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HEALTH Remediation Risk Management, Inc. November 8, 1993 i {_{ ; til SF1RV11__L Santa Cruz Office Pi 2- (} P O Box 1362 Mr Laurence Paradis Aptos,CA 95001 Miller, Starr,and Regalia Tel (408)662-9411Fax (408)6$4-2454 One Kaiser Plaza, Suite 1600 Oakland, CA 94612 SUBJECT. Quarterly Groundwater Sampling Report for the Subject Site Located at 595 East 11th Street in Tracy,San Joaquin County,California. Dear Mr Paradis Remediation Risk Management(RRM) is pleased to submit the following report presenting the procedures and findings of the Quarterly Groundwater Sampling event which was conducted on October 6, 1993 The sampling event marks the first of four quarterly events to be conducted at the subject site over the next year The work «as conducted for Miller, Starr & Regalia, A Professional Law Corporation, and their client, Mr Jack Vaughn,who owns the above referenced subject site SITE BACKGROUND The subject site is located at 595 East 11th Street to Tracy, San Joaquin County, Caltforma The site encompasses a muffler repair shop(Ed's Muffler Shop), welding shop, and residential trailer park Figure 1 shows the general location of the subject site In January 1990, four underground storage tanks were excavated and removed from the site at Ed's Muffler Shop The tank system consisted of an 8,000-gallon capacity tank used to store regular leaded gasoline, 7,500-gallon capacity tank used to store regular unleaded gasoline, and two 4,000-gallon capacity tanks each used for premium unleaded gasoline In addition, a waste oil tank was reportedly also removed at the time Figure 2, presents the location of the former USTs and pump dispenser islands During UST removal, soils were sampled from beneath each end of each tank and from beneath the piping at the pump dispenser islands In addition, a sample was taken of the water which accumulated in the UST excavation Laboratory analyses results of the samples indicated that the soils around the former USTs were impacted with petroleum hydrocarbon products In January 1992, a soil gas survey was performed to test soil vapor for total volatile hydrocarbon (TVH) concentrations A total of 17 temporary vapor probes were installed to approximately 11-feet belo%s grade Results of the soil gas survey indicated TVH concentrations of up to 32,000 parts per million (ppm) near to and north of the former UST locations In March of 1992, three groundwater monitor wells, designated MW-1 through MW-3, were installed at the site Figure 2, shows the locations of the monitor,%ells Each well was sampled for total petroleum hydrocarbons as gasoline (TPHg) and for benzene, toluene, ethyl-benzene, and total xylenes (BTEX) Laboratory analyses results of the samples showed that TPHg concentrations of 14 1 and 2 6 ppm Here found at wells MW-2 and MW-3, respectively March 1992 laboratory results are summarized in Table 1 The average depth to groundwater was reported to be approximately 8-feet below surface grade with an inferred groundwater flow direction to the north-west with a gradient of approximately 0 003 vertical per horizontal feet According to site activity records, the welts have not been sampled since March 1992 COPY