MEPA Supplemental Info - Columbus Avenue Seawall Reconstruction Project-FINAL w AttachmentsAn Equal Opportunity Employer M/F/V/H
M E M O R A N D U M
To:Ms. Purvi Patel
Massachusetts Environmental Policy Act (MEPA) Office
Executive Office of Energy and Environmental Affairs
From:David Smith, Senior Project Manager/ GZA GeoEnvironmental, Inc.
Lucas Taylor, Project Engineer/ GZA GeoEnvironmental, Inc.
Cc:Mr. David H. Knowlton, P.E., City Engineer/DPS Director, City of Salem
ENF Distribution List
Date:October 27, 2021
GZA File No: 18.0171674.04
Re:Supplemental Information to MEPA ENF Application
Columbus Avenue Seawall Reconstruction Project
46 Columbus Avenue, Salem, Massachusetts
Attachments: Attachment A – Revised ENF Permit Plans, Sheet Nos. 4 and 5
Attachment B – PowerPoint Presentation
This memorandum presents supplemental information to the Environmental
Notification Form (ENF) Application for the Columbus Avenue Seawall Reconstruction
Project, prepared by GZA GeoEnvironmental, Inc., and submitted on September 15,
2021, to the Massachusetts Environmental Policy Act Office.
During the remote sitevisit (TeamsMeeting) held on Friday, October 8, 2021, additional
information was requested prior to the end of the public comment period. This
memorandum presents the following supplemental information as requested:
1.Revised resource area values
2.Commentary and analysis for resource area impact mitigation
3.Commentary and analysis for the proposed landing and beach access steps
4.General construction methods and procedures
5.Commentary and analysis for salt marsh planting and associated filling
6.Commentary and analysis for coir roll installation
7.Planting plan for vegetation at southwest corner.
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Columbus Avenue Seawall Reconstruction Project
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1.RESOURCE AREA IMPACTS
Table No. 1 – Summary of Resource Area Impacts (Revised)
Resource Area Temporary Impact Description Permanent Impact Description
Land Subject to
Coastal Storm
Flowage
10,170 SF
Temporary
equipment staging,
temporary excavation
and shoring
5,800 SF
Seawall and landing
reconstructions, new
flood gate barrier,
walkway and grass
strip reconstruction
Coastal Beach 2,670 SF
Temporary
excavation and
shoring
223 SF
Biodegradable coir
rolls and timber post
outhauls
Coastal Bank1 50 LF
Temporary
excavation at
northeast corner
sand build-up
514 LF
City seawall (466 LF),
flood gate (8 LF),
adjacent walls (20) x 2
Coastal Dune2 735 SF
Temporary
excavation and
shoring
--
Salt Marsh 1,000 SF
Augment existing salt
marsh area with new
salt marsh plugs
2,870 SF
Fill large voids/erosion
areas and pockmark
voids with clean sand
Notes:
1TherearenoCoastalBankresourceareasattheProjectSiteperthedefinitionsundertheMassachusettsWetland
ProtectionAct(WPA),andtherefore no impactsto Coastal Bank. Theoriginal applicationinadvertently delineated
the built-up sand corners as Coastal Bank and the existing wall as an armored Coastal Bank.
2Coastal Dune resource areas are delineated as the built-up sand corners at the Project Site. Temporary impacts,
including temporary excavation and shoring/support of excavation, is anticipated to facilitate the construction of
the proposed wall footings. Temporary excavations within the Coastal Dune resource areas (i.e. built-up sand at
corners) will be backfilled with suitable existing sand to match pre-construction conditions. Vegetation removed
at the southwest corner to facilitate the wall reconstruction will be replaced with new native, salt-spray tolerant
shrub/grass species listed within Coastal Zone Management’s (CZM) Coastal Landscaping Plant List (see Section
No. 7).
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Columbus Avenue Seawall Reconstruction Project
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2.COMMENTARY AND ANALYSIS FOR IMPACT MITIGATION (E.G. WALL ROUGHNESS, BEACH
NOURISHMENT)
A.DESIGN MEASURES TO HELP MITIGATE IMPACTS TO RESOURCE AREAS INCLUDE:
The proposed wall reconstruction will conform to the ‘natural’ (existing) shape of the shoreline
and will be reconstructed within the same general footprint as the existing seawall structure and
will not extend further seaward.
The proposed reconstructed wall using cut granite stone masonry will have increased rugosity on
the seaward face as compared to the existing flat-faced masonry wall. See Photograph 1
representing the existing flat faced wall and Photograph 2 showing typical conditions for the
proposed reconstructed wall.
Photograph 1 Photograph 2
Amoreresilientstructureandshorelinearealessproneto degradationfrom wavesurge/flooding
conditions and reduce frequent impacts due to wall maintenance.
Removal of displaced exposed stone and debris adjacent to the existing landing structure within
the Coastal Beach.
Promotion of nature-based and natural elements to provide a more resilient shoreline that will
help to provide increased storm damage prevention and flood control. Specific improvements
include:
o Stabilize toe of existing marsh to reduce erosion and undermining with new coir
rolls/fabric, clean sand fill and salt marsh plantings.
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Columbus Avenue Seawall Reconstruction Project
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o Fill and stabilize ‘pockmark’ voids within the existing marsh.
o Salt marsh enhancement with new supplemental salt marsh plugs.
o Protection and limit disturbance to existing marsh area by removal of timber post
outhauls, installation of seasonal fencing/netting, and installation of new coir rolls at the
seaward edge of the existing salt marsh vegetation.
o Stabilization of Coastal Dune sand area with new salt-spray tolerant plantings at the
southwest corner.
Work will be performed from the landside of the wall and within the footprint of the landing; no
construction vehicles will be allowed on the shoreline beach and salt marsh areas.
The Contractor will perform work during favorable tides for the various aspects of the work. The
Contractor will work the tides to minimize impacts to resource areas.
Temporary shoring and support of excavation measures will be in-place to limit the extent of
excavations and protect adjacent Wetland Resource Areas (e.g. Coastal Dune, Coastal Beach, Salt
Marsh).
B.BEACH NOURISHMENT
Potential future beach nourishment may be considered at the Project Site. Future beach nourishment at
the Site would likely be located on the east side of the landing structure fronting the seawall between
approximate stations 3+00 to 4+00 (refer to ENF Permit Plans for wall stationing). Nourishment may
consist of approximately 100 cubic yards of clean, compatible sand placed generally between stations
3+00to4+00 frontingtheseawallwherethebeachelevationislowestalongtheseawall.Theaerialextent
of the possible beach nourishment is anticipated to be less than 3,000 square feet.
Thesandnourishmentmaybeplaceduptoadepthof18-inchesto24-inchesalongtheseawallandsloped
at an approximate eight horizontal to one vertical (8H:1V) to generally match the existing beach
topographic slope until it meets existing grade up to approximately 30 feet seaward of the seawall.
Although beach nourishment may be considered in the future it is not being proposed as part of the
currentseawallreconstructionproject.Beachnourishmentisnotfavorableatthistimeduetothenumber
of challenges and site constraints, as follows:
Site constraints such as existing salt marsh, beach access landing structure, and the existing
stormwateroutfall pipe atapproximately48feet seawardof the seawallatstation 4+00, limitthe
area suitable for beach nourishment.
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Columbus Avenue Seawall Reconstruction Project
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Relative stability of the beach elevation in recent years.
Concern from public and direct abutters of the already built-up sand at the wall corners.
Cost implications and possible monitoring and maintenance requirements of the City.
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3.COMMENTARY AND ANALYSIS FOR LANDING AND BEACH ACCESS STEPS
The following includes alternatives analysis forthe landing and beach access steps at the Project Site, and
the basis of the selected alternate.
A.DO NOTHING
The do-nothing alternate means the existing landing structure and steps would be left in-place. This
alternative is not considered appropriate due to the unsafe degraded and damaged conditions of the
existing landing and steps. The existing landing was observed to have minor vertical deviation along the
top surface whichmaysuggest differential settlement, undermining, or heaving.Also, raveling and lossof
stone and mortar/concrete fill material was observed along the sides of the landing. If left as-is, the
landing and steps structure is likely to continue to degrade with continued loss of fill, and is likely to
continue to ravel, further impact the Coastal Beach, and possibly fail.
B.PILE-SUPPORTED DECK AND STEPS
The pile-supported deck and steps alternative would consist of the complete demolition and removal of
the existing granite block landing structure and stone steps; and replacement with a pile-supported
structure. Generally, pile-supported structures are preferred over solid fill structures due to less impacts,
and in this case, reflective wave energy. At the Project Site however, a pile-supported structure is not
considered a favorable alternative for the following reasons.
Likely inadequate embedment depths for typical driven pile-supports (e.g. timber or steel piles)
due to shallow bedrock in the area of the landing and access structure. The United States
Geological Survey (USGS) Surficial Geologic Map dated 2006 indicates shallow bedrock with
surficial materials less than 5 to 10 feet thick at the Project Site.
The landing structure has existed since before 1938. The change to a pile-supported deck would
alter the historic aesthetic of the landing.
Concern over resiliency and longevity of a pile-supported structure. A typical timber-framed and
pile-supported structure would deteriorate and degrade faster than stone and concrete due to
the constant inundation and wave effects at the landing area. If aluminum were used it would
prevent degradation from corrosion but would still be at risk of damage due to wave surge
conditions.
Continual maintenance and associated costs of a timber structure by the City.
Susceptibility to storm/wave damage impacts and repetitive damage.
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C.GRANITE BLOCK TOPPED LANDING WITH STEPS ON THREE SIDES (CHOSEN ALTERNATIVE)
The granite block topped landing with steps on three sides is the most favorable alternative due to its
increased resilience and ability to resist degradation from wave surge and consistent inundation
conditions. Specific benefits are as follows:
Increasedresiliencewithconcretecoreanddowelledlargecutgranitestoneblocks.Moreresilient
to wave surge and inundation conditions.
Ability to be dowelled into bedrock if encountered at shallow depths.
Steps on three sides for increased safety and public access to the beach.
Maintain historic aesthetic with granite stone topped surface and stone steps.
Removal of displaced exposed stone and debris adjacent to the existing landing structure,
reducing existing impacts to the beach.
Generallymaintainssimilarlanding areafor beachgoers and recreationalusesuchas enjoyingthe
unobstructed views of the cove.
Three-sidedsteppedstructureactsasaslopedstructuretominimizewavereflectionascompared
to a vertical face with limited width steps.
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4.GENERAL CONSTRUCTION METHODS AND PROCEDURES
A.GENERAL CONSTRUCTION DESCRIPTION
Construction duration for this Project is anticipated from November 2022 to May 2023 (pending
permitting and funding). The general construction process consists of site mobilization and preparation,
establishmentofsitesurveycontrols,installationoftemporaryperimeterfencing/barrieranderosionand
sedimentation measures, temporary removal of existing site features (benches, signage, trash
receptacles, etc.), phased removal and disposal of existing seawall and phased construction of new
seawall structure with concrete footing and mortared granite block wall, partial removal and
reconstruction of adjacent walls to tie-in with new City wall, removal and reconstruction of granite block
landing structure, hand placement of coir rolls, new sand fill, and new salt marsh plugs within the existing
salt marsh area, backfilling and site restoration including new concrete walkway landward of the wall,
new loam and seed, and curbing as necessary.
B.CONSTRUCTION ACCESS, STAGING, AND LIMITS OF WORK
The proposed work will be accessed and staged along Columbus Avenue between the properties of 44
Columbus Avenue and 30 Bay View Avenue. It is anticipated that temporary fencing/barriers and erosion
controls will be placed along the landward limitsof the Site and that this section of Columbus Avenue will
temporarily be converted to one-way traffic to facilitate the proposed construction. Additionally, public
walkway access will have to be temporarily routed around the Site. Signage will be in-place throughout
the duration of construction.
Land-based equipment will be used to perform the work and workers will access the intertidal zone as
necessary to perform the work. No equipment will be allowed on the beach or salt marsh vegetation. The
staging and stockpiling of equipment and materials will be on the landward side of the wall within a
portion of Columbus Avenue roadway and along the paved walkway and grass buffer strip. Equipment,
materials, debris, or other items will be stored such that they will be protected from rising water when
not being utilized.
The Contractor will be advised to monitor the weather forecasts and marine forecasts throughout the
duration of the construction project. Areas temporarily disturbed by construction activities will be
restored to pre‐construction conditions at the completion of the project.
C.SUPPORT OF EXCAVATIONS AND DEWATERING
Excavationsshall be kept to a minimum as necessary to complete the proposed work. Temporary support
of excavation will be utilized for construction of the proposed concrete footings, reconstruction of the
landing, and as necessary to protect existing salt marsh vegetation and adjacent seawall structures. It will
be up to the Contractor for means and methods to control erosion that may include, trench boxes, sheet
piles, planking, or sand bags to the extent that impacts are minimized or avoided such as in the case of
the work adjacent to the salt marsh. Support of excavation may consist of steel trench boxes, steel plates
or sheeting, or timber planking as required to facilitate the proposed wall and landing reconstructions.
Support of excavation will be performed in accordance with the Occupational Safety and Health
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Administration’s (OSHA) safety requirements. The Contractor will proceed with caution to avoid damage
to the seawalls, however, damage to privately owned seawalls from construction related activities will be
repaired, in‐kind, by the Contractor.
The Contractor will have to perform work in a manner that considers the tide cycle, as excavations will
extend below Mean High Water. Dewatering of excavations may be necessary during construction
activities. Dewatering of excavations will be performed so as to prevent siltation into wetland resource
areas. Discharge from dewatering activities will be filtered through straw bale sediment traps, silt filter
bags, or other means approved by the City and Conservation Commission.
D.CONSTRUCTION METHODS
Construction of New Seawall: The new seawall will be constructed in sections. Construction equipment
will be used to demolish and remove the existing stone wall. Temporary support of excavation will be
installedtoprotectadjacentsitefeaturesandfacilitatethebelowgradeexcavationandwallconstruction.
Acast-in-placereinforcedconcretefootingwillbeinstalledoverapreparedsubbase,thennewcutgranite
stone blocks will be lifted and set in place along the proposed wall alignment. Each course will be set in
mortar and the top three courses will be doweled together.
Salt Marsh Improvements:The salt marsh improvements include the hand-placement of seaward edge
coir rolls staked with timber wedge stakes, placement of clean sand to fill voids and eroded areas, the
placement of biodegradable coir blankets over backfilled areas, and the installation of new and
supplemental salt marsh plugs. No construction equipment will be allowed within the marsh area. The
proposed work will be accomplished by hand during times of low tide.
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5.COMMENTARY AND ANALYSIS FOR SALT MARSH PLANTING AND FILLING (E.G. THATCH PLUGS,
DRAINAGE, SUBSTRATE)
Thefollowingincludesanalysisoftheproposedsaltmarshwork.Thegoalistohelpstabilizetheexistingmarsh
and protect it against significant erosion and damage. Stabilization of the seaward edge would be performed
by using biodegradable coir rolls (refer to Section No. 6 for details on anchoring, monitoring and
maintenance). The majority of the ‘pockmark’ voids observed throughout the existing marsh are proposed to
be filled using clean sand wrapped in biodegradable erosion control blanket and new salt marsh plugs placed
at approximately 18-inches on center.
During the remote site visit there were comments about using a similar method as ditch remediation as
outlined in the Great Marsh Integrated Restoration Project, Ipswich, MA. Based on our preliminary review of
this method, the ditch remediation method generally consists of the gradual restoration of salt marsh by
placing and securing 6 to 9-inches of hay in the bottom of a salt marsh ditch to allow for the gradual natural
deposition of sediment to accumulate.
The majority of the existing ‘pockmark’ voids contain pooled water. Too much standing water can drown
plants or prevent growth of salt marsh grasses. The Project proposes to fill the majority of the ‘pockmark’
voidsasdescribedabovetoprovideasubstrateelevationsuitableforgrowthofsaltmarshvegetation.Atvoid
locations that appear to be preferential drainage paths no alterations or filling is proposed. The existing
drainage paths will be left as-is to maintain the hydrology and drainage of the marsh.
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6.COMMENTARY AND ANALYSIS FOR COIR ROLLS (E.G. ANCHORING, MONITORING, MAINTENANCE)
Proposed salt marsh protection/enhancement includes the installation of a temporary toe protection using
biodegradable high-density coir rolls. The coir rolls will be a minimum diameter of 12-inches and will be
anchored using minimum 4-foot-long, 2-inch by 4-inch timber wedge stakes placed on both sides of the coir
rolls at 2-feet on-center. The coir rolls will also be tied to adjacent timber wedge stakes using biodegradable
twine.
Finaldesignofthecoirrolltoeprotectionandanchoringsystemwillbedeterminedanddevelopedthroughout
the project permitting phase and for final design/preparation of project bid documents.
The Contractor will be responsible for initial maintenance of the coir roll and anchoring until acceptance by
the Project Engineer and the City. Initial maintenance may include, but is not limited to, resetting coir
rolls/anchors, repairing coir rolls/anchors, adjustments/additions of anchors, or replacement of
damaged/displaced coir rolls/anchors. Upon initial acceptance, the City will maintain the integrity of the salt
marsh toe protection system consisting of coir rolls and anchor stakes as required for protection and
establishment of the salt marsh vegetation area. We suggest that the salt marsh planting area be monitored
once per year during the peak biomass period (i.e. July or August) so that the vegetative cover may remain
complete and durable.
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7.PLANTING PLAN AT SOUTHWEST CORNER
Vegetation removed at the southwest corner to facilitate the wall reconstruction will be replaced with new
native, salt-spray tolerant shrub/grass species listed within CZM’s Coastal Landscaping Plant List. The
proposed plant species and typical spacing requirements are shown in Table 2.
Table No. 2 – Typical Proposed Planting Schedule
Proposed Shrubs
Common Name Scientific Name Size Spacing
Beach Heather Hudsonia tomentosa 6-inch pot 4-foot-on-center
Bearberry Arctostaphylos uva-ursi 4-inch pot 1-foot-on-center
Northern Bayberry Myrica pensylvanica 3-gallon 4-foot-on-center
Seaside Goldenrod Solidago sempervirens 4 to 6-inch plug 2-foot-on-center
Proposed Grasses / Seed Mix
New England Coastal Salt Tolerant Grass Mix1 Applicator’s Instructions
Notes:
1Species include Canada Wild Rye (Elymus canadensis), Red Fescue (Festuca rubra), Atlantic Coastal Panic Grass
(Panicum amarum), Big Bluestem (Andropogon gerardii), Indian Grass (Sorghastrum nutans), Switch Grass
(Panicum virgatum), and Path Rush (Juncus tenuis). (New England Wetland Plants, Inc.)
Final planting plan/schedule with total plant quantities will be determined and developed throughout the project
permitting phase and for final design/preparation of project bid documents.
Finalplantinglocationsshallbedeterminedinthefieldbasedonsiteconditionsencounteredduringconstruction.
In accordance with USACE methodology, “during planting, a qualified wetland professional may relocate up to 50
percent of the plants in each community type if as-built site conditions would pose an unreasonable threat to the
survival of plantings installed according to the plan. The plantings shall be relocated to locations with suitable
hydrology and soils where appropriate structural context with other plantings can be maintained.”
ATTACHMENT 1 – REVISED ENF PERMIT PLANS:
SHEET NO. 4 PROPOSED PLAN AND PROFILE
SHEET NO. 5 PROPOSED SECTIONS
HYDHYDSSSDWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWxWx0+001+002+003+004+004+740ELEVATIONS IN FEET (NAVD88)2468101214-2-4-6STATION (FEET)SHEET NO.PREPARED BY:PREPARED FOR:PROJECT NO.DATE:REVISION NO.DESIGNED BY:PROJ MGR:DRAWN BY:REVIEWED BY:CHECKED BY:SCALE:GZAGeoEnvironmental, Inc.Engineers and Scientistswww.gza.comCOLUMBUS AVENUE SEAWALL RECONSTRUCTIONSALEM, MASSACHUSETTS(EEA #258-2020-2-3)PROPOSED CONDITIONS PLAN AND PROFILECITY OF SALEM98 WASHINGTON STREET, 2ND FLOORSALEM, MASSACHUSETTSOCTOBER 202118.0171674.04-DRAWING44 OF 7DASDASDASLFTABBAS SHOWNCOLUMBUS AVENUEEBBFLOODJUNIPER COVE44 COLUMBUSAVENUE30 BAY VIEWAVENUESTONE SEAWALL,TO BE PROTECTEDAPPROXIMATE LIMITOF SALT MARSHEXISTING STONERIPRAP, TO REMAINPROPOSED RECONSTRUCTED GRANITEBLOCK SEAWALL, SEE DETAIL SHEET 6PROPOSED HINGEDFLOOD GATE BARRIER,SEE DETAIL SHEET 7DD'EE'SCALE: 1" = 20'PROPOSED SITE PLANAA'COASTAL BEACHLAND SUBJECT TOCOASTAL STORMFLOWAGEPROPOSED WORK LEGENDSCALE IN FEET010204060MHWNAVD88 = 0.0MLWMLLW0.34'5.0'9.0'11.0'DATUM RELATIONSHIPNOT TO SCALEFEMA 100 - YEAR FLOOD16.0'4.0'NPROPOSED HIGH MARSH PLANTINGS (SPARTINAPATENS)EXISTING LIMIT OFSALT MARSH (TYP.)'POCKMARK' VOIDS FILLED WITH A STONEINFILL WRAPPED IN EROSION CONTROLBLANKET AND SURROUNDED WITH SANDFILL AND MIN. 6" CLEAN SANDY FILL COVERVOID AREA WITHIN SALT MARSH,FILLED TO MATCH ADJACENTMARSH HEIGHT AND PLANTEDWITH SALT MARSH PLUGSBB'CC'-3PROPOSED SAND FILLEXISTING UPLANDVEGE., REMOVEDAND REPLACEDVERTICAL SCALE: 1" = 5'PROPOSED SEAWALL PROFILEHORIZONTAL SCALE: 1" = 20'TOP OF EXISTING STONEMASONRY SEAWALL(TYP.), TO BE REMOVEDEXISTING STONE MASONRYPILLAR / PLANTER (TYP.),TO BE REMOVEDGRANITE BLOCK LANDINGAND CONCRETE STEPS,RECONSTRUCT, SEEDETAILS SHEET 6EXISTING SEAWARD GRADE (TYP.)EXISTING LANDWARD GRADE (TYP.)HTL = 6.4MHW = 4.0MLW = -5.0FEMA 100-YRFLOOD = 11.0002.551015VERTICAL SCALE IN FEET10204060HORIZONTAL SCALE IN FEET'STEPS BEACH'STONE SEAWALL,TO BEPROTECTEDEXISTING BENCH, REMOVED ANDRESET UPON COMPLETION OFWORK (TYP.)PROPOSED CAST-IN-PLACECONCRETE FOOTINGPROPOSED LOW MARSH PLANTINGS (SPATINAALTERNIFLORA)PROPOSED BIODEGRADABLE COIR ROLLPROPOSED TOP OFSEAWALL, EL 11.5 (TYP.)PROPOSED CAST-IN-PLACE CONCRETE FOOTING (TYP.)PROPOSED HINGEDFLOOD GATE BARRIER8'VOID AREA WITHIN SALT MARSH,FILLED TO MATCH ADJACENTMARSH HEIGHT AND PLANTEDWITH SALT MARSH PLUGSCOASTALDUNECOASTALDUNEPROPOSEDBIODEGRADABLE COIRROLLS ALONG EDGE OFEXISTING VEGETATIONPROPOSED RELOCATEDTIMBER POST OUTHAULS,FINAL QUANITITY ANDLAYOUT LOCATION TO BEDETERMINED BY CITY (TYP.)12"Ø DRAIN PIPE WITH TIDE GATEEXISTING TIMBER POSTOUTHAULS (TYP.),REMOVED/CUT TOGRADE AND RELOCATEDSHELLFISH SUITABILITY AREALIMITS (SEE NOTE 6 ON SHEET 1)APPROXIMATEPROPERTY LINE(TYP.) (SEE NOTE 5ON SHEET 1)APPROXIMATE PROPERTY LINE(TYP.) (SEE NOTE 5 ON SHEET 1)MHW=4.0MHW=4.0REMOVE ANDRECONSTRUCTGRANITE BLOCKLANDING, SEEDETAILS SHEET 6PROPOSED SALT MARSH PLANTINGSQTYCOMMON NAMESCIENTIFICNAMESIZELOCATION1000SALT MEADOW HAYSpartina patens6" PLUGHIGH MARSH: ABOVEMHW (EL. 3.95)2500SMOOTHCORDGRASSSpartina alterniflora6" PLUGLOW MARSH: BELOWMHW (EL. 3.95)REMOVE AND RESET ADJACENT PORTION OFWALL TO FACILITATE CONSTRUCTION OFNEW CITY WALL, SEE DETAIL SHEET 7REMOVE AND RESETADJACENT PORTION OF WALLTO FACILITATECONSTRUCTION OF NEW CITYWALL, SEE DETAIL SHEET 7EL 6.0EL 5.0EL 4.0EL 3.0EL 2.0EL 0.5EL 0.5EL 2.0EL 4.0RESTORE 3'-4' WIDE GRASSED AREAWITH BENCHES, SEE DETAIL SHEET 7PROPOSED RECONSTRUCTEDCONCRETE WALKWAY MIN. 5'WIDE, SEE DETAIL SHEET 7TEMPORARY FENCE / BARRIER WITH EROSION CONTROLTEMPORARY CONTRACTORSTAGING/ACCESSPROPOSED TEMPORARY FENCE / BARRIER WITHEROSION CONTROLPROPOSED TEMPORARY STAGING AND ACCESS20'REMOVE MISC.EXISTINGSTONE DEBRISLOWELL STREETPERMITTING ONLYNOT FOR CONSTRUCTIONREVISED RESOURCE AREA LOCATIONSDASOCT.. 20211
SHEET NO.PREPARED BY:PREPARED FOR:PROJECT NO.DATE:REVISION NO.DESIGNED BY:PROJ MGR:DRAWN BY:REVIEWED BY:CHECKED BY:SCALE:GZAGeoEnvironmental, Inc.Engineers and Scientistswww.gza.comCOLUMBUS AVENUE SEAWALL RECONSTRUCTIONSALEM, MASSACHUSETTS(EEA #258-2020-2-3)PROPOSED SECTIONSCITY OF SALEM98 WASHINGTON STREET, 2ND FLOORSALEM, MASSACHUSETTSOCTOBER 202118.0171674.04-DRAWING55 OF 7DASDASDASLFTABBAS SHOWNFEMA 100-YRFLOOD = 11.0MHW= 4.0EXISTINGGRADEEXISTING STONE MASONRYSEAWALL, TO BE REMOVEDFEMA 100-YRFLOOD = 11.0HTL = 6.4EXISTINGGRADEEXISTING STONE MASONRY SEAWALL, TO BE REMOVEDFEMA 100-YRFLOOD = 11.0EXISTINGGRADEEXISTING STONE MASONRYSEAWALL, TO BE REMOVEDRECONSTRUCTEDCONC. WALKWAYMIN. 5' WIDE, SEEDETAIL SHEET 7HTL = 6.4HTL = 6.4SCALE IN FEET024812FEMA 100-YRFLOOD = 11.0HTL = 6.4MHW = 4.0EXISTING STONE MASONRY SEAWALL, TO BE REMOVEDPOCKMARKS (VOIDS) FILLED WITH STONEINFILL WRAPPED IN EROSION CONTROLBLANKET AND SURROUNDED WITH SANDFILL AND MIN. 6" CLEAN SANDY FILL COVEREXISTING RIPRAP STONE, TO REMAINMHW = 4.0MHW= 4.0EXISTINGGRADEAPPROX. HIGH MARSHAPPROX. LOW MARSHEL. 0.0 NAVD88EL. 0.0 NAVD88EL. 0.0 NAVD88EL. 0.0 NAVD88FEMA 100-YRFLOOD = 11.0MHW= 4.0HTL = 6.4EL. 0.0 NAVD88SCALE: 1" = 4'PROPOSED SECTION A - A': STA 0+14RESTORE 3'-4' WIDE GRASSEDAREA, SEE DETAIL SHEET 7COLUMBUSAVENUESCALE: 1" = 4'PROPOSED SECTION B - B': STA 1+63RESTORE 3'-4' WIDEGRASSED AREA,SEE DETAIL SHEET 7COLUMBUSAVENUESCALE: 1" = 4'PROPOSED SECTION C - C': STA 2+77COLUMBUSAVENUESCALE: 1" = 4'PROPOSED SECTION D - D': STA 3+59COLUMBUSAVENUERECONSTRUCTEDCONC. WALKWAYMIN. 5' WIDE, SEEDETAIL SHEET 7RESTORE 3'-4' WIDE GRASSEDAREA, SEE DETAIL SHEET 7SCALE: 1" = 4'PROPOSED SECTION E - E': STA 4+70COLUMBUSAVENUERESTORE 3'-4' WIDEGRASSED AREA,SEE DETAIL SHEET 7PROP. TOW = 11.5PROPOSED RECONSTRUCTED GRANITE BLOCK SEAWALL2'6.5'2'6.0'2'6.5'2'6.5'2'5.5'PROP. TOW = 11.5PROPOSED RECONSTRUCTED GRANITE BLOCK SEAWALLPROP. TOW = 11.5PROPOSED RECONSTRUCTED GRANITE BLOCK SEAWALLPROP. TOW = 11.5PROPOSED RECONSTRUCTED GRANITE BLOCK SEAWALL (IN BACKGROUND)PROP. TOW = 11.5PROPOSED RECONSTRUCTED GRANITE BLOCK SEAWALLPROPOSED SUPPLEMENTAL PLANTINGS (TYP.)PROPOSED SAND NOURISHMENT WITHBIODEGRADABLE EROSION CONTROL BLANKET TOMATCH ELEVATION OF ADJACENT EXISTING MARSHPROPOSED SAND NOURISHMENT AND SALT MARSHPLANTINGS INTEGRATED AROUND EXISTING RIPRAP STONEPROPOSED COIR ROLL AND BIODEGRADABLEEROSION CONTROL BLANKET BETWEEN EXISTINGSTONES AND NEW SAND NOURISHMENT FILL2'RECONSTRUCTEDCONC. WALKWAYMIN. 5' WIDE, SEEDETAIL SHEET 7PROPOSED FLOOD GATEBARRIER AT WALL OPENING2'2'2'2'EL = 4.7±PROPOSED RECONSTRUCTED GRANITE BLOCK TOPPED LANDING ANDSTEPS ALONG SIDES, SEE DETAILS SHEET 6 (TYP.)RECONSTRUCTED CONCRETEWALKWAY, 9'-10' WIDE MATCHEXISTING CONDITIONSPROPOSED FILTER FABRICLIMIT OF EXCAVATION, BACKFILLWITH SUITABLE GRANULAR FILLBACKFILL EXCAVATION WITHEXISTING SUITABLE BEACH SAND6" CRUSHED STONE SUBBASEOR SUITABLE SUBGRADEEXISTING UPLAND VEGETATION,REMOVED AND REPLACED WITH NATIVESALT-SPRAY TOLERANT PLANTINGSPROPOSED FILTER FABRICLIMIT OFEXCAVATIONAND SHORING,BACKFILL WITHSUITABLEGRANULAR FILL6" CRUSHED STONESUBBASE ORSUITABLE SUBGRADEBACKFILL EXCAVATIONWITH EXISTING SUITABLEBEACH SANDPROVIDE SHORING ASNECESSARY TO PROTECTEXISTING SALT MARSH (TYP.)EL = 2.7±PROPOSED FILTER FABRICLIMIT OF EXCAVATION AND SHORING,BACKFILL WITH SUITABLE GRANULAR FILL6" CRUSHED STONE SUBBASEOR SUITABLE SUBGRADEBACKFILL EXCAVATIONWITH EXISTINGSUITABLE BEACH SANDRECONSTRUCTEDCONC. WALKWAYMIN. 5' WIDE, SEEDETAIL SHEET 7PROPOSED FILTER FABRICLIMIT OF EXCAVATION, BACKFILLWITH SUITABLE GRANULAR FILL6" CRUSHED STONE SUBBASEOR SUITABLE SUBGRADEBACKFILL EXCAVATIONWITH EXISTINGSUITABLE BEACH SANDLAND SUBJECT TO COASTAL STORM FLOWAGECOASTAL DUNECOASTAL BEACHLAND SUBJECT TO COASTAL STORM FLOWAGECOASTAL BEACH AND SHELLFISH SUITABILITY AREACOASTAL BEACH AND SHELLFISHSUITABILITY AREALAND SUBJECT TO COASTAL STORM FLOWAGEEXISTING SALT MARSHCOASTAL BEACH AND SHELLFISH SUITABILITY AREALAND SUBJECT TO COASTAL STORM FLOWAGELAND SUBJECT TO COASTAL STORM FLOWAGEPROTECTION OF EXISTING FEATURES NOTE:1.PROVIDE SHORING/SUPPORT OF EXCAVATION BETWEENPROPOSED WORK AREA AND EXISTING FEATURES TO REMAIN(E.G. UTILITIES, ADJACENT STRUCTURES, CURB AND ROADWAY).1.5% SLOPE1.5% SLOPE1.5% SLOPE1.5% SLOPE1.5% SLOPEEL = 7.0±PROPOSED REINFORCED CONCRETE FOOTINGPROPOSED REINFORCED CONCRETE FOOTINGPROPOSED REINFORCED CONCRETE FOOTINGPROPOSED REINFORCED CONCRETE FOOTINGPROTECT AND RESTORE ROAD ANDCURB IN-KIND, AS NECESSARYPROTECT ANDRESTORE ROADAND CURB IN-KIND,AS NECESSARYPROTECT AND RESTORE ROAD ANDCURB IN-KIND, AS NECESSARYPROTECT AND RESTOREROAD AND CURB IN-KIND,AS NECESSARYPROTECT AND RESTORE ROADIN-KIND, AS NECESSARYPROPOSED RECONSTRUCTEDCONCRETE STEPS TO LANDINGTEMP. SHORING/SUPPORT OF EXCAVATION,RESTORE BEACH ELEVATION UPONCOMPLETION OF WORK (TYP.)PERMITTING ONLYNOT FOR CONSTRUCTIONREVISED RESOURCE AREA LOCATIONSDASOCT.. 20211COASTAL DUNE
ATTACHMENT 2 – POWERPOINT PRESENTATION
COLUMBUS AVENUE SEAWALL RECONSTRUCTION PROJECT
CITY OF SALEM, MASSACHUSETTS
MEPA Presentation October 8, 2021
SITE LOCATION
COLUMBUS AVE SEAWALL
SALEM SOUND /
ATLANTIC OCEAN
EXISTING SEAWALL
SITE NO. 1
GLADES – GANNETT RD. ACCESS
SITE NO. 1
7 SURFSIDE ROAD
PHOTOGRAPH BY GZA 3/27/18
PHOTOGRAPH BY GZA 3/31/20
PHOTOGRAPH BY GZA 1/3/19
PHOTOGRAPH BY GZA 1/10/19
EXISTING MARSH
SITE NO. 1
GLADES BEACH
SITE NO. 1
GLADES – GANNETT RD. ACCESS
SITE NO. 1
7 SURFSIDE ROAD
CLIFF ESTATES RD.
PHOTOGRAPH BY GZA 3/18/20
PHOTOGRAPH BY GZA 3/18/20 PHOTOGRAPH BY GZA 3/18/20
SITE NO. 1
GLADES BEACH
SITE NO. 1
GLADES – GANNETT RD. ACCESS
CLIFF ESTATES RD.
HISTORY
No Historic Permits Found
Originally Constructed Pre-1938
Stone/Masonry Construction
Several Repairs (Mortar and
Chinking)
Sustained More Significant
Damage and Flooding 2018
USGS Aerial 12/01/1955
COLUMBUS AVE SEAWALL
SITE NO. 1
GLADES – GANNETT RD. ACCESS
FLOODING
January 2018
SITE NO. 1
GLADES – GANNETT RD. ACCESS
COASTAL MODELING
SITE NO. 1
GLADES BEACH
SITE NO. 1
GLADES – GANNETT RD. ACCESS
SITE NO. 1
7 SURFSIDE ROAD
CLIFF ESTATES RD.
EXISTING SITE PLAN
SITE NO. 1
GLADES BEACH
SITE NO. 1
GLADES – GANNETT RD. ACCESS
SITE NO. 1
7 SURFSIDE ROAD
CLIFF ESTATES RD.
EXISTING SECTIONS
SITE NO. 1
GLADES BEACH
SITE NO. 1
GLADES – GANNETT RD. ACCESS
SITE NO. 1
7 SURFSIDE ROAD
CLIFF ESTATES RD.
PROPOSED PLAN
SITE NO. 1
GLADES BEACH
SITE NO. 1
GLADES – GANNETT RD. ACCESS
SITE NO. 1
7 SURFSIDE ROAD
CLIFF ESTATES RD.
PROPOSED SECTIONS
SITE NO. 1
GLADES BEACH
SITE NO. 1
GLADES – GANNETT RD. ACCESS
SITE NO. 1
7 SURFSIDE ROAD
CLIFF ESTATES RD.
PROPOSED DETAILS
SITE NO. 1
GLADES BEACH
SITE NO. 1
GLADES – GANNETT RD. ACCESS
SITE NO. 1
7 SURFSIDE ROAD
CLIFF ESTATES RD.
PROPOSED DETAILS
CLIFF ESTATES RD.
WETLAND RESOURCE AREAS
RESOURCE AREA IMPACT
LAND SUBJECT TO
COASTAL STORM
FLOWAGE
±15,970 SF TOTAL and entirely within areas of existing improvement (seawall, walkway, landscaping, etc.)
±10,170 SF TEMPORARY impact for construction access/staging temporary excavation and shoring.
±5,800 SF PERMANENT seawall and landing reconstructions, new flood gate barrier, walkway and grass strip reconstruction.
COASTAL BEACH
±2,893 SF TOTAL
±2,670 SF TEMPORARY impact for temporary excavation and shoring.
±283 SF PERMANENT Biodegradable coir rolls and timber post outhaul relocations.
COASTAL BANK
±564 LF TOTAL
±50 LF TEMPORARY temporary excavation at northeast corner sand build-up.
±514 LF PERMANENT City seawall (466 LF), flood gate (8 LF), adjacent walls (20 LF x 2).
SALT MARSH
±3,870 SF TOTAL
±1,000 SF TEMPORARY Augment existing salt marsh area with new salt marsh plugs.
±2,870 SF PERMANENT Fill large voids/erosion areas and pockmark voids with clean sand.
ANTICIATED PERMITTING
1. Massachusetts Environmental Policy Act (MEPA)
File an Environmental Notification Form (ENF) [SUBMITTED September 15, 2021]
2. Salem Conservation Commission
o Notice of Intent (NOI) Application
3. Massachusetts Department of Environmental Protection, Waterways Regulation Program
o Chapter 91 License and 401 Water Quality Certification
4. US Army Corps of Engineers
o Pre-Construction Notification (PCN) Application
ANTICIATED PROJECT TIMELINE
1. Permitting – On Going
o Estimated Completion by August 2022
2. Final Design – Bid Documents
o Estimated by September 2022
3. Construction November 2022 to May 2023
DISCUSSION / QUESTIONS
COLUMBUS AVENUE SEAWALL RECONSTRUCTION PROJECT