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Geological Techgics W Page 2 Groundwater Monitoring Report Project No 640 2 May 8,2002 ' The groundwater gradient flow direction at the UST portion of the site has been consistently to the west or northwest for the nine events that it was measured a is Figure 2 groundwater gradient map for the event of January 17, 2002 A rose diagram g illustrating the historical groundwater gradients is presented in Figure 3 Table 1 in rAppendix A contains the groundwater elevations and gradients to date 12 Groundwater Sampling Procedure On January 17, 2002, Del-Tech Geotechnical Support personnel arrived on-site, opened the wells and measured the depths to water with an electrically actuated sounding tape The water level readings were recorded to an accuracy of 0 01 foot In wells where free-floating product is suspected, a clear disposable bailer is used to gauge the interface During this monitoring, free product was not observed Stagnant water in the well casing was purged using a centrifugal pump, as recorded on the field logs (Appendix Q The rate of well purging was monitored The wells were purged of at least three casing volumes and until the groundwater parameters (temperature, conductivity and pH) had stabilized (Appendix Q indicating that water representative of actual aquifer conditions was entering the well Groundwater parameter stabilization was characterized by three successive readings within 10% Before a sample was collected, the well's water level was allowed to recharge to at least 80% of the initial level All water removed from the monitoring well and not used as a sample, was placed in a properly labeled 55-gallon DOT (Department of Transportation) approved container and temporarily stored on-site A stainless steel bailer was used to collect each sample Extreme care was exercised while collecting samples to prevent agitation of the water contained in the bailer Water samples were transferred from the bailer into 40-m1 VOA vials preserved with hydrochloric acid, using a bottom-emptying device that minimizes sample aeration during transfer of the sample All samples were checked for headspace bubbles, labeled, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory The sampling technician wore disposable gloves while collecting all samples A chain of custody document, listing all samples collected and their intended analyses, accompanied the samples from the field to the laboratory, thereby providing a means to track their movement and insure their integrity