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in compliance with the requirements of Rule 4.15.10. <br />E. The Division approved of the reference azeas which the applicant selected based on <br />the requirements of Rule 4.15.7(3). <br />F. The reference areas will be utilized to determine revegetation success in a manner <br />which the Division finds acceptable 4.15.7(4)). <br />VII. Protection of Underground Mining <br />A. The Division approved surface coal mining activities being conducted within 500 <br />feet of an active or abandoned underground mine. This approval was based on the <br />fact that approval for such was granted by MSHA and the Colorado Division of <br />Mines. The variance was granted by MSHA based on the thickness of material <br />vertically separating the current strip operation from previous underground workings <br />(4.19(1) and 4.22.4(1)). <br />VIII. Operations on Alluvial Valley Floors <br />Alluvial Valley Floor Identification <br />Information on alluvial valley floors can be found in Volume 2, Section 2.4, Volumes 3 and 4, <br />Section 2.5, Volume 5, Section 2.9 and Volumes 11 and 12, Section 4.6 of the permit application. <br />U <br />From an investigation of potential azeas using geomorphic and water-availability criteria, one <br />alluvial valley floor (AVF) has been identified along Trout Creek. The area has unconsolidated <br />alluvial deposits and sufficient water available to be classified as an alluvial valley floor. <br />The alluvial depositsalong Trout Creek consist of four terraces (Q,1, Q,2, Q,3, Q,4), of which only <br />two (Q,1 and Q,2) are water bearing. The terraces are shown on Map 2.5-21 of the permit <br />application, which delineates the boundaries of the AVF. The Q,I terrace, equivalent to the active <br />floodplain, is hydrologicallyconnected with Trout Creek. Since Trout Creek is a perennial stream, <br />baseflow throughout the year is maintained by discharge from the Q,1 alluvial groundwater. The Q2 <br />terrace is also water bearing since it contains a perched aquifer situated atop bedrock; the Q,2 terrace, <br />however, is not in direct communication with the Q,1 terrace. Dischazge from the Q,2 terrace will <br />eventually reach Trout Creek via seeps along the bedrock face which separates the Q,2 terrace from <br />the modem floodplain. Recharge of the Q,2 terrace is from infiltration of local precipitation only, <br />and not from any type of hydrologic connection with the active Trout Creek floodplain. On the <br />permit area (east) side of Trout Creek, only the Q,1 predominates, although the Q,2 terrace is present <br />on a limited basis. <br />The operator calculated the mean annual water yield of Trout Creek at a point immediately <br />Edna Mine 35 p~Rni1 Renexal IJo. 3 <br />