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1 <br /> 25 August 1995 <br /> AGE-NC Project No. 95-0136 <br /> Page 2 of 4 <br /> 2.4. MONITORING WELL INSTALLATION <br /> Betweeen June 1992 and June 1993 five ground water monitoring wells(MW-I through MW-5) were <br /> installed at the site. Low concentrations of toluene and xylenes were detected only in soil samples <br /> from MW-1, immediately north of the former UST. <br /> 2.5. GROUND WATER MONITORING. <br /> 1 Ground water at the site has been sampled on ten occassions between 1992 and 1995. Low <br /> concentrations of petroleum hydrocarbons have been consistently detected in samples from MW-1 <br /> and intermittently detected in samples from MW4 and MW-5. Monitoring procedures have been <br /> detailed in numerous Quarterly Reports,prepared by GAS between 1992 and 1995. Analytical results <br /> of ground water samples are summarized in Table 2. <br /> The depth-to-ground water at the site has fluctuated from 37 to 42 feet below surface. The ground <br /> water flow direction varied from northwest in November 1992 to northeast in February 1994. <br /> • 2:6. SOIL BORING INSTALLATION <br /> -1 to <br /> On 13 July 1994, GAS drilled one soil monitoring 7 feet north of monitoringng well MW determine if <br /> residual soil contamination was present. Three consecutive samples, from depths of 35, 40 and 45 <br /> feet, were analyzed for petroleum hydrocarbons; no petroleum hydrocarbons were detected in any <br /> of these samples. Therefore, it was detemined that no residual soil contamination was present in the <br /> area of <br /> 3.0. PROCEDURES <br /> 3.1. MONITORING WELL PURGE PROCEDURES <br /> On 222 May and 22 June 1995, a Solinst water level meter was used to measure the depth to ground <br /> water in each well relative to the top of each casing. The relative ground water elevations and <br /> hydraulic gradient were determined from these data(Table 1). <br /> After depth to ground water measurements, monitoring wells MW-1, MW-4 and MW-5 were purged <br /> ' using 2-stage submersible purge pump. The purge pump was decontaminated between each well using <br /> an Alconox solution. Approximately 8 to 11 gallons of water(minimum of three well volumes)were <br /> removed from each well to stabilize temperature, pH and conductivity. Stabilization parameters were <br />