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documentation, it is possible additional cover material will be required prior to bond release where existing material is shown to be less than the required depth. Timing of the RDA's final reGamation is uncertain at this time due to the mine's temporary cessation of operations and assumption of the permit by Picketwire Processing. As shown by photographs, a benched keyway cut was constructed to stabilize the pile's toe and allow for sub-drainage. Prior to construction of the RDA, drainage through the undisturbed canyon was ephemeral and there were no springs or seeps. An underdrain was constructed in accordance with section 4.09.1(13). The drain branches into east and west segments in smaller tributary canyons, and the western arm branches into a third segment. Underdrain construction progressed in segments as waste disposal progressed northward up the canyon, again as shown in photographs. Mirafi filter fabric was used to cover the drain. Short sections of the underdrain were visible where they protruded from the coal refuse material at the RDA's northeastern and northwestern limits. One of the northwestern branches of the underdrain was covered with coal refuse just beyond the end of the Mirafi fabric as a result of grading the operational surtace to maintain positive drainage. The permittee intends to remove the refuse before tieing-in the fabric for the next drain extension at this location. Other branches of the underdrain, inGuding portions covered with Mirafi fabric, extended from under the refuse. Conclusions DMG found that the MWDP and RDA appeared to be in compliance with the approved pemtit. I agree with that finding, but note the limitations inherent in verifying construction using field measurements in the absence of engineer's certifications to that effect. While most measurements appeared to be within design parameters or Gose to them (knowing our field measurements were not exact), an engineer's certifications that structures were built as designed would provide the level of assurance about the piles' construction and stability that DMG's rules intend them to provide. Mr. Thompson was advised that a number of items need maintenance or should be monitored. Items needing maintenance and/or monitoring inGuded: • the gully erosion of the southwestern outslope of the RDA's operational surtace; • erosion of the outer berm of the western side ditch on the second lift of the RDA; • terrace grading where drainage off the RDA to side ditches needs improvement; • grading on the operational surtace of the RDA where surface runoff should be distributed more evenly between the eastern and western side ditches; • seepage from the west side of the RDA's third reGaimed lift outslope about two thirds of the way up from the second terrace; and 7 1997 New Elk Special Focus