Minnehaha Creek Stormwater Management
Both Minnehaha Creek and Lake Hiawatha are on the State Impaired Waters List and have had Total Maximum Daily Load Studies completed. The proposed work would focus on park land along Minnehaha Creek which is a highly-recreated corridor with public trail systems throughout. In 2014, the District experienced record flooding resulting in substantial erosion and tree loss along Minnehaha Creek. In 2015, the District completed an assessment of flood damage and received FEMA funding for bank repair at 31 sites along the Creek within Minneapolis Park and Recreation Board property. Before moving forward with stream restoration, the District would like to explore opportunities to align these improvements with green infrastructure storm water quality management opportunities in the area.
See http://www.bwsr.state.mn.us/aboutbwsr/index.html and http://www.bwsr.state.mn.us/aboutbwsr/boarddirectory.pdf
See http://www.bwsr.state.mn.us/aboutbwsr/index.html
Marcey Westrick
This effort would bring together the data and recommendations from past studies as well as bringing together the goals and priorities of the District, City, MPRB, and FEMA. The assessment would allow the District to capitalize on the funding obtained from
The first step in this study was to evaluate the current information available to help cite where stormwater BMPS could be placed in the landscape. For this step, the following data was assembled: public land, proximity to existing storm sewer networks, contributing land area, City of Minneapolis CIPs, TMDL studies, and past BMPs studies for the area.
The second step was to fill data gaps. This was done through the use of field surveys and as-built information.
The third step was to develop a model and update it with it with BMPs. The BMP hydrology was modeling with P8 and XP-SWMM. Total phosphorus (TP) loading rates and removal rates were modeling in P8. Using this model, stormwater BMPs were identified and preliminary sized for nutrient reductions and cost.
The fourth step was then to evaluate the cost-benefit of each BMP and assemble a prioritization list on which would provide the highest return on investment. When normalizing costs they ranged from $5- $25 per cubic foot of treatment volume. When normalizing costs in terms of dollars per pound of TP removed over 20-years, costs ranged from $644-$8,014 per pound of TP. Beyond cost, each BMP was also ranked for total phosphorus removal, effectiveness of total phosphorus removal cost rank, and design challenges.
The final step was to develop a report that summarized the methods, the modeling results, the BMP locations, cost and removal efficiencies, and recommendations. This report has been completed and as noted, identified 13 potential BMPs and all of the data that informed the development of those BMPs. Treatment efficiency ranged from 3-74 pounds per year of TP removal, with an average removal of 31 pounds. If all 13 BMPs were to be constructed they would remove approximately 399 pounds of TP per year, which would contribute significantly towards the City of Minneapolis? goal to reduce 400.4 pounds of TP per year to Minnehaha Creek and Lake Hiawatha.
LOCAL LEVERAGED FUNDS