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storage areas u•i[hin the Floodplain, thz applicant will also need to address protection measures that will be employed to contain the materials on-site in the event of a flood even[). 3. The applicant lists on page 2 (item 13.2) of the application form that Fly ash will be used or stored within the permit area. The Division will require the applicant, prior to any use and/or storage of fly ash within the permit area, to clarify their intentions and provide the following information: the source of fly ash, the approximatz volume to be used or stored, the length of time for Fly ash use or storage, the location(s) where fly ash will be used or stored, and the purpose for storage or usz of Fly ash. If the flyash is to used as a concrete admixture, the Division recommends that the Flyash be stored out of the Floodplain in a silo or other suitable storage vessel. If [he flyash is to be used as backfill in the pit areas, the Division will require a geochemical characterization, as assessment of potential impacts to surface and groundwater quality, and assurances that any potential adverse impacts to surface and groundwater quality will be mimimizzd. Please respond. 4. The applicant states on page 15 [hat inert fill from off-site may also be brought on site for use as backfill. Prior to any use of inert fill being brought in from off-site, [he opzrator will need to provide a notice which meets the minimum requirements of Rule 3.1.5(9). Attached is a copy of Rule 3.1.5(9) for your use. Please respond. 5. Review of the Mining Plan Map, Exhibit C-3 indicates a potential concurrent wetland mitigation area of approximately 13.9 acres immediatzly south of Cell 3. Please explain the what the potential wetland mitigation will consist of, ie: Is there a need for any excavation to occur in this area? Will the excavation expose groundwater? Will wetlands' be created in this area? Please respond. 6. Review of the Mining Plan Map, Exhibit C-3 indicates [hat the applicant has proposed to mine in Cell 4 within 110' of the west bank of the Big Thompson River. A significant portion of Cell 4 is also within the Floodplain (?100-year?) of the Big Thompson River. In order to ensure the structural integrity of the river channel throughout [he life of the mining operation, the proposed mining plans will need to be revised to conform with [he criteria listed in the Division's August ] 998 In-Stream Aggregate Extraction & Reclamation Guidance Document. (Please see at[achzd guidance document). The following options are acceptable to the Division: Option A: The applicant may revise the mine plan map to show [he boundaries of the "floodway" of the Big Thompson River and clearly show that all mining will occur outside the floodway. In conjuction, the applicant should revise the narrative in [he mine plan by providing a commitment [o no extraction within the floodway of the Big Thompson River. Option B: The applicant may revise the mine plan and mine plan map to clearly demonstrate that no mining will occur within 400 feet of the west bank of the Big Thompson River. Option C: The applicant may keep the proposed 1 10' setback upon submission of an approvable plan and cross-sectional design for side channel spillways allowing for pressure equalization of Floodwaters between Cell 4 and the channel of the Big Thompson River. For acceptablz design criteria, please refer to the attached guidance document (Appendix D and Figure D-16). Option D: The applicant may keep the proposed 110' setback upon submission of an approvable plan and cross-sectional design for channel riprap slope protection and pitside riprap slope protection. For acceptable design criteria, please refer [o the attached guidance document (Appendix D and Figure D-5, a) and c)).