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rmst <br /> • <br /> r4;f:etel, <br /> CONK� <br /> - - Howard RGreen Company <br /> Form <br /> CONSULTING ENGINEERS. l►ssNCISA <br /> Formerly MSA <br /> July 16, 1997 Consulting Engineers <br /> File: 800720J-0240 <br /> Mr. Steve Rohlf <br /> Building & Zoning Administrator <br /> City of Elk River <br /> 13065 Orono Parkway <br /> P.O. Box 490 <br /> Elk River, MN 55330 <br /> RE: TILLER CORPORATION MINERAL EXTRACTION AND HOT-MIX ASPHALT PLANT <br /> PERMIT APPLICATION <br /> Dear Mr. Rohlf: <br /> As you requested, we have reviewed the package of information submitted by Tiller Corporation <br /> concerning their request for a mineral extraction and hot-mix asphalt plant permit. As you are <br /> aware, the property in question is approximately 130 acres of land located in the northwest <br /> • quadrant of 221st Avenue and TH 169. There is a small portion of the property in question that is <br /> south of 221st Avenue. Much like the plant along Proctor Avenue, the proposal is to operate both <br /> sides of the road utilizing a culvert conveyor system under 221st Avenue. The application indicates <br /> that it will take approximately 20 to 25 years to complete mining the entire site. <br /> We have reviewed this permit application from two standpoints, one being drainage and the other <br /> being transportation considerations. With regard to these two issues, we would offer the following <br /> comments: <br /> 1. DRAINAGE <br /> The permit indicates that during the mining operation, surface water drainage will be <br /> directed to low areas within the property. No surface water drainage is expected to be <br /> directed off-site. Sedimentation would occur in these temporary ponding areas. The permit <br /> application indicates the ponds could be readily cleaned by on-site equipment. Erosion will <br /> be minimized by seeding and mulching side slopes as appropriate. <br /> The reclamation plan for the site indicates a lowest finished elevation of approximately 956 <br /> in the northeast quadrant of 221st and TH 169. The Highway 169 intersection elevation is <br /> approximately 1,010. This would indicate that the finished mine elevation will be <br /> approximately 50 feet below TH 169. It appears that the only reasonable long-term <br /> drainage scenario for this site would be an on-site retention basin preceded by <br /> appropriately sized sedimentation basins for quality control. This type of drainage pond <br /> • with no outlet would have to be appropriately sized for the worst storm event that might be <br /> 1326 Energy Park Drive • St.Paul, MN 55108 • 612/644-4389 fax 612/644-9446 toll free 800/888-2923 <br />