The U.S. Navy, Southwest Division, Naval Facilities Engineering Command, executed Environmental Services Cooperative Agreement (ESCA) N68711-01-MDC-1061 with the City of Vallejo on September 20, 2001. The ESCA transfers responsibility to the City for completing environmental remediation for portions of Investigations Area I (dredge ponds), Area J (tidal marsh) and the Western Submerged Lands (mud flats) at Mare Island, collectively known as the Areas Covered by Environmental Services (ACES). The City of Vallejo and Weston Solutions Inc.entered into the Mare Island Remediation Agreement (MIRA) under which Weston will perform these environmental services and obtain regulatory closure. Long-term monitoring and maintenance will also be performed by Weston. The ACES also includes Investigation Area H1 (containing the historic landfill areas and the Industrical Wastewater Treatment Plant), the Western Magazine Area, and the former ordnance and explosives demolition area at the southern end of Mare Island known as Installation Restoration (IR) Site 05. The Navy is providing annual, incremental funding to the City through FY06 for the ESCA, with a total grant amount of $54,961,000.

On September 20, 2002, Weston Solutions, Inc. in its role as both Remediation Contractor and Developer, announced the successful Early Transfer of the Western Parcel of the former Mare Island Naval Shipyard in Vallejo, CA from the Navy to the State of California through the State Lands Commission. This process provides significant clean-up and O&M cost savings to the Navy and accelerates redevelopment and remediation activities compared to conventional processes.