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I A S S O C I A T E S I N C wells MW4 and CW contained no detectable concentrations of petroleum hydrocarbons Groundwater samples from wells MW1, MW3, and MW7 continue to contain elevated concentrations of TPHg and BTEX A summary of analytical results is presented in Table 1 Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 GROUNDWATER FLOW DIRECTION Water level measurements were collected from wells MWI through MW7, and CW on March 16, 1999 Water levels ranged from 20 77 to 23 71 feet below the tops of the well casing elevations, representing an average increase in the water table elevation of approximately 0 92 feet since December 1998 The water level data were used to develop the groundwater elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed towards the northeast The average hydraulic gradient on March 16, 1999 was calculated to be 0 006 ft/ft or approximately 32 ft/mile A summary of groundwater monitoring data is presented in Table I ADDITIONAL SITE ACTIVITIES On May 27, 1999, ATC personnel supervised the transport and disposal of 850 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 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 from wells MW1 through MW7 and CW remain consistent with the results from previous sampling events It appears as though there are petroleum hydrocarbons remaining in the soil The direction of groundwater flow and the magnitude of hydraulic gradient are consistent with the previous event Groundwater elevations have increased since December 1998 RECOMMENDATIONS Based on the results of the First quarter 1999 monitoring episode, we recommend the following o Conduct the Second Quarter 1999 groundwater monitoring and sampling wells MW1 through MW7 and CW and analyze samples for TPHg and BTEX by EPA Method 8020 w\625961quartlyllgr-1999 doc 3