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ti 3.0 PROPOSED REMEDIAL ACTION. 3. 1 Soil Remediation Procedure The proposed remediation procedure involves the excavation of the contaminated soil and aeration until an exceptable level of contam- ination is obtained. The excavation will be adjacent to the exist- ing one and will cover the area outlined in Figure 9. The depth of the excavation will extend to 25 feet. The determination of the dimensions of the excavation was based upon a number of factors. Contamination at all intervals above 25 feet was not detected except in samples taken in borings number 3, 7, 9, and 10. The contamination found in boring seven is at such low levels that it does not pose a threat to groundwater or public health. The proposed excavation includes the deepening of the ex- isting one to a depth of twenty-five feet. This action will serve to remove the contaminated soil in the base of the pit near boring nine. The motor oil contamination (7 ppm) at the 5 to 6.5 foot interval of boring number 10 is a result of spillage from the fuel island that has seeped through cracks in the concrete slab. Given its low concentration, depth of occurrence, and site lithology (predominantly clays) it is not expected to become mobile and affect groundwater quality at the site. To alleviate the possibility of the situation worsening, the cracked concrete will be repaired and procedures for usage of pumps and oil refill containers will be implemented at the site. The levels of contamination in boring three are high enough to war- rant removal of soils in the vicinity. The area encompassed by the proposed excavation will remove all of the highly contaminated soils from the area. To insure that all of the tainted soil has been re- moved samples will be taken from the sides of the excavation at five foot intervals and screened with a TIP I Photo Ionization Detector for the presence of volatile organics. The total amount of soil to be excavated is estimated at 386 cubic yards. The material will be removed with a backhoe and placed in a dumptruck where it will be transported to an on-site location for subsequent aeration. Clean fill will be placed inside the pit and compacted so that settling does not occur. A fresh concrete slab will be placed over the fill. Stockton Scavenger has contracted with Stockton Service Station Equipment to perform the excavation and filling of the hole. 3 .2 Aeration of Contaminated Soil Soil obtained from the excavation and drill cuttings will be aerated in accordance with San Joaquin County Air Pollution Control District (11)