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
The incorporation of the Shared-Use Path will be consistent with the USDOT Policy Statement on
Bicycle and Pedestrian Accommodation Regulations and Recommendations (March 15, 2010) and
MassDOT‘s GreenDOT initiatives policy.
Benefits to the Public Trust Rights in Tidelands or Other Associated Rights
The project design includes three sets of piers for each bridge structure, totaling six piers in the
Merrimack River for the northbound and southbound structures. There would be four spans or
openings beneath both bridges, with the existing navigable federal and steamboat channels
maintained for marine traffic. The bridge piers for both structures will be constructed in the same
east-west alignment. The distance between the existing piers within the federal channel is
approximately 280 feet, while distance between the proposed piers will provide a wider 360-foot
opening beneath the bridge. Similarly for the steamboat channel, the opening will increase from
approximately 200 feet between the piers to a width of 360 feet.
1.4.13 Stormwater Management
Minor revisions have been incorporated into the proposed stormwater management system as a
result of the coordination with MassDEP and in response to the various comments received during
the wetlands permitting process. Additional documentation has been provided to the conservation
commissions to demonstrate how the new development components of the project comply with the
stormwater performance standards. Supporting information has also been provided to demonstrate
how the redevelopment components of the project comply to the maximum extent practicable and
improve existing conditions.
MassDOT has also submitted additional documentation which demonstrates how the project
qualifies for Low Impact Development (LID) disconnection credits for a small portion of the project in
Salisbury.
Additional recharge and detention provisions have been incorporated into the design for the portion
of the project that is tributary to land in Amesbury referred to as the Golden Triangle.
The bottom elevation of proposed recharge basins have been raised to provide the required
separation distances between estimated seasonal high groundwater and the bottom of the basins.
Check dams have been incorporated into the design of the water quality swales to induce additional
recharge.
Finally, MassDOT has prepared and submitted to the conservation commissions a project-specific
Operation and Maintenance Plan (O&M) and Long Term Pollution Prevention Plan (LTPPP). A copy
of the document is included in Appendix A.
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