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Historic Alluvial Valley Floor Investigations in the New Horizon North Mine Area <br />The first formal alluvial valley floor (AVF) investigations performed in the NHN Mine Area <br />were performed by the Office of Energy Activities associated with the Region VIII office of the <br />Environmental Protection Agency in Denver. These reports were initially published by the EPA <br />in a draft report (Hardaway and others 1977a) and then subsequently published in October of <br />1977 (Hardaway and others 1977b). A seven page subset of Hardaway and others (1977a) was <br />copied by Peabody Coal Company (PCC) and included as Appendix 7 -7 to satisfy the AVF <br />permit requirements of the New Horizon Mine permit submitted in October 1981. As directed <br />by the DRMS these reports are included in this section as Appendix 2.06.8 -1, Appendix 2.06.8 -2 <br />and Appendix 2.06.8 -3. <br />The EPA AVF study area included all of Sections 25 and 36 of Township 47 North, Range 16 <br />West of the the Meridian and thus included all of the area that now corresponds to the current <br />NHN mine permit area. This initial study was largely done based upon the detailed <br />interpretation of color infra -red aerial photography, coupled with reconnaissance field work <br />performed by other agencies. These investigators concluded based upon these methods that there <br />were no alluvial valley floors located within this study area at the Nucla Strip Mine. <br />In the current NH2 Mine Permit there is a map called Figure II found in Section 2.06.8 entitled <br />Potential Alluvial Valley Floors in the Vicinity of the Nucla Strip Mine. In the consultation <br />meeting held in Grand Junction on February 1, 2011, DRMS provided this information to WFC <br />along with a "Checklist for NHN AVF Determination." DRMS concluded that the areas <br />identified on this map with a blue crosshatch represented AVF's. The conclusion is incorrect for <br />a number of reasons. The map refers to these areas not as AVF's but as "Valley Fill Areas." As <br />defined on page A -1 of the Office of Surface Mining (OSM) AVF identification guideline, <br />"Valley Fill Areas" consist of deposits "composed of the debris left by several processes, such as <br />streamflow, slopewash, wind, and/or other landsliding." This reference states that in the AVF <br />identification process, these different deposits must be differentiated since only those deposits <br />and landforms "whose origin is a function of streamflow" can be considered to be potential <br />AVF's. Thus, this map is only what the title says it is. It is not a map of AVF's as the DRMS has <br />mistaken reported, but rather it is a map of "Valley Fill Areas" which might be potential AVF's <br />and nothing else. <br />Based upon the negative findings from this EPA study, and in every subsequent mid -term permit <br />review from the January 1983 "The Nucla Mine (C- 008 -81) Proposed Decision and Findings of <br />Compliance" document and every permit renewal performed by the DRMS since then, the <br />DRMS has concluded there are no AVF's within the area corresponding to old NH1 Mine and <br />current NH2 Mine area and that the closest AVF's to these areas is the San Miguel River <br />floodplain located approximately 2.5 miles SW or 4 miles west of this area. <br />Current Alluvial Valley Floor Investigations in the New Horizon North Mine Area <br />As pointed out by the DRMS, many of the issues regarding AVF's are based upon information <br />that is nearly 30 years old and needs to be reevaluated in light of the current regulatory <br />Section 2.06.8 Page 2 April 2011 <br />