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4.05.8 Acid-forming and Toxic-formin 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 conducted as <br />set forth in Section 2.04.6. A discussion of the overburden monitoring plan is set forth in <br />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 are <br />essential and basic to the management of the rangeland post-mining land use of livestock <br />grazing and wildlife habitat. The design of the impoundments provides for structures having <br />a vertical height less than five feet from the bottom of the channel to the bottom of the <br />spillway and impound less than two acre feet of water. As such they are exempt from <br />Division of Water Resources, Office of State Engineer requirements. Water harvesting <br />ditches may also be used to enhance the function of the impoundments, which is consistent <br />with practices employed on adjacent rangelands. The locations of the impoundments are <br />shown on May 12 -Hydrology -South additional information is provided in Exhibit 7, Item <br />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 quantity <br />• of water for downstream water users. Colowyo is the holder of water rights immediately <br />downstream. During periods of low precipitation the impoundments may be dry, which is <br />consistent with regional practices on similar rangelands. Since the source of water is surface <br />runoff from revegetated areas the quality of the water will meet the requirements of the <br />intended use. <br />The impoundments have areas of 4h:1 v slopes or less to provide easy access to both livestock <br />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. <br />Prior to construction, all designs are submitted to the Division. A copy of the as-built design <br />information will be submitted after construction for inclusion into Exhibit 7, Hydrology. In <br />addition, sedimentation ponds that are subsequently approved as part of the post-mining land <br />use, as shown on the hydrology -South Map (Map 12), will remain as permanent <br />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. [f not, rock or gravel will be used on <br />the embankment. The quarterly routine inspections of these structures were conducted <br />through calendar year 2001 as required by Rule 4.05.9(17). <br /> <br />4.05-8 Revision Date: 6/25/02 <br />Revision No.: TR-55 <br />