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4.05.8 Acid-forming and Toxic-forming Spoil <br />Acid forming materials do not exist within the overburden to be removed by the mining <br />operations. A discussion on the overburden at the Colowyo operation has been <br />conducted as set forth in Section 2.04.6. A discussion of the overburden monitoring plan <br />is set forth in Section 2.05. <br />4.05.9 Permanent and Temporary Impoundments <br />Colowyo constructs small impoundments on reclaimed area in accordance with Section <br />4.05.9 of the CMLRD regulations for Coal Mining, 3/21/01. These small impoundments <br />are essential and basic to the management of the rangeland post-mining land use of <br />livestock grazing and wildlife habitat. The design of the impoundments provides for <br />structures having a vertical height less than five feet from the bottom of the channel to <br />the bottom of the spillway and impound less than two acre feet of water. As such they <br />are exempt from Division of Water Resources, Office of State Engineer requirements. <br />Water harvesting ditches may also be used to enhance the function of the <br />impoundments, which is consistent with practices employed on adjacent rangelands. <br />The locations of the impoundments are shown on May 12 -Hydrology -South <br />additional information is provided in Exhibit 7, Item 11 Small Depressions/Tanks. <br />The impoundments collect surface runoff from precipitation events and snowmelt from <br />reclaimed areas. The impoundments do not result in the diminution of the quality or <br />quantity of water for downstream water users. Colowyo is the holder of water rights <br />immediately downstream. During periods of low precipitation the impoundments may be <br />dry, which is consistent with regional practices on similar rangelands. Since the source <br />of water is surface runoff from revegetated areas the quality of the water will meet the <br />requirements of the intended use. <br />The impoundments have areas of 4h:1v slopes or less to provide easy access to both <br />livestock and wildlife. These impoundments and any associated ditches, while intended <br />to be permanent, will be classified as temporary until the requirements of Rule 4.05.9. <br />are met. Prior to construction, all designs are submitted to the Division. A copy of the <br />as-built design information will be submitted after construction for inclusion into Exhibit 7, <br />Hydrology. In addition, sedimentation ponds that are subsequently approved as part of <br />the post-mining land use, as shown on the hydrology -South Map (Map 12), will remain <br />as permanent impoundments after the requirements of Rule 4.05.9. have been met. <br />All embankments, impoundments and associated structures will be revegetated if <br />construction materials are conducive to plant growth. If not, rock or gravel will be used <br />on the embankment. The quarterly routine inspections of these structures were <br />conducted through calendar year 2001 as required by Rule 4.05.9(17). <br />4.05-8 <br />June 25, 2002 <br />TR-55 <br />CF 4.1.2.6 <br />