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<br />r~ <br />L <br />-2- <br />The specific task posed <br />million ton load might <br />extracted F-seam. <br />is to determine whether the imposition of the 9 <br />precipitate a lateral failure within the partially <br />The applicant proposes the construction of a 2500' length of 30' wide haul <br />road to be used to transport waste to the pile for placement. However, the <br />design information contained within the permit revision application is limited <br />to a brief discussion and a map exhibit. Slope stability problems have been <br />encountered throughout portions of the existing surface facility area's road <br />cut slopes and fill embankments. For this reason, the Division believes it <br />appropriate to require more thorough design information regarding the <br />geotechnical specifics of the proposed road corridor. The applicant should <br />provide cross-sections on an appropriate station frequency, such as 200'. <br />Worst case representative cut slope and embankment fill sections should be <br />analyzed to determine whether artificial slope reinforcement or subsurface <br />moisture drainage will be necessitated. As in analogous situations regarding <br />the existing surface facilities, the design analyses should include stability <br />and drainage considerations of both the operational and proposed reclaimed <br />haul road configurations. <br />******[BOB YOU'LL PROBABLY WANT TO ELABORATE ON THE ABOVE ROAD COMMENT]****** <br />The application correctly observes that the stability of the waste structure <br />might be critically affected by infiltration of waters, resulting in increased <br />pore water pressure ratios. Therefore, the applicant appropriately proposes <br />the installation of coarse aggregate backfilled trench subdrains. However, <br />the design and construction specifications presented for these proposed <br />subdrains are inadequate. The applicant should include a projection of the <br />maximum flow to be accommodated by these subdrains. Further, the applicant <br />should provide complete size gradation specifications for the subdrain <br />aggregate material. Using that specified gradation, the applicant should <br />demonstrate the adequacy of the cross-section of these proposed subdrains to <br />accommodate the expected maximum flows. In addition, the applicant should <br />elaborate upon the stated intention to obtain on-site materials of sufficient <br />durability and proper gradation to meet the require~~material specifications. <br />The application observes that a filter fabric will be used to cover the <br />completed drain. The Division believes that the aggregate drain should be <br />enveloped in geotechnical filter fabric, in order to assure maintenance of the <br />necessary effective cross-sectional area and prevention of fine material <br />invasion. <br />The application states that inspections of the waste structure will be <br />performed on a quarterly basis. The Division, through reference to Rule <br />4.09.1 from Rule 4.10.1(1)(a), requires that inspection also be performed <br />during specific critical periods; such as "(1) removal of all organic material <br />and topsoil, (2) placement of underdrainage systems, (3) installation of <br />surface drainage systems, (4) placement and compaction of fill materials, and <br />(5) revegetation". Specific attention should be paid to any item of <br />significant design importance while completing inspections, regardless of <br />whether they are exposed during the specific quarterly inspection. <br /> <br />