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July 27, 2001 Project No 2005-2050-01 page 7 . and BTEX were detected at 93 feet bgs at offsite boring CPT-11 TPHG (1 2 mg/kg) and total xylenes (11 µg/kg) were detected at 122 feet bgs at CPT-2 MTBE, ETBE, TAME, DIPE, TBA, and 1,2-DCA were not detected in any of the soil samples Groundwater analytical results (from samples collected during the CPT testing) are presented in Table 3 and Certified Analytical Reports with chain-of-custody documentation are presented in Appendix D Concentrations of TPHG, benzene, TBA, and 1,2-DCA to groundwater at select CPT locations are shown on cross sections A-A' through D-D' (Figures 7 through 10) The highest concentrations of benzene (23,000 µg/l) and toluene (26,000 µg/l) in groundwater were detected at 88 feet bgs at boring CPT-10 The highest concentration of ethylbenzene (4,300 pg/1) and total xylenes (30,100 µg/1) In groundwater were detected at 87 feet bgs at boring CPT-11 TPHG was detected at 150 mg/l at CPT-10 (88 feet bgs) and CPT-11 (87 feet bgs) in groundwater Toluene (0 94 µg/1 and total xylenes (0 90 µg/1) were detected at 132 feet bgs (the lower- most sampling interval) at boring CPT-1 TPHG and BTEX were detected at 152 feet bgs at boring CPT-8 TPHG was detected at 86 feet bgs at boring CPT-13 at a concentration dust above laboratory method detection limits The vertical extent of petroleum hydrocarbon impact to groundwater was not determined at borings CPT-1, CPT-8, and CPT-10 TBA and 1,2-DCA were detected in groundwater samples collected at bonngs CPT-1, CPT-4, CPT-8, and CPT-13 1,2-DCA was also detected to samples collected at borings CPT-5, CPT-7, CPT-10, and CPT-11 MTBE, ETBE, TAME, and DIPE were not detected in any of the groundwater samples Groundwater analytical results of samples collected from monitoring wells MWA, MW- 2, and MW-4 through MW-12 are presented In Table 1 MW-3 had an obstruction and was not sampled The highest concentrations of TPHG and BTEX were detected in the sample collected from monitoring well MW-9 TPHG and BTEX were also detected in the samples collected from monitoring well MW-1, MW-5, and MW-8 1,2-DCA was detected in the samples collected from monitoring wells MW-1 (290 µg/l), MW-2 (180 µg/1), MW-5 (40 µg/1), MW-6 (9 1 µg/1), and MW-10 (39 µg/1) TBA (70 µg11) and benzene (0 90 µg/1) were detected in the sample collected from monitonng well MW-10 MTBE was reported at a concentration of 0 66 µg/l in the sample collected from monitoring well MW-5 RECOMMENDATIONS Based on the data collected during the soil and groundwater investigation, further assessment is warranted Two additional groundwater monitoring wells should be installed north of the former UST to a depth of approximately 90 feet bgs (benzene detected at 6,700 ug/l to CPT-11) The proposed groundwater monitoring wells can be used to evaluate the lateral extent of petroleum hydrocarbon impact to groundwater in the water bearing zone encountered from approximately 85 to 90 feet bgs in the northern portion of the study area Further assessment should also be performed south and east of . CPT-10 to define the vertical extent of hydrocarbons that were detected in soil and water samples collected from CPT-8 and CPT-10 C Trolect FileslApache PlasticslReportslApache Soil&GW 072001 A doe I