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v o . A S S O C I A T E S I N C GROUNDWATER FLOW DIRECTION Water level measurements were collected from wells MW1 through MW5 on September 13, 2000 Water levels ranged from 21 21 to 22 09 feet below the tops of the well casing elevations, representing an average decrease in the water table elevation of approximately 1 72 feet since June 2000 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 southwest The average hydraulic gradient on September 13, 2000 was calculated to be 0 0006 ft/ft or approximately 3 ft/mile A summary of groundwater monitoring data is presented in Table 1 ANALYTICAL RESULTS The groundwater samples collected from wells MWl, MW2 and MW4 contained TPHd at concentrations of 57 parts per billion (ppb), 960 ppb and 55 ppb, respectively The groundwater sample collected from well MW2 also contained detectable concentrations of TPHg, toluene, ethylbenzene, and xylenes at concentrations of 3,400 ppb, 1 3 ppb, 83 ppb and 300 ppb, respectively Samples from wells MWl and MW4 contained no detectable concentrations of TPHg or BTEX . The groundwater samples collected from wells MW3 and MW5 contained no detectable concentrations of TPHg, TPHd, or BTEX Analytical results of groundwater samples are summarized in Table 2 and laboratory data sheets are contained in Attachment 2 ADDITIONAL SITE ACTIVITIES ATC contacted Dale J Ramey, city engineer for the City of Ripon, on September 8, 2000 to approve the discharge of purgewater from the site to the City of Ripon municipal sewer system Mr Ramey approved the discharge of up to 500 gallons of purgewater from the site into the sewer system On September 13, 2000, approximately 230 gallons of purgewater generated during the first, second, and third quarter 2000 sampling events was discharged manually to the City of Ripon sanitary sewer system CONCLUSIONS Concentrations from wells MW1 through MW5 remained consistent with the previous sampling event The direction and magnitude of groundwater flow is consistent with the previous event Groundwater elevations have decreased since June 2000 W M0991quart1y13gr-2000 doc 3