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COAL <br />COMPANY <br />AkooLE• PRODUCTtO� £ <br />historically addressed the Hydrologic Soil Group (HSG), in particular <br />showing the selection of HSG B for reclaimed soils. CCC also added a <br />note in the footnotes of Table 1 to reinforce that all soils would be <br />considered as HSG C. The sentence on the page previous to Table I <br />which stated that reclaimed soils should be treated as HSG B was not <br />removed. That sentence, and the overall approach, had been in place <br />since at least the TR -56 submittal. CCC suspects that it is also the basis <br />of the hydrologic modeling of other nearby mines which also assign HSG <br />B to reclaimed soils and use curve numbers in the 60s for reclaimed lands. <br />This TR -95 seeks only to move Curve Numbers for reclaimed lands part of <br />the way back to their historic values. Those were consistent with a strict <br />reading of the recommendations of NEH Chapter 7 and the results of the <br />1981 Strifjler and Rhodes infiltration study. <br />A graph of the "accepted" curve numbers over the years is presented as <br />Figure 1. Figure I is for illustration purposes only and is not intended to <br />be part of the TR -95 revision. It is evident that TR -73 resulted in an <br />abrupt rise in curve numbers for reclaimed lands with no technical basis. <br />It is also evident that the proposed curve numbers in TR -95 would return <br />only part of the way back to the historic curve numbers. <br />DRMS July 2, 2012 Follow up Comment to Comment 1 above: <br />The Division is certainly willing to consider changes in Hydrologic <br />Soil Group (HSG) values and the related curve number values. <br />However, we stand by our assertion that information from other <br />mines and information from a small area on Colowyo Mine is not <br />enough information to identify all reclaimed land on Colowyo as C <br />soils. <br />Furthermore, the intent of TR -73 was not "more conservative <br />modeling" but rather to move the model closer in line with flows <br />witnessed on the ground. <br />Colowyo's Second Round Response to Original and Follow up Comment 1: <br />As identified in our June 25, 2012 letter regarding Comment 1, Colowyo is <br />amenable to no longer pursuing changes to the modeling for the area <br />directly reporting to Prospect Pond, the Divisions major point of concern. <br />A Western Fuels - Colorado, LLC mining property <br />