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CVVo <br /> A S S O C I A T E S I N C <br /> GROUNDWATER FLOW DIRECTION <br /> Water level measurements were collected from wells MW 1 through MW3, on December 16, <br /> 1998. Water levels ranged from 25.38 to 25.97 feet below the tops of the well casings elevation, <br /> representing an average increase in the water table elevation of approximately 0.49 feet since <br /> September 1998. 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 east-northeast. The average hydraulic <br /> gradient on December 16, 1998 was calculated to be 0.002 f1/ft or approximately 10.5 ft/mile. A <br /> summary of groundwater monitoring data is presented in Table 1. <br /> ADDITIONAL ACTIVITIES <br /> On October 27, 1998, ATC personnel transported twelve drums of soil cuttings to Forward <br /> Landfill in Stockton, California. The soil cuttings were generated during the installation of <br /> monitoring wells MW1 through MW3. The drums were transported under a non-hazardous <br /> waste manifest and disposed of at Forward Landfill. A copy of the non-hazardous waste manifest <br /> is included in Attachment 3. <br /> CONCLUSIONS <br /> Concentrations from wells MW1 and MW2 remain consistent with the results from the previous <br /> sampling event. Concentrations of TPHd and TPHss in well MW3 increased by one to two <br /> orders of magnitude. The direction of groundwater flow is consistent with the previous event. <br /> Groundwater elevations have increased since September 1998. <br /> RECOMMENDATIONS <br /> Based on the results of the fourth quarter 1998 monitoring episode, we recommend the following: <br /> o Conduct the First Quarter 1999 groundwater monitoring and sampling of wells MW1 <br /> through MW3 and analyze samples for TPHg, TPHd, TPHss, and BTEX. <br /> 0 <br /> ":1172951guaaztfyl4gr-1999.doc 3 <br />