SITE INFORMATION AND CORRESPONDENCE

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MEMORANDUM - CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 255-3000 Sacramento, CA 95827-3098 CALNET: 8-494-3000 TO: Wendy L. Cohen FROM: Joel M. Weiss Senior Engineer . Engineering Geologist DATE: 14 February 1994 SIGNATURE: SUBJECT: SOUTHERN PACIFIC TRANSPORTATION COMPANY (SPTCo), OLD TRACY YARD, SAN JOAQUIN COUNTY Background The subject site operated as a maintenance facility until it was decommissioned in the mid-1940s. The site then operated as a rail welding facility until the 1980s. American Transit Mix Company (ATMCo) rented the southeast corner of the property where two underground tanks were removed in 1989. Leaks from these tanks contaminated approximately 16 cubic yards of soil which were excavated and disposed of offsite. Three ground water monitoring wells installed near the underground tanks have been sampled quarterly since 1992. No total petroleum hydrocarbons (TPH) or benzene, toluene, ethylbenzene, or xylene (BTEX) have been detected in the ground water since sampling began. The geology at the site consists of Quaternary sands, silts and clays. The hydraulic gradient of the ground water is 0.003 in the direction north 100 west. Ground water is approximately 12 feet below the ground surface (bgs). A 1991 Phase I site assessment report noted the presence of a large stockpile of soil and debris at the site. The report also noted oil-filled sumps and a refuse pit adjacent to a former car repair shop. Six soil borings were drilled and sampled, and two ground water monitoring wells were installed as part of an October 1992 Phase II site assessment. The study revealed a variety of metals in the soil. Total lead in particular ranged from 19 to 2,100 mg/kg. Soluble lead analyses by the waste extraction test (WET) were run on five of the six samples (where total lead was found above 50 mg/kg) and produced the following results: B1 - 2 feet bgs - 0.17 mg/l B3 - 0.5 feet bgs - 28 mg/l B4 - 0.5.feet bgs - 9 mg/1 MW 1 - 0.5 feet bgs - 110 mg/1 MW2 - 0.5 feet bgs - 17 mg/l The soil from boring MW 1 contained barium, cadmium, copper, mercury and zinc at high levels. In addition, B3 had 0.06 mg/kg toluene and 0.005 mg/kg xylene; MW 1 had some polynuclear aromatics; and MW2 had 0.08 mg/kg toluene and 0.01 mg/kg xylene. None of the soil samples contained TPH. Water samples were analyzed for TPH, BTEX, and volatile organic compounds (VOCs), but none were detected. Purged ground water was spread on the ground at the site.