SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

. R RECE Ep _ ow[RnaD G, BROWN c..iFex x,• �,�� 2 8 ZO'r1` NiMROORIOUEz Water Boards ENv1R%l NWRRNMEN,N, RRR.ER,eN t:H Central Valley Regional Water Quality Control Board MMSERVICES 26 September 2012 DESJC, M.BENSON Defense Distribution Depot San Joaquin P.O. Box 960001 Stockton, CA 95296 CLOSURE CONCURRENCE UST SITE 13; DEFENSE LOGISTICS AGENCY DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN, TRACY SITE Dear Mr. Benson: California Regional Water Quality Control Board, Central Valley Region (Central Valley Water Board) staff has reviewed the Final— UST Site 13 Request for Closure. The Defense Logistics Agency Enterprise Support (DLA) submitted the document for its Tracy depot located in the city of Tracy, San Joaquin County. One 2,000 gallon No. 2 diesel fuel metal underground storage tank (UST) was located at UST Site 13. DLA installed the tank in 1982 and used it for supplying fuel to a steam boiler inside of Warehouse 10. DLA removed the tank in 1987 and filled the excavation with pea gravel. DLA conducted soil removal actions in 1997 and 1999. After the 1999 action, DLA detected total petroleum hydrocarbons in the diesel range in one of nine confirmation soil samples at a concentration of 48 milligrams per kilogram. Prior to demolition of the warehouse in 2009, the U.S. Army Corp of Engineers collected a subsurface soil sample near the 1999 confirmation sample location. The concentration of TPHd was less than the laboratory reporting limit of 6 mg/kg. DLA installed water table monitoring wells in 1993. Laboratory analyses of groundwater samples collected from the wells through 2008 did not detect TPI-Id. In 2009, DLA demolished the warehouse and paved the site with asphalt. Attached is a memorandum dated 20 September 2012 prepared by Central Valley Water Board staff detailing the rationale for concurrence with closure of the former UST site. Central Valley Water Board staff based its concurrence on the following: achieving site cleanup through removal of the UST and associated piping, excavation of contaminated soil, and monitoring of groundwater for more than 15 years to show that the site has not impacted groundwater quality. The DLA has satisfactorily completed site investigation and remedial action, achieved applicable remedial action standards and objectives, and implemented a permanent remedy at UST Site 13. Therefore, closure is appropriate. Closure concurrence for UST Site 13 does not preclude future action by the Central Valley Water Board staff. Future action could be required if subsequent monitoring, testing, or analysis indicates that DLA has not achieved the remedial action standards and objectives that are required to prevent a significant risk to human health and safety, the environment, or water quality. KARL E. LONGLEV ScD, P.E., CRAIR I PAMELA C. CREEOON P.E.• BCEE, EXECUTIVE OFFICER 11020 Sun Center Drive%200.Rancho Cordova.CA 95670 1 www.walarboatdS.ca.gov/contralvallay l Rmvm Eo RAPER