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4 Hydrogeologic Measurements and Predictions A step drawdown test was performed for 6 hours on well TEX-1. The flow rates were measured by reading the pump's totalizer flow meter and recording the total gallons pumped at predetermined time increments. Flow was adjusted using a gate valve. A digital stop watch was used to track time. Numerous flow readings were taken throughout the test to control the flow rate. Water levels were recorded using either an electronic sounder or a pressure transducer controlled by a data logger (in-Situ Hermit Model SE 1000B). The data from the data logger Figure 3 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 shows 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 ftlday. 'Kruseman, G.P., DeRidder, N.A., 1983, Analysis and Evaluation of Pumping Test Data, pg. 38, International Institute for Land Reclamation and Improvement 1LRI, Wageningen, The Netherlands, 200 p. "Oai9SE'\7403,RFP PM7403-0LR•t QMS-PS2000