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Geofogical Techaks Inc. Page 2 Groundwater Monitoring Report Project No. 662.2 March 31,2003 L1.0 GROUNDWATER MONITORING L1.1 Hydrogeology of Site The dominant soil type in the upper 40 feet of subsurface geologic soils investigated is fine to course grained sand alternating with thinner beds of plastic clay. The average groundwater elevation on December 13, 2002 was approximately 14.50 feet above MSL, which is about 25 feet below,ground surface. Groundwater gradient was calculated for this event and the groundwater was found to flow ! r N770E at 0.0008 ft/ft. Groundwater elevation and gradient data are summarized in Table 1, 1.� Appendix A. Gradient direction is shown on Figure 2: Gradient Map, and Figure 3: Groundwater Gradient Rose Diagram. 1.2 Groundwater Sampling Procedure On December 13, 2002, Don Light of Del-Tech mobilized to the site to conduct a groundwater monitoring of the four monitoring wells on site. Before sampling was performed the wells were sounded for depth to water and then a clear disposable bailer was used to determine if floating product was present. The wells were purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball t` assembly and 1/2 inch tubing. Purging continued until the temperature, conductivity, and pH of the groundwater stabilized (<10% variation between three readings) indicating that formation water representative of aquifer conditions was entering the wells. These water quality parameters were measured at intervals of each well volume purged. Once purging was complete, a water sample was collected from the Waterra tube. Care was taken to minimize sample agitation. Once the sample container was filled and capped, the bottle was inverted, tapped, and checked for headspace bubbles. The sample container was identified and labeled with a unique designation, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory. All non-disposable sampling equipment was decontaminated using a hot water washer and detergent before and between uses. Disposable gloves were used by the technician to collect all samples and were changed with each sample collection. L A chain of custody document, listing all samples collected, accompanied the samples from field' to laboratory, thereby providing a means to track their movement and insure their integrity.