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Christine Johnston, kent Gorham. Jim Pendleton <br />September 18. 199 <br />• Page 2 <br />is 0.~ epm. This leads to an average annual measured sprine discharee in the Apach: <br />Rocks permit revision area of 3 gpm. <br />4. To be conservative, however, assume that each of the ]4 springs produces 1 gpm, for <br />a total of 14 gpm (nearly, ve times the actual measured discharges). <br />5. Per pages 2.05-14. and ]48, 65 percent of the sprines in the permit azea aze <br />alluvial/colluvial and 3~ percent aze bedrock springs. <br />~, These percentages indicate that there are nine alluvial~colluvial sprines. The primary <br />risk to alluvial/colluvial springs is surface cracks. As explained on page 2.0~-13~, the <br />probability that any given alluvial/colluvial spring will encounter a surface crack is <br />0.2 percent (0.002). This means that the average annual, risk-based alluviaUcolluvial <br />spring "loss" can be calculated as follows: <br />(9 springs) (0.002) (1 gpm)(60 min/Iv)(24 hrs/day)(365 days/}~) = 9500 gal = 0.03 AF <br />• 7. Equation 1 demonsvates that the average annual "loss" for the alluviaUcolluvial <br />springs is roughly 0.03 AF. <br />8. There aze five bedrock springs in the Apache Rocks permit revision area, each of <br />which (conservatively) has an average annual flow of 1 gpm. <br />9. Assume, conservatively, that 50 percent of the bedrock springs are affected by <br />fractures given that 64 out of 69 springs in the permit azea have 300 feet or more of <br />overburden. This is a very conservative assumption. <br />10. Of those springs that aze affected by fractures, assume that 50 percent relocate and 50 <br />percent are "lost" to the mine workings. Assumptions 9 and 10 combined, indicate <br />that one bedrock spring is "lost" to the mine workings and the other four aze either <br />unaffected or relocate. <br />11. The average annual water loss associated with one spring flowing at 1 gallon per <br />minute is ].6 acre-feet (1 gallon per minute flowing constantly for one year is l.f <br />acre-feet). <br />12. The combined alluvial/co/lwia/ spring loss (about 0.0j acre feet) and bedrock spring <br />loss (1.6 acre feet) is 1.6 acre-feet. <br /> <br />STREAMS <br />