan (MCP) should
apply to a proposed facility. These criteria include a facility Hl of one (1) and an ELCR of one
in one hundred thousand (1 x 10-5)14
Proposed facilities that pose a de minimis risk are generally approvable at any location.
A de minimis risk is generally considered an insignificant risk. A de minimis risk is defined as a
Total Facility ELCR of one in one—million (l x 10-6) and a Total Facility HI of 0.1. Where a
facility exceeds de minimis risk and there are other significant emissions of VOCs in the
immediate area, more stringent risk management criteria may be appropriate.
The risk posed by other facilities in the area is qualitatively evaluated using a sum of total VOC
emissions from air point sources 15 within a mile of the proposed facility, unless otherwise
determined by MassDEP. The quantification of cancer and non-cancer risk posed by these
1"These are the same risk management criteria that apply to exposures associated with the post-closure,off-site
migration of COC(including landfill gas emissions)from Solid Waste Management Facilities pursuant to the
"Adequately Regulated'provisions of the MCP(310CMR 40.0114)
15 As listed in MADEP's Stationary Source Emissions inventory System database
50
emissions is not required. As discussed in Section 1.2, use of this indicator assumes that the
higher the emissions are from adjacent air point sources, the higher is the potential risk in the
community affected by these facilities. Total VOC emissions should be compiled from the
MassDEP SSEIS database from all point sources registered in the database that are within one
mile of the proposed facility's perimeter, unless determined otherwise by MassDEP. This total
should also include emissions from all existing point solid waste facilities at the proposed
location. The facility proponent may choose to conduct multiple facility source modeling and
quantitative risk assessment of the adjacent sources to provide a refined estimate of overall
risk".
Facility specific and emissions of total VOCs from point sources in the area are evaluated within
the context of a number of other criteria including other factors affecting environmental
conditions in the community, uncertainty of the available quantitative data and the status of any
commitment to clean up any surface and groundwater contamination to comply with applicable
laws and regulations if the plan is a proposed landfill expansion. (A remediation plan must be
approved by MassDEP before the expansion is approved.). Other factors affecting the
community's environmental conditions might include possible mitigation/offset measures
offered by the proponent, expected future change to emissions from facilities in the area, types of
land uses, and specific particulate matter sources such as solid waste management facilities, junk
yards, auto salvage shops, bus and truck depots, etc., and the environmental impacts of not
constructing the facility.
Figure 2, entitled "Quantitative Assessment Review" illustrates MassDEP's risk
management approach for evaluating quantitative information that has been developed using the
protocol described in this document. The darkly shaded area below represents those facilities
with an estimated Excess Lifetime Cancer Risk(ELCR)greater than one in one hundred
thousand or an estimated Hazard Index greater than one. Outside the darkly shaded area, the
facility itself poses an acceptable risk. The facility site may be approved unless emissions from
adjacent air point sources are high. In that case, additional mitigation may be required.
"The facility proponent should consult with MADEP prior to initiating such work. Such an analysis could be part
of the initial proposal,prior to a requirement for mitigation,prior to the issuance of a negative site suitability report,
or as part of a request for reconsideration.
51
Figure 2.
Quantitative Evaluation Review
- I --
<1x10 < 1x10 > 1x10 IE LCR
Facility Risk Estimates
a s S and
<O1 < 1 > 1 HI
(Emissions
.. —
r From 0
I Adjacent —
Pur Point
I Sources
I
tons/yr) n - -
_ .Ai..
. I HigL1
In general, MassDEP would likely issue a positive site suitability report if the risk
management criteria are clearly met, suggest mitigation measures if the results are near the proposed
limits, or require changes to the proposal or mitigation measures if one or more of the criteria are
exceeded. Mitigation options may include controls on emission sources at the site and/or off-site
mitigation.
MassDEP's assessment will be based on site-specific factors. Where the combination of
factors indicates that the location may not be suitable for the proposed facility,the burden of proof
is on the applicant to overcome the presumption that the facility would result in unacceptable
environmental and public health impacts.
52
SECTION 5: Water Resources
Proponents of landfill expansion projects must evaluate the impacts of the existing
facility on groundwater and surface water. Where an existing facility has affected groundwater
or surface water, the risk of harm to public health and the environment from the contamination
must be characterized, and a plan for remediation developed if necessary for compliance with
appropriate water quality standards. MassDEP will review plans for assessment and remediation
in conjunction with its review of applications to construct landfill expansions, and will establish
permit conditions requiring implementation of remedial action plans where necessary.
MassDEP has published a separate guidance document titled Guidance for the
Assessment of Groundwater and Surface Water for Solid Waste Facility Site Assignment and
Permitting in Support of 310 CMR 16.00& 19.000, which provides more extensive guidance on
what groundwater and surface water assessments should cover. This guidance includes a
discussion of important considerations that should be addressed regarding the assessment of
water resources around an existing or expanded solid waste facility. The overlap between the
MCP (3 10 CMR 40.0000) and site assignment (3 10 CMR 16.00) is discussed with regard to
water resources, including the MCP "adequately regulated"provision. This guidance specifies
the performance standards that should be met for the assessment of water quality. In addition, it
also includes checklists to assist in identifying the components of the water assessment.
53
SECTION 6: Facility Impact Assessment Report Content and
Submission Process
This section addresses the minimum types and amounts of information that should be
submitted in a timely fashion in support of a Level I or Level II assessment. The Facility impact
assessment submitted in support of a decision for site suitability or authorization to construct
permit should provide a comprehensive picture of the risks associated with the proposed facility
in accordance with this Guidance Document.
Appendix A of this document contains a checklist, entitled"Checklist for Facility impact
assessment of Solid Waste Facilities", that summarizes the minimum descriptive and technical
components that the Facility impact assessment should include. This checklist may be used for
planning an optional Scope of Work or in preparing the report within the applicable permit
application process. A discussion of report content is provided in Section 6.1. The provision for
submitting an optional Scope of Work is discussed in Section 6.2. The timing and requirements
of the overall permit application process are discussed in Section 6.3.
6.1 Report Content
The facility impact assessment report should include the descriptive and technical
information described below. The report should include an overview that includes a basic
description of the site and of the proposed facility/expansion. Important components of the
overview should include:
• the purpose of the assessment(i.e., is it for a new site assignment or a modification of an
existing one);
• the proposed development schedule (if there are multiple stages);
• historical and current use of the site;
• a description of the location (including an address) of the proposed facility;
• important topographical and meteorological features of the area and/or the facility itself;
• a description of best management practices(BMPs)that will be incorporated in the
design and operation of the facility;
• a map of the facility and its surroundings (indicating the permitted area of the proposed
landfill or expansion), including:
o the location of any receptors;
o amount and types of waste to be disposed;
o the proposed capacity of the facility; and
o a justification for the selected method of assessment(i.e., Level I or Level II).
The report should next describe the basic components of the qualitative or quantitative
assessment. For a Level I qualitative assessment, the report should provide information on
facility size, best management practices (BMWs) proposed for the facility and information on
emissions from adjacent sources, preferably within the context of the information presented in
the overview.
For a Level 11 quantitative assessment, the following additional information should be
submitted:
54
• an overview of the general modeling approach - The name and reference information
for the emissions and dispersion models to be used should be included in this
information.
• a description of modeling inputs and assumptions - This information should include
appropriate documentation as to the source of these factors, including the source of
meteorological data used for modeling;
• basic risk assessment components—This information should include the list of
Chemicals of Concern (COC), along with the basis upon which the list was compiled, the
list and sources of dose-response information, a description of risk assessment exposure
assumptions and adjustments made to exposure point concentrations, a description of
equations used to calculate non-cancer and cancer risks and a description of the
uncertainties inherent in the modeling and risk assessment calculations;
• a summary of tons per year VOCs emitted from adjacent facilities within a mile of
the solid waste facility—This information should include a brief description of the
facilities identified and the types of VOCs they generate. The printout from SSEIS
should be included in the report. For a landfill expansion, the quantification of facility-
related VOC emissions should also include an estimate of total VOCs generated from the
existing portion of the solid waste facility as available from SSEIS.
• a description of current and proposed BMPs at both the existing portion of the
facility, if applicable, and the new or expanded area - This information should include
a description of all BMPs currently in place at the existing facility, a description of the
landfill double liner system that will be installed at the new or expanded portion of the
facility, as well as a description of all BMPs to be installed.
Finally, for any landfill for which an expansion is proposed, the report must include an
assessment of the impacts of the existing facility on groundwater and surface water. See Section
5 and Appendix B for guidance on conducting this assessment and determining whether remedial
action is needed. Appropriate documentation as specified in this Appendix should be submitted
to support the assessment of groundwater and surface water resources.
6.2 Submission of Proposed Facility impact assessment Protocol and Scoping Activities
For facilities that take in a large amount of non-traditional or special wastes or in cases in
which the default modeling and/or impact assessment approaches presented in the Guidance
Document are inappropriate, the facility assessment report may be preceded by an optional scope of
work (SOW) or report protocol A SOW may be submitted by a facility applicant for MassDEP
review and feedback. The facility applicant should submit one (1) copy of the SOW directly to the
appropriate regional office, and two (2) copies of the SOW to MassDEP-Boston, at the following
address:
55
Massachusetts Department of Environmental Protection
Bureau of Waste Prevention
Attn.: FIA Review
One Winter Street—8th Floor
Boston, Massachusetts 02108
The applicant should contact the appropriate MassDEP regional office to discuss the
applicant's project and determine whether a SOW review is necessary. MassDEP will review a
draft SOW if necessary and provide either written comments and/or hold a scoping session to
discuss comments with the applicant. The appropriate regional office will schedule and coordinate
any necessary scoping session. In addition, the appropriate regional office will coordinate all
communication to MassDEP-Boston regarding any review of a proposed SOW.
The SOW may describe the planned content of the report, or details pertaining to other
aspects of the assessment including, for example, landfill gas sampling and analysis protocol,
modeling methodologies, proposed changes to default methods or data sources or other
alternative assessment approaches. After the protocol has been reviewed, the proponent may
prepare the final facility impact assessment report, guided by the decisions made in the SOW.
The SOW should be submitted well in advance of the beginning of the affected permit review
period (including both the administrative and technical review periods)to allow time to
coordinate the preparation of the impact assessment report with all other required permit
application submittals.
6.3 Submission of a Facility impact assessment within Applicable Permit Applications
Permit applicants must comply with the permit submittal requirements governing the
specific solid waste management facility permit being requested (e.g., 310 CMR 16.04(b) for a
Site Suitability Report. In addition to the submittal requirements stated in 310 CMR 16.00,the
applicant should submit one (1) copy of the permit transmittal form along with three(3) copies
of the complete impact assessment report, including all supporting documentation,to
MassDEP's Boston office at:
Massachusetts Department of Environmental Protection
Bureau of Waste Prevention
Attn.: Facility impact assessment(FIA) Review
One Winter Street—8th Floor
Boston, Massachusetts 02108
Increasingly,the Massachusetts Environmental Protection Act(MEPA)has required
either the facility impact assessment or at the very least, a discussion of the applicant's proposed
plans to proceed with such an assessment as required in 310 CMR 16.00. MassDEP encourages
a facility impact assessment during the MEPA process. The performance of an impact
assessment during the MEPA process allows the facility applicant additional time to conduct the
assessment and to receive comments from MassDEP prior to MassDEP's review of the impact
assessment report during permit application review. If the applicant conducts a facility impact
assessment during the MEPA process, the applicant should submit one(1) copy of the
56
Environmental Notification Form and any subsequent Environmental Impact Report(including
any subsequent Supplemental and Final Impact Reports)to the appropriate MassDEP regional
office and three (3) copies of the facility impact assessment to MassDEP's Boston office at:
Massachusetts Department of Environmental Protection
Bureau of Waste Prevention
Attn.: Facility Impact Assessment (FIA)Review
One Winter Street—8th Floor
Boston, Massachusetts 02108
If an applicant has completed a facility impact assessment for the proposed facility for
MEPA, the applicant should resubmit one (1) copy of the impact assessment to the appropriate
MassDEP regional office and three (3) copies to MassDEP's Boston office (at the above
address), including all relevant appendices cited in the impact assessment, all public and MEPA
comments received with respect to the impact assessment, and documentation of MEPA's
acceptance of the facility impact assessment(this may be in the form of MEPA's final comments
and Project Certification). MassDEP will review impact assessment reports submitted as part of
site assignment applications of solid waste facility permit applications. if MassDEP identifies
deficiencies in the report, MassDEP will provide comments to the facility applicant.
For Site Suitability Permit Applications (3 10 CMR 16.00):
1. During the initial 40 days of the Review Period, MassDEP may require the
applicant to respond to any comments it has received from the local board of
health and other interested persons pursuant to 310 CMR 16.11 (3) (a).
2. The Applicant may modify its impact assessment within the initial 40 days of
the Review Period in accordance with 310 CMR 16.11 (3) (a-b)Application
Response and Modification.
3. If MassDEP determines that the deficiencies are significant in accordance
with 310 CMR 16.11 (5) MassDEP may require the applicant to provide
additional information. At the point of MassDEP's request for additional
information the applicant may:
a. Submit the information and be subject to 310 CMR 16.11 (3)(b)(c)
modification of application regulations
b. Formally withdraw the site suitability application until such time as a
complete application, including a complete facility impact assessment,
may be submitted; or
c. Let MassDEP continue its review of the unmodified application.
MassDEP reserves the right to rescind any approval of a facility impact assessment if
significant information is received in the future regarding the scientific integrity of the
information in the impact assessment report. In addition, MassDEP will require all BMPs and
mitigation activities proposed by the applicant to be implemented as a condition of the applicable
facility permit. Failure to implement BMPs and other approved commitments would constitute a
violation of the facility permit and may result in enforcement actions.
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58
References
Massachusetts Department of Environmental Protection (MassDEP). July, 1988. Ash Sampling
and Analysis Guidance. SWM-9-7/88 (as further clarified in 7/97 MassDEP communications to
facility operators).
Massachusetts Department of Environmental Protection. (MassDEP). July, 1995. Guidance for
Disposal Site Risk Characterization—in Support of the Massachusetts Contingency Plan. Bureau of
Waste Site Cleanup and Office of Research and Standards.
United States Environmental Protection Agency(USEPA). December, 1989. Risk Assessment
Guidance for Superfund(volume 1)—Human Health Assessment Manual (Part A)—Interim Final.
Office of Emergency and Remedial Response.
United States Environmental Protection Agency(USEPA). 1997a. Compilation of Air Pollutant
Emission Factors, AP-42. 5t'ed. Supplement C. Office of Air Quality Planning and Standards.
Research Triangle Park,NC.
United States Environmental Protection Agency (USEPA). 1997b. Exposure Factors Handbook.
National Center for Environmental Assessment
United States Environmental Protection Agency(USEPA). 1997c. Health Effects Assessment
Summary Tables(HEAST). Solid Waste and Emergency Response. FY 1997 Update.
United States Environmental Protection Agency (USEPA). 1997d. Emission Factor
Documentation for AP-42 Section 2.4—Municipal Solid Waste Landfills—Revised.
United States Environmental Protection Agency (USEPA). February, 1998. User's Manual—
Landfill Gas Emissions Model. Air Pollution Prevention and Control Division; Control Technology
Center; and Office of Research and Development.
United States Environmental Protection Agency (USEPA). 2001. Integrated Risk Information
System (IRIS)database. htti)://www.ena.eov/neisvem3/iris/subst/index.html.
59
APPENDIX A
Checklist for Facility impact assessment
of Solid Waste Facilities
i
Md
Checklist for Facility impact assessment of Solid Waste Facilities
For All Level 1 and Level 2 Assessments
Facilitv Based Imoact Assessment(FIA) Submissions:
Scope of Work(SOW) >>(See Section 6.2)
❑ Submit one (1) copy of the proposed SOW to the appropriate MassDEP regional office
❑ Submit two (2) copies of the proposed SOW to MassDEP - Boston office
FIA Assessment Performed During META >>(See Section 6.3)
❑ Submit one (1) copy of the ENE and subsequent EIR (including any subsequent SEIR and
FEIR) to the appropriate MassDEP regional office
❑ Submit three (3) copies of the FIA assessment (including all relevant appendices cited in
the FIA assessment)to MassDEP—Boston office
❑ If submitting an FIA assessment performed during MEPA within a formal Site
Assignment or Solid Waste Facility Permit, submit:
■ One (1) copy of the FIA Assessment to the appropriate MassDEP regional
Office
• Three (3)copies of the FTA Assessment to MassDEP—Boston office
• All relevant appendices cited in the FIA assessment
■ All comments received regarding the impact assessment from all
interested parties and MEPA
■ Documentation of MEPA's acceptance of the FIA assessment
General FIA Assessment >>(See Section 6.3)
❑ Submit one (1) copy of the FIA Assessment to the appropriate MassDEP regional Office
❑ Submit three (3) copies of the FIA Assessment to MassDEP—Boston office
All Submissions to MassDEP—Boston should be directed to:
Massachusetts Department of Environmental Protection
Bureau of Waste Prevention
Arm.: FIA Review
One Winter Street—8th Floor
Boston, Massachusetts 02108
Acronyms:
SOW—Scope of Work SEIR—Supplemental Environmental Impact Report
ENE—Environmental Notification Form FEIR—Final Environmental Impact Report
EIR—Environmental Impact Report FIA—Facility impact assessment
2
Descriptive Information: >>(See Section 6.1)
❑ Description of proposed facility/expansion, potentially exposed receptors and
surrounding land uses within one mile
❑ Purpose of assessment
❑ Information on historical/current use of site
❑ Description and address of proposed facility/expansion
❑ Pertinent site-related information (e.g.,topography, meteorology, etc.)
❑ Proposed capacity of the facility in tons per day
❑ Description of development schedule
❑ Level of impact assessment(i.e., Level 1 or Level 2) with justification for selection
❑ Map of the proposed facility/expansion and surroundings
❑ location of receptors indicated
❑ map of permitted area of the proposed facility
Industrial Emissions from Adjacent Sources >>(See Section 1.2)
❑ Description and quantification of total facility-related VOC emissions within one mile of
the facility provided (from SSEIS database)
❑ Printout from SSEIS
❑ For a facility expansion,total VOC estimate from SSEIS for the existing facility
Best Management Practices >>(See Section 2.1)
❑ Detailed assessment of the proposed facility with respect to the major"areas of concern"
❑ Proposal of specific BMPs to be implemented by the facility and a detailed discussion
regarding their ability to reduce potential impacts in relation to the major"areas of
concern"
For All Landfills
Water Resources Assessment: >>(See Section 5.0 and Appendix B)
❑ Description of cleanup plan to achieve groundwater and surface water standards under
the Solid Waste and MCP programs(if applicable). (See Section 5 and separate
MassDEP guidance titled Guidance for the Assessment of Groundwater and Surface
Water for Solid Waste Facility Site Assignment and Permitting in Support of 310 CMR
16.00& 19.000.)
A-3
For Level 2 Assessments—Ouantitative Assessment
Hazard Identification >>(See Section 4.1)
❑ Chemicals of Concern (COC) identified
❑ For a MS W landfill, AP-42 chemicals
❑ Exceptions to AP-42 list(based on monitoring and/or literature information)
explained and MassDEP approval obtained before risk assessment undertaken
❑ Based on nature of waste proposed to be handled by the facility (e.g., special wastes;
other) additional COC proposed and approved by MassDEP (if applicable)
❑ Toxicity profiles for each COC
Dose-Response Assessment >>(See Section 4.2)
❑ Dose-response information (including source and/or values) identified for each COC in
the risk assessment
❑ Use of the toxicity information for the AP-42 chemicals
❑ Source of and/or dose-response values proposed and approved by MassDEP for other
COC
Exposure Assessment >>(See Section 4.3)
❑ Screening case exposure profile and/or refined exposure profile developed
❑ Name of emissions model used
❑ Name of dispersion model
❑ Receptor network defined and (for refined exposure profile) sensitive receptors
identified/included
❑ Modeling inputs defined
❑ Modeling outputs defined
❑ Risk assessment exposure assumptions defined and explained (including source of data)
❑ Description of approach used to calculate exposure point concentrations
Risk Characterization >>(See Section 4.4)
❑ Description of approach used to calculate non-cancer and cancer risks
❑ Statement as to whether the MassDEP-developed spreadsheet was used in conducting the
risk
Uncertainty Analysis >>(See Section 4.5)
❑ Description and quantification of facility-related VOC emissions from SSEIS database
A-4
A-5
V
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