Manchester Demolition, Landfill Closure and Intertidal Remediation

The Manchester Annex Superfund Site is located on Clam Bay approximately one mile north of Manchester, Washington. The current site owners are the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA), both of which operate laboratory facilities on the site. The first phase of work included: demolition and disposal of the concrete simulator structures; perimeter dust monitoring and dust control measures; demolition and removal of underground concrete vaults and piping; pressure washing and decommissioning of additional concrete vaults; capping of abandoned underground utilities; sampling and analysis of contaminated soils, water and demolition debris; collection and disposal of contaminated waste water; excavation and disposal of dioxin contaminated soils; and construction of a paved parking lot over the site.

The second phase of work began in 1999, and consisted of placing a sediment cap over 5 acres of contaminated intertidal areas, shoring, dewatering, and excavating approximately 1,200 linear feet of shoreline, reconstructing the shoreline, installing a hydraulic cut off wall and perimeter drainage system around the upland landfill, rerouting underground utilities, and constructing over 4 miles of paved roadways. During construction, comprehensive air monitoring and water quality monitoring programs were successfully implemented.

Project Performance

The first phase of work was completed in late 1998. The USACE gave an Outstanding Contractor Performance rating, and NOAA also sent a letter of appreciation for its work on the site. Tthe second phase of work was completed in February 2001.