2007-06-29_PERMIT FILE - C1981022A (2)

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Section - 2.05.3 The underdrains are designed and constructed to use the naturally-occurring sandstone boulders and • cobbles, which are a significant component of the alluvial/colluvial deposits in the small ephemeral drainages in the area, as a drainage medium. This material is non-degradable and non-acid- or toxic- forming and typically meets the size consist requirements of Rule 4.09.2(2)(d). Rock underdrain materials are placed and wrapped with a suitable geo-textile material to maintain effective drainage characteristics and prevent or minimize clogging. Designs for required rock underdrains aze included with the coal refuse facility designs in Exhibit 2.05-E4, Mine Development Rock/Coal Refuse Facility Design. General coal refuse facilities construction and operation practices include the following activities: 7) Establish upgradient dean-water diversion(s) to intercept and route undisturbed drainage around the refuse pile azea 2) Constmct perimeter collection ditch(s) and sedimentation control structure(s) or alternative sediment controls, as required to collect and control disturbed azea drainage and sediment from the refuse pile area 3) Establish road access to and in the refuse pile area 4) Clear and grub large vegetation and strip available soil material, remaining vegetation, and any organic material from the initial pile footprint area. Soil materials will be temporarily stockpiled as berms in the intermediate catch bench areas between successive fill benches. Large rock recovered during foundation prepazation activities will be temporarily placed along the inside edge of the perimeter drains for use as riprap in the • perimeter drains and for use in construction of the rock underdrain. 5) Construct initial section of underdrain using rock and appropriate geo-textile filter fabric 6) Selectively place and compact coal refuse materials in successive horizontal lifrs (maximum 2-foot thick, compacted to 90 percent of maximum dry density) consistent with design specifications 7) Progressively expand the pile from the toe upward by repeating steps 1 through G as each bench is completed to it's design elevation 8) Grade bench outslope and surface to final configuration (maximum 2H:1V slopes) and construct designed bench drains on the intermediate catch benches 9) Place a minimum of 4 feet of suitable (non-toxic, non-combustible) cover material on the regraded surfaces and seed to establish permanent vegetation Coal refuse facility construction will be supervised and moriltored by a qualified Registered Professional Engineer. Inspections of refuse fill construction activities will occur on a quarterly basis, at a minimum, and will specifically include inspections during the critical construction activities of; 1) Foundation prepazation; 2) Underdrain construction; 3) Surface drainage construction; 4) Refuse fill placement and compaction; and 5) Cover material placement and revegetation. The inspecting engineer will provide a certified report to the CDMG within two weeks following each inspection documenting construction in compliance with the design specifications. Inspection reports will identify and describe any observed instability or potentially hazardous conditions and will include • photographic documentation of construction activities. Copies of the inspection reports will be retained on-site for future reference and review. TR-43 2.D5-46 Revised August 2003