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There was an increase in methyl tertiary butyl ether (MTBE) and tert- <br />. -jr butanol (TBA) concentrations in groundwater samples collected from <br /> monitoring well MW-3, near the diesel-fuel and high octane UST, to 650 <br /> parts per billion (ppb) and 2,700 ppb respectively These concentrations <br /> represent historical highs, and the first time these compounds have been <br /> detected in this well This MTBE concentration exceeds the California <br /> Department of Health Services (DHS) maximum contaminant level (MCL) <br /> for drinking water All other MTBE concentrations detected at the site <br /> were below previous laboratory detection limits and did not exceed t h e <br /> DHS MCL for drinking water No TBA was detected in groundwater <br /> samples collected from any of the other wells Methanol was detected in <br /> groundwater samples collected from monitoring well MWA, MW-2 and <br /> MW-8 at concentrations of 69 ppb or less No analyses for methanol were <br /> previously conducted <br /> Tetrachloroethene (PCE), trichloroethene (TCE) and cis-1 ,2-dichlororthene <br /> (cis-1,2-DCE) were detected in groundwater ndwater usam0es collected from <br /> monitoring well MW-1 at 26 ppb, 94 ppb and 1 ppb, respectively The <br /> PCE and cis-1,2-DCE concentrations exceeded DHS MCLs for drinking <br /> water Both TCE and cis-1,2-DCE are breakdown compounds of PCE <br /> 1,2-dichloropropane continues to be detected in the deeper wells (MW-7, <br />• MW-8, MW-9 and the drinking water well) at concentrations up to 1 8 <br /> ppb These concentrations do not exceed DHS MCLs for drinking water <br /> This compound has not been detected in groundwater samples collected <br /> from any of the shallower groundwater monitoring wells <br /> TPH-G was detected in groundwater samples collected from monitoring <br /> wells MW-4 and MW-6 at 86 ppb and 46,000 ppb, respectively No TPH-G <br /> was detected in groundwater samples collected from any of the remaining <br /> wells No TPH-D was detected in any of the groundwater samples <br /> collected this quarter <br /> The toluene, ethylbenzene and total xylenes concentrations in <br /> groundwater samples collected from monitoring well MW-6 exceeded DHS <br /> MCLs for drinking water These compounds were not detected in <br /> groundwater samples collected from any of the other groundwater <br /> monitoring wells No benzene was detected in groundwater samples <br /> collected from any monitoring well <br /> 6.0 RECOMMENDATIONS <br /> ASE recommends the following <br /> Frank's One Stop Quarterly Report -- December 1999 Sampling <br /> -4- <br />