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existing (previously placed) coal waste. The vertical cut for each key into the <br />coal waste should be on the order of 4 to 6 feet high. Keying the additional coal <br />mine waste into the existing waste will eliminate a potentially weak surface along <br />the previous and newly places waste. If any zones of seepage are encountered <br />during the benching /keying operations, we recommend construction of a gravel <br />drain to allow drainage and relieve pore pressures. Care should be taken during <br />fill placement, keying and benching to not damage the vibrating wire piezometers <br />and inclinometers installed at CWDA. The piezometers have cables that are <br />routed through the coal waste to the bench located 50 feet above the toe of the <br />waste bank. <br />Inspection <br />The waste rock disposal area will be inspected for stability by a qualified <br />registered engineer or other qualified professional specialist experienced in <br />construction of earth and rockfill embankments under the direction of a qualified <br />professional engineer, on a quarterly basis, beginning within 7 days after the <br />preparation of the disposal area begins. In addition the area will be inspected <br />during the following critical periods: removal of all organic material and topsoil as <br />previously described, placement of underdrainage systems, installation of <br />surface drainage systems, placement and compaction of fill materials, and <br />during revegetation. Inspections shall include such observations and tests as <br />may be necessary to evaluate the potential hazard to human life and property, to <br />ensure that all organic material and topsoil have been removed and that proper <br />construction and maintenance are occurring in accordance with the approved <br />plan. A report will be provided to the Division by the inspecting engineer within <br />two weeks of the completed inspections. A copy of this report will be kept at the <br />mine site. <br />The certified report addressing the underdrain system and protective filters will <br />include color photographs taken during and after construction, but before <br />underdrains are covered with excess spoil. If the underdrain system is <br />constructed in phases, each phase shall be certified separately. The color <br />photographs accompanying each certified report will be taken in adequate size <br />and number with enough terrain or other physical features of the site shown to <br />provide a relative scale to the photographs and to specifically and clearly identify <br />the site. <br />TR -76 - 13 - 11/12 <br />