2012-08-21_REVISION - M1980244 (32)

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C. Related to Comment 12, the Division's review of the Phase 1 and 2 sediment ponds for the SGVLF (reference Drawings A505 and A520), and storm water management plan sediment pond designs (reference Appendix 12, Volume VI, Drawing Nos. CCV 10 -SA4, -SAS; specifically EMT -8a, -09, -16, -17M, -18, -20 and -21) appear to exceed the 10 -foot height limit for non jurisdictional dams. Please substantiate why these ponds are non jurisdictional or commit to getting dam construction permits from the OSE for each jurisdictional dam. RESPONSE: AMEC is re- configuring the layout /design of the Phase I and Phase 2 sediment ponds to meet the non jurisdictional criteria, and will be included in the final construction drawings. The final configuration of these ponds will be submitted to the Division for review, and included in the final As -built reports. CC &V and AMEC has also reviewed the storm water control structures associated with the High Grade Mill Platform since submittal of the application and provides herein improved storm water management control structures for the High Grade Mill Platform area within Attachment 10. d. The Division's review of the Phase 1 and 2 sediment ponds for the SGVLF (reference Drawings A505 and A520), and EMP -8a (reference Appendix 12, Volume VI, Drawing No. CCV10 -SA5) indicate these ponds have no spillways. Even if they are "zero- discharge" ponds, a spillway is required to pass the peak flow resulting from the 100 -year, 24 -hour storm event. Please provide spillway designs certified by a licensed professional engineer for these ponds. RESPONSE: AMEC is re- configuring the layout/design of the Phase I and Phase 2 sediment ponds to include a spillway that will safely pass the 100 year, 24 -hour storm event, and will be included in the final construction drawings. The final configuration of these ponds will be submitted to the Division for review, and included in the final As -built reports. e. The Division's review of the SGVLF Phase 1 diversion channel (reference Drawings A505 and A520) indicate there is no designed conveyance for over 200 feet between the pond and sta. 0 +00 of the channel. Please explain the lack of designed conveyance. (Note: the proposed diversion channel would be expected to bring much higher flows to this reach than what the reach has been exposed to prior to receiving flows from the diversion channel). RESPONSE. The Phase I channel utilizes an existing railroad cut in the existing topography to convey the channel over the first 200 feet into the pond to drain into the proposed sediment pond. The contractor may need to do some additional reshaping of the existing railroad cut during construction to improve the flow into the pond, and will be shown in the as -built report. f. North arrows are useful in orienting drawings. Please resubmit all six drawings in Appendix 12, Volume VI with north arrows for each plan view. RESPONSE. North arrows have been added to all six drawings in Appendix 12, Volume VI and are submitted herein Attachment 11. 48. Page 10 -5, last paragraph — Hay bales attract large game animals such as deer and elk, which eat the hay and destroy the BMP. Please confirm the use of "hay" in the last paragraph is a typographic error and that straw will be the only material used in bales for this project. RESPONSE: This is a point well taken, however, based on experience by professional Environmental Resources Staff at CC &V, "straw" bales too attract large game animals such as deer and ells which then can destroy the BMP. CC &V will however, commit to use "straw" bales utilized for BMPs. 49. Page 11 -1. Surface water monitoring — Poverty Gulch is not mentioned in this section. Please provide a discussion on surface water monitoring in Poverty Gulch. RESPONSE: As presented in more detail in Section 5.1.3 Appendix 2 of Volume II of the Application, there are no surface water resources in Poverty Gulch and that is why, there is no mention of surface water monitoring in Poverty Gulch on Page 11 -1 of Project Description.