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R603 UPDATE-12 12/22/92 i 2 2 GROUND WATER QUARTERLY SAMPLING Ground water samples were: collected on December 9, 1992, see Table 1 . These samples were collected by a WEGE sample technician and "Chain of Custody" hand delivered on ice to a state certified testing laboratory (MATRIX Analytical Laboratories) for chemical analyses These samples were analyzed for TPH and BTEX concentrations using EPA Methods 8015 and 602 respectively. Since diesel has never shown up in the sample results, the samples obtained on 11/27/90 and later were analyzed using EPA methods 5030 and 602 for Total Feel Hydrocarbons and BTEX The next quarterly sampling will occur in March, 1993 3 . 0 RESULTS 3 . 1 PRODUCT AND RECOVERY During the initial site assessment and subsequent site visits, floating product was observed in monitor wells MW-1, MW-3 and MW10 Product thickness in MW-1 has ranged from 0 01' to 1 26 ' and from 0 17' to 1 . 66' in MW-3 Only a product sheen has been observed in MW10 during the March, June and September, 1991 and the March 10, 1992 sampling Observations made during this update status report period show that all wells are free of any floating product, see Figures 5A and 5B and Table 1 The removal of the floating product can be attributed to the active vapor extraction at this site 3 . 2 GROUND WATER SAMPLE RESULTS With the exception of MW10, ground water samples were obtained from all of the monitoring wells, MW10 did not recharge enough volume for a sample This latest sample results shows the continual decline in contaminant levels associated with the ground water at this site Of the wells that have some degree of ground water contamination (MW1, MW2 , MW3 , MW8 and MW12) MW1, MW2 and MW3 showed reductions MWS continues to show fluctuations and increased from the September, 1992 sampling These fluctuations seem co be associated with ground water elevation, as is shown on Table 1, gasoline range hydrocarbons an concentrations of 5 ppm or greater are associated with depth to ground water measurements between 53 . 5 feet to 55 22 feet, samples obtained outside these depths are 3 ppm or less . The increase in contaminant concentrations found at MW12 is thought to be associated with similar conditions as found at MW8 Whereas, contaminant levels are associated with the ground water elevation and associated Qo'ls that have capillary contamination upgradient of MW12 , see Table 1 and Figures 5A, 5B and 6 . PAGE 4