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Response to Technical Adec~y Review, 19 March, 2001 • Page 3 <br />Item no. 6 Issue: Aerial hoto ermit bounda <br />Commentldeficienc Please show the ennit bounda on the aerial hoto, Ma C-3. <br />Res onse <br />Anew version of Ma C-3 is rovided to show the uested information. <br />Item no. 7 Issue: Geolo is information <br />Commentldeficiency Identify the thickness of the deposit to be mined and the stratum <br /> immediate) beneath the material to be mined. <br />Res onse <br />This information is now explicitly stated in Exhibit D, as wel{ as in Exhibit J. As discussed in those exhibits, there is <br />considerable speculation as to the actual thickness of the alluvial deposit which will be mined. Based on mining at <br />other locations and well depths, it appears to be between 30 and possibly as much as 125 feet in depth; we have <br />taken the conservative approach of stating "at least twenty feet" (the depth planned for mining) and in other locations <br />usin a neater thickness so that worst case on matters such as roundwater drawdown is used. <br />Item no. 8 Issue: Classification of Dolores River <br />Commentldeficienc The Ian stated that the Dolores River is a warm-water fishe <br />Res onse <br />This statement was in error and has been cortected. The Dolores River at this point is scold-water fishery and <br />tem ereture re ulaGon ma be r wired. <br />Item no. 9 Issue: Potential for floodin and storm water controls. <br />Commentldeficiency Potential for flooding of the permit area, potential for off-site damage, <br /> and details for spillways, and other storm water controls, as well as <br /> locations, should be rovided. <br />Res onse <br />Various exhibits, especially Exhibit G, have been revised to provide the requested information, including showing the <br />baseline Flood elevations and boundary of the 100-year floodplain on various maps. We believe that there is no <br />reasonable potential for the planned pit to cause increased adverse impacts from floodwaters downstream (outside <br />the permit area). We are also providing (as an attachment to this letter) a copy of a standard attachment to the <br />Surface Water Management Plan which is required under the CDPS permit issued by CDPHE under which we <br />expect to obtain coverage for this site. It provides details of various storm water controls. We have understood in the <br />past that such details were beyond the level normally required fora 112 application, and so had not included them. <br />The exact location of most storm water controls cannot be identified at this point, as properly implemented controls <br />are not placed arbitrarily in the area, but based on actual requirements to meet a perceived or anticipated problem at <br />a particular point. (For example, the best management prectices of placement of silt fences at the toe of stockpiles <br />and of placement of ditches at the toe of stockpiles are not both done the full length of the toe of the piles, but one or <br />the other may be done where needed to control sediment in runoff from that stockpile.) As discussed in the Exhibits, <br />the term "spillways" was probably inaccurate to describe openings in the berms to allow flood backwaters to remain <br />at the baseline elevation, rather than being impounded. However, the anticipated location of these is shown on one <br />of the Reclamation Ma sin Exhibit F, as re uested. <br />Item no. 10 Issue: Com arison of ost-minin land use to other land use <br />Commentldeficienc Please rovide a com arison <br />Res onse <br />The com arison is now ex licit) rovided as an item in the revised Exhibit E. <br />