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08 January 1996 • AGE-NC Project No 95-0137 Page 3 of 4 Temperature, pH, and conductivity were measured at approximately one-gallon intervals using an ICM Water Analyzer Model No 52200 Purged water stabilization data and field data sheets are included in Appendix A The purged water was stored on-site in 55-gallon drums 3 2 GROUND WATER SAMPLE COLLECTION After stabilization,water samples were collected from each well using a new, clean, disposable Teflon bailer The samples were transferred into 40-m1 EPA vials and 1-liter amber bottles and subsequently transported in a chilled container, under chain-of-custody,to Castle analytical Laboratory, in Atwater, California The samples were analyzed for TPH-g, TPH-d and BTE&X in accordance with EPA methods 503018015, 5030/8015m and 602, respectively ' 4.0. FINDINGS 4 1 GROUND WATER GRADIENT AND DIRECTION On 09 October 1995, the depth to ground water at the site ranged from 19 02 to 19 72 feet The data indicates a decrease of approximately 0 2 feet in each well since May 1995 Based upon data collected during this monitoring event, the ground water gradient was calculated to be 0 00078 ft/ft, directed southwest (Figure 3) The flow direction seems to be consistent with seasonal changes observed at the site Ground water elevation data is summarized on Table 1 4 2 PETROLEUM HYDROCARBON-IMPACTED GROUND WATER TPH-g was detected in each monitoring well at concentrations ranging from 83 ppb in MW-5 to 14,000 ppb in MW-2 TPH-d was also detected in samples from each well at concentrations ranging ' from 430 ppb in MW-5 to 12,000 ppb in MW-2 Samples from MW-1 and MW2 were found to contain BTE&X at concentrations up to 1,000 ppb (MW-2, benzene) No BTE&X were detected in samples from MW-3, MW-4 or MW-5 The analytical results of ground water samples are summarized in Table 2 The laboratory report and chain-of-custody are included in Appendix B 5.0. CONCLUSIONS AND RECOMMENDATIONS ' In October 1995,the highest concentration of dissolved hydrocarbons in ground water was detected in MW-2, located in the northern portion of the property The lowest concentrations of petroleum ihydrocarbons were detected in wells MW-4 and MW-5, west and south of the former UST areas