2013-10-30_PERMIT FILE - C1981038A (2)

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designated Reference Area. The sample will be obtained by directing drainage into a collection container. Appropriate samples will be taken from this container. The samples will be sent to an approved laboratory for analysis of sample conditions. Any unusual erosion concern or sediment problem shall be noted immediately to the Environmental Specialist. Corrective work shall begin as soon as practical and will be completed after consultation with the CWI Engineering Department. Inspections shall be completed once a month until a baseline of conditions has been established. After that time, a qualified professional engineer will evaluate changes to this inspection procedure. 3. Topsoil would be stored on the mine bench fill outslopes in depths noL exceeding four feet. Revegetation and erosion control activities would be conducted on the fill outslopes during construction. No other ongoing operational activities would be conducted on the outslopes. 4. The smaller, north facing fill outslope is 0.6 acres. The total acreage of the south facing fill outslope is 2.7 acres, but is divided into two drainage areas of 1.9 acres (Section A) in the western portion and 0.8 acres (Section B) in the eastern portion. See the drainage map attached. The total disturbed area of the Orchard Valley and Orchard Valley West Mine sites, including the timber storage area and train loadout, is 142.3 acres. Two small area exemptions for the fan level bench of the Orchard • Valley Mine were approved in October, 1982, totalling 3.74 acres. Including the proposed small area exemptions, the total area to be exempted from drainage through sedimentation facilities ie 7.0 acres (or 4.9% of the total disturbed area). 5. Ae the mine bench fill outslopes could not be drained to the sedimentation pond north of the mine site, Golder Associates, Inc., consultant to CWI, has studied a potential sedimentation pond located over the culvert at the toe of south fill elope and a "finger" pond, sized to contain drainage from both outslopes. The studied pond, located at the toe of the elope, is a risk to the stability of the fill, as the toe could become saturated causing failure. As shown on the attached drawings, the "finger" pond was proposed to be located on either the east or west side of East Roatcap Creek, south of the fill outslopes. The pond was determined to be unfeasible in either location for several reasons. The pond on the east side of the creek would be clearly unstable. With steep cutalopes of 1.25 H 1.0 V (which exceeds CMLRD guidelines for pond cutslopes), the resulting disturbance would be excessive. Because of the very steep hillside (60X or greater) to the east of the creek, cute or fills on these elopes would be unstable, probably even in an unsaturated condition. The pond located on the east side of the creek has also been designed to- be the smallest, least disturbing configuration, yet sized large enough to contain runoff from the fill outslopes in the case of a 10-year, 24-hour precipitation event. Cutslopea would be steep (1.25 H 1.0 V and again exceed CMLRD guidelines), and on the ezieting steep hillside, would cause - 3 -