Laserfiche WebLink
Typical overburden/interburden handling operations are described in Section 2.05.3, Operation <br />Plan and Section 2.05.4(2)(c), Backfilling and Grading. The overburden/interburden material <br />excavated by truck and shovel from the cropline pit is placed in box cut spoil stockpiles as shown <br />on Map 2.05.3-1,Current Mine Plan -New Horizon 2. Based upon the existing spoil stockpile at <br />New Horizon 1 mine area, the overburden/interburden will likely be stratified by individual distinct <br />lifts of different lithologic material. Lithologic Unit 1 material will typically be placed near the base <br />of the stockpile with a thin topdressing of Units 2, 3, and 4. As the stockpiled material is returned <br />to the final pit, mixed Units 2, 3, and 4 will be placed near the pit base and subsequently covered <br />with Unit 1 material. Mixed Units 2, 3, and 4 have mean pH and ABP values of 6.0 and -1.8, <br />respectively, which are both considered suitable for aquifer or root growth medium material <br />(Section 2.04.6, Table 2.04.6-3). <br />The following overburden/interburden handling techniques are being utilized after the lower <br />Dakota Coal has been removed from the box cut pit. Initially, the upper unconsolidated <br />overburden is removed by shovel and trucks and placed into the adjacent pit void. Cast blasting <br />is being utilized, when possible, to fracture the remaining consolidated overburden/interburden. <br />• During cast blasting, portions of Units 2, 3, and 4, in addition to the lower part of Unit 1, will likely <br />be projected into the adjacent pit. Lastly, dozers, trucks and shovel will be utilized to remove the <br />remaining overburden/interburden material down to the top of the Lower Dakota Coal. <br />Where blending or normal burial are ineffective (as defined by the Regraded Spoil Monitoring <br />Program), Unit 1 overburden will be selectively handled to replace afour-foot root growth medium <br />at the regraded spoil surface. In these situations, unsuitable spoil will be topdressed with a <br />minimum of four feet of suitable material (includes replaced topsoil thickness). <br />Lastly, ameliorating reclamation practices will primarily be utilized in those areas where unsuitable <br />spoil reaction, acid-base potential, particle size, saturation percentage, salinity, or sodicity values <br />are identified by the regraded spoil quality control program. Reclamation practices will include <br />either a selectively handled suitable spoil topdressing or incorporating adequate quantities of <br />agricultural grade limestone. <br />• (Revised 24 AUG O6) 2.05.4(2)(d)-5 <br />