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Kiowa Clay Mine, M-2007-009 <br />Response to Atlequacy Comments <br />17 April 2007 <br />Page 3 <br />4. Please specify the thickness of the overburden or quantity of waste rock, if <br />any, to be removed to reach the deposit. <br />Underlying the topsoil layer of, on average, six inches, approximately one foot of <br />weathered clay material unsuitable for commercial purposes will be removed <br />across the site. This weathered clay is actually integral to the deposit to be <br />mined but is not capable of use in the intended manufacture of bricks. Other <br />than this weathered substrate, there is no overburden within the area to be <br />mined. The deposit will be exposed after approximately one and one-half feet of <br />material (6 in. topsoil, 12 in. overburden) is removed. <br />Because waste rock is interbedded with the desired clay resource, no thickness, <br />per se, can be provided in response to the Division's question. A volume of <br />waste rock generated during the mining process is described in response to <br />Comment 10, below. <br />For the purposes of Rule 6.4.4, waste rock is significant as an "incidental <br />product" of mining. Rule 6.4.4(h} requires an applicant to "name and describe <br />the use" of such incidental products. As noted in the narrative of Exhibit D, the <br />deposit of clay desired for commercial purposes is interbedded with other <br />sedimentary rock (e.g., lignite seams) and other grades and types of clay not <br />desired for commercial use. Approximately 50 percent of the mined volume is <br />calculated to be waste rock by the operational criteria. This waste material may <br />be placed in a surge pile, the stockpile shown on Exhibit C-3, as revised, but any <br />waste will be replaced relatively quickly as backfill within the mining area; the <br />concurrent mining process will generally include the replacement of all waste <br />rock, including stockpiled material generated during the annual mining <br />campaigns. <br />5. Please describe the nature of fhe stratum immediately beneath the <br />material to be mined in sedimentary deposits and the effects of this <br />stratum on plant growth and revegetation potential. <br />This site is being mined for clay deposits, which extend substantially below the <br />mining depth of 60 feet. <br />The sedimentary deposit is a thick sequence of claystone, siltstone, sandstone, <br />and lignite, any one of which could be exposed on the pit floor. However, plant <br />growth will not be affected due to the fact that the strata in the ridge are <br />consistently clay with some heterogeneous sedimentary rock. Revegetation <br />potential will stay consistent because the medium for plant growth will be <br />reestablished in a configuration that effectively replicates the existing condition. <br />It may be noted, for example, that the effective rooting depth for plants in the <br />