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1 <br /> Geologcral Technics kc page 2 <br /> Groundwater Monitoring Report <br /> Project No 723 2 <br /> April 18,2003 <br /> in the shallow wells ranged from 32 15 — 32 97 feet eet bgs It is noted that the water table <br /> ' exceeded the screened interval of all of the site's eight wells <br /> Figure 2 is a groundwater gradient map for the March 5, 2003, event Figure 3, <br /> ' Groundwater Gradient Rose Diagram, includes historical groundwater directions and <br /> gradients <br /> Table 1 in Appendix A contains the groundwater elevations and gradients for the site <br /> Vertical Groundwater Gradients <br /> Under vertical groundwater flow conditions, the water level in a monitoring well is a <br /> function of the length of the well screen and its depth or vertical position in the aquifer As <br /> with horizontal flow conditions, the diameter of the well or piezometer is immaterial A <br /> ' vertical gradient was calculated for well pair MW-3/MW-201 These wells are located <br /> approximately 5 feet apart <br /> The following procedure is used to calculate vertical groundwater gradient <br /> • Determine vertical distance between the two measuring devices by the distance from the <br /> mid-point between the top and bottom seal of the deep well (MW-201) and the mid- <br /> point between the groundwater elevation and the bottom seal in the shallow well (MW- <br /> 3) <br /> ' • Measut e 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 pairs used for calculating vertical groundwater <br /> gradient in this report MW-3/MW-201 Table 1 shows a Summary of Water Level and <br /> Gradients Slope and Bearing and Table 3 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 March 2003 event, the vertical gradient for the MW-3/MW-201 pair ws 0 000 ft/ft , <br /> ' or no vertical gradient This is the sixth time that vertical gradients were calcul for-this <br /> well pair Previous calculations have revealed both positive and negative gradients but <br /> additional monitoring is needed to determine long teen trends <br /> 1 <br />