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�. CVV/ 0 V9 A S S O C I A T E S I N C GROUNDWATER FLOW DIRECTION Water level measurements were collected from wells MWl through MW3 on June 8, 1999. Water levels ranged from 23.13 to 23.72 feet below the tops of the well casings elevation, representing an average increase in the water table elevation of approximately 0.5 5 feet since March 1999. The water level data were used to develop the groundwater elevation contour map (Figure 2). Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed towards the northeast. The average hydraulic gradient on June 8, 1999 was calculated to be 0.002 ft/ft or approximately 10 ft/mile. A summary of groundwater monitoring data is presented in Table 1. ADDITIONAL SITE ACTIVITIES On May 27, 1999, ATC personnel supervised the transport and disposal of approximately 490 gallons of purge water stored on site. Prior to the purge water disposal, analytical data was supplied to Clearwater Environmental to profile the purge water for the appropriate disposal method. Clearwater pumped the 490 gallons of purge water into a vacuum truck and transported the purge water to Alviso, California where it was recycled by Alviso Independent Oil. Copies of the non-hazardous waste manifests are included in Attachment 3. CONCLUSIONS Concentrations of TPHd decreased in well MW2 from the previous sampling event. Concentrations of TPHd and TPHss decreased in well MW1. Concentrations of TPHg, TPHd, and TPHss decreased in well MW3. The direction of groundwater flow is consistent with the previous event. Groundwater elevations have increased since March 1999. I RECOMMENDATIONS Based on the results of the second quarter 1999 monitoring episode, we recommend the following- 0 Conduct the Third Quarter 1999 groundwater monitoring and sampling of wells MW1 through MW3 and analyze samples for TPHg, TPHd, TPHss, and BTEX. i wAl72951quart1y12gr-1999.doc 3