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-3- <br />Alluvial Valley Floors (2.06.81 <br />The Division, in reviewing and approving the National King Coal Mine <br />permit determined that Hay Gulch is an alluvial valley floor (AVF), <br />This finding was reiterated upon the issuance of the Proposed Findings <br />of Compliance for the adjacent Blue Flame Coal Mine. Based upon these <br />findings, the applicant should revise the application to delete <br />reference to the "possible" Hay Gulch AVF throughout the Permit <br />Application. <br />As the applicant indicates on page 2.06-5, the Division is concerned <br />about potential affects to the quality of the water within the Hay <br />Gulch alluvial aquifer when water which is detained in the sediment <br />pond infiltrates into the AYF, To alleviate these concerns, the <br />applicant should (A) develop and present to the Division for approval a <br />plan for sealing the sediment pond to minimize infiltration into the <br />Hay Gulch alluvial aquifer; (B) develop a plan to monitor the Hay Gulch <br />alluvial aquifer immediately down-gradient from the sediment pond. <br />This plan, when submitted to the Division for approval, should include, <br />but not be limited to, a) proposed well location; b) a diagram <br />depicting proposed well completion methods and materials; c) a proposed <br />method of determining aquifer transmissivity in the vicinity of the <br />well; d) a detailed description of a quarterly monitoring program which <br />should include a proposal to measure depth-to-water and the specific <br />water quality parameters proposed to be monitored. <br />3, The applicant may delete its commitments to specifically defining depth <br />and width of the alluvium, (the thickness of the aquifer must be known <br />to calculate transmissivity), and the storativity of the aquifer. The <br />applicant should define "depth of molthing" (p. 2.06-5). <br />Acid-Forming and Toxic-Forming Spoil (4.05.8) <br />1. The applicant states that no acid-forming or toxic-forming materials <br />exist at the La Plata Number 1 Mine site (page 4.05-6). Given that no <br />geochemical information has been supplied by the applicant, this <br />statement appears to be unsubstantiated. Upon satisfying Preliminary <br />Adequacy Review comments 2.04.6(2) and (3), an evaluation of potential <br />acid-forming and toxic-forming materials can be made by the applicant. <br />Upon evaluation of the geochemical data, the applicant should <br />completely address Rule 4.05.8. <br />Subsidence (2.05.6, 4.20.1) <br />1. The operator has performed an inventory of the overlying area (affected <br />area), and has determined that no renewable resource lands or <br />structures exist above the proposed mine. <br />The operator has proposed a three point subsidence monitoring program <br />in Section 29 of the permit area. Each subsidence monument will be <br />located over an area of coal extraction. In order to determine the <br />relative movement of each subsidence monument, it is a commonly <br />