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I cleological nclutks/etc. Page 3 Groundwater Monitoring Report i Project No. 750.2 August 16,2002 :water table between the wells. The calculation considers the slope of the water table and the distance in a down-gradient direction between the two wells used in the calculations. Figure 2 shows the location of the well cluster used for calculating vertical groundwater gradient in this report, MW-1 and MW-101. Table 1 shows a Summary of Water Level and Gradients Slope and Bearing and Table 3 shows the calculated vertical gradients. The ' information used in the calculations is shown below. Vertical gradient calculation formulas are as follows: • vertical correction for gradient: [(gw gradient slope) x (distance) =vertical correction] • ,vertical head: [(head of deep well) - (head of shallow+ correction)=vertical head] • vertical gradient: [(vertical head) /(vertical,distance) =vertical gradient] k'r For the June 28, 2002, groundwater measurement, the vertical gradient was calculated for the;MW-1/MW-101 pair. The vertical gradient was negative (a downward direction) and approximately equal to the water table horizontal gradient. The vertical gradient has been progressively decreasing in magnitude over therlast several events. f 1.2 Groundwater Sampling Procedure On-June 28;.2002, Don Light of Del-Tech mobilized to the site to conduct a groundwater- monitoring event. The wells were first sounded for depth to water and then they were purged of at least three well volumes of stagnant water using a dedicated Waterra pump. Purging continued until the temperature, conductivity and pH of the groundwater stabilized (<10% variation among three readings) indicating that formation water representative of aquifer conditions was entering the well. These water quality parameters were measured at intervals of each well volume purged. { A ii ' Once purging was complete, a water sample was collected from the Waterra tube. Care was taken to minimize sample agitation from the initial filling of the bailer to the transfer of the sample to the VOA vials. Once the sample containers were filled and capped, the bottles were inverted, tapped and, checked for headspace bubbles. Each sample container was f 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 steam cleaner before and between uses. Disposable gloves were used by the technician to collect all samples and were changed with each sampling event. 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 ensure their integrity. 1