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Estimates of evaporation from the pond were based on pan evaporation data from the <br />Western Regional. Climate Center (WRCC; www.wrcadri.edu) for Alamosa, <br />Colorado. Pond evaporation was assumed to be equivalent to lake evaporation. Lake <br />evaporation was assumed to be 70 percent of measured pan evaporation, and equal to <br />37.7 inches per yeaz with seasonal distribution occurring over the months from April <br />through October. The monthly pan evaporation is also shown in Figure G.2-2. <br />Seepage was estimated with the engineered liner system having a saturated hydraulic <br />conductivity less than 1x10 centimeters per second (cm/s). Stage-capacity curves <br />for the pond were used to estimate the seepage. <br />Results of the irrigation pond water balance modeling indicate that under normal <br />operating conditions, the average required storage (for the period from November <br />through Mazch) is 134.4 acre-feet (Figure G.2-3). Average combined flow from the <br />West Pit and alluvial aquifer ground water wells is about 236 gallons per minute, with <br />seasonal peak flows occurring in late spring/early summer, and low flow during the <br />winter months. Precipitation inflows averaged approximately 9.9 acre-feet annually <br />to the pond, while evaporation removed about l9 acre-feet. Seepage resulted in an <br />additional 52.5 acre-feet loss from the pond volume. <br />G.2.2 Irrigation Pond Design <br />The configuration and design details for the irrigation pond aze shown on Sheets 13 <br />and 14 of the Design Drawings (Appendix D). The criteria used in the design of the <br />irrigation pond include the following: <br />• The pond shall provide for safe storage of the design volume while <br />maintaining adequate (2 foot minimum) freeboard under normal operating <br />conditions. <br />• The pond design shall meet [he requirements of the Office of the State <br />Engineer (SEO) for classification of the pond as anon-jurisdictional <br />structure (SEO, 1988, 1999, 2000, 2005a, b), while limiting excess <br />excavation to the extent practical. In order to be considered anon- <br />jurisdictional structure, the statutory embankment height at the maximum <br />. section, defined as shown on Section A-A' on Sheet No. 13 of the Design <br />Battle Mountain Resources, Inc. G-3 Telesto Solutions, /nc. <br />P:~Pmjects~212-Newmont(SaN-uis)VSenl.uis~Permit Amendmem- West Pit MVwgr~cem~PenvitAmendmen~ v].Eac .~nl~'2~6 <br />