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Record of Decision System (RODS)



City & State:  NEW LONDON  CT  06349
EPA ID:  CTD980906515
EPA Region:  01
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/541/R-99/157
ROD Date:  09/30/1999
Operable Unit(s):  05
Abstract:  The United States Navy Submarine Base New London (NSB-NLON) consists of approximately 547 acres of land and associated buildings in southeastern Connecticut in the towns of Ledyard and Groton. NSB-NLON is situated on the east bank of the Thames River, approximately 6 miles north of Long Island Sound, and is bounded to the east by Connecticut Route 12, to the south by Crystal Lake Road, and to the west by the Thames River.

In 1867, the State of Connecticut donated a 122-acre parcel on the east bank of the Thames River to the Navy. The Navy began using the property in 1868 when it was officially designated as a Navy Yard. The Navy designated the site a Submarine Base in 1916. Between 1935 and 1945, the Navy built in excess of 180 buildings and expanded NSB-NLON from 112 to 497 acres through the acquisition of adjacent land.

NSB-NLON currently serves as a major support center for the U.S. Atlantic fleet. Additionally, NSB-NLON includes housing for Navy personnel and their families, submarine training facilities, military offices, medical facilities, and facilities designed for the maintenance, repair, and overhaul of submarines. Land use adjacent to the NSB-NLON is generally residential or commercial.

The Groton Water Department supplies potable water to NSB-NLON. The primary sources of the Groton water supply are reservoirs that are supplemented with wells. The water supplies are located within the Poquonock River Watershed, located east of NSB-NLON, which is not within the NSB-NLON watershed. Groundwater at NSB-NLON is not used for potable water.

In 1975, the Department of Defense developed a program, known as the Installation Restoration Program (IRP) to investigate and clean up problem areas involving contamination at federal facilities such as the NSB-NLON. The NSBNLON was placed on the National Priority List (NPL) in August 1990.

The Goss Cove Landfill is located in the southwestern corner of the base, along the eastern bank of the Thames River.
The landfill was operated at the base from 1946 through 1957. Incinerator ash and inert rubble were disposed at the site. It is not known if any other materials were disposed in the former landfill. The Nautilus Museum and a paved parking lot are constructed directly over the site of the former landfill. The ROD addressing this OU was completed in
September 1999.
Remedy:  Engineered Control Cap with Institutional Controls and Monitoring: An engineered control cap will be employed to prevent human contact with contaminants within the landfill area of the site. The cap will also serve as an infiltration barrier and minimize the potential for any long-term vertical contaminant migration from the landfill. Institutional controls: Future land use would be limited under the deployment of institutional controls to ensure that the site is not used in a manner that would disturb the cap or the soil. Monitoring the groundwater to evaluate the effectiveness of the capping system and to ensure that contaminants do not migrate. The remedial action also consists of excavation of surface soil, compacting excavated soil over the existing paved parking lot area, and five-year reviews. No further action is proposed for the sediments within Gross Cove.

Estimated Capital Cost: $2,271,000
Estimated Annual O+M: $27,400
Estimated Present Worth Cost: $2,6578,000
Text:  View full-text ROD [ 349K ]
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