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t Wright EnmronmerrW Sennoes Inc 6.1 CPT Groundwater Sampling Data P 9 Borings CPT-03, CPT-04 and CPT-05 generally confirm this contaminant dispersal (see Table 1) The A-aquifer depth samples were collected at depth intervals from between about 47 to 57 feet and 70-77 feet B-aquifer samples were collected at Intervals of about 115 to 120 feet Boring CPT-03 drilled up gradient of the site revealed no TPHG, BTEX or 1,2-DCA at 51-56 feet The small related aquifer strata at 73-77 feet revealed TPHG at 90 micrograms per liter (ugll) and 21 ug/1 DCA TPHG at 130 ug/l was present in the B-aquifer at 115-119 feet Boring CPT-04 drilled just down gradient east of the site showed no TPHG, BTEX or 1,2-DCA at 56-60 feet TPHG at 100 ugll and 1 2-DCA at 36 ugll was present at 71-75 feet In the A- aquifer No contaminants were present in the B-aquifer at 116-120 feet Boring CPT-05 drilled down gradient and across Charter Way showed 1,2-DCA at 12 ug/1 at 47-57 feet in the A-aquifer A longer interval was sampled through about 10 feet since the interval below about 53-57 feet did not yield any water for sampling The aquifer strata textures at 70 feet observed in boreholes CPT-03 and CPT-04 were not present at the CPT-05 location No contaminants were present in the B-aquifer at 115-120 feet 6.2 Discussion . CPT-03 revealed an up gradient source of TPHG and 1,2-DCA in the lower portion of the A- aqulfer (in the 70-75 foot depth) CPT-03 also revealed an up gradient source of TPHG in the B-aquifer These contaminants were present in the same ranges in CPT-04 A-aquifer sampling CPT-05 showed only 1,2-DCA in the shallow portion of the A-aquifer (47-57 feet) but no contaminants present in the B-aquifer The A-aquifer is complexly interbedded creating numerous vertical and lateral sediment facies changes that might create local contaminant pathways An interconnection of shallow and deeper A-aquifer beds between the 60 and 70- foot depths is interpreted near MW-2 This may account for presence of contaminant In the deeper beds east under Sheba Liquors Contaminant movement is Interpreted to have been slow through these beds and may have been Influenced by historic vertical rise in groundwater Contaminants may have migrated through a former vadose zone that has since become saturated due to the regional water level rise Into what is now the A-aquifer TBA was detected in CPT-04 at 5 1 ug/l and Chloroform at 5 0 ugll These detections are just at the detection limit These contaminants have not previously been historically observed in site monitoring and are attributed to drift of instrument detection in the chemical analysis Dissolved groundwater contaminant movement appears slow and limited on the basis of historic monitoring data Wells MW-2 and MW-3 have the most elevated levels and these wells are in the vicinity of the former tank pit where it is assumed that the majority of contaminant vertical migration occurred at the time of the leak Lateral movement appears limited and is attributed to the A-aquifer strata containing much dispersed fine-grained sediment This would tend to lower the overall vertical and lateral hydraulic conductivity Stefands—CPT Report Page 6 of 11