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RULE 4 PERFORMANCE STANDARDS <br /> <br />Rule 4 Performance Standards 4-13 Revision Date: 4/16/19 <br /> Revision No.: MR-200 <br />ponds associate with the Collom Pit be found in Exhibit 7, Item 23. For compliance purposes, in <br />systems that incorporate ponds in a series, CDPS effluent quality parameters will only apply to the <br />last pond in the series that directly discharges into the receiving stream or drainage. Out of pit <br />designed ponds internal to the last pond in the series will be inspected and maintained in the same <br />manner as the “compliance” pond to ensure proper sediment control and design performance. <br /> <br />The sumps along Haul Road A are required to have flow measurement devices at the outflow of <br />each sump. Each sump therefore will have a flume installed at the outflow to measure any flow <br />discharged from each sump. <br /> <br />4.05.8 Acid-forming and Toxic-forming Spoil <br /> <br />Acid forming materials do not exist within the overburden to be removed by the mining operations. <br />A discussion on the overburden at the Colowyo operation has been conducted as set forth in <br />Section 2.04.6. A discussion of the overburden monitoring plan is set forth in Section 2.05. <br /> <br />4.05.9 Permanent and Temporary Impoundments <br /> <br />Colowyo constructs small impoundments on reclaimed areas in accordance with Rule 4.05.9. <br />These small impoundments are essential and basic to the management of the rangeland post- <br />mining land use of livestock grazing and wildlife habitat. The design of post-mining <br />impoundments provides for structures having a vertical height less than five feet from the bottom <br />of the channel to the bottom of the spillway and impound less than two acre-feet of water. As such <br />they are exempt from Division of Water Resources, Office of State Engineer requirements. Water <br />harvesting ditches may also be used to enhance the function of the impoundments, which is <br />consistent with practices employed on adjacent rangelands. <br /> <br />The impoundments collect surface runoff from precipitation events and snowmelt from reclaimed <br />areas. The impoundments do not result in the diminution of the quality or quantity of water for <br />downstream water users. Colowyo is the holder of water rights immediately downstream. During <br />periods of low precipitation, the impoundments may be dry, which is consistent with regional <br />practices on similar rangelands. Since the source of water is surface runoff from revegetated areas <br />the quality of the water will meet the requirements of the intended use. <br /> <br />The post-mining impoundments have slopes of 3h:1v or less to provide easy access to both <br />livestock and wildlife. These impoundments and any associated ditches, while intended to be <br />permanent, will be classified as temporary until the requirements of Rule 4.05.9 are met. Prior to <br />construction, all designs are submitted to the Division. A copy of the as-built design information <br />will be submitted after construction for inclusion into the permit document. In addition, <br />sedimentation ponds that are subsequently approved as part of the post-mining land use, as shown <br />on the hydrology Maps, 41A and 41B, will remain as permanent impoundments after the <br />requirements of Rule 4.05.9 have been met. Please refer to Section 4.05.6 for additional <br />information regarding compliance with Rule 4.05.9(7)(a thru e). <br /> <br />All embankments, impoundments, and associated structures will be revegetated if construction <br />materials are conducive to plant growth. If not, rock or gravel will be used on the embankments.