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Naval Weapons Station (WPNSTA) Concord (also known as Naval Weapons Station Seal Beach Detachment, Concord) is a 12,800-acre area in north-central Contra Costa County, California. WPNSTA Concord is composed of two geographically separate units, the Inland (5,170 acres) and Tidal (7,630 acres) Areas, and a 1-acre radiography facility in Pittsburgh, California. Aside from typical administrative and support work activities, this facility is a major ammunition trans-shipment port of the West Coast for the Department of Defense (DoD), operated by the U.S. Army. Following immediate actions to protect human health and the environment, site investigations and long-term cleanup are ongoing.

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What Has Been Done to Clean Up the Site?

The site is being addressed through federal actions.

In November 2005, WPNSTA Concord was recommended for partial closure and realignment under the Base Realignment and Closure (BRAC) process. The final BRAC determination that was made resulted in about half of the facility (the Tidal Area) being transferred to the Department of the Army in 2008. The remaining area (the Inland Area) was closed, transferred and redeveloped.

Initial actions such as wetland restoration and excavation of contaminated soils are helping to protect nearby populations and the environment.

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What Is the Current Site Status?

The site is being addressed in two stages: immediate actions and a long-term remedial phase focused on cleanup of the entire site.

Initial Actions

Since 1983, WPNSTA Concord has excavated contaminated soils from the Litigation Area and disposed of them off site. In addition, WPNSTA Concord performed wetlands restoration activities. Replanting of the site finished in the fall of 1995.

Remedy Selected

The 2004 remedy for the Tidal Area Landfill (Site 1) consisted of a California Title 27 municipal solid waste multilayer prescriptive soil cap. Construction of the cap is underway, but has been delayed due to the discovery of munitions in the debris. Because of the munitions, a new landfill cap design is being employed.

Site Studies

The Litigation Area Sites Feasibility Study (FS) and Proposed Plan have been issued, proposing additional remedial actions necessary to address contaminated aquatic sediments and wetlands soils.

A supplemental remedial investigation for Inland Area Site 22 (Building 7SH5 and Main Magazine Area) finished in the summer of 2004. It has been determined that the main magazine area (about 530 acres) has been contaminated with elevated levels of arsenic as a result of Navy pesticide and herbicide practices. The Navy has developed remedial alternatives and issued its Proposed Plan.

WPNSTA Concord is participating in the Installation Restoration Program (IRP), a specially funded program established by DoD in 1978 to identify and investigate military and other DoD facilities. There is a Federal Facilities Site Remediation Agreement (FFSRA) between the Navy and the State of California. The purposes of the FFA are to establish roles and responsibilities of the parties; establish an enforceable schedule for environmental investigations and cleanup actions; and ensure that the Navy will obtain necessary funding for the environmental investigations and actions.

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