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28 May 1991 <br /> GeoAudit CV 43C4 . 1. 1 -- Work Plan for Vacuum Extraction <br /> ' Page 5 of 10 <br /> 2 . OBJECTIVES <br /> ' The main objective is to treat the contaminated soil until an <br /> acceptable level is achieved. A secondary objective includes the <br /> monitoring of hydrocarbon degradation on the ground water. This <br /> work plan pertains only to the mitigation of the soil contamination <br /> in the vadose zone. A work plan for the secondary scope of work <br /> will be submitted at a later date. <br /> The plan calls for vapor extraction from a well in the location of <br /> the former tank. The well, which will be installed to a total depth <br /> of 70 feet, is designed to facilitate extraction from practically <br /> the entire casing. In order to facilitate a supplementary cleanup, <br /> a provision is provided to extract vapor from the existing <br /> ' monitoring MW-2 as well. The contamination in this well is assumed <br /> to be attributed to a lateral migration along the capillary fringe, <br /> which is restricted to the perforated portion of the well casing. <br /> Technologically, a site mitigation that achieves non-detectable <br /> levels of both total petroleum hydrocarbons (TPH) and purgeable <br /> aromatic hydrocarbons (BTE&X) in the vadose zone is feasible. <br /> ' However, due to budgetary constraints, we propose to perform this <br /> treatment until a significant decrease of volatile organics in the <br /> recovered vapor has levelled off, typically at 500 parts per <br /> million (ppm) as hexane. Subsequently, confirmatory soil sampling <br /> will be conducted to document the concentration and extent of the <br /> contamination left in place, if any. See Section 9 . 5 for a detailed <br /> confirmatory sampling plan. <br /> 3 . VACUUM EXTRACTION METHOD AND EQUIPMENT DESCRIPTION <br /> To meet the objective, an Environmental Techniques - Vapor <br /> Extraction and Treatment System - Vaclean 1000 (ET Vaclean 1000) <br /> will be used. In order to maximize the efficiency of the treatment, <br /> a 24-hour operation of the unit is planned. This system is designed <br /> to remove volatile organic/ hydrocarbon compounds from the voids of <br /> contaminated soil, both in-situ and on the surface (post <br />' excavation) . This particular vapor extraction system has been <br /> approved by the South Coast Air Quality Management District and is <br /> currently in operation in Southern California under application/ <br /> permit No. 201584 - I.D. No. 071489 . An application to construct <br /> and operate this unit is submitted to the San Joaquin County - Air <br /> Pollution Control District (APCD) . A copy of the application <br /> package is attached (Appendix 6) . <br /> 1 <br />