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protection during [he 100-year flood. A floodplain impact analysis report may need to be submitted by the applicant to adequately address this issue. I I. As previously noted, [he applicant intends to construct a lateral berm approximately 42 feet wide that will contain the Lupton Bottom Ditch, the pipeline, maintenance road and overhead utilities. As noted in the application, [he entire property is located in the South Platte River 100-year Floodplain. Lateral berms are defined as constructed berms or areas left in place between pits which are perpendicular to the general direction of flow of a river. Lateral berms may be overtopped during major floods, which can cause extensive erosion due to the high flow velocity. Extensive erosion can damage the lateral berm as well as the reconstructed Lupton Bottom Ditch, pipeline, road and overhead utility lines. The operator will need to provide a plan to stabilize the lateral berm to withstand overtopping during the 100-year flood event and to ensure the rerouted structures are not adversely affected. Such measure can be by increasing the width of the lateral berm, designed spillways and/or pitside bank protection. The Technical Review Guidelines for Gravel Minin¢ Activities W ithin or Adjacent to the 100-Year Floodolains. 1987 by Wright Water Engineers, Inc. provides some guidelines regarding protection of lateral berms. 12. The applicant makes note of 2 residential irrigation wells within 600 feet of the permit boundary. Exhibit C depicts 5 alluvial wells within 600 feet of the permit area. Please clarify this discrepancy and identify the owners of all the wells. In addition, please describe how the wells and the water rights of the well owners and irrigation ditch owners will be protected and comply with the applicable Colorado Water Laws and Regulations governing injury to existing water rights. Any well within 200 feet of the affected area will also need to meet the performance standards for permanent man-made structures (Rule 6.4.19). Please see question # 14 below. Rule 6.4.12 Exhibit L- Reclamation Costs 13. The Division will estimate the cost to reclaim the site once the applicant addresses the concerns noted in this letter. Rule 6.4.19 Exhibit S- Permanent Man-Made Structures 14. Rule 6.4.19 states that where the mining operation will adversely affect the stability of any significant, valuable or permanent man-made structure within 200 feet of the affected land, the applicant may either; • Provide a notarized agreement between the Applicant and the Person(s) having an interest in the structure, that the Applicant is to provide compensation for any damage to the structure; or • Where such an agreement can not be reached, the Applicant shall provide an appropriate engineering evaluation that demonstrates that such structure shall not be damaged by activities occurring at the mining operation. a) A number of structures will be directly affected by the mining operation including; the Lupton Bottom Ditch, pipelines, overhead utility lines, houses and outbuildings and wells.