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ei petroleum hydrocarbons were present in the on-site soils in a small area centering around borehole W3. Dissolved petroleum hydrocarbon residues were also found in the shallow groundwater at two of the three wells. No floating product was observed. In response to the findings of the soil and groundwater sampling � . program, WESTCN was directed by the County of San Joaquin to evaluate alternatives for remediating the soils at site and to prepare a final soil remedial plan. The groundwater issue will not be addressed at this time as further investigation is war- ranted. 'tA 2.0 REMEDIAL PROJECT ALTERNATIVES As detailed in the Problem ?assessment Report, the . .1 and groundwater sampling program identified the lateral and ..rtical Es extent of the petroleum hydrocarbon presence within the soil at the site. As the concentration levels detected were sufficient to require remediation, a limited feasibility evaluation was conducted to assess alternative approaches to remediate the area. Three approaches were considered as follows: ' A. Excavation to remove soils contain1.ng TPH concentrations in excess of lop mg/kg down to first groundwater. B. In-situ volatilization (ISV) to remediate the soils in place. C. In-situ flushing of the soils to remediate the soils in place. Approach A was revised to follow the revised March 1989 Leaking ;.x Underground Fuel Tank Manual guidelines. The cleanup level was lowered to 10 mg/Kg of TPH with a goal of non-detectable TPH concentrations. � 4 Summarized below are the principle factors considered during the evaluation of three alternatives. A. Excavation of Soils in Excess of 10 mg/kg TPH with a goal of e non--detection (ND) . While no definitive limit has been established for in-place petroleum hydrocarbon compounds, the cleanup criteria for the site of 10 mg/kg TPH with a goal of ND was selected based on discussions with the San Joaquin Local Health District, the known, site conditions and the lack of domestic wells in the vicinity of the site. This level was revised from that identified within the Problem Assessment Report. ; . This alternative is feasible due to the limited area which ! will require excavation, the accessibility of the area and ba the remediation deadV ne required in order not to delay construction (July 1989) of the Human Services Building. - 3 _ I , w,