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Excavation by itself is effective in removing the affected soils from the <br /> site to limit potential migration of the hydrocarbons However, it is <br /> not effective in remediating the affected soils unless further treatment <br /> or disposal is undertaken Excavation would therefore be appropriate <br /> as part of other alternatives, but would not be appropriate as a separate <br /> ' remedial alternative for the site <br /> -On-,Site Ex Situ Soil Aeration <br /> This alternative would consist of excavating the affected soils and <br /> removing the volatile hydrocarbons from the soil via aeration The <br /> excavated soils would be spread over a treatment area at a depth of <br /> 6-to-8 inches, covered, and allowed to dry After the sods are dry, <br /> agricultural equipment would then be used to mix the soils, allowing <br /> the hydrocarbons to volatilize After the aeration is complete, the <br /> treated soils could be backfilled into the excavation <br /> This treatment alternative is an effective and proven method of <br /> treating hydrocarbon-containing soils The technology is also easily <br /> implemented because it only requires conventional construction <br /> equipment In addition, the area of the site can easily accommodate the <br /> treatment process The affected site soils consist of semi-consolidated <br /> clays which may require several weeks or months to dry before <br /> aeration could proceed <br />' Approval from the San Joaquin Valley Unified Air Pollution Control <br /> District (APCD) would be required prior to implementation of on-site <br /> soil aeration APCD regulations restrict the rates of volatile <br />' hydrocarbon emissions from the stockpile based on the concentration <br /> levels present in the soils According to APCD requirements, if the <br /> concentration of volatile hydrocarbons in the soils is less than <br /> 5,000 mg/kg (ppm), volatiles can be aerated directly to the atmosphere <br /> No collection and/or treatment of the volatilized hydrocarbons would <br /> be necessary Since investigation data have demonstrated that <br /> hydrocarbon-containing sods at both Saes #1 and #2 are well below <br /> 5,000 ppm, on-site soil aeration would be a cost-effective and easily <br /> implemented remedial alternative To meet APCD requirements, it <br /> would stili be necessary to aerate discrete portions of the stockpile over <br /> time to control the rate of volatile emissions <br /> Off-Site Soil Treatment <br /> This alternative would involve excavation and transportation of the <br /> affected sods to an off-site treatment facility The excavated area would <br /> ' then be backfilled with imported fill The soils would be treated to <br /> 4-3 <br />