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1.0 Executive Summary This Corrective Action Plan (CAP) includes an assessment of the impacts from the UST release, proposed cleanup levels for groundwater and soils, a feasibility study to evaluate alternatives for remedying or mitigating the actual or potential adverse effects of the release, and proposed ' monitoring and reporting requirements for the recommended remediation technology Pre- approval for the CAP and pilot testing was received from the San Joaquin County Public Health Services, Environmental Health Division on August 27, 2001 IThe Former Canteen Facility is located lust 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 andgroundwater sampling conducted during the assessment portion of the project indicate that the horizontal and vertical extent of the hydrocarbon impact from the underground storage tank(UST) release has been delineated Concentrations of adsorbed-phase hydrocarbons detected in the soil were compared to the Environmental Protection Agency (EPA) Region 9 Preliminary Remediation Goals (DRGs) The soil 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 (520 mg/kg), and xylenes (210 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 Contaminant Levels (CAMCL) for benzene (1 0 ug/l), toluene (150 ug/1), ethylbenzene (700 ug/1), xylenes (1,750 ug/1), MTBE (13 ug/1), and 1,2-DCA (0 5 ug/1) TPH-G concentrations ranged from <50 to 170,000 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 I Based on the site assessment results, remediation of both soil and groundwater is required. Fourteen remediation technologies were evaluated according to their performance, reliability, and applicability to the site-specific conditions Three of the fourteen technologies screened ' were deemed feasible for remediation of both the impacted site soil and groundwater These technologies included In-Situ Air Sparging, In-Situ Well Aeration, and Enhanced Bioremediation IAn air sparge/soil vapor extraction pilot test was conducted at the site to determine the feasibility of In-Situ Air Sparging and In-Situ Well Aeration technologies In addition, soil samples were ' collected from select areas of the site for physiochemical and microbiological analyses and bench scale studies for assessing the feasibility of Enhanced Bioremediation technology The results of the air sparge/soil vapor extraction pilot test indicated this is a feasible treatment IQ.4.GU1,� 4O�.t 4