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

to limit turbidity impact from dewater to fishery and avoid discharge oflead or asbestos in the
dewater (see MassDEP comment-6, DEIR Chapter 8, page 8-19).
Stormwater
DEP's review includes MassDOT's Stormwater Report dated November 16, 2011 including
Appendix J and Pavement Disconnection addendum dated November 28, 2011. The DEIR
indicates MassDEP endorsed MassDOT's use ofStorlnwater Handbook/or Highways and
Bridges published by the then MassHighway in 2004, including use ofthe so-called "macroapproach".
MassDEP and MassDOT concur that the "macro approach" does not address new
wetlands and 401 regulations promulgated in 2008 regarding stormwater. For example, the 2008
regulations amended the redevelopment provisions, and now require stormwater recharge to be
addressed on sub-watershed basis when using "macro approach" and require elimination ofillicit
discharges to waters ofthe Commonwealth (ground and surface waters, including wetlands) ­
Accordingly, while the "macro approach" will be applied to this review, it is with the mutual
understanding that the "macro approach" was explicitly modified by MassDEP, including but not
limited to the redevelopment (310 CMR 10.05(6)(k)(7) and 314 CMR 9.06(6)(a)(7)) and
recharge (310 CMR 10.05(6)(k)(3) and 314 CMR 9.06(6)(a)(3)) provisions. Fmiher, MassDEP
has historically interpreted Stormwater Standard No.1 (310 CMR 10.05(6)(k)(1) and 314 CMR
9.06(6)(a)(l) as not allowing any new direct untreated stormwater discharges to wetlands and
waters, regardless ofthe applicability ofthe "macro-approach." MassDOT is in the process of
updating its Stormwater Handbook to address these and other stormwater compliance issues.
Existing conditions contain 49.2 acres ofimpervious road and bridge surface. Approximately
15.2 acres ofnew impervious road and bridge surface is proposed (64.4 acres impervious total);
a 27% increase in impervious area. Accordingly, 49.2 areas will be treated as redevelopment and
15.2 acres as new development pursuant to 310 CMR 10.05(6)(k)(7) and 314 CMR 9.06(6)(a)(7)
towards meeting the stormwater regulatory standards. Wetland regulation 310 CMR
10.05(6)(k)(7) and 401 regulation 314 CMR 9.06(6)(a)(7) were amended in 2008 to require
redevelopment projects to meet the following stormwater regulatory standards to the maximum
extent practicable: 2 (peak rate attenuation), 3 (recharge) and pretreatment and structural
stormwater best management practice requirements ofstandards 4 (water quality treatment), 5
(land uses with higher potential pollutant loads), and 6 (critical areas). Existing stonnwater
discharges are required to comply with stormwater regulatory standm'd 1 (no new untreated
discharges and no erosion to waters ofthe Commonwealth) to the maximum extent practicable.
Redevelopment projects are required to fully meet the following standards: 4 (long term
pollution prevention plan), 5 (source control/pollution prevention), 8 (erosion control plan and
implementation), 9 (operation and maintenance plan and implementation) and 10 (eliminate
illicit discharges).
Standard1-no new untreated discharges 01' erosion to waters/wetlands (310 CMR
1O.05(6)(k)(1) and 314 CMR 9.06(6)(a)(1): The DEIR indicated 50 separate outfalls plus an
unspecified number ofbridge scuppers are proposed to discharge stormwater runoff from
redevelopment and new development sections ofthe roadway and bridges1. The DEIR did not
1 MassDEP has concurred with MassDOT that it is infeasible for the Whittier Bridge to incorporate stormwater
treatment for the discharges from the bridges' scuppers into the Merrimack River. Therefore, references in this
document to stonnwater treatment do not include this stormwater source.
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