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California Regional Water Quality Control Board
<br /> Central Valley Region
<br /> Robert Schneider,Chair
<br /> Winston H.Hickox Gray Davis
<br /> Secretaryfor Sacramento Main Office Governor
<br /> Environmental Internet Address: http://www.sweb.ca.gov/mgcb5
<br /> Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003
<br /> Phone(916)255-3000•FAX(916)255-3015
<br /> TO: John Russell FROM: Marcus Pierce, C.Hg.
<br /> Senior Engineering Geologist /Engineering Geologist
<br /> DATE: 24 June 2004 SIGNATURE:
<br /> SUBJECT: REVIEW FOR NO FURTHER ACTION: SITES 6,7, 9, 10, 14, 18, 19,20, 24, 27,
<br /> 32, AND BUILDING 201 SUMP
<br /> DEFENSE DISTRIBUTION DEPOT SAN JOAQUIN-TRACY(DDJC-TRACY)
<br /> SAN JOAQUIN COUNTY
<br /> Based on review of the Final UST Preferred Alternatives Report, UST Sites 6, 7, 9, 10, 14, 18, 19, 20, 24,
<br /> 25, 27, 32, and Building 201 Sump, no further action(NFA)is warranted for Sites 6, 7, 9, 10, 14, 18, 19,
<br /> 20,24, 27, 32,and Building 201 Sump. A brief summary of site history and current site conditions is
<br /> presented below along with the rationale to support closure. Most of the USTs were removed in 1988
<br /> and the subsurface sampling that was done at that time was not well-documented. Therefore,this data is
<br /> not summarized below for most of the sites.
<br /> Site 6
<br /> UST Site 6 is located in the northwestern portion of DDJC-Tracy. Two 12,000-gallon steel USTs were
<br /> installed prior to 1956 and were used to store gasoline. The tanks were abandoned in-place in 1975 and
<br /> removed in 1988. Approximately 106 cubic yards of contaminated soil were excavated and removed
<br /> from the area of the former UST in 1997.
<br /> Subsurface investigations were conducted in 1993, 1998, and 1999. The maximum historical
<br /> concentration of total petroleum hydrocarbons as gasoline (TPHG)of 3,900 mg/Kg was detected in 1998.
<br /> Benzene,toluene, ethylbenzene, and total xylenes(BTEX) and ethylene dibromide (EDB)were detected
<br /> in one or more soil samples collected during the 1993 investigation. BTEX was not detected in any soil
<br /> samples collected during the 1998 investigation and EDB was only detected in the historical hotspot area.
<br /> Concentrations of EDB ranged from ND to 0.0021 gg/Kg.
<br /> TPHG, total petroleum hydrocarbons as diesel (TPHD), benzene, ethylbenzene, and total xylenes were
<br /> detected at respective concentrations of 90,000, 32,000, 820, 2,200,and 6,000 pg/L in groundwater grab
<br /> samples collected in 1998. EDB was not detected in any of the groundwater grab samples.
<br /> Four monitoring wells were installed at Site 6 in 1999 as part of a natural attenuation study. Except for
<br /> benzene, concentrations of these petroleum constituents in the four wells declined steadily to below
<br /> detection by 2002. Well LM171AU, located approximately 20 feet down gradient of the historical
<br /> hotspot,declined from 4,200 µg/L in July 1999 to ND in July 2001. Benzene concentrations have
<br /> California Environmental Protection Agency
<br /> Co Recycled Paper
<br /> The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. Fora list of
<br /> simple ways you can reduce demand and cut your energy costs,see our Web-site at http://www,swrcb.ca.gov/mgcb5
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