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for benzene, toluene, ethylbenzene, and total xylenes (BTEX) and methyl tert-butyl ether <br /> (MTBE) by USEPA method 8020. MTBE was confirmed using USEPA method 8260. <br /> TPHG was detected in 5 of the 10 sampled monitoring wells at concentrations ranging from 650 <br /> pg/1 (MW-8) to 15,000 pg/1 (S-1). Benzene was detected in 5 of the 10 sampled monitoring <br /> wells at concentrations ranging from 3.5 µg/l (MW-4) to 1,200 µg/l (S-1). MTBE was detected <br /> by method 8260 in 6 wells at concentrations ranging from 0.82 µg/l (MW-6) to 15,000 �Ig/l (S- <br /> 1). Analytical data are summarized in Table 1 and illustrated on Figure 3. Certified Analytical <br /> Reports and chain of custody documentation are presented in Appendix B. <br /> 5 CONCLUSIONS <br /> Groundwater samples from 6 of the 10 sampled monitoring wells (MW-3, MW-4, MW-6, MW- <br /> 8, S-1, and S-2) contained detectable concentrations of petroleum hydrocarbons. Groundwater <br /> flowed toward the south-southeast and southwest during the second quarter 1999. <br /> As presented in the Remedial Action Pian, and based on telephone conversations with Mr. <br /> Harlan Knoll of the San Joaquin County Public Health Department, USA will submit a workplan , <br /> and drilling permit applications to install two additional groundwater monitoring wells and one <br /> • air sparge well. The two groundwater monitoring wells will delineate the extent of petroleum <br /> hydrocarbon impacts to the west-southwest of the site. The air sparge well will be used to <br /> remediate groundwater in the vicinity of the tank complex. <br /> The material and data in this report were prepared under the supervision and direction of the <br /> undersigned. <br /> Pinnacle Environmental Solutions Pinnacle Environmental Solutions <br /> �D GE��O <br /> HAROLD R. <br /> arold R. Drake,R.G. 6763 DUKE 48. Toi Anenson,C.E.M. <br /> Project Geologist No.8763 siness Line Manager <br /> CPIC:IWINDOWSITEMP10065g299.doc-951it:1 2 The IT Group <br />