PERMFILE72174 - Laserfiche WebLink

Home Browse Search

Mr. Joe Intermill March 22, 2005 ~~ Paget CIVIL RES'sJURCES, LLC In addition, the owner of the water storage facility is liable for the safety of the project in accordance with State Statutes. Should any wave erosion occur in the embankments, the problem will be quickly repaired. We believe that the significant freeboard, Zone 2 material, low occurrence of maximum prevailing winds arising from the east, and the full-time operation and maintenance of the facility will provide adequate protection to traffic along Highway 85. Please clarify the points of discharge for water that is dewatered to (acildate mining and reclamation plan. CDOT is concerned if the structures under Highway 85 are adequate to handle the flows from pit dewatering. Please demonstrate that the outlet structures (such as ditches, culverts, pipes, etc.) are adequate to handle the flows from water discharged off-site. The two existing culverts associated with the site are adequate to handle flows from pit dewatering and for water storage. Historically, these culverts have been used for flow from tail water return ditches from the agricultural lands. The sources of return water have historically included groundwater from agricultural wells and surface rights that were used to imgate the crops. Farmers who benefit from seepage rights and other water rights from the South Platte River have also traditionally used the culverts. The culverts, identified on Sheet 3 of 7, are concrete box culverts with approximate dimensions 6' high by 8' wide. The calculated discharge, assuming a zero percent slope, was 525 cfs (235,620 gpm) per culvert using only ten feet of the existing 15 feet of headwater (see attached analysis). The agricultural lands and surface irrigation will be replaced by the mine and dewatering operations that is anticipated to discharge a maximum of 20-,000 gpm in total. We propose that the mine dewatering be conveyed through the culverts in HDPE pipelines (or similar). The pipelines will reduce effective area of the culverts by approximately one percent (assuming 12" diameter pipelines in each culvert). This is not anticipated to significantly restrict the flow through the culverts. Please call either Danna Ortiz or myself if you have further questions or concerns about the Lupton Lakes Project. Sincerely, Civil'R~e'~sou~rce~s, LLC ~~ ~. i~ Mark Relner, P.E., P.G. Project Engineer Llprgec151SW InvesMenl Gmup - 12315W TKO Join[VenWrelOMG PERMIMtlequary ReviewWdequacy Review 71CDGT response.tlce