Nat'l Grid PIN Pad-Mounted Electrical Transformer-Melrose, MA RECEIVED
ENVIRONMENTAL
C O N E C O JAN 2 8 2020 ECOLOGICAL
ENERGY
Engineers & Scientists CITY OF SALEM SURVEY
January 14,2020 BOARD OF HEALTH CIVIL
Coneco Project No. 5650.D
Mr.David Greenbaum,Health Agent
City of Salem Board of Health
120 Washington Street,0'Floor
Salem,Massachusetts 01970
RE: Public Involvement Notification
Phase III-Remedial Action Plan and Phase IV-Remedy Implementation Plan
Non-PCB Mineral Oil Dielectric Fluid Release
Pad-Mounted Electrical Transformer
200 West Foster Street
Melrose,Massachusetts
Release Tracking Number 3-30705
Dear Mr. Greenbaum:
On behalf of New England Power Company d/b/a National Grid(NEP),pursuant to 310
CMR 40.1403 of the Massachusetts Contingency Plan(MCP),Coneco Engineers&
Scientists,Incorporated submits the following letter serving as written notification of the
submittal of Phase III-Remedial Action Plan(RAP)and Phase IV-Remedy Implementation
Plan(RIP)for the above-referenced location, hereinafter,the"Site." This submittal is
regarding remedial activities taken to address a release of non-polychlorinated biphenyl
mineral oil dielectric fluid from an electrical power transformer in use at the Site. This letter
follows submittal of the Phase II-CSA to the Massachusetts Department of Environmental
Protection(MassDEP)on or about January 14,2019,and the submittal of the above-
mentioned report on or about January 14,2020.
A copy of the Phase III RAP summary of findings and statement of conclusions and Phase IV
RIP description of the Comprehensive Remedial Action is attached to this letter.
This letter provides requisite notification of the proposed schedule for implementation of the
proposed Comprehensive Remedial Altemative under the Phase IV RIP. Phase IV field
activities are scheduled to commence in the winter of 2020 and will be conducted on a
monthly basis pending an on-going evaluation of Site conditions. It is expected that Phase IV
activities will be conducted on a periodic basis for a duration of approximately 1 to 5 years.
Phase IV field activities will not require the use of respirators nor Level A,B,or C personal
protective equipment.
The submitted Phase III RAP and Phase IV RIP is available in the files at the MassDEP -
Northeast Regional Office and online through the MassDEP website at
htt s://eeaonline.eea.state.ma.us/EEA/fileviewer/Rtn.as x?rtn=3-0032689. A copy of this
report may also be obtained by contacting the undersigned in writing. For more information
about the public involvement regulations that require this notice and a description of such
public involvement activities available under the MCP, see
htt s://www.mass. ov/lists/waste-site-cleWu -laws-and-re lations. Pursuant to the
4 First Street,Bridgewater,MA 02324 (508)697-3191 (800)548-3355
Coneco.com
RTN 3-32689
Salem Harbor No.45 Substation January 14,2020
Salem,Massachusetts Page 2
provisions of 310 CMR 40.0000,additional response actions are warranted at the Disposal
Site prior to the submittal of a Temporary or Permanent Solution Statement. This submittal
is being made on behalf of NEP,the party conducting response actions relating to this
release.
If you have any questions regarding the above information,please contact the undersigned.
Sincerely,
Coneco Engineers& Scientists,Incorporated
Michael J.Philbin Brian . ingler,PG, LSP
Project Manager Principal Geologist
PAJ:MJP:JDA:BFK;jw
Z:\\5650.D-Municipal Ph.III_Ph IV.doc
Enclosures: Phase III RAP Summary of Findings and Statement of Conclusions and
Phase IV RIP Description of the Comprehensive Remedial Action
cc: MassDEP
NEP
• f I1 -Ir.: n :-..i.... •-'- INCORPORATED
Phase III-Remedial Action Plan: Summary of Findings and
Phase IV-Remedy Implementation Plan: Description of Comprehensive Response Actions
Non-PCB Mineral Oil Dielectric Fluid Release
1 Bank A Transformer
Salem Harbor No. 45 Substation
24 Fort Avenue
Salem,Massachusetts
Release Tracking Number 3-32689
Phase III_Remedial Action Plan: Summary of Findings
It is the opinion of Coneco Engineers& Scientists, Incorporated(Coneco)that the most feasible,
cost-effective,and timely remedial response action for the Disposal Site will be passive LNAPL
recovery in the short term(up to 2 years)until the removal and replacement of the 1 Bank A
Transformer is completed by New England Power Company(NEP), expected to occur circa Summer
2021. At that time,upon removal of the transformer from service, excavation of contaminated soil
with concurrent groundwater and/or light non-aqueous phase liquid(LNAPL)extraction will be
conducted, if necessary,to achieve a permanent solution.
Phase IV-Remedy Implementation Plan: Descri tion of Comprehensive Response Actions
Test Borings and Groundwater Monitoring Wells
In order to support regulatory closure at the Disposal Site, it is the opinion of Coneco that additional
assessment is required. Coneco proposes utilizing a Geoprobe®sampling system to install up to four
to six additional test borings and monitoring wells at the Disposal Site. The Geoprobe®system
consists of a pneumatically driven steel shaft and Macrocore®sampler that can be used to obtain
continuous soil samples in a rapid and efficient manner. As needed,pre-clearing will occur by
means of vacuum excavation to depths of approximately 4 feet below grade in order to maximize
worker safety and reduce the possibility of contact with underground utilities when working in the
vicinity of energized electrical equipment. Equipment will be decontaminated between sampling
intervals and samples will be collected in discrete acetate liners so as to prevent cross-contamination.
Test boring/monitoring well locations will be placed within the release area and assumed down-
gradient and/or cross-gradient locations to obtain adequate coverage to evaluate whether residual
impacts from the release are present. Coneco will conduct field observations and collect soil samples
on a continuous basis. Soil samples will be evaluated for visual and olfactory evidence of non-PCB
MODF impact. Select soil samples will be submitted to an independent,Massachusetts-certified
laboratory for analysis of EPH carbon fraction ranges by the MassDEP Method and PCBs by EPA
Method 8082.
If feasible,test borings will be advanced until groundwater is encountered,at which point monitoring
wells will be installed within the respective boreholes. Monitoring wells will be constructed with 2-
inch diameter PVC pipe with an approximately 10-foot long section of 0.010-inch slotted screen to
intercept the water table,with solid PVC riser pipe from the top of the well screen to grade.
Monitoring wells will be completed with at-grade aluminum road boxes. Groundwater monitoring
wells will be installed and developed in accordance with MassDEP Policy WSC-310-91,Standard
Reference for Monitoring Wells(April 19, 1991). To ensure proper hydraulic communication with
the surrounding aquifer,monitoring wells will be developed until a minimum of three well volumes
of groundwater is removed or suspended fines are no longer noted.
RTN 3-32689
Salem Harbor No.45 Substation January 14,2020
Salem,Massachusetts Page 2
Approximately one week after installation,monitoring wells will be gauged to evaluate whether
LNAPL is present and obtain groundwater elevations. Using MassDEP and EPA sampling protocols,
a groundwater sample will be collected from each monitoring well and screened in the field for
temperature,pH,and specific conductivity. One groundwater sample from each monitoring well will
be submitted to an independent,Massachusetts-certified laboratory for analysis of EPH carbon
fraction ranges by the MassDEP Method and PCBs by EPA Method 8082.
Well locations will be surveyed, and water table elevations will be measured to the nearest 0.01 foot.
Based on this information, groundwater elevations will be used to establish the inferred direction of
groundwater flow.
Based on the findings of the initial groundwater sampling event, additional quarterly groundwater
sampling may be warranted. The number of rounds of quarterly groundwater sampling will be
determined based on guidance provided in Table 4-2 in Section 4.1.1 of MassDEP Policy#WSC-02-
411, Characterizing Risks Posed by Petroleum Contaminated Sites:Implementation of the MADEP
VPHIEPHApproach (October 31,2002). Following the receipt of laboratory analytical results and
the performance of a Risk Characterization pursuant to 310 CMR 40.0900,Coneco will determine if
Disposal Site conditions meet the requirements for the preparation and submittal of an Permanent
Solution Statement,or if additional response actions are warranted in relation to the non-PCB MODF
release associated with RTN 3-32689.
LNAPL Gauging and Passive Recovery
Coneco will resume periodic product gauging and the passive recovery of LNAPL, as needed, at the
Disposal Site. The depth to groundwater and/or LNAPL will be measured and,if present,the
approximate thickness of the LNAPL will be determined. If encountered,LNAPL and impacted
groundwater will be removed. The gauging and removal frequency may be modified periodically
based on field observations. If warranted,the oil-absorbent sock may be added to CMW-03 to aid in
the passive LNAPL recovery process.
Excavation of Contaminated Soil with Groundwater Extraction
The removal and replacement of the 1 Bank A Transformer is expected to be undertaken by NEP
circa Summer 2021; as such,the excavation of contaminated soil and the concurrent recovery of
impacted groundwater and/or LNAPL will be conducted in conjunction with the transformer removal
and replacement operations,to achieve a permanent solution. Once the removal of the transformer
from service within the Disposal Site has occurred, Coneco will oversee the removal of contaminated
soil coupled with groundwater and/or LNAPL extraction.
Groundwater Sampling
In conjunction with implementation of the proposed RIP activities,Coneco will collect groundwater
samples from viable Disposal Site groundwater monitoring wells on a quarterly basis,with the next
sampling event scheduled during January 2020. Groundwater samples will be collected using
appropriate MassDEP sampling protocols and submitted to an independent,Massachusetts and
NELAP-certified laboratory for analysis of EPH carbon fraction ranges by the MassDEP Method and
PCBs by EPA Method 8082.
RTN 3-32689
Salem Harbor No.45 Substation January 14,2020
Salem,Massachusetts Page 3
Quarterly groundwater gauging and sampling will continue following completion of passive LNAPL
recovery and soil excavation activities. The duration of post-remediation monitoring will be
sufficient to confirm stability of Site conditions in support of a Permanent Solution for the Disposal
Site.
ISTS, I