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44 <br /> to estimate the effect of the mine discharges is used. Unfortunately, there <br /> is no effective means of directly measuring the quantity of water passing <br /> through the waste dump and it is necessary to estimate the deep percolation <br /> through the use of water balance procedures. <br /> This analysis of hydrologic balance is restricted to the refuse dump <br /> at the Allen Mine. A map of the dump is presented in Figure 13. The <br /> water balance is analyzed on an average annual basis using long term mean <br /> climatic data where available. The overall hydrologic system is broken <br /> 1 down into two subsystems, the subsurface water budget and the surface water <br /> budget. The two subsystems are linked by infiltration (see McWhorter, 1980, <br /> for basic details). <br /> Climatic Summary - Precipitation, temperature, and solar radiation data <br /> l utilized in the computations are presented in Table 9. Mean temperature <br /> and precipitation data based on 20 years of record are available at Trini- <br /> dad approximately 25 miles east of the Allen Mine and at North Lake approxi- <br /> mately five miles west of the Allen Mine. Elevations at these two sites <br /> ! are 6030 feet and 8800 feet, respectively, while the elevation of the refuse <br /> pile is approximately 7470 feet. The means for these two locations show <br /> substantial variation, probably due to elevation differences. Therefore, <br /> the mean precipitation and temperature data presented in Table 9 were ob- <br /> tained by interpolating on elevation between data for Trinidad and North <br /> Lake. (The means for Trinidad and North Lake are presented in Appendix F. ) <br /> Solar radiation data is available at only a few locations in Colorado, all <br /> of which are some distance north of the mine site. For this reason the amount <br /> of. solar radiation was calculated using a method presented by Jensen (1973). <br /> Details and comparative data are presented in Appendix F. <br /> 1 <br /> Potential Evaporation - The amount of water lost to the atmosphere was <br /> j calculated by dividing the year into a winter season (Nov. through Mar. ) <br /> and a growing season (Apr. through Oct. ). Winter period losses result from <br /> sublimation and evaporation and were estimated using the following equation <br /> ;Wymore, 1974) . <br /> Ew = Kc (0.006T + 0.05) Rs C <br /> in which Ew represents evaporation losses from snow pack (inches) , T <br /> represents mean monthly temperature (OF) Rs is the solar radiation (ly./d) <br /> 1 <br />