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i r02 June 1999 AGE-NC Project No 97-0326 ' Page 6 of 7 Ground water elevation contours based upon the data for the December 1998 monitoring event is ' illustrated on Figure 3 The ground water flow direction was calculated to be S 13° E with a gradient of 0 0072 ft/ft 4 4 ANALYTICAL RESULTS OF WATER SAMPLES TPH-g was detected in MW1, MW2 and MW3 at concentrations of 190,000 parts per billion (ppb, reported as micrograms per liter), 110 ppb and 330,000 ppb, respectively BTEX compounds were ' detected at concentrations as high as 29,000 ppb, 54,000 ppb, 6,500 ppb and 36,000 ppb, respectively (MW3) MTBE was detected in MW1, MW2 and MW3 at concentrations of 510 ppb, 24 ppb and 260 ppb, respectively TBA was detected in MW I and MW2 at concentrations of 830 ppb and 42 ppb, respectively DIPE, ETBE and TAME were not detected at the site Analytical results of water ' samples are summarized on Table 3 The laboratory report(AAL Batch No 98-1218-012), chain-of- custody hain-ofcustody forms and QA/QC are included in Appendix E 1 • 5.0. SUMMARY AND CONCLUSIONS Based on the data collected from the site, AGE finds ' • High concentrations of petroleum hydrocarbons have been detected in soil samples collected beneath the former UST location at depths as great as 40 feet bsg Low hydrocarbon concentrations were detected at depths of 45 and 55 feet bsg beneath the former UST location • High concentrations of hydrocarbons were detected beneath the southern dispenser island to the total depth explored (45 feet bsg) Low concentrations of hydrocarbons were detected beneath the northern dispenser island 1 • The lateral and vertical extent of impacted soil has not been defined at the site • The calculated ground water flow at the site is toward the south However, historical ground water flow at adjacent sites has been toward the northeast ' • Very high concentrations of petroleum hydrocarbons were detected in ground water samples collected from all three monitoring wells installed at the site Hydrocarbon concentrations ' detected in the sample collected from MW3 may indicate the presence of unencountered or • undetected free product at the site Ad►anced GeoEnwonmentei,Inc