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12 June 1996 <br /> AGE-NC Protect No 95-0104 <br /> Page 2 of 5 <br /> borings and in ground water samples collected from MW-1 Between 1988 and 1992, this well <br /> became dry due to a declining water table <br />' Between December 1992 and September 1993,three additional monitoring wells(MW-2,MW-3 and <br /> MW-4)were installed at the site Petroleum hydrocarbons were not detected in soil samples collected <br />' during installation of the additional wells However, bromomethane was detected in one soil sample <br /> collected from MW-4 Installation and sampling procedures, and the results of laboratory analysis <br /> were included in the Quarterly Report - October 1993 prepared by Geological Audit Services, Inc <br />' On 04 April 1995, one vapor extraction well (VW-1)was installed at the site near the center position <br /> of the former UST Petroleum hydrocarbons were detected in soil samples collected during well <br />' installation at concentrations as high as 14,000 parts per million (ppm) Subsequently, AGE <br /> performed a soil vapor extraction (SVE) pilot test in March 1995 to evaluate remedial options for <br /> the site Details of the SVE pilot test, as well as recommendations for soil and ground water <br />' remediation, were included ;n the Corrective Action Plan dated 28 April 1995, prepared by AGE <br /> 3.0 PROCEDURES <br /> 3 1 MONITORING WELL PURGE PROCEDURES <br />' On 24 April 1996 the depth to round water in each monitoring well was measured to the nearest <br /> P � P g b <br /> 0 01 foot utilizing a Solinst water level meter Relative ground water elevations were calculated by <br /> subtracting the depth to ground water from the relative casing elevations surveyed from a temporary <br /> benchmark (Table 1-Relative Ground Water Elevations) Relative ground water elevations were <br />' plotted and contoured on a scaled site map, from which the ground water gradient was estimated <br /> (Figure 3- Relative Ground Water Elevation A1ap) <br />' After water levels were measured, a minimum of three well volumes of ground water were purged <br /> from each well using a Grundfos Redi-Flo II submersible pump Between 7 5 and 15 gallons of <br /> water were removed from MWA and VW-1,between 75 and 90 gallons of water were removed from <br />' wells MW-2, MW-3 and MW-4 <br /> Temperature, pH and conductivity were measured at regular intervals from each well using an ICM <br />' model 52200 water analyzer Stabilization data and field logs are in Appendix A Purged ground <br /> water was stored in 55-gallon drums on-site in an area inaccessible to the general public <br /> 1 <br /> 1 <br />