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parameters were conservatively assigned as zero effective cohesion (c'= 0 psf) and <br />• effective friction V = 36 °. These are reasonable estimates for a medium dense sand to <br />gravelly sand material (Ref 2) The results of stability analyses for all embankments are <br />summarized graphically on Figure 2, including illustration of the surface with the <br />minimum safety factor as well as other potential failure surfaces of interest. The <br />minimum static factor of safety for each embankment is presented in Table 1. It can be <br />observed that each embankment has a minimum safety factor greater than the required <br />1.3. <br />4.05.9 (13) (a) Quality of impounded water shall be suitable for its intended use. <br />The approved post- mining land use is livestock grazing and wildlife habitat. All water <br />that will be impounded will originate as snowmelt or storm runoff from the reclaimed <br />areas of the mine. There is no indication that the underlying spoil or the replaced topsoil <br />cover contains potentially acid or toxic forming material that could adversely impact <br />surface water quality for this use. It is not expected to differ from surface waters <br />routinely confined and utilized in stock tanks constructed in nearby areas in the same <br />soils that are not disturbed by mining. <br />4.05.9 (13) (b) Water level sufficiently stable for the intended use <br />• Given the semi -arid nature of the climate at the mine site and the ephemeral nature of the <br />drainages tributary to the stock tanks, it is likely that they will fill only during spring melt <br />and large thunderstorm events, but the impounded water will gradually evaporate or seep <br />out. Such intermittent and seasonal shallow water impoundments will nonetheless be of <br />use for wildlife and /or grazing operations. <br />4.05.9 (13) (c) Adequate safety and access to impounded waters <br />Stability issues regarding the embankments themselves are discussed above, where all <br />embankments have been demonstrated to be safe with regard to slope failures. With <br />regard to safety of access, all of the stock tanks are constructed in the gently sloping <br />reclaimed topography and can be easily accessed by grazing animals and /or agricultural <br />equipment. <br />4.05.9 (13) (d) Impoundments shall not harm downstream water right holders <br />Because of their deminimis size (impoundment volumes all smaller than 0.2 acre feet), <br />and the fact that all of the tanks are on ephemeral drainages, none of these stock tanks <br />pose a risk of damage to senior downstream water rights owners as referenced in 4.05.9 <br />(13) (d). The State Engineer's Office Form DWR 1/91 "Application for Livestock Water <br />is <br />Exh. 7 -13 -6 Revision No.: TR -89 <br />Revision Date: 02/11/11 <br />