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' 19 July 2005 . AGE-NC Project No 05-1306 ' Page 2 of 4 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Ground water samples were collected from each monitoring well using the dedicated, disposable bailers after allowing the well to achieve a minimum 80%recovery of the pre-purge water volume The samples from each well were transferred into three 40-milliliter(ml)volatile organic analysis (VOA)vials containing 0 5 ml 18%hydrochlonc acid solution as a sample preservative,and into one 1-liter amber bottle without preservative The samples were labeled with the monitoring well designation, date,time of sampling, and the sampler's initials and transported in a chilled container under chain of custody to Kiff Analytical LLC (Kiff), a State of California Department of Health Services (DHS)-certified analytical laboratory, for analysis The samples were analyzed for ' • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 8260B, and ' • Total petroleum hydrocarbons quantified as diesel(TPH-d)in accordance with EPA Method 8015M 3.0. FINDINGS Ground water elevation and flow direction were inferred from field data, hydrocarbon impact to ground water was quantified by laboratory analysis of the ground water samples ' 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION The elevation of ground water in each of the monitoring wells was calculated by subtracting the ' depths to ground water from the surveyed relative casing elevations (Table 1) Depths to ground water ranged from 5 52 feet (MW-5) to 18 36 feet (MW-2) below the tops of the well casings Ground water elevation at the site ranged from 0 27 feet to 0 76 feet below mean sea level (MSL) During the May 2005 ground water monitoring event, ground water was inferred to be flowing toward the southwest and northeast under hydraulic gradients of approximately 0 056 footlfoot(ft/ft) ' and 0 011 ft/ft,respectively Historically,groundwater flow direction has been toward the southwest only,however,the low ground water elevation measured this quarter in well MW-1 skewed the flow direction north of wells MW-2 and MW-7 toward MW-1 During this monitoring event, ground 1 water elevations were within the screened Intervals ofthe wells,indicating that the wells are properly screened to yield samples representative of shallow ground water conditions Figure 3 illustrates the ' Advanced GeoEnvironmental,Inc 1