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Working To Restore Nature November 1992 (RESNA, January 1993) investigations have shown that the majority of petroleum hydrocarbons in the soil were present from 0 to approximately 25 feet below grade and within a radius of about 20 feet of the former 1,000 gallon gasoline UST tank pit. A soil ' vapor extraction system was constructed at the site and began operating July 23, 1993 Quarterly groundwater monitoring results have shown detectable levels of petroleum hydrocarbons in the monitoring wells in the past (Table 1) ' GROUNDWATER SAMPLING AND GRADIENT EVALUATION ' RESNA personnel performed the latest quarterly groundwater monitoring of monitoring wells on March 17, 1994. Mr Michael Collins of SJCPHS was present on-site to observe RESNA ' sampling techniques Field work consisted of measuring depth-to-water (DTW) levels in wells MW-1 through MW-6, collecting groundwater samples from wells MW-1, MW-2, and MW-6, and submitting groundwater samples for laboratory analysis Water level measurements were collected from wells MW-1 through MW-6 The depth to water ranged from 66 00 to 66 52 feet below top of well casing elevation In general, groundwater ' elevations have increased an average of 2 41 feet since December 27, 1993 The water level data were used to develop the groundwater elevation contour map (Plate 3). Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed in an easterly direction. The hydraulic gradient on March 17, 1994 was calculated to be 0 001 ft/ft or about 5 feet/mile These data indicate no change when compared with the previous quarterly monitoring results for gradient flow and direction A summary of ' groundwater monitoring data is presented in Table 2 Groundwater elevations are referenced to feet mean sea level. ' Groundwater samples were collected from three shallow groundwater monitoring wells, MW-1, MW-2, and MW-6 Prior to collection of groundwater samples a minimum of three well casing volumes were purged. The depth-to-water, pH, electrical conductivity, and temperature were ' measured and allowed to stabilize before groundwater samples were collected. No evidence of measurable floating product or hydrocarbon vapor was noted in the water samples. Samples were then collected from each well using disposable bailers Purge water was contained in 55 ' gallon DOT approved drums and stored on-site pending proper disposal. The groundwater samples collected from each well were submitted with Chain of Custody Record to Sequoia Analytical Laboratories of Redwood City, California, a State Certified laboratory (State Hazardous Waste Testing Laboratory Certification No 1210) Samples were ' analyzed for total petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), and benzene, toluene, ethylbenzene, and total xylenes (BTEX) utilizing EPA methods 8015/8020 Purge water from the previous quarterly sampling was disposed of on March 1, 1994 at an approved faclWy GI QUARTLYIIQMR1994 FNL 2