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Ms. Carol Oz 3 December 17, 1999 <br /> concentration was 0.66 ug/L in the groundwater sample obtained from groundwater monitoring <br /> 4 <br /> ' well MW-2. <br /> In March 1996, groundwater samples obtained from groundwater monitoring wells MW-1R, <br /> MW-2, MW-5, MW-6 and MW-7 were first analyzed for methyl tert-butyl ether (MTBE) in <br /> accordance with EPA Test Method 8020. MTBE was present in groundwater samples obtained <br /> from MW-1R, MW-2 and MW-5. The maximum MTBE concentration was present in the <br /> groundwater sample obtained from MW-5 (1,100 ug/L). MTBE concentrations in MW-5 <br /> subsequently decreased steadily for five quarters until September 1997 when the MTBE <br /> concentrations rose back to 1,100 ug/L. <br /> In a letter to Quik Stop Markets Inc. dated April 1, 1997, the San Joaquin County Public Health <br /> ' Services Environmental Health Division stated the that "the only remaining issue at the site is the <br /> MTBE currently being detected in Monitoring Well MW-5". The San Joaquin County Public <br /> 1 Health Services Environmental Health Division recommended the sampling of only Monitoring <br /> Well MW-5 for future quarterly monitoring events, therefore, no other groundwater monitoring <br /> wells at the site were sampled during the first quarter 1998 sampling event. However, in a letter <br /> to Quik Stop Markets Inc. dated April 27, 1998, the San Joaquin County Public Services <br /> tEnvironmental Division stated that "each quarter sample and analyze water from all groundwater <br /> monitoring wells until further direction from the San Joaquin County Public Health Services <br /> Environmental Health Division". <br /> ' On March 1, 1999, ATC completed six soil borings (ATC-1 through ATC-6) to further assess the <br /> vertical and lateral downgradient extent of MTBE concentrations in soil and groundwater related <br /> 1 to the site. Soil and groundwater samples were obtained at each location. The soil and <br /> groundwater samples were analyzed for TPH-G, BTEX, and fuel oxygenates including tent- <br /> ' butanol, MTBE, di-isopropyl ether (DIPE), ethyl-tert-butyl ether (ETBE) and tert-amyl methyl <br /> ether (TAME). TPH-G and BTEX were not detected in any of the soil samples. Tert-butanol <br /> was detected in soil samples obtained from ATC-5-18' and ATC-6. MTBE was detected in soil <br /> samples obtained from ATC-1, ATC-5-18', and ATC-6. TPH-G was detected in groundwater <br /> samples obtained from ATC-2, ATC-3, and ATG-6. BTEX (at least one constituent) was present <br /> in groundwater samples obtained from ATC-2, ATC-3, ATC-5-20', and ATC-6. Tert-butanol <br /> 1 <br />