2008-12-04_PERMIT FILE - C1994082A (7)

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SEDIMENT POND 013 PERMANENT IMPOUNDMENT DEMONSTRATION In conjunction with Technical Revision 37, SCC applied for approval of Sediment Pond 013 as a permanent impoundment to support the post mining land use of livestock grazing and wildlife habitat. Under applicable provisions of Rule 4.05.9(13), Sediment Pond 013 must meet the following criteria: (a) The quality of the impounded water shall be suitable on a permanent basis for its intended use, shall meet applicable state and federal water quality standards and discharge of water from the impoundment shall meet applicable State and Federal effluent limitations and shall not degrade the quality of receiving water below applicable stream standards; (a) The level of water shall be suffidently stable, and the configuration of the pond shall be adequate, to support the intended use; (b) Adequate safety and access to impounded water shall be provided for proposed water users; (c) Water impoundments shall not result in the diminution of the quality or quantity of water available to water right holders for agricultural, industrial, recreational, or domestic uses except in accordance with applicable state law; (d) The size of the impoundment shall be adequate for its intended purposes; (e) The impoundment shall be suitable for the approved post-mining land use. Detailed discussions and relevant information is presented in the PAP in various sections of Tab 7, Hydrology and • Tab 13, Facilities. The following is a summary of the details contained in the PAP. Rule 4.05.9(13)(a). Pond 013 is located on an ephemeral tributary to Sage Creek. The location of this pond is shown on Exhibit 20-2, Postmining Topography Map. CDPHE has determined that beneficial uses on Sage Creek include aquatic life and agricultural uses. In 2007/2008, water quality parameters from Pond 013 discharges were below CDPHE agricultural standards, indicating that these waters are suitable for irrigation and livestock use. Attached is a tabulation of the recorded "Excursions of CDPHE Stream Standards" for the 12 month period (7/01/07 to 6/30/08). Rule 4.05.9(]3)(b). This pond was constructed in December 2003. Flow was first observed on March 14, 2005, however the pond does not discharge continuously. The pond is fitted with a principal spillway that controls the permanent pool elevation. Total freeboard (invert of principal spillway to top of embankment) = 2.8 feet. Freeboard (invert of principal spillway to invert of emergenry spillway) = 1.1 feet. Freeboard (invert emergenry spillway to top of embankment) = 1.7 feet. In 2007 water capacity was surveyed and calculated, the water storage capacity was measured at 4.1 ac ft (top of sediment to invert of emergenry spillway). Additional details and discussions a~z contained in the PAP in Tab 13, Attachment 13-20, As-Built Report Sediment Structure Pond 013 and on Exhibit 13-7, As-Built Pond 013. Pond 013 is generally D shaped. This configuration is typical of stock water impoundments throughout northwest Colorado. Pond 013, as currently configured, is adequate to support its intended future use as a Livestock Watering Tank Rule 4.05.9(]3)(c). The pond has relatively shallow inslopes (3H:1V or shallower). There are no cliffs or steep dropoffs along any pond margin. Rule 4.05.9(]3)(d). SCC has no water right for this pond. However, SCC understands that the Division Engineer has the authority to order the installations of low-level outlets capable of releasing all storage from the structures or TR-37 1 08/08