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r 7 , CLEARWATER - ` G , R O U .P, I N C. ~ 3.2 Results Of Soil Field Screening'and Sample Analysis t TPHg, TPHd'and all BTEX compounds were detected in concentrations exceeding the method detection limits 'in soil samples collected'.from all. three'-,borings. Maximum detected concentrations included 2,000 parts per million.(ppm) of TPHg ` 'in the 31- foot sample from. MW-1, 17 ppm of benzene in the 31 foot sample from ' MW-1. and the 35:5 foot sample from MW-2 and 120'ppm of TPHd in the 35.5 foot , sample.from MW-2:- Soil sample analytical results are presented on Table 1. With the exception'of the sample .collected from 36 feet bgs in MW-1, a'positive correlation between field organic vapor measurements and laboratory-determined. " contaminant concentrations is observed. 'Lab analysis of the referenced samplefrom ; MW-1 showed'lower than expected concentrations of hydrocarbon compounds. Lab _results and field observations indicate that the . concentration of fuel t hydrocarbon constituents.is greatest in the unit of silt immediately beneath the sand layer, encountered .from 20.5 to 31 feet bgs. .Hydrocarbon concentrations generally ' decrease significantly with depth below this horizon. A copy of the laboratory report and-chain-of-custody form for the referenced"soil samples is presented.in Appendix . E. Field OVM readings are shown'on the soil boring.logs included in AppendixC. 3.3 Water Bearin ,Zane Characteristics and Groundwater Gradient Groundwater was first encountered during drilling-at approximately 50 feet bgs. On May 1, 1995, the depth to ground water in each of the wells ranged, from 45.87 to ' 47.26 feet bgs. While a slight rise in"groundwater levels was observed following the completion of the. monitoring wells, it does not appear as if groundwater occurs under,.confined conditions. The rise Was more likely 'attributable to the slow're'lease of water from the, silt and silty sand in the water bearing .zone- following the Installation of .the monitoring wells. Depth to water measurements I and wellhead elevation data were used to calculate groundwater elevation contours '(Figure. 3). G_ roundwater flow direction was determined to be towards ,the north, 'at an approximate radient--'of 1.7%. 'A . PP g _ . hydrocarbon sheen was observed on waterpurged from MW-1 and MW-2. I3.4 Results of Groundwater`Sample Analysis, - •TPHg and all B,TEX compounds were detected' in concentrations exceeding the r method detection limits- 'in groundwater samples collected from all; three monitoring Wells. The highest TPHg and benzene concentrations were 120,000 parts per.billion_(ppb) and 18,000 ppb, respectively,,in the sample collected from MW-2. i The lowest benzene- concentration detected was 1,300,. ppb".:in the sample collected' D-105 PSA. 4 ' . May 25, 1995"