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7 . were subsequently downloaded to a portable field computer Water levels were measured periodically in all of the other monitoring wells during the pumping test The test consisted of three pumping steps plus recovery Figure 4 showy the drawdown versus time in the pumping well. TEX-1 Each pumping step lasted for 2 hours During the first step, the average pumping rate was about 7 5 gallons per minute (gpm) The flow rate was increased to 10 7 gpm for the second step, and subsequently increased again to 16 7 gpm for the third step At the end of the 6-hour test. approximately 5 feet of drawdown was measured in TEX-1 Drawdowns, as measured in the observation wells, were insignificant Specifically, a drawdown of approximately 0 1 foot was measured in ATR-4 and 0 03 feet was measured in ATR-2 There was no measurable drawdown in the other monitoring wells In order to determine the horizontal conductivity of the saturated zone around TEX-1, the data collected from TEX-1 were analyzed by the generalized straight-line method of Cooper and Jacob modified for step-type variation of the discharge rate (1983)1 The aquifer is thought to be anisotropic and heterogeneous and hydraulic conductivity values will vary within the aquifer Analysis of these data are shown on Figure 5 The two parallel lines drawn through the data have the same slope from which the transmissivity was calculated The average transmissivity was calculated to be about 1,300 square feet per day (sq ft/day), assuming the saturated thickness of the aquifer to be about 23 feet The average horizontal hydraulic conductivity is about 60 ft/day Due to the heterogeneity of the aquifer and the presence of low permeable layers of . silt, this hydraulic conductivity is probably accurate to an order of magnitude and represents the higher end Thus, the aquifer around TEX-1 is thought to have a hydraulic conductivity between 6 and 60 ft/day Groundwater Extraction (Optional) The decision as to whether or not groundwater extraction is needed to remediate the site will be based on data collected during the fust 6 months to 1 year of sparging and vapor extraction If required, groundwater may be extracted from TEX-1 and from monitoring wells ATR-2, ATR-4, and ATR-5 The purposes of pumping from these wells will be to 1 Keep the water table from rising as a result of vapor extraction so that vapors can be withdrawn from the hydrocarbon-affected soil 1 to 2 feet above the current water table 2 Lower the water table in order to expose more vadose zone. 3 Recover and treat hydrocarbon-affected groundwater from these wells Pumping rates at wells ATR-2, ATR-4, and ATR-5 are expected to be on the order of 0 to 2 gpm, and at TEX-1, 10 to 15 gpm The actual pumping rates will vary depending on water elevations in specific wells and the actual performance of TEX-1 1Kruseman, G P , DeRidder, N A , 1983, Analysis and Evaluation of Pumping Test Data, pg 38, International Institute for Land Reclamation and Improvement ILRI, Wageningen, The Netherlands, 200 p 7403,1ZU0RT9\2EMEDATN PLN