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SECOND QUARTER 2003 GROUNDWATER MONITORING REPORT AND ADDITIONAL ASSESSMENT REPORT JA L4,R OIL DISTRIBUTION JUNE 2003 Groundwater Flow and Gradient Based on depth to groundwater measurements taken on May 29, 2003, the depths to groundwater ranged from 62.28 feet bgs in monitoring well MW-1 to 62.82 feet bgs in MW- 7A. All groundwater elevations were measured to the nearest 0.01-foot relative to the surveyed top of casing elevation. The elevations are based on the survey conducted by 7PCA on August 30, 2000. The survey on August 30, 2000 was completed by setting the corner of the cement sidewalk on the southeastern comer of the store as the benchmark with an assumed elevation of 30 feet above mean sea level (MSL). Based on the surveyed casing elevations and the measured depth to water on May 29, 2003, the groundwater elevations range from -33.93 feet in MW-5 to -34.18 feet in MW-6B. Monitoring wets MW-6B and MW-7B were drilled to 95 feet bgs and have only 5 feet of screen. For these reasons, MW-6B and MW-7B are not being used to calculate hydraulic gradient or flow direction. the other eight wells,the direction of groundwater flow has been calculated to be trending southeast ith a relatively flat hydraulic gradient of approximately 0.0004-feet/foot across the c site. Calculated groundwater elevations are summarized in Table 1, and shown on Figure 4. Groundwater Analytical Results All ten wells are included in this discussion of sampling results. TPH G was detected in the samples from all of the monitoring wells except MW-5 and MW-6A. TPH G ranged from 83 µg11 in the sample from MW-7B to 170,000 µg11 in the sample from EW-1. TPH D was detected in the samples from MW 1, MW-2, MW-3, MW-4, and EW-1 at concentrations ranging from 440 µg11 in MW-2 to 13,000 ug/l in EW-1. Benzene was detected in the samples from all of the wells except MW-5 and MW-6A at concentrations ranging from 16 µg11 in MW-7A to 29,000 pg/l in MW-1. Toluene was detected in the samples from all of the wells except MW-5 and MW-6A at concentrations ranging from 11 pg/l in MW-6B to 14,000 µg/1 in EW-1. Ethylbenzene was detected in the samples from all of the wells except MW-5 and MW-6A at concentrations ranging from 1.1 µg/1 in MW-6B to 2,100 µg11 in EW-1. Total xylenes were detected in the samples from all of the wells except MW-5 and MW-6A at concentrations ranging from 4.8 pg/l in MW-6B to 10,200 µg11 in EW-1. MTBE was detected in the samples from all of the wells except MW-3, MW-5 and MW-6A at concentrations ranging from 6.4 µg11 in MW-7A to 180,000 µg/1 in MW-1. Tertiary butyl alcohol (TBA)was detected in the samples collected from MW-1, MW-4, and EW-1 at 3,000 µg11, 440 pgll, and 480 µg/1, respectively. DIPE, ETBE, and TAME were ND in all samples taken this quarter. 1,2 DCA was detected in samples from MW-1, MW- 4, MW-613, MW-7A, and EW-1 at concentrations ranging from 2,7 µg/1 in MW-7A to 2,000 µg/l in MW-1. 11