Laserfiche WebLink
RULE 4 PERFORMANCE STANDARDS <br />The impoundments collect surface runoff from precipitation events and snowmelt from reclaimed areas. The <br />impoundments do not result in the diminution of the quality or quantity of water for downstream water users. <br />Colowyo is the holder of water rights immediately downstream. During periods of low precipitation, the <br />impoundments may be dry, which is consistent with regional practices on similar rangelands. Since the <br />source of water is surface runoff from revegetated areas the quality of the water will meet the requirements of <br />the intended use. <br />The post- mining impoundments have slopes of 4h:ly or less to provide easy access to both livestock and <br />wildlife. These impoundments and any associated ditches, while intended to be permanent, will be classified <br />as temporary until the requirements of Rule 4.05.9 are met. Prior to construction, all designs are submitted to <br />the Division. A copy of the as -built design information will be submitted after construction for inclusion into <br />Exhibit 7, Item 20. In addition, sedimentation ponds that are subsequently approved as part of the post - <br />mining land use, as shown on the hydrology - South Map (Map 12), will remain as permanent impoundments <br />after the requirements of Rule 4.05.9 have been met. <br />All embankments, impoundments, and associated structures will be revegetated if construction materials are <br />conducive to plant growth. If not, rock or gravel will be used on the embankments. The quarterly routine <br />inspections of these structures will be conducted as required by Rule 4.05.9(17). <br />The Division granted Colowyo a waiver to the requirements of 4.05.9(17) for small impoundments. The <br />waiver applies only to impoundments which are not the primary sediment control structure for a particular <br />area; are constructed in reclaimed areas of the mine to enhance the approved postmining land use; are <br />completely incised, or have a storage capacity no greater than two -acre feet and an embankment no greater <br />than five feet in height. The small impoundments will be inspected on a yearly schedule until removal of the <br />structure or release of the performance bond as directed in rule 4.05.9(14). The inspections will be performed <br />by a qualified registered professional engineer, or other qualified professional specialist under the direction of <br />a professional engineer, or a qualified person other than, and not under the direction of, a professional <br />engineer. <br />Colowyo successfully demonstrated that failure of the small impoundments would not create a threat to public <br />health and safety or threaten significant environmental harm. A written safety demonstration completed by a <br />professional engineer is located in Exhibit 7, Item 11 of the existing permit document in accordance with rule <br />4.05.9(18)(b). None of the small post- mining impoundments act as primary sediment control structure for a <br />particular area; they are all constructed in reclaimed areas of the mine to enhance the approved postmining <br />land use; they are all under two -acre feet. <br />All impoundments will be maintained according to the specifications set forth in this part. Maintenance for <br />impoundments may include mowing and cutting of excess vegetative growth for the purpose of facilitating <br />inspections and repairs and will include keeping ditches, culverts, spillways, and other outflow structures free <br />of debris. All combustible material, other than mulch or other material needed for erosion control and surface <br />stability will be removed. <br />Plans for any modification of any sedimentation impoundments or dams will be submitted to the Division, <br />and no modification will begin until approval of the plans have been granted unless such modification is <br />necessary on an emergency basis for public health, safety or the environment would be endangered. <br />Colowyo will inspect the condition of each pond annually with the reports submitted annually. None of <br />Colowyo's post- mining impoundments will meet the size criteria of 30 CFR 77.216(a)(1989). <br />South Taylor /Lower Wilson — Rule 4, Page 9 Revision Date: 10/31/13 <br />Revision No.: MR -129 <br />