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STOCK POND T -26 <br />PERMANENT POND DEMONSTRATION <br />In 2006, SCC has constructed a stock pond in the southern reclamation area at the II -W Mine and, <br />along with the land owner, believes that the pond should remain permanent. The location of this stock <br />pond T -26 is shown on Exhibit 20 -2, Postmining Topography Map. The purpose of this evaluation is <br />to demonstrate that Stock Pond T -26 meets the design criteria specified in Rule 4.05.9 for permanent <br />impoundments. <br />Water Quality <br />This stock pond is located in the upper portion of a watershed in the southern portion of the <br />reclamation area. There is no indication that either the spoil or the replaced topsoil contains potentially <br />acid or toxic forming material that could adversely impact surface water quality. Results of the 2012 <br />water sample analysis are attached. The analysis indicates that the water is suitable for the approved <br />post mine land use that includes livestock grazing and wildlife habitat. <br />Water Persistence <br />It is expected that this stock pond will contain water from the spring runoff through early summer at a <br />minimum. <br />Accessibility <br />This pond is easily accessible to livestock and wildlife. There are no drop offs or excessively steep <br />slopes around the edges of this pond. <br />Ca aci <br />The water storage capacity at the time of the as-built survey for T -26 was 2.8 ac. ft. The pond will be <br />re- surveyed prior to permitting with the State Engineer's office to determine the type of permit <br />required. A general stability analysis was conducted for stock ponds based on the construction <br />methods and material characteristics. A predicted Factor of Safety of 1.56 was calculated by this <br />analysis. This stability analysis is contained in Attachment 13 -11 and a summary copy is attached. <br />Pond Dimensions <br />The dimensions and capacity for this stock pond are shown on Exhibit 13- 27.T26, Stock Pond T -26 <br />Survey. As shown on the as-built drawing, the embankment is 7.4 feet in height as measured from the <br />pond bottom to the invert of the spillway; however the pond was excavated to provide fill for the <br />embankment. Therefore the embankment is less than 5 feet in height from the upstream natural toe of <br />the embankment to the invert of the spillway. The combined slope of all the embankments do not <br />exceed 5V:IH with no slopes greater than 2H:1V. <br />