GZA
GeoEnvironmental, Inc.
Engineers and
Scientists
August 26, 2015
File No. 01.0025623.10
The Honorable Sefatia Romeo Theken
Mayor of Gloucester
9 Dale Avenue
Gloucester, Massachusetts 01930
Re:
249 Vanderbilt Avenue
Norwood
Massachusetts
02062
781-278-3700
FAX 781-278-5701
http://www.gza.com
Richard Sagall, Chairperson
Board of Health
3 Pond Road
Gloucester, Massachusetts 01930
Notification of Phase IV Remedy Implementation Plan Submittal
Former Gloucester Manufactured Gas Plant (MGP)
Harbor Loop, Gloucester, Massachusetts
Release Tracking Number (RTN) 3-25126
Dear Mayor Theken and Mr. Sagall:
Per the requirements of the Massachusetts Contingency Plan (MCP), specifically 310
CMR 40.1403(3)(a) and (e), this letter is intended to notify you that a Phase IV Remedy
Implementation Plan (RIP) for the above-referenced Site is being submitted to the
Massachusetts Department of Environmental Protection (MassDEP), and that associated
field activities will be initiated shortly thereafter. The Phase IV RIP describes
Comprehensive Remedial Actions (CRAs) that will be conducted to achieve a condition of
No Significant Risk (NSR) at the Site. Related field activities will be conducted over a
period of two to three construction seasons beginning on or after September 8, 2015.
As required by the MCP, the following sections of the Phase IV RIP are attached: a
description and conceptual plan of the activities; and a discussion of the measures that will
be implemented to limit or mitigate impacts to environmental receptors and natural
resource areas. A schedule for the proposed Phase IV Remedy Implementation is also
attached. A copy of the Phase IV RIP submittal can be viewed after August 28, 2015
under
RTN
3-35126
at
the
MassDEP
website:
http://db.state.ma.us/dep/cleanup/sites/search.asp. Copies of the report can also be
obtained by contacting Mr. Kenneth Lento at (781) 907-3655 or the undersigned.
If you have any questions concerning this letter, please contact the undersigned at
781-278-3805.
Very truly yours,
GZA GEOENVIRONMENTAL, INC.
Matthew J. Barvenik, LSP
Senior Principal
cc:
MassDEP – NERO
Kenneth E. Lento, National Grid
Attachments: Description of the Comprehensive Remedial Actions
J:\25,000-26,999\09.0025623.00\Phase IV - RIP\Phase IV Report\Appendices\Appendix Q - Public Notices\BOH & City Notice of Phase IV RIP Submittal.docx
DESCRIPTION OF REMEDIAL ACTIONS
1.00
INTRODUCTION
On behalf of Massachusetts Electric Company d/b/a National Grid (National Grid), GZA
GeoEnvironmental, Inc. (GZA) and Anchor QEA, LLC (Anchor QEA) have prepared this
Phase IV Remedy Implementation Plan (RIP) for the Gloucester Gas Light Company
(GGLC) Manufactured Gas Plant (MGP) facility (the Site). The Site is located off Harbor
Loop and Rogers Street in Gloucester, Massachusetts and has been assigned Release
Tracking Number (RTN) 3-25126 by the Massachusetts Department of Environmental
Protection (MassDEP).
1.10
PROJECT SUMMARY
Response actions are being conducted at the Site to meet the requirements of the
Massachusetts Contingency Plan (MCP, 310 CMR 40.0000). A Locus Map is included as
Figure 1, and an Aerial View of the Site showing properties within the disposal site
boundary is presented as Figure 2. As shown on Figure 2, the Site extends across upland
and in-water (marine) areas of multiple properties, which are owned by various
commercial and governmental entities. To facilitate assessment and remedial activities,
the Site has been divided into Marine and Upland Areas. The Upland Area has been
further subdivided into the Southern Area and Northern Area based on historical and
present-day ownership and land uses.
The MCP Phase IV Comprehensive Remedial Alternatives (CRAs) described in this report
have been designed to address the Southern and Marine Areas1 of the Site, collectively
designated as the Project Area. Property owners within the Project Area include the
United States Coast Guard (USCG), the City of Gloucester (City), National Grid, Maritime
Gloucester; and Kristensen Realty, LLC (KRLLC); additional information about each of
the properties is provided in Section 2.00. Selected CRAs at these properties and in
Gloucester Inner Harbor will include excavation and capping of MGP-impacted soils,
removal of coal tar in the form of dense non-aqueous phase liquid (DNAPL), removal of
MGP-impacted sediment, off-Site treatment and/or disposal of remediation waste, and
post-dredging placement of backfill and a sub-aqueous porewater cap. This will involve
removal and replacement of waterfront pile-supported structures, construction of interim
docking structures, construction and/or replacement of seawalls, excavation and
construction of an engineered barrier, dredging across approximately 7 acres of Gloucester
Inner Harbor, and placement of sub-aqueous fill material in the harbor for seawall stability
and porewater control purposes.
Permits for the project have been sought from multiple local, State, and Federal agencies.
The timing of the project will be affected by Division of Marine Fisheries (DMF) Time of
Year (TOY) restrictions (for in-water work) and the requirements of property owners. The
project is anticipated to begin in September 2015, and given its technical, regulatory, and
logistical complexity, will extend over a period of up to three years. Work will be
sequenced so as to limit impact to operations at each of the properties.
1
Separate MCP submittals have been and/or will be made for the properties within the Northern Area; see Section 2.30
for additional information.
3
7.00 DESCRIPTION AND CONCEPTUAL PLAN OF REMEDIAL ACTIVITIES,
INCLUDING RELEVANT DESIGN PARAMETERS (310 CMR 40.0874(3)(B)(5)
AND (6))
The following sections provide a conceptual plan and description of how the CRAs
outlined in Section 4.00 will be implemented during the Phase IV. Additional information
regarding the proposed sediment dredging, backfilling, and capping, soil excavation,
seawall construction, and marine structure removal and replacement activities is provided
in the Specifications included in Appendix D. A listing of the key elements of the work,
cross-referenced to the relevant Specification sections, is provided in Specification Section
01 10 00 – Summary of Work.
7.10
MARINE AREA SITE PREPARATION
To provide access for in-water remediation equipment, piers and floating docks at the
USCG, City of Gloucester, National Grid, and Maritime Gloucester properties will have to
be removed. As a consequence, interim structures will be constructed to allow some inwater operations at the USCG and Maritime Gloucester properties to continue during the
remedial efforts. In addition, measures to augment structure stability will be implemented
at the USCG and Maritime Gloucester seawalls prior to dredging. The in-water structure
removal and construction activities that will be implemented at the various properties are
described below.
7.10.1
USCG Floating Docks
During each remediation work season, USCG vessels will be temporarily re-located
from their existing floating docks. The existing gangway, steel braces, and timber float at
the Northern Floating Dock will be removed to provide access for dredge equipment, and
will be replaced prior to the end of each work season. The existing gangway and timber
float at the Southern Floating Dock will be used in the construction of the interim floating
dock system described below, and will similarly be replaced prior to the end of each work
season.
To limit disruption to USCG operations during the remediation, an interim floating
dock system for up to three vessels will be constructed adjacent to Pier 2 at 17 Harbor
Loop (see Drawing S-14). To accommodate the interim system, the Pier 2 substructure
will be repaired by replacing timber fender piles and cross-bracing elements that are in
poor condition, and reinforcing additional timber piles with fiber reinforced polymer (FRP)
jackets to enhance their strength and longevity. The interim system will consist of a timber
pile-supported landing, two timber floating docks, and an aluminum gangway. Temporary
fuel, lighting, water, and electrical services for the USCG vessels will be provided at this
location.
This interim location, while suitable for USCG access, is not sheltered from wind
and wave surges. Therefore, a temporary bottom-anchored floating breakwater will be
installed as shown on Drawing S-14. The breakwater will consist of two bottom-anchored
concrete floats, each approximately 13 feet by 41 feet in dimension. These floats will
extend over the 2004 Harbor Commissioner’s line into a Federal anchorage area, under
permit approval from the United States Army Corps of Engineers (USACE) and a 10A
Permit issued by the Gloucester Harbormaster.
4
Following the completion of the remediation project, the interim floating dock
system and breakwater will be removed from Pier 2, and the Northern and Southern
floating docks will be re-located to their existing locations at the USCG property.
7.10.2
National Grid Pier and City of Gloucester Floating Docks
As described in Section 2.20, a wooden pile-supported pier owned by National
Grid extends over both the National Grid property at 19 Harbor Loop and City of
Gloucester property at 19R Harbor Loop. The pier is in poor condition, and an
approximately 1,300-square foot (sf) section of it was removed in July 2012 as a safety
measure at the request of the Gloucester Harbormaster. To facilitate in-water equipment
access to the seawalls and Nearshore Area, the pier will be removed in its entirety at the
start of the remediation project as described in Specification Section 02 40 00 –
Demolition and Structure Moving.
At the end of the first work season, in accordance with an agreement with the City
of Gloucester, National Grid will install an array of steel guide piles to support a new City
of Gloucester floating dock system that will also extend over both properties. The guide
piles will consist of 18-inch-diameter concrete-filled coated steel pipe piles, which will be
drilled into the bedrock beneath the harbor to withstand tidal and wave action. Between
work seasons, i.e., during the summer of 2016, these piles will be used to support an
interim City of Gloucester floating dock system. Following completion of the project, the
piles will support a new City of Gloucester floating dock system, which is described under
Site Restoration activities in Section 7.80 of this Phase IV RIP.
7.10.3
Maritime Gloucester Piers, Floating Docks and Gangway
The anticipated sequence of remediation at Maritime Gloucester includes
construction of a vertical barrier (Section 7.70.2, below) during the first work season and
dredging in the Nearshore Area to remove impacted sediments during the second work
season. This will require temporary re-location of some Maritime Gloucester operations
during the first work season, and removal and replacement of the piers at the property
during the second work season, as described below.
During the first work season, the gangway and floating docks currently attached to
the southern edge of the Main Pier will be temporarily re-located to an alternate location
on the Maritime Gloucester property, and will be restored to existing conditions when
access to the slip is restored. An interim timber landing will be constructed at the Northern
Hauling Pier to provide access for the gig rowers club, which currently accesses the water
via the southern landing at the Main Pier.
During the second work season, the gangway and floating docks at the Main Pier
and the two hauling piers will be removed from their supports and stored. It is anticipated
that the Maritime Gloucester Main Pier decking, and all but the most landward set of piles,
will be removed, unless the contractor’s approach allows for sediment remediation
objectives to be achieved with some portions of the pier remaining in place. Similarly, all
or a select portion of the hauling piers will be removed; where possible, select timber piles
may be left in place, and sediment removed around the piles during dredging. Once
dredging and backfilling has been completed, the Main Pier and hauling piers will be
reconstructed in kind and the floating docks and gangway will be restored.
5
7.10.4
Maritime Gloucester Boat House Seawall Stability Enhancement
The Maritime Gloucester Boat House Seawall (Drawing EC-1) was constructed in
the late 19th century, and does not meet current design factors of safety. Therefore, when
the Maritime Gloucester Main Pier is removed, the existing row of wooden piles closest to
the seawall will be left in place, to improve seawall stability during dredging. These piles
will be augmented with seven steel H-piles and plates driven along the toe of the wall in
front of the boat house. Concrete will be tremie poured between the piles/plates and the
seawall, to provide additional stability specific to the boat house area (Drawing S-21). As
an additional stabilization measure during dredging in front of the boat house, the top
courses of the granite block seawall section will be temporarily removed, and the soil
behind it will be excavated to an elevation of +5 feet NGVD. This will reduce the
effective surcharge load on the wall and thus increase the overturning factor of safety
during dredging in front of the boat house.
Impacted sediment seaward of the steel plates will be removed by interval
dredging, following which the mudline will be brought back to existing grade with
material providing similar strength to that removed (See Section 5.80). Once in-water
backfilling has been completed, the granite blocks will be replaced and the excavation
behind the seawall in the upland area will be filled with concrete. Four of the H-piles will
be cut to elevation -2 feet NGVD; the remaining three will be left in place to support an
approximately 8-foot-wide wooden walkway (Drawing S-29) providing waterfront access.
The soil removed from the upland excavation will be managed under a Release Abatement
Measure (RAM) Plan to be developed for the Maritime Gloucester property prior to the
initiation of this phase of work.
7.10.5
Debris Removal and Pre-Dredge Bathymetric Survey
Following removal/re-location of structures as described above, and prior to the
removal of sediments, a visual debris survey will be performed at each of the areas where
dredging is to be conducted. Industrial debris related to marine activities has been
identified within the Marine Area, including old piles, tires, bricks, cables, lines, and
timber and scrap metal debris. The remnants of the abandoned marine railway at Maritime
Gloucester will also be removed during this phase of work. Proposed debris management
is described in Section 9.30 of this Phase IV and in Specification Section 02 61 00 –
Removal and Disposal of Excess Materials.
The debris survey will be coordinated with a pre-dredge bathymetric survey to
establish baseline conditions prior to the start of remediation. This pre-dredge survey
represents one of a series of surveys that will be conducted throughout the Phase IV in
accordance with Specification Section 02 21 00 – Surveys. The baseline survey will be
compared to post-dredge surveys to verify dredge depths reached and volumes removed in
each area. The survey results will be used to prepare Final Conditions plans that will be
submitted as part of the Phase IV Final Inspection Report (FIR).
7.10.6
Installation of Marine Resuspension Controls
As described in Specification Section 01 57 30 – Marine Resuspension Controls, a
number of in-water controls will be installed prior to the initiation of in-water or waterfront
activities that may generate silt (i.e., turbidity) or sheens. These controls, which will be
6
deployed as shown on Drawings C-3 and C-4, will generally consist of the following
elements as shown on Drawing C-7:

A Mobile Resuspension Control System will be installed prior to dredging
in the Nearshore and/or Offshore Areas. This system will be comprised of
an enclosed moon pool surrounded by permeable turbidity curtains.
Reefing lines will be used to accommodate varying water depths due to
tidal fluctuations, and to maintain the curtains between one and three feet
above the sediment surface. Billow controls will be used to limit drifting of
the curtain due to tidal currents. Sorbent booms will be secured to the inner
and outer edge of the system to absorb potential sheens that may be released
during the work.

A Modified Mobile Resuspension Control System will be installed prior to
dredging in portions of the Nearshore Area where the system described
above cannot be used due to access limitations associated with the system
geometry or shallow water depths. The modified system includes the same
components (i.e., turbidity curtain, reefing lines, billow controls, and
sorbent booms) as described above. Work will be conducted off the back of
the modified system, with additional permeable turbidity curtains installed
from the mobile system to the shoreline as shown on Drawing C-4.

Stand-alone permeable turbidity curtains will be anchored around the work
area during suction dredging at USCG Pier 2 and steel pile installation for
the City of Gloucester floating dock system (Drawing C-3).

Both stand-alone impermeable turbidity curtains and stand-alone permeable
turbidity curtains will be anchored around the work area during seawall
removal and construction activities at Solomon Jacobs Park, National Grid,
and Maritime Gloucester (Drawing C-3).
When left in place overnight, the marine resuspension controls will be lit to warn
boaters in accordance with USCG and Harbormaster requirements.
The marine resuspension controls will be inspected at least twice daily, and will be
modified as necessary to meet Site-specific conditions and the requirements of the Water
Quality Certification (WQC). The controls will remain in place until sheen-generating and
silt-producing activities are complete, and will then be decontaminated and disposed of in
accordance with Specification Sections 02 51 29 – Surface Cleaning and Decontamination
and 02 61 00 – Removal and Disposal of Excess Materials.
7.20
UPLAND AREA SITE PREPARATION
Site preparation in the upland areas will be initiated with the installation of fencing around
the work areas at each of the properties, as shown on Drawings C-13 and C-14 and in
accordance with Specification Section 01 56 00 – Temporary Enclosures and Barriers.
This will be followed by the installation of Erosion and Sedimentation Controls, as shown
on C-3 and C-4 and discussed in Section 8.40 of this Phase IV RIP.
7
Existing features within Solomon Jacobs Park will then be removed as shown on Drawing
CD-3, and the park will be cleared in anticipation of temporary construction features such
as a containment area for temporary stockpiling of impacted materials, a staging area for
clean materials, and a wheel wash station. Also during this stage of work, select
monitoring wells in the Southern Area will be decommissioned in accordance with
Specification Section 33 29 00 – Well Abandonment and Drawing R-9. These wells were
selected based on routine monitoring efforts conducted during IRA activities; new DNAPL
recovery wells will be installed at key locations as described below in Section 7.70.3.
In accordance with the terms of access agreements between National Grid and the property
owners, limited areas of the USCG and Maritime Gloucester properties may be used for
temporary staging of clean materials or equipment (Drawings G-5 and G-6). No
remediation waste will be stockpiled at the USCG property. At the Maritime Gloucester
property, excess soil generated during the Boat House Seawall Stability Enhancement
process described in Section 7.10.4 may be temporarily stored pending characterization
and off-Site disposal. The soil will be managed as described in Section 9.20.2. Granite
blocks removed during the Boat House Seawall Stability Enhancement may also be
temporarily stored at the property pending their re-use following dredging and backfill
placement.
7.30
DREDGING
Dredging to remove sediments with VOT and/or TPAH16 concentrations greater than 135
mg/kg will be conducted over approximately 7 acres of the Marine Area as shown on
Drawings C-17 through C-19. The proposed dredge depths range from approximately 1.0
feet to 6.5 feet below the existing mudline, including an anticipated overdredge allowance
of 6 inches. The deeper dredge depths are located in the Nearshore Area.
Approximately 30,000 cy of sediment containing VOT and/or TPAH16 concentrations
greater than 135 ppm will be removed during the Phase IV Remedy. Additional sediment
volume may need to be removed based on visual observation of the nature and extent of
OHM during dredging implementation.
Dredging equipment and procedures are described in Specification Section 35 01 50.51 –
Marine Dredging, and are summarized below.
7.30.1
Mechanical Dredging
Dredging across most of the Offshore Area, seaward of the Gloucester Harbor Line,
will be performed using an excavator mounted on a barge. The barge will be fitted with
hydraulic spuds and configured with a moon pool (as described above in Section 7.10.6)
within which the dredging operations will be performed. A hydraulically actuated
environmental clamshell bucket will be used to reduce sediment loss during dredging.
Dredging will be conducted within a Mobile Resuspension Control System designed to
maintain the dispersion of turbidity, sheens, floating oil and/or tar within the limits of
work.
Dredging in the Nearshore Area, landward of the Gloucester Harbor Line, will be
performed using one or more excavators mounted on shallow draft barges. These barges
will be similarly equipped with hydraulic spuds and an excavator with environmental
8
clamshell bucket, but without a moon pool. This configuration is required to allow
dredging to be performed up against existing structures. The barge and work area will also
be surrounded by resuspension controls throughout the work.
Dredging adjacent to the USCG, City of Gloucester, National Grid, and Maritime
Gloucester seawalls will be performed in narrow linear segments followed immediately by
backfilling to maintain stability, a process referred to as interval dredging. The technique
involves excavating one narrow “slot” or “interval” perpendicular to the length of the
structure to limit the amount of material removed from the toe of the structure at any given
time. “Slots” or “intervals” will be immediately backfilled to existing, or otherwise
specified grade following excavation. A hopscotch approach will be used to excavate
subsequent “slots” or “intervals” so that no two adjacent slots are excavated and open at
the same time; i.e., the width of any individual open excavation will not exceed the
prescribed slot width.
7.30.2
Dredging at the Maritime Gloucester Marine Railway
Dredging around the active Marine Railway at Maritime Gloucester will be
conducted in the dry within a temporary sheet pile cofferdam. The approximately 16-footwide by 208-foot-long cofferdam will be constructed of inter-locking steel sheet piles. The
footprint of the cofferdam will encompass the end of the railway, estimated to be at -14.29
feet NGVD.
Closure of the landward side of the cofferdam will require removal of
approximately 10 feet of railway and framing timbers. Final closure will be performed as
close to low tide as possible to reduce the amount of water remaining within the closed
cofferdam. Pumping to remove water within the cofferdam will be performed from the
water surface to limit the suction and suspension of sediment from the mud line. As
described in Section 9.40, this water will be treated as necessary prior to discharge within
the limits of the work, in accordance with the WQC.
A mini-excavator will be placed into the cofferdam to remove sediment. In
conjunction with the mini-excavator, laborers will use hand tools to remove impacted
sediment from beneath and around the railway components. Excavated sediment removed
from the cofferdam will be transferred to a material scow and managed with other dredged
materials from the Site, as described in Section 9.10.
7.30.3
Suction Dredging
Diver-assisted suction dredging will be conducted in localized areas where access
is limited, such as under USCG Pier 2. This dredging will be performed by a dive crew to
control the location and depth of the suction head around the existing infrastructure.
Suction dredging may also be used in the area of the active Marine Railway as an alternate
to the cofferdam approach.
7.40
MARINE BACKFILL PLACEMENT
Backfill will be placed in areas of the dredge footprint to manage dredge residuals and to
reestablish benthic habitat following dredging activities. Additional factors, including the
need for structural stability near existing marine structures and design elevations within the
9
Federal navigation channel, were also evaluated prior to developing specifications for
backfilling at the Site. The resulting backfilling plan is graphically depicted on Drawing
C-21, and the materials to be used for backfill in different areas of the Site are specified in
Section 31 05 13 – Soils and Aggregates for Earthwork.
7.40.1
Nearshore Area
Following dredging, backfill will be placed in the Nearshore Area at the USCG,
City of Gloucester, National Grid, Maritime Gloucester, and KRLLC properties as
described below.
USCG, City of Gloucester, and National Grid properties
Outside the porewater cap area (described below in Section 7.50), a minimum 6inch-thick layer of clean backfill will be placed within the Nearshore Area at the USCG,
City of Gloucester, and National Grid properties to reestablish benthic habitat and/or to
manage dredge residuals. The grain size characteristics of the backfill will generally be
similar to existing materials.
Maritime Gloucester
Following dredging and placement of an initial 6 inches of backfill material, a
confirmatory sediment core sample will be collected from each of four quadrants in the
Nearshore Area at the Maritime Gloucester property. The samples will be submitted for
laboratory analysis of TPAH16 by EPA Method 8270D, and the results will be compared to
the remedial objective of 135 mg/kg. As necessary, an additional dredge pass of at least 12
inches in depth will be conducted prior to final placement of backfill to grades shown on
Drawing C-21.
Within the cofferdam at the active Marine Railway, backfill material will be placed
under and around the railway and timber framing to existing grades as shown on Drawing
C-21. Upon completion of backfilling, the cofferdam elements (internal bracing and the
sheet piles) will be removed and decontaminated over an intermodal container. Marine
railway rails/timbers that were removed to close the sheeting will be replaced.
KRLLC property
Sufficient backfill will be placed to restore mudline to the grade shown on Drawing
C-21 at the KRLLC property.
7.40.4
Offshore Area
The majority of the Offshore Area is located within a Federal navigation channel,
which has an authorized elevation. Although the proposed dredging will extend below that
elevation, placement of backfill material after dredging poses the potential risk of
overfilling to an elevation at or above the authorized elevation. To evaluate the need for
backfilling after dredging, as associated with potential dredge residuals, confirmatory
sediment samples will be collected from a representative “test” area and analyzed for
OHM concentrations. If OHM concentrations are consistent with remedial objectives,
backfill will not be placed within the area tested and backfill placement will not be
10
recommended for the Offshore Area. If OHM concentrations are not consistent with
remedial objectives, 6 inches of backfill material will be placed in the “test” area. Then,
confirmatory sediment samples will be collected from another “test” area, and the process
mentioned above repeated. Under either circumstance, the objective is to maintain the
post-remediation mudline within the Federal navigation channel at or below the authorized
elevation. Upon completion of this work, this area will not be subject to restrictions on
future dredging.
7.50
MARINE CAPPING
The objective of the sub-aqueous porewater cap to be constructed in the Nearshore Area
adjacent to the USCG property, Solomon Jacobs Park, and the National Grid property is to
address impacted sediment porewater that has the potential to present a future risk to
ecological receptors. The extent of the cap is based on the porewater studies described in
Section 5.20 and Appendix F, and will cover approximately 10,000 sf (Drawing C-21).
The cap design, which is based on the modeling described in Appendix F, will include a
chemical isolation layer overlain by an erosion protection layer designed to protect the
material within the chemical containment layer from propeller scour and erosion.
The cap materials will be placed using one of two methods: 1) placement of custom
Triton® Marine Armor Mattresses (MAMs) fabricated by Tensar® International
Corporation (Tensar) or equivalent or 2) placement of individual layers of granular
material. Both placement methods provide the same chemical containment as well as
provide adequate erosion protection.
MAMs were selected for placement on the USCG property to accommodate potential
future operational changes on this Federal property, and will also be used in a small
application on the National Grid property to provide increased erosion protection near the
seawall.
The MAMs will comprise dual-layer polymeric (i.e., non-metallic)
compartmental structures. The bottom layer of each MAM will be 12 inches thick,
wrapped in geotextile, and filled with a mixture of sand and CETCO PM-199 organoclay
to attenuate upwelling porewater. The 8-inch-thick upper compartment will be filled with
stone to protect the underlying sand-organoclay layer from damage due to scour and
propeller wash. As shown on Drawing C-22, a rip rap buttress will be placed above the
MAMs, adjacent to the USCG seawall stability wedge. This buttress will be located below
Mean Low Water, and will provide additional stability for the USCG seawall. The rip rap
buttress and MAMs can be removed and replaced as necessary to accommodate future
USCG operational changes or infrastructure improvements. The MAMs will also better
withstand scour associated with Harbormaster operations in the shallow draft areas of the
National Grid property.
At the rest of the National Grid property, and on the City of Gloucester property, the
porewater cap will consist of a multi-layer Granular Marine Cap with the following layers:

A 6- to 12-inch-thick chemical containment layer consisting of a mixture of
50% sand and 50% CETCO PM-199 organoclay to attenuate upwelling
porewater, overlain by

a 6- to 12-inch-thick layer of filter material, overlain by
11

a 9- to 15-inch-thick layer of armor stone to protect the underlying layers from
damage due to scour and prop wash.
Typical cross-sections of the granular cap and MAM cap are shown in Drawing C-22. The
top of cap elevation will be no higher than the existing mudline.
Following the completion of remediation activities, the integrity of the cap will be
monitored over time and maintenance will be conducted as needed, in accordance with the
AUL, or AUL-like instrument, required to reach a Permanent Solution under the MCP. It
is anticipated that the AUL will allow pre-existing activities, i.e., activities consistent with
the current uses of the properties using current operational procedures, but will require
notification to National Grid prior to future changes in operating conditions or invasive
activities (e.g., dredging, pile driving) within the footprint of the cap. Post-construction
conditions surveys of the porewater cap will be conducted by National Grid as described in
Section 13.30.
Note that as shown on Drawing C-21, the porewater cap will be placed entirely within the
nearshore portions of the properties listed above, and it will in all cases be located more
than 100 feet away from the Harbor Commissioner’s Line. As such, the cap will have no
impact on the Federal navigation channel, its side-slope design, or future maintenance
dredging activities.
7.60
USCG STABILITY WEDGE CONSTRUCTION
To enhance the stability of the USCG seawall in order to facilitate dredging of impacted
sediments, a stability wedge of concrete will be constructed along the toe of the seawall.
The wedge will be constructed by interval dredging, matched with intervals of concrete
placement, to alleviate potential stability issues associated with dredging immediately
adjacent to the seawall. The extent of the stability wedge, and a profile view, are presented
in Drawings C-21 and C-22. Note that the wedge will be an integral part of the porewater
cap at the USCG property.
The stability wedge will also create additional intertidal resource area at this location. In
accordance with recommendations made by MassDEP during the EENF review for this
project, at least 18 inches of select fill (see Section 31 05 13 – Soils and Aggregates for
Earthwork) will be placed above the concrete to provide habitat following remediation. A
layer of granite blocks or equivalent will be placed along the seaward edge of the wedge to
create a berm that will limit future scouring and loss of the habitat layer.
7.70
SOUTHERN AREA REMEDIAL RESPONSE ACTIONS
As summarized in Section 4.00, NAPL-impacted fill material behind the granite block
seawalls along the waterfront at the Solomon Jacobs Park and National Grid properties has
been identified as an ongoing source of impact to the environment. In addition, presumed
source material exists behind the National Grid Existing Building Seawall, in an area that
cannot be directly investigated due to the presence of a building partially founded on the
seawall. In support of a Permanent Solution at the park and National Grid properties,
source material will be excavated where accessible. This will entail removal and
replacement of seawalls at Solomon Jacobs Park and a portion of the National Grid
property. For the remainder of the National Grid property, where the existing building is
12
supported on the seawall, a concrete vertical barrier (i.e., a new seawall) will be installed
seaward of the existing seawall for source control.
Further, to address the conditions described in Section 4.00 and achieve a Permanent
Solution in the Southern Area, an automated DNAPL Recovery System will be installed at
the USCG, Solomon Jacobs Park and National Grid properties, and an engineered barrier
will be constructed in the park. The following sub-sections describe each of these CRAs.
7.70.1
Source Removal
The granite block seawalls designated as the Solomon Jacobs Park Seawall, the
National Grid Pier Seawall and the National Grid Access Ramp Seawall on Drawing EC-1
enclose fill material emplaced in the late 19th century during operation of the MGP.
During the Phase IV, these seawalls will be removed to facilitate access to soil impacted
by coal tar (source material), and will be re-built along a straighter alignment which will
also provide additional water sheet for the City of Gloucester Harbormaster and the public.
The excavation and construction efforts are described in Specification Sections 31 00 00 –
Earthwork through 31 50 00 – Support of Excavation (SOE) and 35 31 16.40 – Stone
Seawalls and select S-series Drawings between S-1 and S-10, and are summarized below.
A temporary support of excavation system will be installed landward of the
existing seawalls to support upland excavation (Drawing S-1). The SOE system will
consist of drilled mini piles, with wood lagging used down to MLW, followed by steel
sheets below MLW. The system was designed based on the lithologic and geotechnical
data collected during the Phase II CSA, as well as subsequent investigations described in
Section 5.00. Once the SOE system has been installed, the National Grid Pier Seawall and
the land it encloses (approximately 1,000 cy of fill) will be removed. The Solomon Jacobs
Park Seawall and National Grid Pier Access Ramp Seawall will then be removed, and coal
tar-containing soil behind the seawalls will be excavated to an elevation of approximately 11.5 feet NGVD. This will result in the removal of approximately 2,000 cy of source
material. Additional soil volume may need to be removed based on visual observation of
nature and extent of OHM at depth during source removal activities.
Following source removal, a 6-foot-thick tremie concrete foundation will be
installed below water, and a replacement seawall will be constructed and finished to a
surface elevation of +10.5 feet NGVD. It is anticipated that the granite blocks reclaimed
during removal of the existing seawalls will be cleaned as necessary (to remove coal tar
staining) and re-used to construct the granite block seawalls. Additional granite blocks
reclaimed from the seawall demolition will be placed at the toe of the rebuilt seawalls for
aesthetics and scour protection. A vertical layer of adsorbent CETCO PM-199 organoclay
mixed with sand will be placed landward of the granite walls. This layer is designed to
adsorb residual hydrocarbons if present, thus limiting potential future impact associated
with groundwater drainage to the harbor. As a conservative supplement to source removal,
the seawall design also includes installation of a horizontal 4-inch-diameter perforated
PVC pipe at the base of the organoclay layer, which is accessed through a number of 4inch-diameter solid PVC vertical risers (Drawing S-7). This supplementary system will
facilitate manual collection of DNAPL from the base of the seawall if there is postremediation lateral migration of DNAPL from fill material left in place landward of the
excavated areas.
13
Concurrent with the organoclay and PVC pipe installation, a geosynthetic wrapped
face wall will be constructed behind the organoclay, as shown on Drawing S-7 and S-8.
This seawall design – geosynthetic wall, organoclay layer, and granite block wall - has
been selected to allow for later removal and replacement of the organoclay if necessary,
while meeting current design standards and maintaining the historical appearance of the
waterfront. Following seawall construction, the lagging between the mini-piles will be
removed to the extent feasible and the tops of the mini-piles will be cut off at 3 feet below
finished grade.
Much of the above described source removal and seawall reconstruction work will
be conducted in the wet in conjunction with the tidal cycles at this location.
7.70.2
Vertical Barrier Construction at National Grid and Maritime Gloucester
The objective of the vertical barrier (concrete seawall) to be constructed adjacent to
the National Grid building is to limit the potential migration of source material. This
material is presumed to be located under the building, with potential migration into the
harbor and sediment through the National Grid Existing Building Seawall (see Drawing
EC-1 for location). Given the building location relative to the seawall, it is not feasible to
excavate the presumed source soils without significantly impacting the building.
Therefore, to achieve source control, a low-permeable barrier (i.e., concrete seawall) will
be constructed approximately 10 feet seaward of the current seawall to limit the potential
migration of coal tar toward the harbor. The barrier will extend approximately 5 feet onto
the Maritime Gloucester property to provide additional control of presumed source and
additional stability to the existing Maritime Gloucester seawall at this location. This work
will consequently create approximately 450 sf of new land behind the new seawall,
designated as the National Grid Building Seawall.
Construction of the vertical barrier will include interval dredging in front of the
National Grid Existing Building Seawall to remove unsuitable sediments, constructing a
low-permeability reinforced concrete seawall, and backfilling behind the new seawall with
clean granular material. Due to anticipated soil conditions, the new seawall will be
supported by steel piles driven to refusal. Steel plates will be placed between the piles
closest to the seawall to limit undermining of existing seawall during excavation, and
between the outermost row of piles. Additional steel sheets will be placed between the
remaining piles to facilitate interval dredging adjacent to the existing wall. Following
dredging to remove impacted and structurally unsuitable soils, the new seawall will be
constructed in the wet. The new seawall will have a granite façade to match the
appearance of other seawalls along the waterfront, and granite blocks will be placed at the
toe to provide scour protection. Sand-gravel fill will be placed behind the seawall on the
National Grid property to facilitate the flow of groundwater toward the National Grid
access ramp seawall, where the organoclay layer will be in place to adsorb residual
dissolved hydrocarbons. Concrete fill will be placed behind the seawall at the Maritime
Gloucester property (Drawings S-7 and S-8). The upper surface behind the wall will be
completed with an approximately 45-linear-foot-long publicly accessible concrete
walkway along the water’s edge, with a gangway to the City floating dock system for
Harbormaster access.
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7.70.3
Automated DNAPL Recovery System
The Phase IV Remedy in the Southern Area will include installation of an
automated recovery system to remove DNAPL from well GZ-4C at the USCG Property as
well as locations at the park and National Grid property where residual DNAPL may be
present at depth. Installation of this system will be integrated with seawall reconstruction
efforts as described below.
Following seawall construction, three new 4-inch-diameter stainless steel DNAPL
recovery wells, RW-1 through RW-3, will be installed just seaward of the geosynthetic
wall at the locations shown on Drawing C-23. The wells will be screened to
approximately 55 feet below grade to remove DNAPL from the base of the till layer (see
Specification Section 33 20 00 – Extraction and Monitoring Wells). These wells, as well
as existing GZ-8B (which will be re-built if damaged during construction), will be
completed with precast concrete vaults at each location. The vaults, each with a hinged
steel cover, will be finished to match final grade. The wells will be monitored routinely
following their installation to evaluate whether residual DNAPL is present at depth at any
of these locations.
Automated downhole pumps, similar to that used for the DNAPL recovery pilot
test system under the IRA described in Section 5.60, will be installed in wells with
recoverable DNAPL. DNAPL storage units and control panels for the pumps will be
housed at 19 Harbor Loop (Drawing C-24), and will be connected to the wells by dualcontained DNAPL recovery piping consisting of nylon tubing with secondary PVC piping
for containment. The piping will extend aboveground from well GZ-4C along the landside
of the USCG seawall toward the park, and will then continue belowground at the park and
National Grid properties.
The DNAPL recovery system will be operated in accordance with the provisions of
an MCP Phase V (Operation, Maintenance and/or Monitoring (OMM) of Comprehensive
Response Actions) until DNAPL with Micro-Scale Mobility has been removed to the
extent feasible in support of a Permanent Solution in the Southern Area.
7.70.4
Engineered Barrier at Solomon Jacobs Park
Soils with petroleum hydrocarbon concentrations exceeding UCLs are present
within an approximately 3,600-square-foot area in Solomon Jacobs Park. As discussed in
Section 5.50 and the memorandum in Appendix I, an engineered barrier will be
constructed by excavating soil in this area (Drawing C-16) to between 4 and 6 feet bgs.
The excavation will be coordinated with tidal cycles to limit the volume of water that is
generated; such water will be containerized and properly managed for off-Site disposal.
Given the absence of surface structures at the park and the limited depth of excavation, no
shoring or support of excavation is anticipated.
Approximately 800 cy of soil will be removed from the excavation and will be
managed as described in Section 9.20. Following soil removal, a defining layer consisting
of horizontal chain-link fencing will be placed at a minimum of 4 feet bgs and will be
overlain with clean fill. In addition, as a further conservative measure, a second
demarcating layer of snow fence will be placed at 3 feet bgs to provide an advance visual
warning and limit future penetration of the engineered barrier. The finished grade of the
15
engineered barrier will match existing grade, therefore there will be no change in the
elevation of the park, and there will be no net loss in pervious surface due to the barrier.
The park will be landscaped and restored to its current use, and an AUL will be
implemented for inspection and maintenance of the engineered barrier as required by the
MCP.
7.80
RESTORATION
Following the completion of remedial activities, conditions will be restored at each of the
properties as shown on Drawings R-2, R-5 and R-6 and as described below.
7.80.1
Solomon Jacobs Park
Following the completion of remedial activities, the park will be re-graded as
shown on Drawing R-6, resulting in an approximately 1/2-foot increase in grade toward
the parking area and no change in grade along the harborfront. New landscaping, benches,
and planters will be installed, and existing monuments (e.g., the Harbor Walk granite
monument and the Captain Solomon Jacobs plaque) that were temporarily removed to
facilitate remedial activities will be replaced. The final design of the park has been
approved by the City of Gloucester.
In the Nearshore Area adjacent to the park, the new City of Gloucester-owned
floating dock system will include three shallow-draft concrete floats, three deep-draft
concrete floats, and four adjoining finger floats (Drawing R-2). The floating docks have
been designed to surround Harbor Rock on three sides, reducing the navigational hazard
posed by this natural feature. A new aluminum gangway will provide public access from
Solomon Jacobs Park to the floating dock system. The gangway will be mounted to the
top edge of the new park seawall, and will be compliant with the provisions of the
Americans with Disabilities Act.
7.80.2
National Grid Property
The strip of land to the south of the National Grid building, adjacent to Solomon
Jacobs Park, is currently paved. Much of this area will be excavated during remediation
either as part of the SOE for the new seawalls, to install utilities for the City floating dock
system, and/or to construct a Utility Corridor along the National Grid driveway for future
subsurface work (Drawing C-16). Following the excavation and off-Site removal of soil
from the Utility Corridor trench, orange filter fabric will be placed along the extent of the
trench to serve as a demarcation layer, the sewer force main for the marine sewerage pump
out and spare conduits for future utilities will be installed, and the trench will be backfilled
with compacted sand fill (Drawing C-20). Upon completion, the grade at the seaward edge
of this area will be raised to match the grade within the park, and the surface will be
finished with either bituminous pavement or concrete to match surrounding areas.
As stated earlier, the control panels and storage units for the DNAPL recovery
system will be housed within the building on the National Grid property. This will require
some alterations to the building, such as construction of internal walls or installation of
additional doorways, which will be performed by National Grid during the remediation
project. The building will continue to be occupied by the Gloucester Harbormaster
following the completion of Phase IV activities.
16
The vertical barrier in front of the National Grid Existing Building Seawall will
result in the creation of a publicly accessible concrete walkway along the waterfront, with
signage as required by MassDEP Waterways department. A second gangway will provide
access for the Gloucester Harbormaster from this walkway to the City floating dock
system. A telescoping davit (winch) will be installed near the National Grid access ramp
seawall for operation by the Harbormaster to facilitate moving materials to and from boats.
In addition, a marine sewage pump-out station will be installed at the property for use by
the Harbormaster’s office to service vessels.
7.80.3
Maritime Gloucester
The portions of the Main Pier and hauling piers at Maritime Gloucester that were
removed to accommodate dredging efforts will be reconstructed in kind, and the floating
docks and gangways will be replaced. The area in front of the Maritime Gloucester boat
house, as well as any temporary staging and material storage areas at this property, will be
restored to existing conditions. As described in Section 7.10.4., a timber walkway will be
constructed to provide waterfront pedestrian access between the new land and the existing
land at this property.
7.80.4
USCG Property
The interim docking structure at Pier 2 will be removed, and the USCG floating
docks will be re-located to their existing locations. The dredging operations and MAM
installation will not result in adverse impact to in-water operations at this facility. No
significant remedial response actions are planned in the upland area, but conditions at the
temporary staging and material storage area will be restored to existing conditions.
7.80.5
Marine Area
With the exception of an approximately 10-foot zone along certain seawalls (i.e.,
the USCG stability wedge, the vertical barrier at National Grid and Maritime Gloucester,
and the Maritime Gloucester Boat House Seawall Stability Enhancement), postremediation mudline elevations within most of the Nearshore Area will be at or below
existing conditions. The porewater cap at the USCG, City of Gloucester and National Grid
properties will be subject to post-remediation inspection and maintenance requirements as
described in Section 13.00, but will not adversely impact in-water operations at any of the
properties.
The post-remediation mudline in the approximately 5 acres that comprise the
Offshore Area, including the Federal navigation channel and anchorage areas, will be at or
below existing grades, and will not be subject to restrictions on future dredging.
10.00 INTERACTION OF REMEDIAL ACTION WITH SITE FEATURES, AND
IMPACT ON ENVIRONMENTAL RECEPTORS (310 CMR 40.0874(3)(B)(9) AND
(10))
10.10 RELATIONSHIP TO EXISTING ACTIVITIES OR OPERATIONS
As described in Section 2.00, the Phase IV Remedy will be implemented across properties
with different ownership and uses, including the USCG Gloucester station; the City of
17
Gloucester Solomon Jacobs Park and Public Landing; a commercial property owned by
National Grid and occupied by the Gloucester Harbormaster; and the Maritime Gloucester
marine educational facility. National Grid has worked with each of the property owners to
sequence work such that impact to their operations is limited to the extent possible, and to
provide interim facilities for those operations that must continue during remediation.
Work at each of the properties will be conducted in accordance with the terms of access
agreements between National Grid and the property owners as described in Specification
Section 01 14 00 – Work Restrictions and Sequence. The access agreements include
property-specific restrictions on the periods during which the project contractor may
conduct work in the upland and/or marine area(s) of each property. A graphical
representation of these restrictions is provided on Drawings G-5 and G-6.
10.10.1 USCG Property
Remediation activities in the upland portions of the USCG property will be limited
to installation of DNAPL piping and well vault at GZ-4C and staging of some clean
materials. However, extensive remediation is planned in the Nearshore Area at and
adjacent to this property. This work will be coordinated with the temporary re-location of
the USCG vessels to an alternate docking system at Pier 2, as described in Section 7.10.
This will allow USCG operations to continue throughout the remediation efforts at the
Site.
10.10.2 Solomon Jacobs Park
In accordance with the terms of the agreement between the City of Gloucester and
National Grid, work at Solomon Jacobs Park will not be initiated until after Labor Day,
when there are fewer visitors and less use of the park and public landing compared to the
summer months. The park will be closed to the public between Labor Day and Memorial
Day during each work season. These short-term restrictions are necessary for public
safety. However, on a long-term basis, the project will enhance public use of, and
waterfront access at, Solomon Jacobs Park by restoring infrastructure that is currently in
need of rehabilitation.
10.10.3 National Grid Property
The National Grid building at 19 Harbor Loop will serve as a project office for the
contractors and National Grid’s construction oversight team during the remediation.
Office space will also be provided to the City of Gloucester Harbormaster, whose in-water
operations will be relocated to an alternate location within the harbor during each work
season in accordance with an agreement between National Grid and the City of Gloucester.
Following completion of the project, the Harbormaster will have continued use of the
building and direct access to the City floating dock system, as described in Section 7.80.
In addition, the public will be afforded increased waterfront access along the new land
constructed behind the vertical barrier.
10.10.4 Maritime Gloucester
Under the terms of the access agreement with Maritime Gloucester, a portion of
their property near the boat house will be cordoned off for public safety at the beginning of
18
each season of remediation. During the first remediation work season, when the vertical
barrier construction will restrict access to the area south of the Main Pier, National Grid
will construct an interim landing at the Northern Hauling Pier to allow a gig rowers’ club
access to the waterfront.
During the second remediation work season, the piers at the property will be
removed and replaced, and areas along the seawall and driveway will be used for staging
materials and providing access to land-based equipment. Dredging to remove MGPrelated sediment will be coordinated with dredging to remove sediments impacted by
Maritime Gloucester (RTN 3-3341), which will be documented under separate submittals
to MassDEP.
10.10.5 KRLLC
The extent of remediation at KRLLC is anticipated to be limited to approximately
six cy of dredging along the in-water property line with Maritime Gloucester. This work
will be conducted in accordance with the terms of the access agreement between the
property owner and National Grid.
10.20 RELATIONSHIP TO DRAINAGE FEATURES AND NATURAL RESOURCE
AREAS, AND IMPACTS TO ENVIRONMENTAL RECEPTORS
As required by the MCP, this section provides a discussion of the measures that have been
incorporated into the design, construction and operation of the selected CRA to avoid
deleterious impact on drainage features, environmental receptors and natural resource areas
(including surface water or wetland), or where it is infeasible to avoid such impact, a
discussion of measures to limit or mitigate impacts.
10.20.1 Identification of Natural Resource Areas
In support of a Notice of Intent filing with the Gloucester Conservation
Commission for implementation of the Phase IV Remedy, the following coastal resource
areas were identified within the project boundaries, and were assessed to characterize
existing conditions and potential impacts associated with the proposed remediation
activities. Both temporary and permanent alterations to these resource areas are
anticipated with the implementation of the proposed remedial activities and associated
mitigation. Modification of the resource areas has been limited to the extent practical,
while still allowing the project remediation goals to be accomplished. As demonstrated
below, the remediation has been designed to be protective of the resource areas such that
there should be no adverse impacts to these areas following the completion of the
remediation work.
Designated Port Area (DPA)
The Project Area is located within a developed harbor that is a DPA, described in
Section 301 CMR 25.00 of the Coastal Zone Management (CZM) Regulations for
Massachusetts (Massachusetts 1994). DPAs are a coastal resource area under the
Massachusetts Wetlands Protection Act (WPA; M.G.L Chapter 131, Section 40)). The
WPA is administered on the local level by the Conservation Commission, which
implements the Massachusetts Wetlands Regulations (310 CMR 10.00).
19
The Phase IV Remedy is expected to both temporarily and permanently alter
coastal resource areas located within the DPA; however, the functions of the DPA will not
be significantly impacted by the project. Temporary impacts will include short-term
interference with navigation when remediation work is being performed in the navigational
and anchorage areas. Long-term impacts will benefit the DPA based on a net deepening of
some navigational and anchorage areas. The project has received regulatory approval from
the Conservation Commission (Section 14.20) and from the Massachusetts Office of CZM,
which is tasked with reviewing Federal actions2 affecting coastal uses and/or resources to
ensure that such actions are consistent with the state’s enforceable program policies.
Land Under the Ocean, Land Containing Shellfish and Coastal Beach
Overall, the project will provide a net benefit to these coastal resource areas
because MGP-related impacts, including sediment in the harbor and source material behind
the seawalls, will be removed or contained. However, dredging to remove the sediment,
and excavation/seawall construction associated with source removal and control, will have
the following impacts.
Dredging, backfilling and porewater cap placement will result in both permanent
and temporary impacts to these resource areas because sediment will be removed, new
clean material will be placed in some of the dredged areas, and the harbor bottom elevation
and water depth will be changed in portions of the resource areas. The change in harbor
bottom elevation and water depth is not expected to significantly adversely impact the
resource areas. Backfilling to reestablish benthic habitat, manage residuals, and provide
structural stability is not anticipated to have significant impacts to the resource areas as the
clean material is generally similar to existing material in portions of the Land Under the
Ocean, Land Containing Shellfish, and Coastal Beach. Porewater cap placement will
result in an alteration to Coastal Resource Areas in the Nearshore Area because the cap
materials are expected to be larger or of a different material type (e.g marine armor
mattresses) than existing materials in portions of the Land Under the Ocean and Land
Containing Shellfish. Benthic recolonization is expected to occur following dredging
activities whether dredged areas are backfilled/restored or not, and the quality of benthic
habitat will be improved as described in Section 10.20.5.
Seawall Removal and Reconstruction will result in a permanent increase of Land
Under the Ocean because a portion of the previously built land and enclosing seawall
(National Grid Pier Seawall) will be removed and will not be replaced. The total area of
the Land Under the Ocean will be increased in this area by approximately 1,150 square
feet. At the same time, construction of the vertical barrier for source control will result in
an approximately 450 square-foot reduction in the area of Coastal Beach seaward of the
National Grid and Maritime Gloucester properties. Mitigation for this alteration is
discussed later in this section.
2
CZM review was triggered by the submittal of permit applications to the USACE, and included review of the project in
terms of the State’s Coastal Hazards and Habitat policies as well as applications filed with MassDEP Wetlands and
MassDEP Waterways programs. CZM issued a letter on April 6, 2015 concluding that the activity (i.e. remediation) as
proposed is consistent with their enforceable policies.
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Coastal Bank, Land Subject to Coastal Storm Flowage, and Buffer Zones
Seawall Removal and Reconstruction: The reconstruction of the seawalls at
Solomon Jacobs Park and National Grid will permanently impact Coastal Bank, Land
Subject to Coastal Storm Flowage, and Buffer Zones. Some Coastal Banks such as the
seawall associated with Solomon Jacobs Park and National Grid will be removed and
relocated, with a loss of approximately 50 linear feet of Coastal Bank due to the removal of
land in front of Solomon Jacobs Park and the Existing National Grid Seawall. The
location of the Coastal Bank (i.e. seawall) at a portion of the National Grid and Maritime
Gloucester properties will move approximately 10 feet seaward as a result of vertical
barrier construction.
Soil Excavation and Construction of Engineered Barrier: Work associated with soil
excavation and placement of the engineered barrier will take place entirely within the Land
Subject to Coastal Storm Flowage and the 100-foot and 200-foot Buffer Zones to Coastal
Bank, Coastal Beach, and Land Under the Ocean (relevant under Bylaw). There will be no
permanent changes to the characteristics of the land surface related to the soil removal
work because the area will be returned to pre-remediation grades and there will be no
increase in impervious surface in this area. Due to the removal of previously built land,
there will be a reduction in total impervious Buffer Zone.
10.20.2 Best Management Practices to Limit Impacts
The Phase IV Remedy will be conducted in accordance with the terms of WQC
X255073 issued by the MassDEP Wetlands Program, and two Orders of Conditions (OOC
#28-2369 for the remediation project, and OOC #28-2371 for the City floating dock
system) issued by the Gloucester Conservation Commission, each of which includes
conditions designed to limit the impacts of the project on the natural resource areas and
environmental receptors of Gloucester Inner Harbor. In addition, as described earlier in
this Phase IV RIP, a number of Best Management Practices (BMPs) will be employed
during the work, including the use of erosion and sedimentation controls in the vicinity of
catch basins and drainage areas (Section 8.40) and marine resuspension controls around inwater silt-generating activities (Section 7.10.6).
10.20.3 In-Kind Mitigation - Creation of Compensatory Tidal Area
As a result of the vertical barrier construction, 450 square feet of Coastal Beach and
Land Subject to Tidal Action in front of the National Grid and Maritime Gloucester
properties will be converted to upland in order to control MGP-impacted source material.
The Coastal Beach/Land Subject to Tidal Action in this area consists largely of fill
material emplaced during seawall construction, with cobbles and boulders and some
miscellaneous debris material exposed along the base of the wall at low tide. Because the
Project Area is located within a DPA, these Coastal Beaches and Land Subject to Tidal
Action, are categorically “not likely to be significant to marine fisheries, storm damage
prevention, or flood control” (310 CMR Section 10.206). Nevertheless, the project design
includes the compensatory creation of approximately 750 square feet of Coastal
Beach/Land Subject to Tidal Action on top of the Stability Wedge in front of the USCG
Seawall. This voluntary in-kind mitigation element results in a net gain of approximately
300 square feet of this resource within the Project Area. The surface, which is designed to
provide both scour protection and habitat, will consist of approximately 18 inches of
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materials similar to the Coastal Beach material currently present in front of the National
Grid seawall, with a surface elevation above MLW (-3.79 feet NGVD 29).
10.20.4 In-Kind Mitigation - Increase In Subtidal Habitat Area to Benefit
Protected Fishery Resources and the Environment
In addition to the compensatory in-kind mitigation described above, the project will
result in the removal of 1,150 square feet of land behind the National Grid Pier Seawall
that will not be replaced. Combined with the 750 square feet of Land Under the Ocean that
will be converted to Coastal Beach at USCG property, this will result in a net increase of
400 square feet of Land Under the Ocean. The creation of this new Land Under the Ocean,
in conjunction with the remedial actions to be undertaken at the Project Area, will benefit
two important local species, American lobster (Homarus americanus) and winter flounder
(Pseudopleuronectes americanus). Gloucester Harbor waters continue to support a
productive lobster population, and winter flounder is a key recreational and commercial
fish for the area.
10.20.5 Mitigation - Habitat Enhancement in Existing Areas
Another aspect of the proposed mitigation involves enhancing existing habitat to
improve conditions for biota of the area. Following implementation of the Phase IV
Remedy, a condition of NSR to the environment will be achieved, representing a
significant enhancement of habitat conditions within the harbor.
Additional habitat enhancement for benthic invertebrate and fisheries species will
be provided by elements of the project that will be implemented prior to, during, and
following the proposed remedial dredging within the harbor. A key example is the
removal of intertidal and subtidal debris from within the dredge prism area, which will
benefit benthic invertebrate production. Debris such as bricks, rip-rap, grout, cables,
chains, line, and broken piles has been observed within the Project Area and will be
removed as part of the dredging remediation activities.
In addition, habitat features for fishery species are factored into the design and will
benefit American lobster and winter flounder, as well as other fisheries species. The
increased cobble, gravel, pebble, mud, sand, and flat rock substrates to be placed after
completing remediation are appropriate habitat enhancement features for lobster. A gravel
or cobble habitat will be created in the newly created Land Subject to Tidal Action, and
material that may range from gravel to larger cobble sizes will be placed in areas in front
of the USCG, Solomon Jacobs Park, and National Grid properties where an erosion
protection layer is necessary to mitigate the effects of propeller scour. Flat rock substrates,
consisting of re-used granite block materials from the existing walls to the extent
practicable, will be present along the toe of the newly constructed/rehabilitated seawalls.
For winter flounder, habitat features that will be created or enhanced in the project vicinity
include sand and mud substrates. The removal of impacted sediments and the placement
of the 6-inch layer of backfill in the Nearshore Area, including in the newly created Land
Under the Ocean, will result in habitat enhancement for winter flounder spawning grounds
and will benefit other fishery and benthic species within the Project Area.
In conclusion, the removal of impacted sediments from the Inner Harbor, removal
of debris from the substrate, the post-dredging increase in total area of Waters of the U.S.
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and Land Under Ocean, and the use of habitat enhancing backfill will result in an overall
net benefit to the American lobster, winter flounder and general fisheries resources in the
Gloucester Inner Harbor.
10.30 RELATIONSHIP TO LOCAL PLANNING AND DEVELOPMENT ISSUES
10.30.1 Short-Term Impacts to Local Infrastructure
The primary short-term impact to local infrastructure is associated with the
transport of equipment and materials to and from the Site. As described earlier, the
shipment of remediation waste via barge instead of by land will greatly reduce anticipated
impacts to local roadways during the project. Land-based transport of materials and
equipment cannot be entirely eliminated, but as shown on Drawing C-1, truck traffic
associated with the project will avoid the downtown areas and will be routed along Rogers
Street and East Main Street (Route 127), connecting to Route 128. It is not anticipated that
street closures will be necessary to implement the proposed work, however, as necessary,
traffic details will be utilized.
The project will also have short-term impacts on waterways within Gloucester
Inner Harbor associated with dredging activities and the concurrent barge or scow
transportation of dredged sediments. As part of the Chapter 91 permitting process, a Sitespecific Marine Boating Coordination Plan was requested and approved by MassDEP
Waterways Program, and notifications to local waterways users and Site abutters will be
made in accordance with the plan. There will be a decrease in the ability of watercraft to
access certain portions of the Site during work on and adjacent to seawalls and during
dredging; however, accommodations will be made for safe alternate watercraft passage.
Note that the changes in remediation waste shipment discussed above will also reduce
potential inner harbor traffic congestion, because far fewer transport trips are required with
the much larger scows.
10.30.1 Long-Term Impacts to Local Infrastructure
The long-term impacts to local infrastructure are anticipated to be overwhelmingly
positive. Currently, the wooden pier and concrete landing in front of Solomon Jacobs Park
are in poor condition, and portions are closed to the public. The granite block seawalls in
this area date back to the late 19th century, and do not meet current design standards. The
new seawalls designed as part of source removal and control efforts will meet current
engineering standards and accommodate projected sea level rises over the coming years.
The walls will visually match the existing granite walls along the harborfront to retain the
historical appearance of the harbor. The stability of other seawalls, such as the USCG
seawall and the Maritime Gloucester Boat House Seawall, will also be enhanced as a result
of the project.
Following remediation, Solomon Jacobs Park and the adjacent parking area will be
restored to provide waterfront views and access for local residents and visitors. The new
land at the National Grid and Maritime Gloucester properties will provide additional public
access to the waterfront in this area. The project is also being coordinated with, and
materially contributes to, the City of Gloucester efforts to install a new floating dock
system to provide upgraded landing facilities and facilities for Harbormaster use.
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Within the harbor, commercial and private boaters will benefit from increased
water depth within the navigation channel following the completion of the project.
10.40 SOIL CHARACTERISTICS AND GROUNDWATER CHARACTERISTICS
The remediation efforts will result in removal of MGP-impacted soil from Solomon Jacobs
Park and the National Grid property, and its replacement with clean fill within an
engineered barrier in the central portion of the park, and as part of a geosynthetic wrapped
face wall behind the granite block seawalls. The replacement fill material will be more
suitable than the granular fill material it replaces. For example, some of the existing fill,
particularly proximate to the seawalls, is open-worked, which can result in collapse of
surface pavements. In addition, the replacement fill is anticipated to be more permeable
than the silty clay material encountered in some areas to be excavated. Thus the
replacement fill will promote drainage via infiltration, rather than surface runoff, of
precipitation.
Removal of the MGP-impacted soil is also anticipated to result in lower dissolved
hydrocarbon concentrations in the groundwater beneath the park. Decreasing dissolved
phase hydrocarbons in groundwater will result in lower concentrations discharging to the
harbor. The organoclay layer placed behind the new granite block seawalls will adsorb
residual hydrocarbons, further reducing dissolved concentrations potentially discharging
through the seawalls. Groundwater quality beneath the National Grid building will not be
directly improved by the remediation activities. However, the fill material placed behind
the new vertical barrier will be significantly more permeable than existing fill, and in
combination with the impermeable wall, will channel groundwater flow from impacted
soils beneath the building toward the organoclay barrier behind the new granite block
walls, thus also further reducing impacts to the harbor.
12.20 DESIGN AND CONSTRUCTION SCHEDULE
Design efforts and specification preparation for the project have been completed, the
specifications were put out to bid, bids were received and analyzed, and a contractor was
selected with Notice to Proceed awarded to Charter Contracting Company, LLC (Charter)
of Boston, Massachusetts in June 2015. Construction is planned to occur over two to three
construction seasons starting in September 2015. The following restrictions apply to this
project:

Silt-producing in-water work will be subject to TOY restrictions established by
the DMF, which restricts activities between February 15 and June 30 to avoid
effects on Winter Flounder (Pseudopleuronectus americanus) spawning
activities.

In accordance with the terms of agreements between National Grid and the
property owners, there will be restrictions on remediation activities between
Memorial Day and Labor Day to reduce impacts on public access to Solomon
Jacobs Park, the public landing, and the Maritime Gloucester facility during the
summer.
The primary silt-producing activities during this project will include the dredging of
sediments, backfilling, porewater cap installation, removal of the existing seawalls,
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excavation of associated coal tar-impacted soils/sediment, and installation of piles to
support the replacement of waterfront structures after remediation. To comply with TOY
restrictions, the project schedule calls for dredging and backfilling to be completed prior to
February 15 of each year. Similarly, it is anticipated that removal of the existing seawalls
and the excavation of soils/sediment will also be completed prior to February 15 of each
work season. Every effort will be made to coordinate and expedite activities such that inwater piles can be installed prior to February 15; however, a variance from TOY
restrictions may be requested to allow for the completion of pile installation in some
localized sections of the Project Area. BMPs and environmental controls will be used
throughout the remediation work to limit adverse impacts to environmental receptors.
Subsequent wall re-building activities (including construction of the granite block walls,
organoclay installation, and construction of the geosynthetic wrapped face walls) are not
silt producing; therefore, these activities will continue past February 15, but will be
completed in accordance with property-specific timing restrictions.
The following general remediation sequence is anticipated:
Season 1 (Year 1, September 2015 – May 2016):

Installation of interim docking facility/gig rower access at the USCG and
Maritime Gloucester properties

Source removal/control and seawall rehabilitation at the Solomon Jacobs
Park, National Grid and Maritime Gloucester seawalls

Nearshore remedial activites in portions of the USCG, City of Gloucester,
and National Grid properties

Upland remedial activities (e.g., engineered barrier construction, and
DNAPL recovery system installation) activities at the City of Gloucester
and National Grid properties

Remedial activities in the offshore portion of the marine area
Season 2 (Year 2, currently anticipated to be July 2016 to May 2017):

Completion of remedial activities in the offshore portion of the marine area

Removal and rebuilding of the Maritime Gloucester in-water structures (to
the extent required)

Completion of nearshore remedial activities at the Maritime Gloucester,
National Grid, City of Gloucester, and USCG properties

Completion of upland remedial activities

Re-installation of waterfront structures, and restoration of upland areas to
pre-construction conditions.
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Note that, although the schedule calls for project completion in two work seasons, work
may extend into a third season in areas of the Site due to the logistical complexities and
TOY restrictions applicable to the Site.
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