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ti E ARemediat' isk Management, Inc. f,i t Ji cL 1 f �� , if February 8, 1991 ' a }_ vjc Santa Cruz Office MAR - �, 44 PO Box 1362 Aptos, CA 95001 Mr Laurence Paradis Tel (408)662-9411 Miller, Starr, and Regalia Fax (408)684-2454 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, Inc (RRM) is pleased to submit the following report presenting the procedures and findings of the second Quarterly Groundwater Sampling Event which took place on January 4, 1994 This sampling event marks the second of four quarterly events to be conducted at the subject site over the next year The work was conducted for Miller, Starr& Regalia, A Professional Law Corporation, and their client, Mr Jade Vaughn,who owns the above referenced subject site SITE BACKGROUND The subject site is located at 595 East 11th Street in Tracy, San Joaquin County, California The site encompasses a muffler repair shop(Ed's Muffler Shop), welding shop, and residential trailer park There is also evidence of a large diameter underground cement rasing, visible within the east end of the former underground storage tank excavation pit, which appears to run from north to south 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's 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 I 1-feet below 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 1992, three groundwater monitor wells, designated MW-i through MW-3, were installed at the site Figure 2 shows the locations of the monitor wells Each well was sampled for total petroleum hydrocarbons as gasoline (TPHg) and for benzene, toluene, ethyl-benzene, and total Kylenes (BTEX) Laboratory analyses results of the samples showed that TPHg concentrations of 14 1 and 2 6 ppm and 13TEX compounds were found at wells MW-2 and MW-3, respectively March 1992 laboratory results are _ summani-ed 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