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' Geola uafTechnics Inc Page 2 g g Groundwater Monitoring Report ' Project No 723 2 June 4, 1999 ' calculated A three-point problem was used on MW-4, MW-5 and MW-6 because these three wells are constructed relatively similar in regards to depth of screen interval The average ' elevation of groundwater under the site was —17 54 feet below mean sea level Depths to water ranged from 27 5 to 28 5 feet bgs ' Figure 2 is a groundwater gradient map for the January 25, 1999 event Table 1 in Appendix A contains the groundwater elevations and gradients for the last three ' events This table will be updated to include all groundwater elevation data for the site 1.2 Groundwater Sampling Procedure On January 25, 1999, 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 During this ' monitoring no free product was noted, however sheen was observed in MW-3 Stagnant water in the well casing was purged using a purger pump as recorded in the field logs (Appendix C) The rate of well purging was monitored The wells were purged of approximately 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% 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 55 gallon DOT (Department of Transportation 17-H) approved container that is properly labeled and temporally stored on-site A stainless steel 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 rExtreme 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 Ithe laboratory The sampling technician while collecting all samples wore disposable gloves