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08 January 1996 <br /> AGE-NC Project No 95-0137 <br /> Page 2 of 4 <br /> ' 23 INITIAL INVESTIGATION, APRIL 1994 <br /> On 27 and 28 April 1994, eight soil borings were drilled at the site under the direction of Geological <br /> Audit Services, Inc (GAS) Three of the borings were completed as 2-inch ground water monitoring <br /> wells Soil samples were collected at five-foot intervals during drilling and a total of fourteen soil <br /> samples were submitted to a state-certified laboratory for analysis Total petroleum hydrocarbons <br /> quantified as gasoline (TPH-g) were detected in ten samples at concentrations up to 3,800 mg/kg <br /> (parts per million ppm)in B4-20 Total petroleum hydrocarbons quantified as diesel (TPH-d) were <br /> detected in twelve samples at concentrations up to 9,000 ppm in B8-20 During drilling, ground water <br /> was encountered at a depth of approximately 20 feet <br /> After installation, each well was monitored and sampled Initially, the hydraulic gradient was <br /> ' calculated to be 0 0006 ft/ft, directed S 40° W TPH-g was detected in MW-1, MW-2 and MW-3 <br /> at concentrations of 1,700 pg/l (parts per billion ppb), 14,000 ppb and 2,600 ppb, respectively <br /> ' TPH-d was detected in MW-1, MW-2 and MW-3 at concentrations of 2,400 ppb, 9,200 ppb and <br /> 6,900 ppb, respectively <br /> 24 ADDITIONAL INVESTIGATION, AUGUST 1995 <br /> ' On 14 August 1995, five soil bonngs were drilled at the site under the direction of AGE B9 and B 11 <br /> were completed as 2-inch diameter ground water morutonng wells A total of eleven soil samples was <br /> submitted to a State-certified laboratory for analysis Volatile aromatic hydrocarbons (benzene, <br /> toluene, ethyl benzene BTE&X) were not detected in any of the soil samples analyzed TPH-g was <br /> detected in four samples at concentrations up to 23 ppm TPH-d was detected in six samples at <br /> concentrations up to 1,900 ppm During drilling, ground water was encountered at a depth of <br /> approximately 20 feet <br /> One grab ground water sample was collected from a boring located northeast of the former USTs <br /> Both TPH-g and TPH-d were detected in the grab water sample at concentrations of 6,500 and <br /> 450,000 ppb, respectively However, no BTE&X were detected in these samples <br /> 3.0. PROCEDURES <br /> ' 3 1 MONITORING WELL PURGE PROCEDURES <br /> On 09 October 1995, a Solinst water level meter was used to measure the depth to ground water in <br /> ' wells MW-1 through MW-5 The relative piezometric level in each well and hydraulic gradient were <br /> .' calculated from these data (Table 1) Each monitoring well was purged of approximately 5 to 7 <br />' gallons of water(a mini num of three well volumes)using a pre-cleaned two-stage submersible pump <br /> 1 <br />