2012-07-10_GENERAL DOCUMENTS - C1981041

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presently takes place in the site area. Subirrigation is controlled by the water level in the adjacent Colorado River and is not affected by the reclamation plan. No actions are necessary to reestablish subirrigation. The reclamation procedure will restore the essential hydrologic function of subirrigation. Quantity and quality of water is largely regulated by the Colorado River. Any quality changes resulting from the surface operations will be of short duration due to the close proximity of the Colorado River and the extensive underflow associated with this relatively large surface water flow system. In addition, if a groundwater problem is detected by the monitoring program, mitigation measures will be undertaken prior to reclamation of the site. A flood irrigation system had apparently been abandoned at some point prior to loadout site development in 1977, and areas designated as historically flood irrigated in and adjacent to the permit area, have not been flood irrigated since that time. The quantity of water available from the Highline canal for flood irrigation is 4 A -F per acre and is limited to 14 acres. The original post mining land use for the UTL area was wildlife habitat. The original reclamation plan was to restore the capability of flood irrigation but not necessarily implement flood irrigation. With approval of Permit Revision No. 4, the postmining land use for the loadout area was changed from wildlife habitat to industrial/commercial. This land use change associated with PR -4 will preclude the Operator's from restoring the capability of flood irrigation inside the UTL loop. Exhibit 33 of the permit application package shows the acreage at the UTL area identified as "historically flood irrigated ". With PR-4 approval SCC submitted new exhibits for insertion into the permit application package. Exhibit 33 -1, Irrigated Fields 10 -14 -76 and Exhibit 33 -2, Potentially Irrigated Fields 11 -16 -94 show the irrigated fields prior to, and after loadout site development. Based on aerial photos taken on October14, 1976 there were a total of 26.1 irrigated acres at the UTL. Of the total, 13.9 acres are located inside the loop and 12.2 acres are outside the loop. Therefore, it would be possible for the Operator to restore the capability of flood irrigation to 12.2 acres, 87% of the acreage for which irrigation water is available. Only minor disturbance has occurred outside the UTL loop. Reclamation and restoration of the essential hydrologic functions outside of the UTL loop area involved minimal regrading to reestablish the original topography, replacing topsoil, and revegetating. Although the 12.2 acres outside the loop that were previously irrigated are now heavily overgrown with brush and cottonwood trees, the industrial use will not prohibit the capability to restore flood irrigation to these 12.2 acres. In summary, surface coal mining and reclamation operations will be conducted to preserve, throughout the mining and reclamation process, the essential hydrologic functions of the alluvial valley floors not within the permit area, and operations will be conducted to reestablish the essential hydrologic functions of alluvial valley floors within the permit area (4.24.2(1). The permittee will be required to restore the essential hydrologic functions on the entire alluvial valley floor where disturbance has occurred,with exception of the area located inside the UTL loop as a result of the postmine land use change from wildlife habitat to industrial/commercial with PR -4. As described above, the postmine land use change precludes the Operator's capability to restore flood irrigation to a small amount (1.8 acres) of the original 14 acres for which water is available. Subirrigation throughout the UTL area is not affected by the postmine land use change associated with PR -4 and no actions were necessary to reestablish subirrigation. Permit Revision No. 5 54 July 10, 2012