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XVII. Operations on Alluvial Valley Floors <br />A. The Division has determined that an alluvial valley floor exists within the <br />affected or adjacent area. Therefore, the following findings are in order for the <br />portion of the alluvial valley floor known as Purgatoire River AVF located at <br />the mouth of Lorencito Canyon and flood irrigated by the Chacon ditch. <br />The Division finds that activities proposed by the applicant will not interrupt, <br />discontinue, or preclude farming on the alluvial valley floors that are irrigated <br />or naturally subirrigated. Although the coal loadout was constructed on <br />approximately 7 acres of irrigated pasture, feeder ditches were constructed as <br />necessary to continue irrigation of the remaining pasture. (4.24.3(1)). <br />The proposed activities will not materially damage the quantity or quality of <br />water in the surface or ground water system described above. Locating the <br />coal loadout on the alluvial valley floor did not cause measurable changes in <br />the water quantity or quality. Local material was used for the fill, where <br />necessary. This material was not acid-forming or toxic, as demonstrated by <br />geochemical analysis of materials throughout the permit area. Waters that <br />irrigate the pasture are taken out of the Purgatoire River above the confluence <br />with Lorencito Canyon. At a maximum discharge rate of 65 gpm to Cow <br />Canyon and typical mine water discharge quality, changes to water quality in <br />the Purgatoire would be minimal. TDS may increase from 251 mg/I to 267 <br />mg/I for the waters that irrigate the Chacon pasture. SAR may increase from <br />1.02 to 2.72. Neither of these small changes would affect the usability of this <br />water for irrigation. (4.24.3(3) and 2.06.8(5)(a)(ii)) <br />Surface coal mining and reclamation operations will be conducted to preserve <br />the essential hydrologic functions of alluvial valley floors outside the permit <br />area and to reestablish the essential hydrologic functions of alluvial valley <br />floors within the affected area throughout the mining and reclamation process. <br />The location of the coal loadout on a small portion of the Purgatoire River AVF <br />will not affect the hydrologic function of the AVF, during operations or after. <br />Upon final mine closure, fill materials will be removed, and the disturbed area <br />ripped, topsoiled, seeded and mulched. This will restore the hydrologic <br />function of the immediate disturbed area to pre-mining levels. The disturbed <br />area will be compared to the similar irrigated pasture area for determination of <br />revegetative productivity of the disturbed AVF area.(4.24.2) <br />B. An environmental monitoring system has been installed, maintained, and <br />operated by the permittee on all alluvial valley floors during surface coal <br />mining and reclamation operations and will be continued until all bonds are <br />released in accordance with Rule 3. Alluvial wells hydrologically above and <br />below the coal loadout will be installed as a result of Permit Revision No. <br />1(PR-01). Monitoring of surface water and alluvial water quantity and quality <br />will occur over the life of the mine. (4.24.4) <br />22