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create and enhance wildlife habitat, or assist revegetation; and if they are compatible with stability <br />of the fill, as demonstrated in accordance with 2.05.3(6)(b), (c) and (d). <br />The application is in compliance with this rule. <br />Rule 4.09.1(9) The final configuration of the fill shall be designed to minimize erosion. Terraces may <br />be utilized to control erosion and enhance stability if approved by the Division and consistent with <br />4.14.2(2). <br />A suggested comment to the applicant is: Please include in the detailed design the features of <br />Rule 4.09.1(9). <br />Rule 4.09.1(10) Where the slope in the disposal area is steeper than 2.8h:1v (36percent), or such <br />lesser slope as may be designated by the Division based on local conditions, keyway cuts <br />(excavations to stable bedrock) or rock toe buttresses shall be constructed to stabilize the fill. Where <br />the toe of the spoil rests on a downslope, stability analyses shall be performed in accordance with <br />2.05.3(6)(6), (c) and (d) to determine the size of the rock toe buttresses and keyway cuts. <br />Toes of slopes rest on downslopes. The statement is made on page 11 of the geotechnical report that <br />keyway cuts or rock toe buttresses are not required. A suggested comment to the applicant is: Please <br />indicate in the detailed design that the slopes of the ground under fill areas are -ess than 36 <br />percent. Rule 4.09.1(10) <br />Rule 4.09.1(11) Inspection. See the rules for the text of this rule. It contains performance <br />requirements. I suggest the following comment to the applicant: Please include a description and <br />schedule of excess spoil pile inspections in the monitoring requirements section of the PAP. <br />Rule 4.09.1(11) <br />Rule 4.09.1(12) See the rules for the text of this rule. No coal mine wastes are proposed for disposal <br />in the excess spoil fills. <br />Rule 4.09.1(13) If the disposal area contains springs, natural or manmade watercourses, or <br />wet-weather seeps, an underdrain system consisting of durable non-acid forming and <br />non-toxic forming rockshall be constructed from the wet areas in a manner that prevents infiltration <br />of the water into the spoil material. The underdrain system shall be protected by an adequate falter <br />and shall be designed and constructed using standard geotechnical engineering methods. <br />There are such features under the west and east fills, and lateral drains are provided. However, as <br />depicted, high flows (high elevations of water in the drain) would have an opportunity to infiltrate <br />into the spoil. A suggested comment to the applicant is: To reduce infltration into the fill, please <br />consider flipping the design (Figure 5) such that the apex of the triangle is in the tha-weg of the <br />natural drainage. The drain should be totally incised into in-situ materials so that there is no <br />exposure to spoil sides. Please encapsulate the underdrains with geotextile (line the bottom and <br />sides to inhibit piping of in-situ soils, and a top cover to inhibit infiltration of spoil into the <br />