Lynn, MA

Charlestown Bus Facility Shoreline Stabilization and Yard Improvements

Scope/Solutions

The Charlestown Bus Facility along the Mystic River is the MBTA’s largest bus garage and critical to daily operations. The existing steel sheet pile seawall, which protects the facility from flooding and river erosion, was severely deteriorated. The MBTA undertook a project, partially funded by a Federal Transit Administration Resiliency Grant, to improve resilience to riverine and local flooding. SGH investigated the failing seawall, including the pavement and soil loss behind it, and designed new shoreline stabilization and drainage systems.

Working as the prime consultant, SGH led a team of subconsultants to design a sloped embankment for a more natural appearance along the river and later designed the path behind the embankment. We coordinated with many entities, including the MBTA, DCR, Army Corps of Engineers, city conservation commissions, Mass DEP and DOT, Eversource, Mystic River Watershed Assoc., and Coastal Zone Management. Highlights of our design include the following:

  • Evaluated existing soils and added soilcrete columns with geogrid platforms to reinforce the soils prone to settlement
  • Designed the stone embankment and coordinated with a bioengineering consultant to incorporate a softer solution above the high tide level
  • Coordinated the design with buried electrical distribution lines
  • Evaluated the existing pavement’s ability to support traffic loads
  • Worked with a civil team to analyze site drainage and design outlets with backflow gates to prevent flooding through the system during a surge
  • Collaborated with a coastal science consultant to understand predicted storm surge elevations and wave action
  • Applied an adaptive engineering approach to account for future sea level rise and accommodate additional flood protection as needs change
  • Provided construction phase services for the MBTA, including the following:
  • Inspected jet grouting and embankment construction
  • Evaluated change orders and issues pertaining to the discovery of hydrocarbons in the marine sediments during jet grouting

Project Summary

completion-date

2020

Completion Date
construction-value

32M

Construction Value
Solutions
Repair & Rehabilitation
Services
Structures | Advanced Analysis | Code Consulting
Markets
Infrastructure & Transportation
Client(s)
Massachusetts Bay Transportation Authority (MBTA)
Specialized Capabilities
Repair & Strengthening | Marine & Civil Works | Failure Analysis | Risk & Resilience Assessment

Key team members

Dominic  Kelly
Dominic Kelly
Senior Principal
Paul  Schuman
Paul Schuman
Senior Project Manager