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C3eofoguaf?echmcs Inc Page 2 Groundwater Monitoring Report Project No 425 2 September 22, 1998 • Table 1 of Appendix A summarizes the groundwater level to date Groundwater gradient calculations show that the dominant groundwater flow is in a northern direction with the slope ranging from 0 0012 up to 0 0289 ft/ft The gradient direction for this event was more easterly then has been observed at the site in the past 1.2 Groundwater Sampling}Procedure On May 29, 1998, Del-Tech Geotechnical Support personnel arrived on-site, opened the wells, and measured the depth to water with an electrically actuated sounding tape The water level reading was recorded to an accuracy of 0 01 foot In wells where free floating product was suspected, a clear disposable bailer is used to gauge the interface Stagnant water in the well casing was purged using either a Grundfos pump or electronic bailer as recorded in the field logs (Appendix C) 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 C) indicating that water, representative of actual aquifer conditions, was entering the well Groundwater parameter stabilization was characterized by three successive readings within 10% In this case the lie instrument was not calibrating properly, and pH measurements were not considered reliable Before a sample was collected, the well's water level was allowed to recharge to at least 80% of it's initial level All water removed from the monitoring wells and not used as a sample, was placed in a 55 gallon DOT (Department of Transportation 17-H) approved container that is properly labeled and temporally stored on-site A bailer was used to collect each sample Bailer cleanliness was assured by collecting a bailer blank (pouring distilled water through the bailer and collecting it in a VOA vial) prior to collecting the analytical 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 while collecting all samples wore disposable gloves •