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
1.3 CHANGES TO THE PROJECT SINCE THE EA/DEIR
There have been several project design refinements since the Environmental Assessment/Draft
Environmental Impact Report was published in November 2011, mostly resulting from project design
progression and in response to changes requested by permitting agencies.
The only substantive change to the Whittier Bridge/I-95 Improvement Project (project) since the filing
of the EA/DEIR is the elimination of the permanent impact to the isolated wetland, Wetland 1,
located adjacent to the I-95 northbound Exit 60 off-ramp in Salisbury at the northern project limits.
The wetland would have been affected by toe-of-slope fill for a proposed ramp realignment, a safety
improvement intended to provide a longer deceleration lane prior to the exit ramp. The Preferred
Alternative design included in the EA/DEIR resulted in 1,150 square feet of permanent impact to this
federal-jurisdictional wetland. A refinement of the design of the exit ramp has resulted in the
elimination of the impact to Wetland 1. Figure 1-1 illustrates the design refinement which has
eliminated the impact to Wetland 1.
As a result of the completion of further design analysis for the proposed improvements to the
stormwater management system, temporary wetland impacts to Wetland M for construction of
detention basin 7A have been increased from 150 to 240 square feet in Salisbury. The basin is
located to the west of I-95 immediately south of the I-495 northbound overpass. Temporary
alteration of Wetland M is assumed to be required for purposes of construction access and
installation of inlet and outlet pipes for the detention basin. The impact areas will be restored after
the completion of construction activities. Revised impacts to federal and state jurisdictional wetland
resources are listed in Table 1-2.
Table 1-2:
Revised Wetland Impacts
Impact Type
State Resource Wetland Impact
Permanent Temporary Total
BVW
I Retaining Wall 1,800 0 1,800
H Retaining Wall 1,760 1,400 3,160
Total BVW 3,560 1,400 4,960
New Bridge Piers 17,100 10,290 35,030
Land Under the Ocean/ Fish Merrimack
Removal of Old Bridge Piers 11,500 9,020 11,500
Run
River
Temporary Bridge Supports 0 9,210 9,210
Total LUO/Fish Run 5,600 28,520 55,740
Alteration of Undisturbed Riverfront
6,540 4,770 11,310
Riverfront Area
Land Subject to Coastal
Storm Flowage
Merrimack
River
Wetland I
Area
Alteration of Previously Developed
Riverfront Area
19,614 27,240 46,854
Alteration of Existing Degraded
Riverfront Area
39,385 0 39,385
Total Riverfront Area 65,539 32,010 97,549
Retaining Wall
1,230
(1,500 cf)*
0
1,230
(1,500 cf)
South Bank
Temporary Work Area and Bridge
Support
0 1,885 1,885
North Bank Temporary Work Area 0 912 912
Total LSCSF 1,230 2,797 4,027
Coastal Beach North Bank Temporary Bridge Support 0 190 190
Total Coastal Beach 0 190 190
Isolated Vegetated Wetland M Temporary Excavation 0 240 240
Total IVW 0 240 240
*Cubic feet of flood storage within Land Subject to Coastal Storm Flowage
1-3