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------------ -------------- Geofogicaf7echnics 2nc. C&B Equipment Page 2 Groundwater Monitoring Report Project No.336.2 April 13, 1998 >_ 40.37 feet AMSL. The gradient was North 13° West with a slope of 0.0052 ft/ft (as determined from MW-1,2 &3). Table 1 of Appendix A summarizes the groundwater level measurements to date. Groundwater gradient calculations show that the dominant groundwater flow is in a north- northwesterly direction with the slope ranging from 0.007 ft/ft to 0.0036 ft/ft. Figure 2 is a groundwater gradient map from this latest sampling event. Figure 3 is a rose diagram of the gradients from the four monitoring events. `i 1.2 Groundwater Sampling Procedure On March 18, 1998, Del-Tech Geotechnical Support personnel arrived on-site, opened the wells, and measured the depth to water with an electrically actuated sounding tape.e. The -_ water level reading was recorded to an accuracy of O.01 foot. In wells where free floating "j product was suspected, a clear disposable bailer is used to gauge the interface. Stagnant water in the well casing was purged using centrifugal pump as recorded in the field logs (Appendix Q. The rate of well purging was monitored. The well was 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%. �I 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 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 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 ml VOA vials __s preserved with hydrochloric acid using a bottom emptying device which minimizes sample aeration during transfer of the sample. All samples were checked for head space bubbles, labeled, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory. Disposable gloves were worn by the sampling technician while collecting all samples.