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0069icalTWhniaInc. Page 3 Groundwater Monitoring Report L Project No.750.2 l April 10,2003 '' •'' If the lateral distance between the well pair is greater than a few feet, then calculations must be made to correct the down-gradient piezometric head to account for the sloping water table between the wells. The calculation considers the slope of the water table and j 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 i 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: _ g [(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] i For the December 30, 2002, groundwater measurement, the vertical gradient was calculated' for the MW-1/MW-101 pair. The vertical gradient was negative (a downward direction). However, it was insignificant as head difference between MW-1 and MW-101 was only 0.01-feet. Generally, the magnitude of the vertical gradient has progressively decreased since February 2001. As required under AB2886, the depth to groundwater data was submitted electronically to GeoTracker on April 10, 2003, with confirmation number 1463139176 I 1.2 Groundwater Sampling Procedure On December 30, 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 jstabilized (<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. Once purging was complete, a water sample was collected from the Waterra tube. Care was taken to minimize sample agitation during the filling of 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 identified and labeled with a unique designation, inserted into foam holders and placed in a chilled ice chest for transport to the laboratory. All non-disposable sampling equipment was decontaminated using a steam I