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C404wa!Technxs 144 S, Page 3 1 Quarter 2004 Groundwater Monitoring Report Project No 507 2 May 19,2004 1 Figure 2 shows the location of the well cluster used for calculating the vertical groundwater ' gradient in this report, MW-9 and MW-109 Table 1 shows Summary of Water Level and Gradients Slope and Bearing, and Table 2 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] 0 Vertical head [(head of deep well) - (head of shallow+ correction) = vertical head] • Vertical gradient ((vertical head)/ (vertical distance) = vertical gradient] For the March 2004 monitoring event a verticalradient was calculated ed for the MW-9/MW- 109 pair The vertical gradient was negative (a downward direction) at 0 001 ft/ft and ' approximately 0 4 the magnitude of the horizontal gradient of the water table (0 003) 1.2 Groundwater Sampling Procedure ' On March 19, 2003, Don Light of Del-Tech mobilized to the site to conduct groundwater M monitoring of the site's eleven monitoring wells Before sampling was attempted, the wells were sounded for depth to water and then a clear disposable bailer was used to determine if floating product was present No free product was noted for this event The wells were purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball assembly and '/2 inch tubing or centrifugal pump Purging continued until the temperatuie, conductivity, and pH of the groundwater stabilized (<10% variation in three consecutive ' 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 W p aterra 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 a foam holder and placed into ' 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 ' A chain of custody document, listing all samples collected, accompanied the samples from field to laboratory, thereby providing a means to track the movement of and insure the integrity of the samples