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1 . r5 15 September 1995 AGE-NC Project No 95-0128 ' Page 2 of 3 ' 3.0. PROCEDURES 3 1 MONITORING WELL PURGE PROCEDURES On 30 June 1995, a Sohnst water level meter was used to measure the depth to ground water in the all wells at the site The relative piezometnc level in each well and hydraulic gradient were determined ' from these data (Table 1) Wells MW-1, MW-2, MW-3 and VW-1 were then purged of between 6 to 14 gallons of water each(minimum of 3 well volumes) using clean PVC bailers Temperature, pH and conductivity were measured at 1-or 2-gallon intervals using an ICM water analyzer Monitoring ' well stabilization data and field sheets are included in Appendix A Purged water was stored on-site in 55-gallon drums, pending laboratory analysis ' 3 2 COLLECTION OF GROUND WATER SAMPLES - Water samples were collected from each purged well using new, clean, disposable plastic bailers Immediately upon retrieval, the samples were transferred into two, chilled 40-m1 EPA vials preserved with hydrochloric acid and 1-liter amber bottles The samples were placed in a chilled container and transported under chain-of-custody to Alpha Analytical Laboratories, Inc (AAL) in Ukiah, California Each sample was analyzed for total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d) and volatile aromatics (benzene, toluene, ethyl benzene and xylenes BTE&X) in accordance with EPA methods 5030/8015m and 602, respectively 4.0. FINDINGS ' 4 1 GROUND WATER GRADIENT AND DIRECTION The depth to ground water ranges from 43 40 to 44 39 feet, indicating an average decrease of ground water elevation of approximately 0 25 feet since the March 1995 monitoring event The decrease in ground water elevation corresponds to a seasonal decrease typically observed in the region Ground water elevations are summarized on Table 1 Ground water elevation contours, based upon data collected on 30 June 1995, are depicted in figure 3 The ground water gradient and flow direction were calculated to be 0 0046 ft/ft directed N 28°W (Figure 3) Previously, ground water flow direction was calculated to be 0 002 ft/ft directed N 12°E Since March 1995, ground water flow direction has rotated approximately 40' to the west It should be noted that due to the significant rise in ground water at the site over the past two years, the water level is ten feet above the screened interval in MW-1 and approximately four feet above the screened intervals in wells MW-2 and MW-3 I