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A S S O C I A T E S I N C <br /> Groundwater samples from wells MWI, MW3, and MW7 continue to contain elevated <br /> concentrations of TPHg and BTEX A summary of analytical results is presented in Table 1 <br /> Laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 <br /> GROUNDWATER FLOW DIRECTION <br /> Water level measurements were collected from wells MWI through MW7, and CW on March 9, <br /> 2000 Water levels ranged from 20 39 to 23 46 feet below the tops of the well casing elevations, <br /> representing an average increase in the water table elevation of approximately 1 56 feet since <br /> December 1999 The water level data were used to develop the groundwater elevation contour <br /> map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the <br /> uppermost aquifer beneath the site flowed towards the northeast The average hydraulic gradient <br /> on March 9, 2000 was calculated to be 0 005 ft/ft or approximately 26 ft/mile A summary of <br /> groundwater monitoring data is presented in Table 1 <br /> ADDITIONAL SITE ACTIVITIES <br /> On February 24, 2000, ATC personnel transported and disposed of twelve 55-gallon drums of <br /> soil cuttings generated during the advancement of soil borings and monitoring wells that were <br /> stored on site Prior to the soil disposal, analytical data was supplied to Allied Waste Landfill to <br /> profile the soil for the appropriate disposal method ATC transported the soil to the Allied Waste <br /> Landfill in Stockton, California where it was properly disposed Copies of the non-hazardous <br /> waste manifests are included in Attachment 3 <br /> CONCLUSIONS <br /> Concentrations from wells MWI through MW6 and CW remain consistent with the results from <br /> previous sampling events Concentrations of TPHg and BTEX in well MW7 appear to be <br /> decreasing It appears as though there are petroleum hydrocarbons remaining in the soil The <br /> direction of groundwater flow and the magnitude of hydraulic gradient are generally consistent <br /> with the previous event Groundwater elevations have increased since December 1999 <br /> RECOMMENDATIONS <br /> Based on the results of the First Quarter 2000 monitoring episode, we recommend the following <br /> • Conduct the Second Quarter 2000 groundwater monitoring and sampling wells MWI <br /> through MW7 and CW and analyze samples for TPHg and BTEX by EPA Method 8020 <br /> Perform a vapor extraction and air sparge pilot test to evaluate these methods as remedial <br /> options <br /> s <br /> w 1625961quart1y\1gr-2000 doc 3 <br />