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

Whittier Bridge/I-95 Improvement Project FEIR
Chapter 3.0: Mitigation and Commitments
in river cross section during construction. In-water construction sequencing combined with the use of
temporary cofferdams to facilitate construction of new piers or the removal of existing piers will
further minimize disturbance. Use of a qualified observer during cofferdam construction will further
ensure that there would be no adverse effects to shortnose sturgeon.
3.9 WILDLIFE
No impacts to threatened and endangered species are anticipated, except for minor, temporary
noise impacts related to constructing the bridge. Existing nesting pairs of bald eagles are located
both to the east and west of the I-95 ROW. NHESP, in a letter in review of the NOI applications to
the conservation commission, stated ―…this project, as currently proposed, will not cause adverse
effects to the habitat of state-listed rare wildlife.‖
The project will widen the existing wildlife passage under the Whittier Bridge by relocating bridge
abutments farther back from the Merrimack River shoreline. MassDOT will investigate feasible
methods to enhance wildlife habitat along the Merrimack River corridor, including installation of
plantings with native species with food value for wildlife, and other feasible methods that will not
interfere with future maintenance of the new Merrimack River bridges.
3.10 JURISDICTIONAL WETLANDS
The project will result in 4,960 square feet (temporary and permanent) of direct impacts to
jurisdictional wetlands (Wetlands I and H) in Amesbury. To mitigate for impacts, the Bordering
Vegetated Wetland (BVW) replication concept in Amesbury will consist of expanding Wetland H by
excavating approximately 4,960 square feet of upland near its northern end within the ROW.
Temporary impacts (1,400 square feet) to Wetland H (Amesbury), as well as to Isolated Vegetated
Wetland M (Salisbury), will be mitigated at each wetland location by restoring to pre-construction
grades and stabilizing substrates with a seed mix of annual rye and native wetland species.
3.10.1 Site Selection
As noted in Section 1.4.5, Wetland H site 1 was selected as having the highest potential for success,
and the fewest adverse impacts to the surrounding habitats. Its setting is also best able to meet
criteria 1 through 5 in the MassDEP Inland Wetland Replication Guidelines summarized in Section
1.4.5.
This site occurs adjacent to the north end of the large wetland associated with Wetland. The wetland
to the south of the site is emergent, dominated with invasive species (common reed [Phragmites
australis] and purple loosestrife [Lythrum salicaria]), with soils indicating saturated or flooded
conditions. The drainage adjacent to the highway is forested, partially paved, and provides drainage
from a smaller wetland to the north and stormwater flows from I-95. The wetland creation area
consists of a steep, sandy slope with a mix of trees, saplings, and grasses, attesting to dry
conditions and relatively recent disturbance.
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