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4 Additional Soil and Groundwater Investigation Report Canepa s Car Wash(Park Street) I July 12,2004 Page 6 . the soil samples The lowest BTEX and TPH-G constituent concentrations were detected in the soil I sample collected at 95 7 feet bgs, the deepest sample collected Although the desired sampling depth of 115 5 feet bgs was not achieved due to sampler refusal, results of the sample collected at a depth of 95 7 feet bgs indicate that concentrations of TPH-G and BTEX constituents in the presumed source area soils Ehave attenuated with depth to levels near method detection limits TABLE 1 ISoil Sarni le Laboratory Analytical Results Aril 19, 2004 Other Soil Samples B T ELX MTBE Ox !nates/Additives TPH-G IReporting limits 0 005 0 005 0 005 0 010 0 005 <0 005—<0 50 1 0 Sample I D mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg mg/Kg 2038-B2-82 5-4/19/04 67 97 39 200 <2 0(d) <2 0 - <20 250 2038-132-95 7-4/19/04 <0 005 0 052 0 021 0 094 <0 005 <0 005 - <0 25 1 4 Unit Conversions Analytical mg/Kg milligrams per kilogram or parts per million(ppm) BTEX=benzene,to€uene,ethyl benzene,and total xylenes (d)Denotes elevated detection limit due to interference from TPH-G=total petroleum hydrocarbons,quantified as gasoline high concentrations of non-target analytes MTBE=Methyl Ternary-Butyl Ether r Other Oxygenates/Additives include Ethanol, tertiary-Butanol (TSA), Di- Isopropyl Ether (DIPE), Ethyl-tertiary-Butyl Ether (ETBE), tertiary-Amy] Methyl Ether(TAME),and 1,2-Dichloroethane(1,2-DCA) I . 4 3 GROUNDWATER SAMPLING RESULTS Laboratory analytical results of groundwater samples indicate that gasoline constituents were detected in the most distal down-gradient boring advanced to date (CPT6, approximately 175 feet northeast of the 1 site), and at the greatest depth explored to date (157 feet in CPT3) The groundwater sample collected at 1 a depth between 100 and 104 feet bgs in CPT6 detected TPH-G at 1,400 pg/L and benzene at 79 µg/L The groundwater sample collected at a depth between 154 and 157 feet bgs in CPT3 detected benzene at I a concentration of 3 3 pg/L, DIPS at a concentration of 3 2 pg/L, and 1,2-DCA at a concentration of 0 8 µg/L Highest concentrations of petroleum hydrocarbon constituents were detected in the shallow groundwater sample collected from CPT7 in the presumed source area at 140,000 �tg/L (TPH-G) and 32,000 pg/L, (toluene) Highest concentrations of benzene were encountered in each of the three down gradient groundwater samples collected from intermediate groundwater depths at 6,000 pg/L in CPT3 (80-84 feet), at 8,500 jtg/L in CPT4 (78-82 feet), and at 7,500 gg/L in CPT5 (82-86 feet) MTBE, DIPE, I and 1,2-DCA were sporadically detected in groundwater samples at low levels up to 16 pg/L, 4 1 µg/L, and 23 gg/L, respectively I The laboratory analytical results of the groundwater samples collected from the hydropunch borings are shown in Table 2, on the following page, and in Figure 2, Appendix A Shallow groundwater benzene (<35'), intermediate groundwater benzene (�!40 - <65'), intermediate groundwater benzene (>65 - <90'), I and deep groundwater benzene (>98') iso-concentration contour maps are included as Figures 3, 4, 5, and 6, respectively, Appendix A Laboratory Certificates of Analysis and Cham-of-Custody Records are included in Appendix C • f I � �� CONDOR