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Report of Findings s g Frontier Transportation 0200-024 March 3, 2000 Page 3 define the vertical extent of soil contamination (See Figure 2). Borings were advanced using a direct push hydraulic rig. Soil samples were collected in clear acetate liners 4-feet long throughout the length of the borings. Soil samples were screened for petroleum hydrocarbons in the field using a photoionization detector (PID). Soil samples were analyzed at 5-foot intervals except when no soil samples were obtained upon sampler retrieval. Borings were backfilled with 1 bentonite upon completion. BEII also installed four groundwater monitoring wells (MW-8 through MW-11) to define t the lateral extent of dissolved petroleum hydrocarbons beneath the site (See Figure 2). A hollow stem auger was used to install the monitoring wells. All four groundwater monitoring wells were advanced to 20' bg and screened from 5' bg to 20' bg. The screen slots were standard size 0.02- inch. The annular seal was filled with Monterey #3 sand to 4.5' bg. This was overlain with a a- foot bentonite seal and then grouted to surface. Soil samples were collected at 5-foot intervals from a split spoon sampler that contains three brass liners, which are 2 inches in diameter and 6 ' inches long. Soil samples were screened for petroleum hydrocarbons in the field using a PID. A total of twenty-four(24) soil samples collected from borings B-5 and B-6 and , . monitoring wells MW-8 through MW-I I and analyzed for TPH-g, BTEX, and MTBE using EPA methods 8015 and 8020. Detectable concentrations of MTBE were quantified using EPA method 8260 (See Table 2 for Soil Sample Results and Appendix B for Laboratory Analytical Reports). MTBE was identified exclusively in boring B-6 at 10' bg, 15' bg, and 30' bg. MTBE concentrations were identified as 15,000 pg/kg, 54 pg/kg, and 30 pg/kg respectively, using EPA method 8020. The two high MTBE concentrations were quantified using EPA method 8260 and identified 10,600 ' pg/kg and 37 pg/kg as MTBE, respectively. Soil sample analysis identified detectable concentrations of TPH-g in boring B-6 at 10' bg as 100 mg/kg, exclusively. TPH-g concentrations attenuate to non-detect in boring B-6 at 15' bg. No other detectable concentrations of TPH-g were identified out of the 24 soil samples collected and analyzed. Maximum total BTEX concentrations were identified in boring B-6 at I0' bg as ' 2,343 4g/kg. Total BTEX concentrations attenuate to 34 }Lg/kg at 15' bg and to 10 pg/kg at 20' bg in boring B-6. Benzene exclusively was also identified as 10 µg/kg in boring B-6 at 25' bg and from monitoring well MW-8 at 5' bg. No other soil samples identified any detectable - concentrations of BTEX. The majority of soil contamination was encountered at 10' bg in boring B-6. An attenuation of petroleum hydrocarbon concentrations to greater than 99% was identified in boring