Laserfiche WebLink
Tom Bird, GCC Energy, LLC <br />C- 1981 -035 / TR -20 / AR #2 <br />14- Nov -2014 <br />Page 4 of 7 <br />6.4 of Trautner has been revised to address the requirements for subdrains. This portion of <br />the comment is resolved. However, the permit does not appear to address the Inspection <br />requirements. Please revise the Mine Waste Rock Disposal narrative in Section 2.05.3 of <br />the permit to address inspection elements and frequency for the West Waste Bank, in <br />accordance with Rules 4.09.1(11) and 4.10.2. <br />d) In the 51" paragraph of 6.4, Trautner indicates that water was encountered in Test Boring Six <br />(TB -6) at a depth of 11 feet. Based on the Log for TB -6, this water was at the approximate <br />level of the bottom of the CMW Backfill. The relative location of the six TBs is shown on Page <br />7 of Trautner. Is it possible that TB -6 may have been drilled in the vicinity of the original <br />natural stream channel, and that there is subsurface water present that is not captured by <br />the pipe inlet north of the highwall? Please address whether this may be the case, and what <br />impact this may or may not have on the West Waste Bank. <br />Page 14 of the Revised Trautner study describes the subsurface drain system, which will <br />include a toe drain. This item is resolved. <br />e) Appendix C of Trautner was prepared by a sub - contractor, CDS Laboratories. Their results <br />indicate that subsurface water was found only in TB -1, not in TB -6 as Trautner states. Please <br />address this apparent contradiction on the location of water found in the Test Borings. <br />This question does not appear to have been addressed in GCC's 06- Oct -2014 response. <br />f) Now that the CMW Backfill has been removed, will further examination and analysis of the <br />foundation material be required before construction of the West Waste Bank can <br />commence? Please address this question. <br />This question will be addressed by GCC's response to paragraph c), above. <br />g) In 6.5, Trautner recommends the CMW be placed with a moisture content within 3% of <br />optimum and compacted to a minimum of 90% MDD (standard Proctor). An initial lift <br />thickness of 12" is recommended, possibly adjusted to 24" as field monitoring and testing is <br />done. These recommendations are acceptable; Rule 4.10.4(3)(a) requires that CMW be <br />spread in layers no more than 24" in thickness, and (b) requires compaction of 90% MDD to <br />prevent spontaneous combustion and provide the strength required for stability of the waste <br />bank. <br />6.5.1 says that Trautner should be contacted to observe the materials exposed, to identify <br />any potential sources of moisture that would require the installation of a subdrainage <br />system. Has Trautner evaluated the foundation since the CMW Backfill was removed? (Yes - <br />the Division was present at a site meeting with GCC and Trautner on 11- Sep- 2014.) The <br />second paragraph of this subsection addresses Trautner's monitoring of CMW placement, <br />once construction of the waste bank has commenced. The approach described is generally <br />acceptable. Rules 4.09.1(11) and 4.10.2 address the inspection requirements for spoil and <br />CMW. Please note that 4.09.1(11)(4) requires that an engineer (or representative) be on- <br />hand during placement and compaction of fill materials. On this point (frequency of testing), <br />the current permit is inadequate. Please update the permit to address the frequency of <br />compaction testing that will be conducted for both the West Waste Bank and the Refuse Pile. <br />This item (frequency of compaction testing) does not appear to have been addressed in <br />GCC's 06- Oct -2014 response, but can be incorporated into GCC's response to paragraph c), <br />