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<br />Mr. Keith Vander Horst, P.E. ~~~ <br />Fel)ruary 16, 2000 <br />Page 2 <br />Atlas for the Conti4uous 48 United Stat' n'c (Map 3). Monthly evaporative fosses are determined <br />using percentages specified by the Stare Engineer's Office for locations below G,SOOfeet. l'he <br />nearest weather station is Puehlo NJ5O AP located at the airport east of Puebla, Colorado where the <br />1961-1990 average annual precipitation is t 1.19 inches as reported in the NOAH Climatolostical <br />Data Annual Summary. Colorado 1997. Copies of the evaporation and precipitation sources arc <br />included in Appendix .A. <br />Effective precipitation, that part of historiral precipitation which was constrmud by native <br />vegetation on land to be covered by water surface, is conservatively estimated to be 90 percent of <br />the total precipitation based on results from lysimeter studies conducted at non-irrigated sites by the <br />City of Colorado Springs. The annual average effective precipitation at the Beltramo Mine Pit is <br />estimated to be 1 U.07 inches. Subtracting the effective precipitation from the gross evaporation <br />yields the net annual evaporation of 40.13 'nches, or 3.34 acre-feet per year. Table t shows the <br />tietermina:ion of net evaporative losses. <br />Beltramo projects washing of 11,000 tons of mined aggrega;e per month, or 132,000 tons for the <br />year. At a depletion of 4 percent by weight this results in ar, annual consumptive use of 3,88 <br />acre-feet per year. In addition, an estimated 1.75 are-feet of water per year w+IV be used for dust <br />control hosed approximately on 4,000 gallons per day for 20 days per month for the seven months <br />of April through October. The total operational !oss due to aggregate production and dust control is <br />5.99 acre-feet per year and is distributed according to monthly projections provided by Beltramo as <br />shown in Table 2. The total consumption at the site including evaporation and operational losses is <br />8.93 acre-feet per year, as shown in Table 3. Ti,is amount is reduced from the 11.74 acre-feet <br />proiecrad in the 1999 plan approved by the State. <br />STREAM DEPLETIONS <br />Water losses at the Beltramo Mine Pit will cause IaR_Sed depletions to the Arkansas river. The <br />timing of depletions to the Arkansas River have been determined using the State's Stream Depletion <br />Model lDc'P3.EXE;. The A•;ine Pit is iocated in the Arkansas River alluvial aquifer approximately <br />2,200 feet from the Arkansas River. In Stre m P le i n Factors. Arkansas River Vallev. <br />Southeastern Colorado. (USGS 72-192) Jenkins and Taylor report a value for the Stream Depletion <br />factor (SDF) of 65 days as the mean value for ;he area bounded by the 30-day SCF !ine and the <br />120-day SDF line. The Beltramo Pit lies within this band and the mean band value of 65 days as <br />presented by lenkins and Taylor was selected as the SDF for the project site. The results of the <br />modeling of I:ia,.ged depletions are shown +n Table. 3. Output from the, stream deplet+on model is <br />included in P.ppendix B. <br />REPIACF.MENTS <br />Beltramo will make replacements totaling 9.00 acre-feet for replacement of stream depletions <br />during the Plan Year caused by mining at the tiline Pit. Proposed replacements are shown in <br />Column (5) of Table 3. During the Plan Year the source of replacement water will be <br />