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modified Blaney-Griddle method. In determining the ET rate for the study area it is assumed that <br />the irrigation practices evenly distribute sufficient amounts of water to fulfill the consumptive use <br />water demands required by each of the different vegetation types <br />Based on the vegetation types and the estimated consumptive use rates, there are approximately <br />1,299 acre feet of water evapotranspired within the study area. Evaporation from the pond was not <br />included in this total. Excess irrigation water flows overland and contributes to the streamflow of <br />Calamity and Tuttle Draws. The streamflow from Calamity and Tuttle Draws in turn contributes to <br />the flow of the San Miguel River two and one half miles downstream of mining and the proposed <br />mining disturbance. <br />The total volume of water that could be evapotranspired from the vegetation study is assumed to <br />be under ideal conditions. In reality the evapotranspiration rates are slightly less. In many areas <br />shallow soils and rock ledges restrict rooting depths and inhibit maximum plant growth, thereby <br />reducing ET rates. <br />Aquifer Characteristics of the New Horizon Mining Areas <br />Eleven aquifer tests were conducted within the New Horizon 1 leasehold, the proposed New <br />Horizon 2 mining area and the immediate vicinity. A wide variety of aquifer testing and analysis <br />techniques were employed because of the range of well yields and aquifer types. Aquifer testing <br />techniques include constant discharge tests (Theis, 1935; Neuman, 1975; and Cooper and Jacob, <br />1946); slug injection and withdrawal tests (Cooper et a1., 1967, and Papadopulos et a1., 1973); <br />modified slug tests (McWhorter, 1982); and specific capacity tests. Analysis techniques primarily <br />involve matching the drawdown of recovery data plots against theoretical type curves or tangent <br />lines defining the slope of the data. With the modified slug tests, data analyses included eithertype <br />curve matching or analytical solutions. <br />Transmissivity and hydraulic conductivity values throughout and immediately adjacent to the New <br />Horizon Mine are low to very low. The overburden and underburden aquifers have the highest <br />values and the coal aquifer has the lowest transmissive properties. There is an approximately one <br />order of magnitude range in the transmissivity and hydraulic conductivity values for the overburden, <br />Revised 25 Juf 2002 2.04.7-11 <br />