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1.0 EXECUTIVE SUMMARY This Problem Assessment Report (PAR) summarizes the soil and groundwater investigations conducted at the site to date, and presents a feasibility analysis of various soil and groundwater remediation technologies Estimated costs are provided for the remediation technologies deemed feasible for conditions at the Former Canteen Facility site The Former Canteen Facility is located dust east of Highway 99, between Waterloo Road (Highway 88) and Fremont Street (Highway 26) The one-acre property is zoned for manufacturing and light industrial use, there are no residences in the immediate area It is located in Section 31, T 2N , R 7E , M B B &M , on a portion of Section 54 Weber Grant, San Joaquin County, California. (Figures 1 and 2) Results of the soil and groundwater sampling conducted during the assessment portion of the Iproject indicate that the horizontal extent of the hydrocarbon impact from the underground storage tank (UST) release has been delineated Concentrations of adsorbed-phase hydrocarbons I detected in the soil were compared to the Environmental Protection Agency(EPA) Region 9 Preliminary Remediation Goals (PRGs). The sort samples collected from the south and southeast walls of the UST excavation at depths between 14 and 19 feet below ground surface (bgs) exceeded the Industrial PRGs for benzene (1 5 mg/kg), toluene (5 20 mg/kg), and xylenes (2 10 I • mg/kg) The benzene PRG was also exceeded in borings SB-2 (46 feet bgs) and SB-13D (46 5 feet bgs) TPH-G concentrations detected in these soil samples ranged from 10 3 to 17,600 mg/kg Concentrations of dissolved-phase hydrocarbons in the groundwater exceed the California Department of Health Services Drinking Water Standard Maximum Contammant Levels (CAMCL) for benzene (1 0 ug/1), toluene (150 ug/1), ethylbenzene (700 ug/1), xylenes (1,750 ug/1), MTBE (13 ug/1), and 1,2-DCA(0 5 ugh) TPH-G concentrations ranged from<50 to 220,000 ug/1 The majority of the groundwater impacts are centered on the MW-3 and MW-13 series wells Concentrations of 1,2-DCA have only been detected in off-site monitoring well MW-11 and may not be related to the UST release IAccording to the San Joaquin County Flood Control District map, no water wells are located within one-half mile of the site The groundwater gradient is consistently towards the south- southeast based on 18 monitoring events The closest down gradient water well is located over one mile from the site Available records indicate that most water wells are completed below 125 feet bgs due to seasonal water fluctuations and the lack of sufficient aquifers above that depth I One of the objectives of the PAR is to assess various remediation technologies for applicability to Ithe specific site conditions at the Canteen Facility Based on the site assessment results, 1 I