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1 ' 12 June 1996 AGE-NC Project No 95-0130 ' Page 3 of 5 ' 3 0. QUARTERLY MONITORING PROCEDURES ' 3 1 MONITORING WELL PURGE PROCEDURES On 26 April 1996, the depth to ground water in each monitoring well was measured to the nearest ' 0 01 foot utilizing a Solast water level meter The relative ground water elevations were calculated by subtracting the depth to ground water from the relative casing elevations surveyed from a ' temporary benchmark (Table 1- Relative Ground Water Elevations) Relative ground water elevations were plotted and contoured on a scaled site map (Figure 3 - Relative Elevation Ground Water Map) ' After water levels were measured, approximately 10 to 14 gallons of water (minimum of three well volumes) were removed from wells MW-1 through MW-5 utilizing a Grundfos Redi-Flo II submersible pump Temperature, pH and conductivity were measured at regular intervals from each well using an ICM model 52200 water analyzer Stabilization data and field logs are included with Appendix A Purged ground water was stored in 55-gallon drums and stored on-site in an area inaccessible to the general public 3 2 GROUND WATER SAMPLING Monitoring wells MW-1 through MW-5 were allowed to recover for a minimum of one hour prior to sample collection Water samples were collected utilizing dedicated, disposable polyethylene bailers and new nylon rope Sufficient ground water sample was collected from each well to fill three 40-m1 EPA vials containing hydrochloric acid as a preservative for the samples, and a one-liter amber bottle lacking hydrochloric acid Care was taken to ensure that visible air bubbles were not present in the VOAs after filling and capping Ground water sample containers were labeled with the well designation, date, time, and sampler's initials 3 3 LABORATORY ANALYSIS OF GROUND WATER SAMPLES Each ground water sample was logged on a chain-of-custody form,placed in a chilled container and transported to Castle Analytical Laboratories (CAL), a California state-certified laboratory for analysis of hazardous materials Each sample was analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g), volatile aromatics (benzene, toluene, ethyl benzene and xylene BTE&X), and methyl-tertiary butyl ether(MTBE) in accordance with EPA methods 5030 and 602, respectively The laboratory report (CAL Laboratory No 742) and chain-of-custody forms are presented in Appendix B