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RULE 4 PERFORMANCE STANDARDS <br /> <br />Rule 4 Performance Standards 4-14 Revision Date: 8/21/24 <br /> Revision No.: MR-259 <br />constructed and/or maintained as designed, and in accordance with the approved plan and the <br />applicable regulations. As per Rule 4.05.9(15), certified inspection reports shall include discussion <br />of: <br /> <br />1) Any appearance of erosion, instability, structural weakness or other hazardous <br />conditions; <br />2) Existing and required monitoring procedures and instrumentation; <br />3) The depth and elevation of any impounded waters at the time of the certified report; <br />4) Existing storage capacity of the impoundment; and <br />5) Any other aspects of the structure affecting stability, or requiring maintenance. <br /> <br />Colowyo will maintain a copy of each certified report at the mine site. <br /> <br />Colowyo successfully demonstrated that failure of small impoundments would not create a threat <br />to public health and safety or threaten significant environmental harm. A written safety <br />demonstration completed by a professional engineer is located in Exhibit 7, Item 11, Volume 2B, <br />in accordance with rule 4.05.9(18)(b). None of the small post-mining impoundments act as <br />primary sediment control structure for a particular area; they are all constructed in reclaimed areas <br />of the mine to enhance the approved postmining land use; they are all under two-acre feet. <br /> <br />All impoundments will be maintained according to the specifications set forth in this part. <br />Maintenance for impoundments may include (if necessary) mowing and cutting of excess <br />vegetative growth for the purpose of facilitating inspections and repairs including keeping ditches, <br />culverts, spillways, and other outflow structures free of debris. All combustible material, other <br />than mulch or other material needed for erosion control and surface stability (vegetative growth) <br />will be removed. <br /> <br />Plans for any modification of any sedimentation impoundments or dams will be submitted to the <br />Division, and no modification will begin until approval of the plans have been granted unless such <br />modification is necessary on an emergency basis for public health, safety or the environment would <br />be endangered. <br /> <br />Colowyo will inspect the condition of each pond quarterly (until a waiver for annual inspection is <br />granted) with the reports submitted quarterly as well. None of Colowyo’s post-mining <br />impoundments will meet the size criteria of 30 CFR 77.216(a)(1989). <br /> <br />Streeter Pond has been requested by the surface landowner to remain permanently. Please see <br />Volume 2B, Exhibit 1B for documentation of the request by the surface landowner. As a <br />permanent impoundment the Streeter Pond is required to meet the requirements of Rules <br />4.09.5(13)(a-e). The water quality being discharged from the Streeter Pond does not degrade the <br />quality of the receiving waters [Rule 4.09.5(13)(a)], and the Colorado Department of Public Health <br />and Environment, Water Quality Control Division, released Colowyo of monitoring the discharge <br />from the Streeter Pond in 2017. The Streeter Pond water level stays at constant level unless <br />influenced by precipitation [Rule 4.09.5(13)(b)]. Adequacy safe access to the Streeter Pond is <br />provided through a locked gate on State Highway 13, which includes a road up to and around the <br />pond embankment [Rule 4.05.9(13)(c)]. The surface landowner holds water rights downgradient