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I <br /> 'eologtcal rec<uttcs lit- Page 3 <br /> ' 2"d Quarter 2005 Groundwater Monitoring Report <br /> Project No 507 2 <br /> 0 lune 30,2005 <br /> The following procedure is used to calculate vertical groundwater gradient <br /> • Determine the vertical distance between the two measuring devices by the distance from <br /> ' the mid-point between the top and bottom seal of the deep well (MW-109) and the mid- <br /> point between the groundwater elevation and the bottom seal in the shallow well (MW-9) <br /> • Measure the head in both wells used in the calculations <br /> ' • if the lateral distance between the well pair is greater than a few feet, then calculations <br /> must be made to correct the down-gradient piezometric head to account for the sloping <br /> water table between the wells The calculation considers the slope of the water table and <br /> the distance in a down--gradient direction between the two wells used in the calculations <br /> ' Figure 2 shows the location of the well cluster used for calculating the vertical groundwater <br /> gradient in this report, MW-9 and MW-109 Table 1 shows Summary of Water Level and <br /> Gradients Slope and Bearing, and Table 2 shows the calculated vertical gradients The <br /> ' information used in the calculations is shown below <br /> Vertical gradient calculation formulas are as follows <br /> ' • Vertical correction for gradient [(gw gradient slope) x (distance) = vertical correction] <br /> • Vertical head [(head of deep well) - (head of shallow +correction) = vertical head] <br /> • Vertical gradient [(vertical head)/ (vertical distance) = vertical gradient] <br /> For the February 2005 monitoring event a vertical gradient was calculated for the MW- <br /> 9/MW-109 pair The vertical gradient was negative (a downward direction) at 0 0038 ft/ft, <br /> ' and this is consistent with the historical negative gradients at the site <br /> 1.2 Groundwater Sampling Procedure <br />' On May 27, 2005, Don Light of Del-Tech mobilized to the site to conduct groundwater <br /> monitoring of the site's eleven monitoring wells Before sampling was attempted, the wells <br /> ' were sounded for depth to water and then a clear disposable bailer was used to determine if <br /> floating product was present No free product was noted for this event, however, white <br /> foamy water was noticed in MW-9 The wells were purged of at least three well volumes of <br /> stagnant water using a dedicated Waterra check-ball assembly and 1/z inch tubing or <br /> centrifugal pump Purging continued until the temperature, conductivity, and pH of the <br />' groundwater stabilized (C10% variation in three consecutive readings), indicating that <br /> formation water representative of aquifer conditions was entering the wells These water <br /> quality parameters were measured at intervals of each well volume purged <br /> Once purging was complete, a water sample was collected from the Waterra tube Care was <br /> taken to mimmize sample agitation Once the sample container was filled and capped, the <br />' bottle was inverted, tapped and checked for headspace bubbles The sample container was <br /> identified and labeled with a unique designation, inserted into a foam holder and placed into <br /> an ice chest cooled to 4°C for transport to the Iaboratory <br /> I <br />