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

Whittier Bridge/I-95 Improvement Project FEIR
Chapter 2.0: Response to Comments on the Environmental Assessment/Draft Environmental Impact Report
Response: The City of Newburyport‘s existing drinking water lines would be impacted by the project
and require relocation. The road will follow the route of the relocated water supply lines from the
water treatment plant at Bartlett Spring Pond and will be used solely by the water department for
maintenance and inspection of the relocated water lines. No public vehicles will be allowed to use
the roadway and very minimal water department traffic is anticipated, on the order of several trips
per month on average.
The provisions of the Drinking Water Regulations at 310 CMR 22.20C(2)(l) prohibit within the Zone A
of Bartlett Springs Pond ―land uses that result in the rendering impervious of more than 15%, or
more than 20% with artificial recharge, or 2500 square feet of any lot, whichever is greater.‖ The
proposed access road will be comprised of either crushed stone or open course gravel and is not
considered to be an impervious surface, thus meeting the standard.
DEP-7: The Merrimack River reach that passes under the Whittier Bridge is designated by FEMA as a Floodway.
Floodways are designated on reaches subject to inland flood processes, not coastal flooding. Any work in FEMA's
Floodway and MassDEP Bordering Land Subject to Flooding (BLSF) must result in no increase in vertical or
horizontal extent of flooding up to and including the 100-year flood pursuant to 44 CFR Section 60.3(d)(3) and 310
CMR 10.57. Discussions between MassDEP and MassDOT indicate that there will be a reduction in the crosssectional
area of the bridge abutments within the floodway which will result in compliance with the standards for
BLSF and FEMA requirements. It is MassDEP's understanding that compliance with the FEMA requirements will be
reviewed by Federal agencies. MassDEP recommends that MassDOT use the FEIR to clarify that the project related
activities will be able meet this performance standard and FEMA regulatory requirements.
Response: The Newburyport and Amesbury Conservation Commissions reviewed and approved
Abbreviated Notices of Resource Area Delineations and issued ORADs with the floodplain in the
vicinity of the bridge classified as Land Subject to Coastal Storm. MassDEP has confirmed that the
ORADs are valid. Thus, there are no impacts to BLSF along the Merrimack River.
Project-related demolition of the four piers associated with the existing Whittier Bridge and
construction of the six piers associated with the new bridge could potentially impact the Merrimack
River‘s existing local National Flood Insurance Program Base (100-year) Flood Elevation profile and
Regulatory Floodway delineation.
To address this concern, a tidal hydrodynamic model of the Lower Merrimack River, developed as a
means of providing preliminary bridge foundation design parameters, has been used to complete a
detailed hydraulic/scour safety analysis for the selected bridge alternative. This evaluation includes
assessments of the proposed bridge‘s overall riverine and tidal flood conveyance capacity, potential
impacts of project implementation on mapped National Flood insurance Program (NFIP) assets,
100- and 500-year flood scour potential along the proposed abutment and pier foundations, and the
temporary hydrodynamic impacts of bridge construction activities. A summary report of this final
bridge hydraulic analysis is included in Appendix B. A brief summary of the findings of the analysis
are included in section 1.4.6. This report includes a clear and concise assessment of the degree to
which the project when implemented will meet applicable NFIP Base (100-year) floodplain
development performance standards.
DEP-8: MassDEP recommends that the FEIR clarify the impacts, beneficial and adverse, to wildlife habitats under
NHESP and MassDEP jurisdiction and confirm that mitigation is not recommended.
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