Laserfiche WebLink
Sertian - 7,05.3 <br />The underdrains are designed and constructed to use the naturally-occurring sandstone boulders and <br />. cobbles, which are a significant component of the alluvial/colluvia] deposits in the small ephemeral <br />drainages to the area, as a drainage medium. This material is non-degradable and non-acid- or toxic- <br />forming and typically meets the size consist requirements of Rule 4.09.2(2)(d). Rock underdraiti <br />materials are placed and wrapped with a suitable geo-textile material to maintain effective drainage <br />characteristics and prevent or minimize clogging. Designs for required rock underdrains aze included <br />with the coal refuse faciliry designs in Exhibit 2.05-E4, Mine Development Rock/Coal Refuse Facility <br />Design. <br />Genera] coal refuse facilities construction and operation practices include the following activities: <br />7) Establish upgradient clean-water diversion(s) to intercept and roue undisturbed drainage <br />around the refuse pile area <br />2) Construct perimeter collection ditch(s) and sedimentation control structure(s) or <br />alternative sediment controls, as required to collect and control disturbed area drainage <br />and sediment from the refuse pile azea <br />3) Establish road access to and in the refuse pile area <br />4) Cleaz and grub large vegetation and strip available soil material, remaining vegetation, and <br />any orgaruc material from the initial pile footprint area. Soil materials will be temporarily <br />stockpiled as berms in the intermediate catch bench areas between successive fill <br />benches. Large rock recovered during foundation prepazation activities will be <br />temporarily placed along the inside edge of the perimeter drains fox use as riprap in the <br />perimeter drains and for use in construction of the rock underdrain. <br />• ~ <br />5) Construct ,nitia] section of underdrain using rock and appropriate geo-textile Filter fabric <br />6) Selectively place and compact coal refuse materials in successive horizontal lifts <br />(maximum 2-foot tuck, compacted to 90 percent of maximum dry density) consistent <br />with design specifications <br />7) Progressively expand xhe pile from the toe upward by repeating steps 1 through 6 as each <br />bench is completed to it's design elevation <br />8} Grade bench outslope and surface to final configuration (maximum ZH:IV slopes) and <br />construct designed bench drains on the intermediate catch benches <br />9) Place a minimum of 4 feet of suitable (non-toxic, non-combustible) cover material on the <br />regraded surfaces and seed to establish permanent vegetation <br />Coat refuse facility construction will be supervised and monitored by a qualified Registered <br />Professional Engineer. lnspections of refuse fill construction actinides will occur on a quanerly basis, <br />at a minimum, and will specifically include inspections during the critical construction activities of; 1) <br />Foundation preparation; 2) Underdrain construction; 3) Surface drainage construction; 4) Refuse fill <br />placemem and compaction; and 5) Cover marerial placement and revegetadon. The inspecting <br />engineer will provide a certified report to the CDMG within .two weeks following each inspection <br />documenting construction in compliance with the design specifications. ]nspection reports will <br />identify and describe any observed instability or potentially hazardous conditions and will include <br />• photographic documentation of construction activities. Copies of the inspection reports will be <br />retained on-site for future reference and review, <br />TR-43 2.05-46 Revised August 2003 <br />