Agenda - Council - 11/24/2020 - Laserfiche WebLink

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BROWNS VALLEY FLOOD MITIGATION PROJECT BROWNS VALLEY, MINNESOTA Background The March 2007 spring flood caused substantial damages to the City of Browns Valley, Minnesota, placing severe social and economic hardship on the residents and the community. The Project The Upper Minnesota River Watershed District (UMRWD) retained Houston Engineering, Inc. (1-IEI) to provide technical assistance for the planning, design, and completion of the Browns Valley Flood Mitigation Project in August of 2007. Construction for a diversion dam and floodway bypass channel began in 2009 and was completed in 2012. The constructed Flood mitigation project resulted in 5.9 acres of wetland impact which required mitigation under the Federal Clean Water Act and the Minnesota State Wetland Conservation Act. The UMRWD » Location Browns Valley, Minnesota » Client Upper Minnesota River Watershed District » Contact Dianne Radcrmacher Administrator 320.839.3411 authorized HEI to initiate plans for the restoration of a large 55-acre drained and cultivated basin. The wetland basin had been drained by surface ditches and subsurface tiles with a pumping station outlet to promote conditions conducive to agricultural production. HEI performed field visits, surveys, and hydrologic analyses to determine the most effective methods for hydrologic and vegetative restoration. Termination of the pumping and construction of a clay ditch plug, culvert outlet, and overflow spillway began in 2011 and was completed in 2012. Field vegetation surveys indicated that the drained wetland was generally free of any naturally occurring wetland vegetation. HEI prescribed a detailed mix of wetland plants and seed mixes that matched what would occur in a natural Type 3, 4, 5 wetland basin. Site preparation, planting, and seeding methods were developed. The upland areas adjacent to the basin were also prescribed a native upland prairie seed mix. Scheduled management activities, performance standards, and monitoring activities were prescribed to ensure the ongoing success of this restoration project. [1 Client Benefits Hydrologic restoration returned the basin to its pre -drained conditions. • One year after restoration, the wetland and upland complex was well on its way to becoming a high quality, functioning Type 3, 4, 5 wetland basin. • The restoration project restored approximately 58 acres of wetland basin as well as 25 acres of upland buffer. UMRWD secured permanent easements for the total project area of approximately 83 acres. • As a result of this effort, 42 acres of wetland credits were banked. 12 (5304_002) 10-8-20 I IE1 PROPOSAL OCTOBER 12, 2020 CITY OF RAMSEY REVIEW AND MONITORING OF WETLAND MITIGATION AREAS IN THE COR 18