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llu Fish Crcek "fipple Permit Application (C-036-81) submitted in the fall of 1984 and approved by <br />CMLRD on May 20, 1985 addressed the alluvial valley Floor considerations of the Fish Crcek Tipple and <br />• I I;wlroad areas located on the Fish Creek and Middle Creek drainages. CMLRD issued a Decision and <br />Findings Document for the Fish Creek Tipple Permit Area on May I5, 1985. This document concluded <br />that three areas met the geomorphic criteria of alluvial valley Floors. These areas are: I) the flood plain of <br />Fish Qeek; 2) the flood plain of Middle Creek; and , 3) the flood plain of Trout creek. The alluvial valley <br />Ioor determination concluded by saying: "Based on available information, the unconsolidated streamlaid <br />deposits of Fish and Trout creeks are found to be alluvial valley Floors because of the current or historical <br />existence of flood irrigation and the presumed capability of these areas to support subirrigation during a <br />portion of the growing season. I[ is significant to note that this statement relative to current historic Hood <br />irrigation is applicable only to portions of these to the drainages as a whole. <br />I-his historical perspective is provided to answer concerns relative to how and why the areas marked on <br />M;tp I5, Alluvial Valley Floors and Water Rights was prepared. The basic assumptions used to prepare <br />this map have been accepted in several previous permit submittals prepared by Twen[ymile Coal and its <br />predecessors, Colorado Yampa Coal and Energy Fuels since the promulgation of the interim OSM <br />Regulations in 1977. As can be observed in each of these individual submittals and as painted out <br />previously in this discussion, Map I5, Alluvial Valley Floor and Water Rights, contains all geologically <br />mapped unconsolidated deposits as required under Rule 2.06.8 (3)(b). Tltis approach was taker[ as <br />required under 2.06.8(3}(b), following numerous meetings held with CMLRD. These required <br />consultation meetings were initiated in 1978 and have continued with each permitting action up to and <br />including the present submittal. TCC recognizes that this approach presents a "worse case" scenario since <br />it grossly overestimates the actual extent of alluvial deposits by including all unconsolidated geologic <br />deposits into a designation that should more accurately contain only unconsolidated streamlaid deposits. <br />As :t result, the actual areal extent of alluvium is considerable smaller that depicted on Map I5, Alluvial <br />Valley Floors and Water Rights. TCC recognizes this inconsistency but believes that the present submittal <br />• is consistent with [he regulatory approach of identifying maximum potential impacts and then determining <br />actual anticipated impacts through detailed evaluation. <br />'The extent of alluvial deposits associated with potential alluvial valley toors can easily be determined <br />front the detailed soil mapping information presented on Map 17, Premining soils, and iit Exhibit 1 G, Soil <br />Mapping Unit Descriptions. By combining the land forms associated with alluvial valley Floors (i.e., <br />alluvial fans, terraces, Floodplains, valley bottoms, and alluvial valleys) with mapped alluvium, the <br />delineation of those alluvial deposits potentially associated with alluvial valley floors can be made. Tltis <br />contparisoit results in the following soil mapping units meeting these two criteria: <br />2 -Outlet -Slocum Taxajunct complex, 0-2%slopes; <br />3 -Unnamed -Abel Variant Complex, 0-5%slopes; <br />AW - Aquents-Aquolls Complex; <br />SA - Abslter frne sandy loam, 3%slopes; <br />23A - Capo clay loam, 0-3%slopes; <br />27A - mtrtamed sandy loam, I -10%slopes; <br />~?A -Venable loam, 0-6%slopes; <br />56A - Tonks loath, 0-5%slopes; and <br />G9c - Milrett loan[. 0-6%slopes. <br />Upon locating these areas on Map 17, Pre-mining Soils, within the potential alluvial valley floor <br />htxmdarics presented on Map 11. Alluvial Valley Floors and Water Rights, the actual extent of alluvial <br />deposits can be determined. <br />• <br />N1R97-I;a ?.OG-9 Revised 1~mnioi <br />