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13 August 1996 AGE-NC Project No 95-0125 Page 2 of 3 Only wells MW-2 and MW-6 were sampled in accordance with an agreement with the PHS-EHD Samples were retrieved from the two wells using new disposable plastic bailers Each sample was collected in 40-ml EPA vials and transported in a chilled container under ice, under a chain-of- custody to Alpha Analytical Laboratories, Inc (AAL) in Ukaih, California Each sample collected was analyzed for total petroleum hydrocarbons quantified as gasoline (TPH- g),volatile aromatics (benzene, toluene, ethylbenzene and xylenes BTE&X) and methyl tert-butyl ether (MTBE) in accordance with EPA methods 5030/8015m, 602 and 602, respectively I23 SOIL AERATION On 05 July 1996, approximately 250 cubic yards of excavated soil was transferred into an aeration cell on the western portion of the school property Authorization for the uncontrolled soil aeration was granted by the San Joaquin Valley Unified Air Pollution Control District A copy of the permit is included in Appendix B Stockpile soil samples collected in Januar 1996 indicated that TPH- was resent in the soil at p p Y g p concentrations up to 480 mg/kg (milligrams per kilogram, equivalent to parts per million ppm) and benzene was present at concentrations up to 0 08 ppm Based upon the low concentrations of petroleum hydrocarbons in the soil undergoing aeration, a treatment period of 3 to 6 months was estimated At the end of three months of treatment, soil samples will be collected to verify the progress of the aeration 3 0. FINDINGS 3 1 GROUND WATER ELEVATION AND GRADIENT DIRECTION When measured on 04 June 1996, the depth to ground water at the site ranged from 7 5 to 8 36 feet bsg The relative ground water elevation at the site decreased approximately 2 feet between March and June 1996 The relative elevation of ground water in each well was calculated by subtracting the ground water depth from the surveyed casing elevations,casing elevations were surveyed relative to MW-1, which was assigned an arbitrary elevation of 100 00 feet Table 1 includes the ground water elevations iFigure 3 -Relative Ground Water Elevation, illustrates the ground water elevations at the site, based upon data collected during this monitoring event Ground water flow in the area is toward the north The overall northward trending flow is consistent with the regional ground water flow in the area