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R603 UPDATE-10 11/09/92 <br /> the ground water by tank aeration - vapor destruction <br /> using the REMOX incinerator. <br /> 2 .0 GROUND WATER <br /> 2. 1 LOCAL GROUND WATER FLOW <br /> Ground water flow direction in this region is to the west and <br /> towards south Stockton from the foothills of the Sierra Nevada <br /> Mountain Ranges, and towards the east from the Sacramento-San <br /> Joaquin Delta. At present, encroachment of saline waters from the <br /> Delta is impairing the quality of the ground water in the Stockton <br /> area. <br /> Based upon ground water elevation measurements obtained throughout <br /> the evaluation of this site, the overall local flow direction is <br /> to the east-northeast at a relatively flat slope. Slug tests <br /> performed on the monitoring wells (May 25 , 1990 ) indicated <br /> hydraulic conductivities (K) , ranging from highs of 45 . 43 and <br /> 33 . 48 feet/day at MW9 and MW1 respectively, to lows of 0 . 52 and <br /> • 1. 99 feet/day at monitoring wells MW2 and MW10 respectively. <br /> These drastically different K values (in the above mentioned <br /> wells) along with the monthly depth to ground water measurements <br /> help determine if the ground water beneath the site is in a <br /> recharge or discharge cycle. If the ground water surface shows <br /> flow occurring from MW1 towards MW2, a recharge cycle is occurring. <br /> If the ground water surface shows flow occurring from MW2 towards <br /> MW1, a discharge cycle is occurring. Measurements obtained on <br /> August 14, 1992 , (Figure 4A) , show a continued decline in ground <br /> water elevations with the exception of MW3 which indicates a <br /> recharge to this well. The flow direction flows radially from MW3 <br /> with pronounced depressions forming at MW2 , MW4 and MW5 . This <br /> figure represents a continuation of the discharge cycle that was <br /> initiated in February, 1992 . <br /> Figure 4B, represents the gradient beneath the site from ground <br /> water measurements obtained September 25 , 1992 . This figure is <br /> very similar to the August; 1992 measurements with a continued <br /> aecline in ground waxer elevations. <br /> The dome of ground water that has formed around MW3 may be <br /> attributed to: the slower discharge (recovery) of the silty <br /> clayey sands, vapor extraction vacuum at the MW3 pulling the <br /> ground water up the well , an interval locamed am 1Y1W3 which has <br /> been recharged locally and/or more probably the depth to ground <br /> water probe being .inadvertently positioned into the 1" pvc riser <br /> that has been placed in the well for occasional vacuum lift of <br /> sediment that accumulates from the formation into the well . <br /> PAGE 3 <br />