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r + . AA } Y ( 1 M 29 October 1998 ' AGE-NC Project No. 98-0448 w ' J Page 6 of 9 n z 3 2 FIELD EVIDENCE OF HYDROCARBON-IMPACTED SOIL AND GROUND WATER I ` An unidentified faint to intense odor was noted in soil sample duplicates collected from soil bonngs ' MW-4 at depths between 20 feet and 55 feet bsg, from MW-6 at depths between 30 and 40 feet bsg and from MW-7 at 40 foot bsg Organic vapor was detected from MW4(using a PID)In soilsample duplicates at concentrations as high as 264 parts per million (ppm) Intense petroleum hydrocarbon odor was detected inuarterly ground water samples collected from - 4 P wells MW-2 and MW4A Faint petroleum hydrocarbon odor was detected In ground water samples ' collected from wells MW-1, MW-413, MW-6 and MW-7 ' 3 3 GROUND WATER ELEVATION AND GRADIENT ' On 25 August 1998, the depths to first encountered ground water In wells MW-1 through MW-7 ranged between 16 17 and 18 03 feet below the tops of well casings Ground water elevations, as measured,on 25 August 1998,are depicted In Figure 9 Ground water elevation measured from MW- 4A(screened 8 to 33 feet) was measured 2 34 feet below ground water elevation measured at Mw- 4B (screened 45 to 50 feet) In August 1998, the general ground water gradient at the site was calculated to be approximately 0 009 ft/ft or approximately 46 feet per mile and directed towards the southwest I - On 16 September 1998,the depths to first encountered ground water in wells MW-1 through MW-7 ranged between 16 59 and 19 03 feet below the tops of well casings Ground water elevations, as measured on 16 September 1998, are depicted in Figure 10 Due to anomalous measurements, the ground water elevation data for MW-4B was not utilized to construct Figures 9 and 10 In September 1998,the general ground water gradient at the site was calculated to be approximately 0 015 ft/ft or approximately 79 feet per mile and directed towards the southwest A y rDue to the low gradient at the site, slight variations in-ground water measurements or-changes of recharge/discharge of the local ground water could greatly modify ground water flow direction 34 ANALYTICAL RESULTS OF SOIL SAMPLES A total of ten soil samples were submitted to a DTSC-certified laboratory for analysis of TPH-g, BTE&X and fuel oxygenates TPH-g was detected in soil samples collectedfrom soil boring MW-4 at concentrations as great as 9 5 ppm (milligrams per kilogram ppm) BTEX constituents were detected in soil samples collected from soil boring MW4 at concentrations Advanced Geo£nvironmentsl,Inc