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r� Interim Corrective Action Plan—Tosco(76)Service Station No. 11195,Lathrop, California <br /> "= Au st 28,2002 <br /> OPTION#3 - GROUND WATER PUMP AND TREAT <br /> COST: $100,000 to $350,000 <br /> TIME FRAME: Long term <br /> ADVANTAGES: 1) Potential for hydraulic control. <br /> 2)Removal of hydrocarbon impacted groundwater can reduce dissolved <br /> hydrocarbon concentrations. <br /> DISADVANTAGES: 1)Lawrence Livermore National Laboratory report issued in 1995 found <br /> that pump and treat remediation is recognized as being ineffectual at <br /> reaching cleanup goals, since asymptotic levels are typically reached <br /> prior to achieving cleanup goals. <br /> 2) Construction and operation costs for a extraction system would be <br /> high. <br /> 3) Disruption of station activities in order to install wells and piping. <br /> CONCLUSION: Although this may be a feasible technology for this site, the City of <br /> Lathrop will not allow discharge of treated groundwater to their <br /> sanitary sewer system. <br /> OPTION#4 -VAPOR EXTRACTION WITH AIR SPARGING <br /> COST: $75,000 to $150,000 <br /> TIME FRAME: Medium to long term due to low hydrocarbon extraction rate <br /> ADVANTAGES: 1) Can remediate capillary fringe soils. <br /> 2) Can reduce dissolved concentrations in ground water. <br /> DISADVANTAGES: 1) Ineffective in fine grained soils such as silts encountered at the site. <br /> 2) Disruption of station activities in order to install wells and piping. <br /> 3) Construction and operation costs for a extraction system would be <br /> high. <br /> CONCLUSION: Since the hydrocarbon impact is primarily limited to groundwater, and <br /> the vadose zone is composed of silty sand, vapor extraction may be <br /> ineffective. Due to the size of the dissolved hydrocarbon plume,and its <br /> presence offsite and beneath structures,air sparging is not considered an <br /> aggressive enough remedial option. Not a suitable approach for this site; <br /> more appropriate methods are available. <br /> 140193.13 9 <br />