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I revealed in the collected samples of soil or groundwater Analytical results of soil samples collected from ASB-1 were wholly nondetectable Based on these results, Water Works concluded that waste-oil contamination did not appear to spread laterally beneath the on-site building ' On December 15, 1989, soil was overexcavated from the western wall near the former diesel UST area Laboratory analytical results revealed a TPH-d concentration of 30 6 ppm at 6 feet, TPH-d was not detected in samples collected at depths of 2 feet or 16 feet ' Ground-water samples collected from MW-1 in February of 1990 indicated a TPH-d concentration of 350 ppm A TPH-d concentration of 59 ppm was detected in a sample collected ' two months later in April of 1990 On September 27, 1993, Roger Foote Associates (RFA) of West Sacramento drilled three (3) soil ' borings, two (2) of which were converted to ground-water monitoring wells MW-2 and MW-3 Soil boring ASB-2 was drilled at an angle of about 30° to vertical and was extended to an ' equivalent vertical depth of 33 5 feet Both monitoring wells were completed to a total depth of 50 feet Selected soil samples were analyzed for TPH-d, TPH-g, and BTEX constituents by California ' Laboratory Services of Rancho Cordova, a State-certified analytical laboratory Soil samples collected from ASB-2 @ 6 & 19 feet, MW-2 @ 15, 35 & 40 feet, and MW-3 (& 35 & 40 feet below surface grade (bsg) were found nondetectable for all constituents Ground water was encountered at an average depth of 45 feet bsg GROUND-WATER MONITORING ' W W Irwin, Inc of Merced was awarded the contract to perform ground-water monitoring by Ms Carmen Punla in January of 1995 Monitoring wells MW-1 through MW-3 were sounded on February 6, 1995 Mr Harlin Knoll of the San Joaquin County Division of Environmental ' Health attended the monitoring activities Utilizing a Keck* interface probe, the W W Irwin, Inc staff geologist determined that the average piezometric depth-to-water underlying the site was 36 03 feet bsg ' The soundings were converted using casing-top elevations previously established by RFA The elevation data were used to calculate the present ground-water flow direction and gradient by ' the three-point method The local flow direction on February 6, 1995 was approximately N83°E along a gradient of 0 004 foot/foot as shown on the Ground-Water Gradient Map, Figure 3 Sounding and flow direction data are listed in Table 1 1 W w I., me Prc)ect No 33236 DO March 1995 3 1