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i h f III x 15 October 2000 AGE-NC Project No 96-0232 Page 14 of 15 Ethanol was detected in water samples collected from MW-10C, MW-10D, MW-11B, MW-13A and MW43B at concentrations as high as 120,000 µg/1 AGE suspects the high ' concentrations of ethanol detected in ground water samples collected from the multi-level ' monitoring wells were due to the coated bentonite pellets utilized during construction of the wells I I ' The elevated petroleum hydrocarbon concentrations detected in water samples collected from well MW-1 (screened between 9 and 24 feet bsg)suggest this well maybe screened within or near the dissolved petroleum hydrocarbon"core area" of the plume ' Between June and August 2000, MTBE concentrations decreased from'9 9µg/1 to non detect levels in samples collected from the Rocky's domestic drinking water well (RDW-1). 7,0, CONCLUSIONS The decrease of MTBE concentrations detected from well MW-1 samples between the June and August 2000 monitoring events may be related to the extraction of ground water from the adjacent extraction well EW-1 (screened 8% to 33'/2 feet bsg) Decreasing MTBE concentrations in ground water samples collected from EW-1 may indicate plume control and plume mass reduction in the area of EW-1 , ' AGE roughly calculates that the arithmetic average concentration of MTBE in ground water extracted during the quarter(771 ug/1) multiplied by 126,500 gallons (equivalent to 478,803 liters ' or 1,054,631 pounds) of water extracted yields 369 grams of MTBE removed from the plume of v impacted ground water Based on the conversion of one gram equal to 0 002205 lbs ,then 369 grams of MTBE can be multiplied by 478,803 liters to yield 0 81 pounds of MTBE removed with the ' 1,054,631 pounds of extracted water from EW-1 ,r Analytical results from the August 2000 quarterly monitoring event indicates the most intense on-site ' MTBE impact isan the First Zone of MW-1 (3,900µg/1), the most intense off site MTBE impact is , tn Rock y' Upper Zone of MW-11B (260 µg/1), probably influenced by the pumping operation=of RDW-1 Significant concentrations of MTBE were quantified in samples from well MW-7 (First Zone, 90 1,ig/1), MW-9A (Second Zone, 83 µg/1), and MW-13A (First Zone, 1 10 µg/1). Based on data collected from the intervening well MW-7, the MTBE-unpact detected in MW-13 may not be related to`a Flag City Chevron release Z Between the June and August,2000 monitoring events, significant TPH-g and TPH-d increases were quantified in MW-11B (Rocky's Upper Zone) Based on all ground water momtonng data collected ' during the investigation, the TPH-g and TPH-d impact detected in MW-11B and the TPH-gITPH-d impact detected in MW-12 and MW-13 may not be directly related to the Flag City Chevron release, ' additional investigation may provide more insight to the nature of the MW-12 and MW-13 , ' 3 Advanced GeoEnvironmentai,Inc,i I