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' The slug testing method and apparatus proved satisfactory for wells at the <br />h1t. Gunnison ~1 D1ine with the unusual situation of deep wells (up to 982 feet <br />'' to water) completed in very low permeability materials. Other well testing <br />methods involving setting pumps in the wells or using air-lift to remove water <br />F:'.: <br />i~.-:~ from the wells would be unpractical in most of the wells tested due to extreme <br />.lift heights, small well diameters, and the need for steady, very low flow pro- <br />[: <br />~.:: duction rates. <br />B. Analysis of Slug Test Data <br />Two methods were used to calculate transmissivity from the water level <br />versus time data collected for each well. These are the Cooper et, al. (1967) <br />type curve method and the Ferris and Knowles (1954) method. A third method <br />which was mentioned in ESA's proposal is the Bouwer and Rice (1976) method. <br />The Bouwer and Rice method relies on drawing a straight line through very early <br />test data and knowledge of well construction and borehole geometry. Since early <br />data at close time intervals is difficult to obtain without the use of pressure <br />transducers, and well geometry was unknown for some wells, this method was not <br />used to evaluate the slug tests conducted in this study. <br />C' <br />~.:: ~ <br />The Cooper et. al. method involves plotting H/Ho against log t on semi-loga- <br />f rithmic paper and matching the test data to a type curve. With the arithmetic <br />{.i <br />(H/Ho) axes coincident, the data is matched to a best fit with the type curves <br />(Figure III-2; in back cover pocket) and the time value from the test data which <br />~: <br />~:.: <br />overlie the point at which T t/rc = 1.0 is used to calculate transmissivity by <br />the following equation: <br />1,0 r2 <br />T = c <br />t <br />where <br />H =head above static water level; <br />j:::: Ho = initial head increase in the well (either calculated or assumed <br />based upon observations); <br />t =time since instantaneous injection; <br />k.. rc = radius of well casing in which water level fluctuates; <br />• T =transmissivity of aquifer. <br />7 ESA Geotechnical Consultants <br />