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STOCK POND T -2 <br />PERMANENT POND DEMONSTRATION <br />In 1991, SCC constructed a stock pond south of the shop area and on the fill side of the haul road at the <br />II -W Mine and, along with the land owner, believes that the pond should remain permanent. The <br />location of this stock pond T -2 is shown on Exhibit 20 -2, Postmining Topography Map. The purpose <br />of this evaluation is to demonstrate that Stock Pond T -2 meets the design criteria specified in Rule <br />4.05.9 for permanent impoundments. <br />Water Quality <br />This stock pond is located along side a permanent haul road and contains water that originates from <br />surface runoff from the haul road. There is no indication that the runoff contains potentially acid or <br />toxic forming material that could adversely impact surface water quality. Results of the water sample <br />analyses are attached. The analysis indicates that the water is suitable for the approved post mine land <br />use that includes livestock grazing and wildlife habitat. <br />Water Persistence <br />It is expected that this stock pond will hold 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 />Capacity <br />The water storage capacity for T -2 is 0.3 ac. ft. Since the capacity is under the 2 ac. ft. limit, the State <br />Engineer's office does not need to review the permanency request and the pond should not have any <br />significant effect on downstream users. A general stability analysis was conducted for stock ponds <br />based on the construction methods and material characteristics. A predicted Factor of Safety of 1.56 <br />was calculated by this analysis. This stability analysis is contained in Attachment 13 -11 and a <br />summary copy is attached. <br />Pond Dimensions <br />The dimensions and capacity for this stock pond are shown in the PAP on Exhibit 13- 27.T2, Stock <br />Pond T -2 Survey. As shown on the as-built drawing, the embankment is 5 feet in height as measured <br />Yon: t .v pod cotton1 to the invcrt of the spillway; however the pond was excavated to provide fill for <br />the embankment. Therefore the embankment is less than 5 feet in height from the upstream natural toe <br />of the embankment to the invert of the spillway-. The cotibit.ed slope of all the embankments do not <br />exceed 5V: 1H with no slopes greater than 2H: 1V. <br />MR -76 T -2.1 Revised 12/13 <br />