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C~ <br />The semi-log plot of drawdown data from well A is presented in Figure A-52 and <br />shows [he typical two straight line portions of the drawdown curve with a relative <br />flat portion between these two straight lines. The early straight line is <br />influenced by the aquifer's transmissivity and storage coefficient and well <br />penetration while the late straight line is mainly influenced by the specific yield <br />and transmissivity of the aquifer. Aquifer properties should not be determined from <br />the straight line method without a comparison of slopes of the Theis straight line <br />and Neuman's type curve straight line plot. <br />The Neuman unconfined aquifer theory was used to analyze this pump test <br />• <br />because it best fits the Yampa alluvial aquifer. Section A-3.0, Part A of Appendix <br />V, Aquifer-Test Theory, presents the Neuman and Theis aquifer theories. Figure A-53 <br />also presents the Neuman type curve for well A. The drawdown data best fits the type <br />curve for a Kv/Kh of 0.01 and a S/Sy of 0.2. This type curve fit yields a <br />transmissivity of 17,900 gal/day/ft and a specific yield of 0.21. A horizontal <br />hydraulic conductivity permeability) was calculated from the transmissivity and <br />aquifer thickness of 15 feet. Horizontal and vertical permeabilities near well A <br />are 160 and 1.6 ft/day respectively. <br />A storage coefficient of 0.042 was also <br />calculated from this match. <br />YAMPA ALLUVIUM OBSERVATION WELL B <br />Observation well B consists of a sand point with a two foot length of screen <br />positioned 7.6 to 9.6 Feet below land surface. Well B was located 42.6 feet from <br />the center of the sump along a straight line with well A. Table A-45 presents the <br />drawdown data for observation well B while Figures A-54 and A-55 show the plots of <br />A-25 <br />ISED FEB 13 "~~ <br />