2007-12-19_REVISION - M1988112 (12)

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Precipitation inflows averaged approximately 9.9 acre-feet annually to the pond surfaces, while evaporation removed about 24.7 acre-feet. G.2.2 Irrigation Pond Design The configuration and design details for the irrigation ponds are shown in Figures G.2-4 through G.2-10. The criteria used in the design of the irrigation ponds include the following: • The combined capacity of the ponds shall provide for safe storage of the design volume while maintaining adequate (2 foot minimum) freeboard under normal operating conditions. • The ponds shall be designed to meet the requirements of the Office of the State Engineer (SEO) for classification of the ponds as non jurisdictional structures (SEO, 1988, 1999, 2000, 2005a, b), while limiting excess excavation to the extent practical. In order to be considered non- jurisdictional structures, the statutory embankment heights at the maximum sections must be less than 10 feet. In addition, the individual pond water surface areas at the maximum pool level must be less than 20 acres each. Finally, the individual above-grade storage capacities, defined as the storage volume available between the statutory ground elevation and the maximum pool elevation (the embankment crest elevation in this case) must be less than 100 acre-feet each. • Since the ponds will be constructed above the local ground water table, SEO rules regarding construction of below-grade water storage reservoirs, where inflow from a surrounding alluvial aquifer may occur, do not apply. • The ponds will be constructed with an engineered, synthetic (HDPE or equivalent) geomembrane liner. A transfer pipeline currently exists between the West Pit and the TDA. Solutions associated with the water treatment are periodically transferred to the TDA as authorized under TR-30. The ability to transfer water to the TDA will remain as part of the permit amendment to provide a contingency water transfer location during shakedown of the irrigation pond system and in the unlikely case that there arise ground water flows significantly different than what has been observed since pumping began in 2000. Battle Mountain Resources, Inc. 25 P:\Pmjms\212-Newmont(S=LLis)\SsnLuis\Pa tAmedmrnt- Wet Pit Memgement\VS Report &PDFs\Tem\PetmitAmedment_v5c.doc December 2007