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I 27 July 1998 AGE-NC Project No 95-0130 IPage 2 of 5 2 2 GROUND WATER SAMPLING The ground water levels In all monitoring wells achieved a minimum of 80 percent recovery prior to sample collection Ground water samples were collected utilizing disposable polyethylene bailers and new nylon rope Sufficient ground water sample was collected from each well to fill three EPA- approved 40-m1 VOA vials containing 0 5 ml 18%hydrochloric acid as a sample preservative Care was taken to ensure that visible air bubbles were not present in the VOA vials after filling and capping Ground water sample containers were labeled with the well designation, date, time, and sampler's Initials 2 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 Itransported to a California state-certified laboratory for analysis in accordance with • EPA Method 8015M for total petroleum hydrocarbons quantified as gasoline (TPH-g), • EPA Method 8020 for volatile aromatics (benzene, toluene, ethyl benzene and xylene BTE&X) with methyl-tertiary butyl ether (MTBE), and ' • EPA Method 8260 for volatile organics (Including oxygenates) ' 3.0. FINDINGS I3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT The depth to ground water in wells MW-1 through MW-5, VW-1C, VW-2A and VW-3A was ' measured at 40 53 to 42 24 feet below the top of well casings Between December 1997 and June 1998, ground water elevation Increased an average 6 36 feet at the site The ground water elevation data for MW-1 though MW-5 during the June 1998 ground water monitoring event is depicted in ' Figure 3 ' During the June 1998 monitoring event, the ground water surface was between 9 17 and 19 47 feet above the top of screened Intervals from monitoring wells MW-1 through MW-5, ground water was between 0 76 and 6 33 feet above the top of screened Intervals from extraction wells VW-1 through ' VW-3 As a result,the screened Intervals from these wells are completely submerged, and may not yield water samples fully representative of ground water conditions near the top of the saturated zone where fuel hydrocarbons would be expected to have the greatest Impact Advanced GeoBnN irpnmental,Inc I