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Doc Date:12/11/2001 <br />4.05 HYDROLOGIC BALANCE <br />~ 111 lllllllll1111111 <br />999 <br />4.05.1 General Requirements <br />• <br />The surface mining activities at Colowyo have been planned and will be conducted <br />to minimize changes in the prevailing hydrologic balance, in both the pextnit and <br />adjacent areas, and to .prevent long term adverse changes in the balance that <br />might result from the activities. <br />As a preliminary step in minimizing adverse changes, hydrologic baseline <br />information has been and is being collected, compiled and analyzed. The baseline <br />monitoring programs are outlined in Section 2.04.7. This data provides detailed <br />information on quality and quantity of surface water, drainage patterns, and <br />geology. The description of the current hydrologic monitoring program is <br />included in the following pages and results of the current monitoring program are <br />included in the Annual Reports for 1983 through 1990. In addition, Section <br />2.05.6 details the specific mining and reclamation techniques which Colowyo will <br />implement to minimize changes to the hydrologic balance. <br />The post-mining land use as described in detail under Section 2,05.5, will be <br />rangeland, Changes in the hydrologic balance will be minimized so that the post- <br />mining land use will not be adversely affected. <br />. Water quality standards and effluent limitations at the existing mining operation <br />are regulated by the U. S. Environmental Protection Agency and the Colorado <br />Department of Health under the terms of an NPDES Permit, (See Exhibit 7, <br />Hydrological Information), and by the Coal Regulations of the Colorado Mined Land <br />Reclamation Board. The applicable effluent limitations will be met by using <br />treatment methods which will include prompt revegetation, minimizing disturbed <br />areas, sediment retention, use of contour furrows, terraces, sediment ponds and, <br />if necessary, strategically placed energy dissipaters, such as riprap, check <br />dams, mulches, filters and dugouts. Water quality control measures are discussed <br />in detail under Section 2.05.4 and 2.05.6. <br />Where practicable, diversion methods will be used to change the flow of water <br />from undisturbed areas so as to bypass the disturbed areas rather than using <br />treatment facilities. The principal technique to be used for this purpose will <br />be diversion ditches. These diversion ditches are located on the Hydrology - <br />South Map (Map 12) and the Hydrology - North Map (Map 11), and discussed in <br />detail under Section 2.05.6. Their design is specified in Exhibit 7, <br />Hydrological Information. <br />No acid-forming materials are present in the area to be mined which would require <br />• selective placement and sealing of overburden. The chemical characteristics of <br />the overburden is presented under Section 2.04.6. The overburden sampling <br />program is presented under Section 2.05. Results of the current overburden <br />Revision Submitted 6 -> • ~ 1 <br />4 .0 5 -1 Revison No. -r R• s i <br />