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RULE 4 PERFORMANCE STANDARDS <br />All embankments, impoundments, and associated structures will be revegetated if construction materials <br />are conducive to plant growth. If not, rock or gravel will be used on the embankments. The quarterly <br />routine inspections of these structures will be conducted as required by Rule 4.05.9(17) if and until a <br />waiver is granted to allow for annual inspections of these structures in the future. As per Rule 4.05.9(14) <br />requirements, inspections performed during and after construction of these structures will be performed <br />by a qualified registered professional engineer or other qualified professional specialist under the <br />direction of a professional engineer. The inspections will be made regularly during construction, at <br />completion of construction, and at least annually (quarterly until such a time as annual inspections are <br />requested from granted by DRMS) until removal of the structure or release of the performance bond. The <br />qualified registered professional engineer shall provide the Division with a certified report that the <br />impoundment has been constructed and/or maintained as designed, and in accordance with the approved <br />plan and the applicable regulations. As per Rule 4.05.9(15), certified inspection reports shall include <br />discussion of - <br />1) <br />f1) Any appearance of erosion, instability, structural weakness or other hazardous 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 />Colowyo will maintain a copy of each certified report at the mine site. <br />Colowyo successfully demonstrated that failure of small impoundments would not create a threat to <br />public health and safety or threaten significant environmental harm. A written safety demonstration <br />completed by a professional engineer is located in Exhibit 7, Item 11, Volume 213, in accordance with rule <br />4.05.9(18)(b). None of the small post -mining impoundments act as primary sediment control structure for <br />a particular area; they are all constructed in reclaimed areas of the mine to enhance the approved <br />postmining land use. <br />All impoundments will be maintained according to the specifications set forth in this part. Maintenance <br />for impoundments may include (if necessary) mowing and cutting of excess vegetative growth for the <br />purpose of facilitating inspections and repairs including keeping ditches, culverts, spillways, and other <br />outflow structures free of debris. All combustible material, other than mulch or other material needed for <br />erosion control and surface stability (vegetative growth) will be removed. <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 be <br />endangered. <br />None of Colowyo's post -mining impoundments will meet the size criteria of 30 CFR 77.216(a)(1989). <br />4.05.10 Underground Mine Entry and Access Discharges <br />Colowyo currently conducts surface coal mining exclusively. <br />4.05.11 Ground Water Protection <br />There are no aquifers or continuous sources of ground water within the stratigraphic section from which <br />the Colowyo Mine mines coal using surface mining techniques. This is also noted in Section 2.04.7. In <br />addition, there are no continuous aquifers of regional extent within the entire Williams Fork Formation in <br />Rule 4 Performance Standards 4-13 Revision Date: 8/28/17 <br />Revision No.: TR -115 <br />