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Page 3 of 8 <br />10. Please commit to providing the Division with an approved NPDES discharge permit from the Colorado <br />Department of Public Health and Environment. <br />11. Please commit to providing the Division with a copy of the Drainage Report prepared for Weld County. <br />12. The Applicant states stockpiles will be broadcast seeded and incorporated into the weed control <br />program. Please provide the Division with a copy of the weed control plan for the Iverson Mine. The <br />weed control plan must include the following requirements and be prepared in consultation with the <br />appropriate local weed control authority; a list of potential noxious weed species (target species), the <br />control methods and treatment window for each species, monitoring plan and follow-up plan. <br />13. The Applicant states Lafarge is working with the Corps of Engineers regarding the regulatory <br />requirements related to the created wetland area on the east edge of the mining cell. Please commit <br />to providing the Division with a copy of the 404 permit or documentation a 404 permit is not required <br />by the Corps of Engineers. <br />14. The mining plan proposes a 100-foot setback from the Cache La Poudre River. In order to mine within <br />400 feet of the river, plans for engineered inflow and outflow structures must be submitted to the <br />Division for review. <br />15. Due to the prevailing wind direction and fetch distance of the final lake configuration, the Division will <br />require the Applicant to complete a wave analysis and wind erosion study for the site. <br />16. Portions of the proposed mine site lie within the 100-year flood plain of the Cache la Poudre River. In <br />the event of a significant flood event (100-year flood or greater) it is likely the proposed pit will be <br />captured by the Cache La Poudre River. Wherever mining will occur within 400 feet of the river <br />channel, a flood analysis and flood control plan must be evaluated and submitted. This would include <br />pit side armoring, river side armoring, inflow and outflow channels, or other appropriate measures. <br />Accordingly, the Division requests the Applicant provide the flood elevations(s) to be expected under a <br />"worst case" flooding scenario and specific mitigation measures that will be implemented to minimize <br />the potential for any offsite impacts. <br />The potential for "berms" around gravel pits to be damaged during flooding is discussed in detail in the <br />1987 Urban Drainage and Flood Control District (UDFCD) Publication "Technical Review Guidelines for <br />Gravel Mining Activities within or Adjacent to 100-year Floodplains." Strips of native ground or <br />constructed fill between the stream and the gravel pit, and generally aligned with the flow diirection cif <br />the stream are referred to in the UDFCD document as riverside berms. Riverside berms are proposed <br />in the Iverson Mine application, which may be prone to erosion during a flood event. The required <br />inflow/outflow structures are intended to mitigate possible slope failure during flood events for these <br />berms. The Iverson Mine is outside of the political boundaries of the UDFCD, but the technical <br />floodplain factors that led to the formation of the L IDFCD -L!idance still apply and Lyill be used to <br />review the adequacy of the flood mitigation structures proposed for the site. Additionally, the site and <br />surrounding area have a history of flooding as demonstrated by flooding event last summer which