Coastal, River, & Wetland Restoration
- New Bedford Harbor Salt
Marsh Restoration
New Bedford, Massachusetts
the challenge New Bedford Harbor supports a large saltmarsh complex ringed by dense urban and industrial development. In 1983 New Bedford Harbor and some adjacent upland areas were added to the Superfund National Priorities List, and a Record of Decision adopted in 1998 directed its cleanup by the U.S. Environmental Protection Agency, implemented by the US Army Corps of Engineers. In this cleanup, sediments were dredged or excavated from over 66 acres of tidal flats and marshland requiring the restoration of the intertidal habitat with a goal of 1:1 replacement of wetland functions and values. The Bioengineering Group was retained to develop methods for re-establishing stable soil, vegetation, and drainage patterns after removal of surface layers of contaminated marsh material.
the interdisciplinary approach The Bioengineering Group worked closely with the team responsible for design of removal actions in order to coordinate and streamline and link the processes of cleanup and restoration. We identified locations and measures that would allow restored resource areas to serve additional functions such as management of urban stormwater runoff, and establishment of a waterfront access trail. In a detailed restoration master plan, we evaluated specific opportunities to modify the restoration scenario in order to attain greater functions and values at a more reasonable cost when compared with a direct in-kind replication. This approach won rapid approval in a series of agency and public meetings.
Bioengineering Group staff conducted hydraulic and hydrologic modeling and developed a conceptual design for the restoration of salt marshes, mudflats, and tidal creeks utilizing a variety of bioengineering techniques, and prepared a phased implementation scheme to match the multi-year cleanup schedule. Our staff then completed construction plans and SPECSINTACT specifications, developed an MCACES cost estimate, and provided construction support for restoration of salt marsh in the uppermost area of the harbor north of the Wood Street Bridge , the first phase completed.
the results The Bioengineering Group developed a comprehensive strategy for restoring the inter-tidal areas of the upper harbor based on future use, potential for natural recovery, and risk of erosion and other ecological problems. The design relied on bioengineering techniques to re-create and stabilize the interfaces between mudflats and low marsh. Native species were planted in the low and high marsh zones and in the surrounding upland fringe. Establishment of salt marsh vegetation has been rapid, helping to stabilize the area and initiate restoration of healthy ecological functions, meeting with solid public acceptance and cost-effective implementation performance.