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i i Site Background Information : Stallworth Auto Sales Page 8 of 11 The following COC were detected in the soil samples collected from boring MW11 : • TPH-g was detected in soil samples collected from MW 11 at depths of 60 feet , 65 feet and 70 feet bsg at concentrations of 320 mg/kg , 340 mg/kg and 44 mg/kg, respectively. • TPH-d was detected in soil samples collected at depths of 50 feet, 60 feet and 65 feet bsg at concentrations of 150 mg/kg , 140 mg/kg and 130 mg/kg , respectively. • BTEX compounds were detected at depths of 60 feet, 65 feet and 70 feet bsg at maximum concentrations of 0 . 17 mg/kg benzene (60 feet bsg) , 4 .0 mg/kg toluene (60 feet bsg), 1 .9 mg/kg ethylbenzene (60 and 65 feet bsg) , and 11 . 7 mg/kg total xylenes (60 feet bsg ) . • TAME was detected at depths of 60 feet , 65 feet and 70 feet bsg at concentrations of 0 . 11 mg/kg , 0. 15 mg/kg and 0 .060 mg/kg , respectively. • 1 ,2-DCA was detected at depths of 60 feet and 65 feet bsg at concentrations of 0 . 034 mg/kg and 0 .038 mg/kg , respectively. • The following additional VOCs were detected : 0 .23 mg/kg (60 feet bsg), 0.43 mg/kg (65 feet bsg ) and 0 . 070 mg/kg (70 feet bsg) isopropylbenzene ; 0 . 96 mg/kg (60 feet bsg), 1 . 1 mg/ kg (65 feet bsg ) and 0 . 16 mg/kg (70 feet bsg) n-propyl benzene ; 2 .2 mg/kg (60 feet bsg ), 0 . 22 mg/kg (65 feet bsg ) and 2 . 1 mg/kg (70 feet bsg ) 1 ,315- trimethylbenzene; 7 . 1 mg/kg (60 feet bsg ), 7. 0 mg/kg (65 feet bsg ) and 0 .30 mg/kg (70 feet bsg ) 1 ,2 ,4-tri methyl benzene ; 0 . 11 mg/kg (60 feet bsg ), 0 . 16 mg/kg (65 feet bsg) and 0 . 020 mg/kg (70 feet bsg) p-isopropyltoluene ; 1 .3 mg/kg (60 feet bsg), 2 .0 mg/kg (65 feet bsg) and 0 .21 mg/kg (70 feet bsg) naphthalene ; and 0 . 10 mg/kg (70 feet bsg ) n butylbenzene. HYDROGEOLOGIC MODEL Hydrogeologic or hydrostratigraphic units (HUs) are defined as a body of rock or sediment that has hydrogeologic characteristics (i . e . hydraulic conductivity, pore pressure, etc. ) that make it distinct from surrounding bodies of rock or sediment (Sanders, 1998 ), or a part of a body of rock that forms a distinct hydrologic unit with respect to the flow of ground water (Maxey, 1964 ). A 'flow unit' may be defined as a hydrogeologic unit and is characterized by significantly greater hydraulic conductivity values than overlying and underlying units ; a flow unit is capable of serving as a preferred migration route , and could potentially allow migration of large contaminant masses over great distances. Based on the CPT results and comparison with soil descriptions from borings previously advanced on-site , AGE has refined the previous subsurface hydrogeologic model presented in the AGE-prepared Cone Penetrometer Testing Report, dated 10 December Advanced GeoF,nvirmimental, Inc.