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1 <br /> assessment of the impacted soil and groundwater Between 1987 and 1992, 10 groundwater <br /> monitoring wells were installed at the site <br /> I No petroleum hydrocarbons were detected in soil samples collected during the installation <br /> of the monitoring wells, only very low organic vapor readings were detected in samples from <br /> MW-6 and MW-7 However, no investigation of soil in the vicinity of the tank pit or <br /> Inorthwest of MW-2 has been undertaken <br /> 2.4 Groundwater Monitoring <br /> Groundwater samples have been collected at the site on seven occasions since June 1987 <br /> Petroleum hydrocarbons were detected in the groundwater in the vicinity of the former <br /> dispensers GTI has delineated the groundwater plume as having a roughly elliptical shape, <br /> extending from MW-2 at the south to near MW-5 at the north The center of the plume has <br /> apparently remained near NNW-6 (GTI report dated March 3, 1992) <br /> The depth to groundwater at the site vias approximately 8 feet below surface grade durinb <br /> the last sampling event (January 1992) Groundwater flow direction at the site has <br /> historically been to the north at a gradient of approximately 0 01 ft;ft <br /> Since 1992, representatives of LSD haze been collecting and reporting ¢round"zater depths <br /> in all wells intermittently The most recent report %gas dated INSaich 29M1994. groundwater <br /> depths ranged from approvniately 7 9 feet to 8 5 feet <br /> 30 PROCEDURES <br /> 31 ?Monitoring Well Purge Pioceduies <br /> On October 13, 1994, the water levels in all ten wells were measured relative to the top of <br /> the casing, on November 23, 1994, the water levels were measured in NIW-2, MW-3, MW-4 <br /> and MW-8 Groundwater depths were measured using a Solinst water level Dieter The <br /> relative piezometrrc level in each well and hydraulic gradient ,veie. determined from these <br /> data Groundwater depth data is included in Table 1 <br /> After depth measurements were collected, a submersible pump was used to remove <br /> apprommately 4 or 5 gallons of water from each well (except MW-2) to stabilize <br /> temperature, pH and conductivity Stabilization parameters were measured at one-gallon <br /> intervals using an ICM Water Analyzer A disposable bailer was used to remove water fiorn <br /> MW-2 Only one pint of water was removed from MW-2 before it was bailed dry Purge <br /> water was stored on-site in DOT drums Field data sheets are included in Appendix A <br /> Gnbgcal AW.1 S.-A 1. <br /> SC%07 10 oCCZ4,AXIMEASM UZ Q W 2 9i <br />