Final Environmental Impact Report - Whittier Bridge/I-95 ...

Whittier Bridge/I-95 Improvement Project FEIR
Chapter 1.0: Changes Since the Draft Environmental Impact Report and Resolution of Additional Issues
Sedimentation and erosion control plans will be developed and implemented by the contractor and
monitored by the MassDOT Resident Engineer and the environmental monitor. Compost filter tubes
will be installed at the bases of both the temporary fencing and chain link fence at the edge of the
work zone adjacent to wetland resource areas. The locations of the compost filter tubes are also
indicated on the NOI plans.
MassDOT anticipates the design/build contractor to utilize upland areas within the state highway
layout for staging or lay down areas. If the contractor chooses to create staging areas outside of the
state highway layout, the contractor must delineate all wetland resource areas adjacent to such
staging areas, and must isolate said wetland resource areas from staging areas with orange snow
fence, compost filter tubes and limit of work signage. The contract documents will include language
that there will not be any wetland impacts beyond those permitted within the applicable
environmental permits; such applies to the entire project area, including any staging areas the
contractor may choose.
1.4.4 Riverfront Area Mitgation and Restoration
The DEIR Certificate requested that MassDOT ―…identify how Riverfront Area (RFA) mitigation or
restoration will comply with the Wetlands Protection Act.‖ The EA/DEIR described the RFA impacts
in Newburyport and Amesbury adjacent to the Merrimack River resulting from the construction of the
new Merrimack River bridges.
In Newburyport and Amesbury, there will be alteration to undisturbed RFA, existing degraded RFA,
and previously developed RFA. Alterations to RFA include impacts due to construction of the I-95
northbound and southbound bridge abutments, grading, temporary construction access, the
construction of a utility access path in Newburyport, and new pavement. The project will result in an
overall improvement to the RFA by demolishing the existing abutments, building the new abutments
approximately 50 feet behind the existing abutments, removing existing riprap, and restoring the
approximate 80-foot slope with slope protection covered by soil, seed and plantings to create a
natural riverfront corridor which connects water supply land on either side of I-95.
Performance standards for RFA are included in the Wetlands Regulations at 310 CMR 10.58(4) and
(5). Compliance with the RFA performance standards in Newburyport and Amesbury is described
below.
In Newburyport, the total amount of 200-foot RFA on the project site (MassDOT State Highway
Layout and Newburyport Water Department parcels) is 356,000 square feet. Alterations to
undisturbed RFA due to grading, construction access, and a proposed gravel access path will be
4,770 square feet (temporary) and 1,060 square feet (permanent), and cumulatively are below 10
percent of the RFA on the lot (310 CMR 10.58(4)(d)(1)). Alteration to existing degraded RFA will be
22,925 square feet due to reconstruction of existing pavement, retaining walls, and bridge
abutments, and does not require mitigation (310 CMR 10.58(5)). Temporary alteration to previously
developed RFA (engineered side slopes; previously graded areas) due to grading and construction
access for the construction of new bridge abutments, wingwalls and pavement will be 15,590 square
feet and mitigated at a 1:1 ratio on-site and ―in kind.‖ Permanent alteration to previously developed
RFA due to construction of new bridge abutments, wingwalls and pavement totals 13,614 square
feet, and will require mitigation for those impacts that alter over 10 percent of the RFA on the site
(310 CMR 10.58(5)(e)).
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