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JrX�"MWAAV—= Working To Restore Nature Based on the currently estimated areal extent of contamination, and assuming that an extraction well would optimally be located near MW5 (the well impacted to the greatest extent), a ' downgradient capture zone radius of approximately 100 feet would be necessary to capture the plume. The pumping rate required to achieve this can be calculated using the above equation ' and other pertinent data. The estimated pumping rate is approximately 21,300 gpd or 15 gpm. . ' Using an average water column depth of 15' as the maximum acceptable drawdown and applying the observed value of specific capacity of approximately 2 8 gpm/ft, the theoretical sustainable ' pumping rate for the extraction well would be approximately 42 gpm However, the existing site wells are all 2 inches in diameter and the maximum capacity for a pump less than 2 inches in diameter is 3 gpm. This rate would not be sufficient to effect hydraulic control over the plume of groundwater contamination A dedicated extraction well with a diameter of 4 to 6 ' inches would be required . The results and conclusions presented herein are based on data obtained from the pumping well only, as no response was seen in observation wells An interpretation of pump test data from observation wells more accurately estimates aquifer parameters such as transmissivity. Therefore, actual aquifer characteristics and well responses may differ from those estimated here. ' The ability of groundwater extraction and treatment to cost effectively achieve remediation is dependent on several factors in addition to aquifer transmnssnvlty and yield. Chef among these are the type and cost of treatment, the type of discharge permit obtainable, groundwater cleanup ' standards and potential re-introduction of contaminants from both vadose and phreatic soil ' 6.0 SITE CHARACTERIZATION I Site Geology ' Subsurface soils beneath the site consists predominately of clays from surface grade to approximately 12 to 20 feet below grade, clayey sand to well graded sand from approximately 150008UUT0RT3\CAP-0794 DRF 12