Silver Line Gateway Service to Chelsea, East Boston & the Blue Line Single Environmental Impact Report (Single EIR) EEA # 15124

Submitted to: Executive Office of Energy and Environmental Affairs MEPA Unit March 31, 2014 Submitted by: Massachusetts Department of Transportation

TABLE OF CONTENTS

Silver Line Gateway Service to Chelsea, East Boston & the Blue Line Page i Single EIR March 31, 2014

TABLE OF CONTENTS

COVER

1 Introduction .................................................................................................................................. 1-1 2 Project Description ...................................................................................................................... 2-1

2.1 Introduction ...................................................................................................................... 2-1 2.2 Changes since EENF Filing / Proposed Conditions ........................................................ 2-1

2.2.1 Overview ............................................................................................................. 2-1 2.2.2 Busway / BRT Update ....................................................................................... 2-12 2.2.3 Commuter Rail Station Relocation Update ....................................................... 2-27 2.2.4 Shared-Use Path Update .................................................................................. 2-29 2.2.5 Washington Avenue Bridge Update .................................................................. 2-31

2.3 Additional Design Elements ........................................................................................... 2-38 2.4 Construction Phasing ..................................................................................................... 2-38

3 Wetlands ....................................................................................................................................... 3-1 3.1 401 Alternatives Analysis ................................................................................................. 3-4 3.2 Wetlands Evaluation ........................................................................................................ 3-6

3.2.1 Nexus to Navigable Waters (USACOE 404b Permit) ......................................... 3-6 3.2.2 Wetland Functions and Values ........................................................................... 3-7 3.2.3 Vegetated Wetlands Impacts .............................................................................. 3-7 3.2.4 Wetlands Function and Values Impacts ............................................................. 3-8

3.3 Wetland Replication and Management Plan .................................................................... 3-8 3.3.1 Wetland Replication ............................................................................................ 3-8 3.3.2 Wetland Mitigation ............................................................................................ 3-11

4 Stormwater Management ............................................................................................................ 4-1 4.1 Stormwater Summary ...................................................................................................... 4-1

4.1.1 Existing Conditions and Proposed Stormwater Management ............................ 4-2 4.1.2 Impacts During Construction ............................................................................... 4-4 4.2.2 Post-Construction Impacts .................................................................................. 4-6

4.3 Proposed Development ................................................................................................... 4-8 4.4 Regulatory Compliance .................................................................................................... 4-8 4.5 Stormwater BMPs .......................................................................................................... 4-12

4.5.1 Pre-treatment Stormwater BMPs ...................................................................... 4-12 4.5.2 Structural Stormwater BMPs ............................................................................. 4-12

4.6 Water Quality and Quantity Impacts .............................................................................. 4-12 4.7 Implementation of Low Impact Development (LID) Techniques .................................... 4-13

5 Potential Infrastructure Impacts ................................................................................................. 5-1 5.1 Groundwater Discharge ................................................................................................... 5-1 5.2 Gas/Oil Separators Installation ........................................................................................ 5-1 5.3 MWRA Water and Wastewater Impacts .......................................................................... 5-1 5.4 8(m) Permit Requirement ................................................................................................. 5-3

TABLE OF CONTENTS

Silver Line Gateway Service to Chelsea, East Boston & the Blue Line Page ii Single EIR March 31, 2014

5.5 Other Infrastructure Impacts ............................................................................................ 5-3 6 Greenhouse Gas Emissions ....................................................................................................... 6-1

6.1 De Minimis Exception....................................................................................................... 6-1 6.2 GHG Emissions Compared to the No-Build Condition .................................................... 6-2

6.2.1 Background ......................................................................................................... 6-2 6.2.2 Transit-Only and Overall Project-Related Emissions.......................................... 6-2

6.3 Other Measures to Reduce Emissions ............................................................................ 6-4 6.4 MEPA GHG Consultation Meeting ................................................................................... 6-4

7 Construction Period Impacts ...................................................................................................... 7-1 7.1 Construction Management Plan (CMP) ........................................................................... 7-1

7.1.1 Anticipated Construction Sequencing ................................................................. 7-2 7.1.2 Access, Staging and Site Preparation ................................................................ 7-2

7.2 Potential Construction Period Impacts ............................................................................. 7-3 7.3 Measures to Address Materials Management ................................................................. 7-3 7.4 Measures to Protect Wetland Resources ........................................................................ 7-4 7.5 Measures to Control Erosion ........................................................................................... 7-4 7.6 Solid Waste and Air Quality Control Regulations ............................................................ 7-6 7.7 Compliance with MCP and Recycling of Construction and Demolition Waste ................ 7-6

7.7.1 Environmental Pre-Characterization Assessment .............................................. 7-6 7.7.2 Management of Soil and Proposed Next Steps .................................................. 7-7

7.8 GreenDOT Policy ............................................................................................................. 7-8 8 Mitigation and Section 61 Findings ............................................................................................ 8-1

8.1 Cultural Resources........................................................................................................... 8-1 8.2 Proposed Mitigation Measures ........................................................................................ 8-2 8.3 Summary of Mitigation Measures .................................................................................... 8-3 8.4 Proposed Section 61 Finding ........................................................................................... 8-5

9 Response to Comments .............................................................................................................. 9-1 9.1 Certificate of the Secretary of Energy and Environmental Affairs on the Expanded

Environmental Notification Form (EEA) ........................................................................... 9-9 9.2 Boston Water and Sewer Commission (BWSC) ............................................................ 9-14 9.3 WalkBoston (WB) ........................................................................................................... 9-17 9.4 George Bacon (GB) ....................................................................................................... 9-20 9.5 Department of Environmental Protection (DEP) ............................................................ 9-28 9.6 Massachusetts Water Resources Authority (MWRA) .................................................... 9-38 9.7 Metropolitan Area Planning Council (MAPC) ................................................................. 9-45 9.8 A Better City (ABC) ........................................................................................................ 9-51 9.9 City of Chelsea Department of Planning and Development (CDPD) ............................. 9-53

10 Silver Line Gateway Single EIR Distrib