Laserfiche WebLink
41 <br /> 22 7°W The corresponding minor hydraulic conductivity is about 50 7 Ft/Day oriented at a <br /> right angle <br /> 5 0 CAPTURE ZONE ANALYSIS OF EXTRACTION WELL EW-1 <br /> A capture zone is defined as the area of an aquifer in which all of the groundwater will be <br /> removed by a pumping well (or wells) at a specific pumping rate over a certain period of time <br /> The capture zone analysis does not consider the presence of the apparent boundary condition <br /> 5 1 CAPTURE ZONE METHODOLOGY <br /> The capture zone analyses for extraction well EW-i was conducted using equations outlined in <br /> Javandel and Tsang, 1986 for confined aquifers Work by Grubb, 1993 lists equations for both <br /> confined and unconfined aquifers However, the method of Grubb, 1993 incorporates data from <br /> wells upgradient and downgradient from an extraction well in order to ascertain discharge <br /> . potentials across the field of the extraction well Furthermore, Grubb (1993) shows that the <br /> confined aquifer analysis method overestimates the capture zone for an unconfined aquifer <br /> Therefore, the capture zones for the wells reported herein are overestimated, relative to the <br /> unconfined aquiter method of Grubb (1993) Both of these techniques assume the achievement <br /> of steady state conditions(long continuous pumping) and that the aquifer is homogeneous, <br /> isotropic, and infinite in horizontal extent, a situation that is never attained <br /> As indicated above, the equations outlined in Javandel and Tsang (1986) are utilized These <br /> equations are discussed below and are used to determine the distance between dividing stream <br /> lines at the extraction wells (i e , the cross-gradient edge of the capture zone) and far upstrearn <br /> from the extraction wells (the upgradient extension of the capture zone), and the distance from <br /> the extraction wells to the stagnation points (downgradient end of the capture zone) <br /> According to Javandel and Tsang (1986) the distance between dividing stream lines at the <br /> extraction well is represented by the equation <br /> 49} Q_ <br /> 2BU <br /> H 2OGEOL A GROUNDWATER CONSULTANCY <br />