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Nydrolo%ic Arsessmem <br />3.3 HYDROLOGIC TESTING AND INTERPRETATION <br />Slug tests were conducted at the site on the N-Decline, RSS and the UTL wells. The RSN well <br />was artesian and flowing over the collar at approximately 0.25 gallons per minute (GPM). The <br />slug tests of the N-Decline well and RSS well were conducted by adding a volume of water and <br />monitoring water level changes in those wells. These slug tests were analyzed by Cooper- <br />Papadapoulous (Cooper and Papadapoulous 1967) method for confined aquifers. The UTL well <br />located on the north side of the Colorado River appears to be asemi-confined aquifer with a <br />recharge influence from the Colorado River. The slug of water was added to this well and the <br />water levels were monitored over time. Additionally, a slug of water was removed from the well <br />and the subsequent water levels monitored over time. The Bouwer and Rice method (Bouwer and <br />Rice 1976) for unconfined and the Cooper-Papadapoulous method for confined aquifers were used <br />to analyze the data. Data collected from both slug tests conducted on the UTL well indicated <br />groundwater fluctuation. Stabilization occurred within 10 seconds on each test within the UTL <br />well and fluctuated up and down after initial stabilization. <br />Graphs and analyses derived by the AQTESOLV Program (Duffield and Rumbaugh, 1991) are <br />included in Appendix III. An example of the aquifer properties calculations for the N-Decline <br />well is provided below. A summary of the aquifer characteristics for the remaining wells is <br />provided in Table 2. Slug test results for the N-Decline well indicated a transmissiviry (T) of 1.30 <br />• ft~/day or 9.7 gal/day/ft. This transmissivity value was used to estimate an approximate hydraulic <br />conductivity (K) by the equation T = Kb, where T is transmissiviry, K is hydraulic conductivity, <br />and b is aquifer thickness. The average thickness of the Rollins Sandstone was 95 feet and was <br />used as the aquifer thickness. Therefore: <br />T = Kb <br />1.30 ftZ/day = K (95 ft) <br />K=1.30 ftz/day/95 ft <br />K = 0.014 ft/dm' <br />The transmissiviry (T) can be used to estimate a potential pumping rate (Q) by the equation Q = <br />Ts/1500, where Q is the pumping rate in gal/min, T is the transmissivity in gal/day/ft, s is the <br />available drawdown in feet (total height of water column in the well), and 1500 is a constant. <br />Therefore: <br />Q = Ts/1500 <br />Q = 724 gal/day/ft(95 feet)/1500 <br />Q = 0.62 ga!/min <br />The hydraulic conductivities encountered within the N-Decline and the RSS wells are within the <br />expected range for a sandstone (Heath 1983). However, the hydraulic conductivity derived from <br />• <br />Y1.593\I\Sepmmber 16. 1997 7 <br />