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A s s O C 1 A T E s I N C <br />GROUNDWATER FLOW DIRECTION <br />Water level measurements were collected from wells MWl through MWS on July 3, 2002 <br />Water levels ranged from 23 57 to 24 48 feet below the top of the well casing elevations, <br />representing an average decrease in the water table elevation of approximately 0 84 feet since <br />April 2002 The water level data were used to develop the groundwater elevation contour map <br />(Figure 2) Assuming horizontal isotropic conditions, groundwater in the uppermost aquifer <br />beneath the site flowed towards the west at an average hydraulic gradient calculated to be 0 0005 <br />ft/ft or approximately 2 6 ft/mile on July 3, 2002 A summary of groundwater monitoring data is <br />presented in Table 1 <br />ANALYTICAL RESULTS <br />The groundwater samples collected from wells MW1, MW3, MW4, and MW5 contained no <br />detectable concentrations of TPHg, TPHd, or BTEX The groundwater sample collected from <br />well MW2 contained detectable concentrations of TPHg at 1,400 ppb, ethyl benzene at 29 ppb, <br />and xylenes at 92 ppb respectively TPHd, benzene, and toluene were not detected in the <br />groundwater sample from well MW2 Analytical results of groundwater samples are <br />summarized in Table 2 and laboratory data sheets are contained in Attachment 2 <br />CONCLUSIONS <br />Concentrations from wells MW1, MW3, MW4, and MW5 remained consistent with recent <br />sampling events, with no detectable concentrations of petroleum constituents Concentrations of <br />TPHg and BTEX in well MW2 continue to decline and are at their lowest recorded levels The <br />direction and magnitude of groundwater flow is consistent with previous monitoring events <br />Groundwater elevations have decreased since April 2002 The hydrocarbon plume appears to be <br />limited to the immediate vicinity of well MW2 and concentrations of petroleum constituents are <br />declining, which has been verified through twelve quarters of groundwater monitoring <br />RECOMMENDATIONS <br />Based on the results of the third quarter 2002 monitoring episode and the results of the previous <br />groundwater monitoring events, it appears that the hydrocarbon plume in the groundwater is <br />stable and shrinking, and we recommend the site be granted closure A Site Closure Report has <br />been prepared on behalf of Ripon Unified School District and was submitted June 27, 2002 <br />w 1130991quart1yl3gr-2402 doe 3 <br />