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• s <br />resulted in desiccation and an unacceptable increase in clay permeability; appropriate <br />mitigation actions shall be taken. <br />4. The clay liner shall be constructed with a minimum of 2 feet of compacted clay over the <br />entire impoundment. The clay liner shall be compacted in 6 inch lifts to at least 95'% <br />standard proctor density. The clay shall have a hydraulic conductivity of 10'' cm/sec or <br />less. The clay material shall also be compatible with other materials used in the <br />construction of the cap, so that its integrity and hydraulic conductivity is not diminished <br />by physical or chemical contact with the other construction materials. <br />5. Proof rolling of a test fill of waste rock with a minimum 10 ton smooth face vibratory <br />roller shall be conducted to determine proper lift thickness of the backfilled waste rock. <br />The results of the proof rolling test shall be provided to the Department as part of the plans <br />and specifications and construction quality assurance plan submission. <br />6. For the drainage ditch on the impoundment, rip rap shall consist of non-acid generating <br />rock, preferably limestone. <br />7. Open blast holes in the pit floor shall be plugged in accordance with ARSD 74:11:08 prior <br />to constructing the waste rock impoundment. <br />8. To determine proper clay moisture content and proper functioning of the frost <br />protedion/drainage layer in terms of potential desiccation of the underlying clay layer due <br />to capillary action and/or evapotranspiration, LAC Minerals shall monitor for moisture <br />content within the clay layer. The monitoring shall be done with a frequency of once per <br />year for five years after installation of the clay layer, with insults submitted to the <br />Department annually. The monitoring shall be done during the fall (dry season). <br />Upon completion of processing, the spent ore shall be neutralized to comply with <br />regulations, water quality standards, and permit conditions, as applicable. <br />2. LAC Minerals shall submit to the Department for approval an updated closure and <br />postclosure plan for leach Pads Nos.' 1, 2, and 3, taking into account the additional <br />information obtained as a result of additional drilling and acid generating predictions. <br />Erosion and sedimentation controls shall be in place and functional during all phases of <br />waste rock removal, earthwork, cap construction and tecLrmaflon in the amendment area. <br />The sediment controls shall be maintained as necessary and kept functional during the <br />course of the project. <br />