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10 January 1996 <br /> AGE-NC Project No 95-0105 - <br /> Page 3 of 4 <br /> 3.0. PROCEDURES <br /> 31 MONITORING WELL PURGE PROCEDURES <br /> rOn 19 October 1995, a Solinst water level meter was used to measure the depth to ground water in <br /> each well relative to the top of the well casing The ground water elevation to each well was were <br /> ' determined from these data(Table 1) <br /> Each monitoring well was then purged using a three-stage submersible pump Approximately 9 to <br /> ' 10 gallons of water(minimum of 3 well volumes) were evacuated from each well to stabilize ground <br /> water parameters Temperature, pH and conductivity were measured at 2-gallon intervals using an <br /> ICM model 52200 water analyzer Stabilization data and field logs are included in Appendix A <br /> Purged water was contained in 55-gallon drums for temporary storage on-site <br /> 3 2 COLLECTION OF GROUND WATER SAMPLES <br /> Water samples were collected from each monitoring well using new disposable bailers The samples <br /> were transferred into 40-m1 EPA vials preserved with hydrochloric acid and 1-liter amber bottles <br /> The samples were transported in a chilled container to McCampbell Analytical, Inc (MAI) in Pacheco <br /> and analyzed for total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d), <br /> volatile organics (benzene, toluene, ethyl benzene and xylenes BTE&X) and halogenated <br /> hydrocarbons in accordance with EPA methods 8015m, 602 and 601, respectively <br /> 4.0. FINDINGS <br /> ' 4 1 GROUND WATER ELEVATION AND GRADIENT <br /> The elevation of ground water in each well was calculated by subtracting the depth to ground water <br /> from the surveyed casing elevation (Table 1) Monitoring well casing elevations were surveyed <br /> relative to a City of Tracy bench mark Ground water dropped an average of i 1 feet between July <br /> ' and October 1995 <br /> Ground water gradient for 19 October 1995 was calculated to be 0 0032 ft/ft directed N 10° E The <br /> ' relative ground water elevation at the site is illustrated in Figure 3 -Relative Ground Watet Elevation <br /> Map Both the flow direction and hydraulic gradient are consistent with previous measurements at <br /> the site <br /> 1 <br />