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5 4.0 SUMMARY 4F RESULTS A summary of the analytical results from current and past well sampling is presented in Table 1. Based on the water-level data for February 23, 200I. ATC has interpreted the groundwater gradient and flow direction for the upper aquifer, as shown on Figure 3. In the upper aquifer (monitoring wells MW-5, MW-6, and MW-7), the groundwater elevation increased from the previous quarter an average of 0.44 feet, ranging from 0.08 feet in monitoring well MW-6 to 1.14 feet in monitoring well MW-7. The apparent groundwater flow direction in the upper aquifer was southeasterly at a gradient of approximately 0.004 (Figure 3). Based on the, water-level data for February 23, 2001 (Table 1), ATC has interpreted the groundwater gradient and flow direction for the lower aquifer, as shown on Figure 4. In the lower aquifer (monitoring wells MW-1 R, MW-2, MW-3, MW-4), the groundwater level increased from the previous quarter an average of 0.07 feet, ranging from 0.06 feet in monitoring wells MW-1, MW-3 and MW-4 to 0.10 feet in monitoring well MW-2. The apparent groundwater flow direction in the lower aquifer was southeasterly at a gradient of approximately 0.0013 (Figure 4). iAs part of construction activities for widening West Hammer Lane, the casing of MW-8 was cut, and the well box lowered by V&W Drilling on August 11, 2000. The well was recently paved over by the City of Stockton preventing access to it. ATC collected a sample from this well. The groundwater elevation could not be calculated for well MW-8 this quarter. ATC will re-survey �{ the well so that groundwater elevation for MW-8 can be calculated for the previous and next quarter. 1� Laboratory analysis of the water samples collected on February 23, 2001 indicate that TPH-G BTEX, and MTBE were not detected in groundwater samples collected from MW-3, MW4 and MW-8 in the Iocal'lower aquifer. In the local upper aquifer TPH-G, BTEX, and MTBE were not detected groundwater samples collected from MW-6 and MW-7. TPH-G was detected in groundwater samples collected from MW-1 R, MW-2 and MW-5. BTEX was not detected any of the wells samples with the exception of an insignificant total xylenes concentration in MW-5. Laboratory results of fuel oxygenate compounds by USEPA Method 8260 indicates that MTBE was detected in the groundwater samples obtained from monitoring wells MWA R at a concentration of 97 micrograms per liter (pg/l), MW-2 (4,900 pO), and NRR-5 (3,400 4g11). 2000 F.+lush Ql v a l;rulm<Iwatcr%1.,mrmvn Rrpvt J V1,FTnVr—kQUTK Vr0P1 S 1 tT RHPI'k'1 S',_Ofl1 w rr:OflIq)j Lw