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    Stormwater Pond Maintenance, and Wetland Management for Phosphorous Retention
    (Minnesota Department of Transportation, 2023-06) Janke, Benjamin D.; Natarajan, Poornima; Gulliver, John S.; Finlay, Jacques C.
    Reduction in phosphorus is critical because phosphate, a dissolved form of phosphorus, sustains algal and cyanobacteria growth and causes a wide range of water-quality impairments in the ponds and downstream waters including algal blooms, excess floating plants, taste, and odor problems. Many stormwater ponds and wetlands that treat stormwater appear to be less effective than expected or originally intended in phosphorus retention, a key function of these ponds in urban environments. There is evidence that many old ponds are releasing phosphorus from bottom sediments at high rates and likely exporting phosphorus to downstream surface water bodies. A major outcome of this project is a pond Assessment Tool to assess the risk of high phosphorus concentrations in ponds and sediment release of phosphorus. The tool is based on 20 ponds with detailed water quality and phosphorus release measurements and a meta-analysis of 230 ponds in the Twin Cities metro area. Other outcomes included a working definition of a constructed stormwater pond and a wetland treating stormwater in the framework of water-body regulations, the development of recommendations for stormwater pond maintenance and wetland management, and an update to the sections on the constructed stormwater ponds section of the 2009 Stormwater Maintenance BMP Guide.
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    Biofiltration Media Optimization Final Report
    (2022-12) Erickson, Andrew J; Kozarek, Jessica L; Kramarczuk, Kathryn A; Lewis, Laura
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    Assessment of Internal Phosphorus Release and Treatment with Iron Filings in five RPBCWD Ponds
    (University of Minnesota, College of Science and Engineering, 2022-06) Natarajan, Poornima; Gulliver, John S.
    Five ponds, Aquila Pond (in Bloomington), Pond BC-P4.10C (in Chanhassen), Bren Pond (in Eden Prairie), Pond 849_W (in Minnetonka) and Pond 42 (in Shorewood), were evaluated in this two-part study. a) In the first part of the study, the potential anoxic sediment phosphorus release was evaluated using laboratory sediment cores. A moderately-high flux of phosphate was measured under anoxic conditions, which was supported by high sediment oxygen demand and high organic matter content in the sediments. A low oxic flux was observed only for Pond BC-P4.10C and Bren Pond sediments, indicating mobilization of organic P by bacteria. Detailed sediment phosphorus characterization revealed low to moderate concentrations of mobile P (redox-P + labile organic P) mass, which is releasable under low oxygen conditions and by microbacterial degradation under both oxic and anoxic conditions. The relative mobile P mass (as % of the total sediment phosphorus mass) was 53% in Aquila Pond, 43% in Pond BC-P4.10 C, 47% in Bren Pond, 41% in Pond 42, and 63% in Pond 849_W, highlighting the importance of mobile phosphorus in driving internal phosphorus loading during anoxia in the ponds. b) In situ monitoring of surface to bottom DO and temperature profiles in the ponds were indicative of a stratified water column that was anoxic from top to bottom during much of the summer period. The observation of pervasive anoxia was common in Pond BC-P4.10C, Bren Pond, Pond 849_W, and Pond 42 during all three field seasons, as indicated by the relatively high summer anoxic factor (AF) for these ponds. Aquila Pond appeared to partially mix intermittently although bottom DO was still low during certain periods. c) All five pond sites had floating vegetation (duckweed and watermeal) that had a dense surface coverage (nearly 100%) from June to September. We have found strong evidence of duckweed cover influencing the DO dynamics in several ponds and have observed a strong pattern between summer anoxic factor and duckweed cover in our pond research projects. It is possible that the effect of duckweed may be exacerbated in dry years (like 2021) when stormwater inputs to provide direct mixing are less frequent. d) The application of iron filings was utilized to reduce phosphate release from the pond sediments. Ponds BC-P4.10C and 849_W were treated with iron filings in February 2020 and Bren Pond was treated in February 2020. Aquila Pond can be used as a control for the RPBCWD region, where surface water TP was seen to increase greatly from 2019 to 2020, and then stayed about the same in 2021. In Pond BC-P4.10C, the average TP went up after treatment with iron filings in February 2020, but not as substantially as the Aquila Pond. In Bren Pond, the average TP had a slight reduction in all three years. In Pond 849_W, the average TP went up in 2020 but then reduced in 2021. A similar reduction can be seen in comparing average TP for Shoreview Commons Pond (a fourth iron-treated pond located in the Ramsey Washington Metro Watershed District) to the Alameda Pond (located in v Roseville), where Shoreview Commons had a reduced average TP in 2021 after iron filings addition and the Alameda Pond, with no iron filings addition, did not. e) The analysis of the iron-treated sediments from Pond BC-P4.10C, Pond 849_W, and Bren Pond showed an increase in the iron-bound P mass and a concomitant decrease in the mass of labile organic P and loosely-bound P after iron filings application to the sediments, suggesting the partial or full movement of phosphate from the organic P form and loosely- bound P to iron-phosphate minerals in the sediments. The iron-treated sediment cores from Bren Pond exhibited an anoxic phosphate flux that was significantly lower than the phosphate flux from untreated sediments. f) While the column studies confirmed that sediment phosphate flux was controlled after iron addition, the reduction in internal phosphorus loading in the ponds was not directly assessed. The post-treatment water quality data showed reductions in SRP levels (surface and epilimnion) at the three iron-treated ponds but did not conclusively show reductions in TP levels, specifically in ponds BC-P4.10C and 849_W. The interpretation and assessment of treatment effectiveness is complicated by the year-to-year variation in pond water quality driven by rainfall patterns and runoff inputs among other factors, especially in ponds BC- P4.10C and 849_W, which have pretreatment data for only one year before iron filings were applied. Treatment of the ponds will likely require a combination of remediation techniques such as sealing the sediments from phosphate flux, aeration to enhance mixing and watershed-based phosphorus control actions to reduce the inflow of TP. Aeration may work well in Pond 849_W, which has a small amount of inflow or outflow.
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    Wet Pond Maintenance for Phosphorus Retention: LRRB 2019 KB 03 MnDOT Agreement No. 1034035
    (2022-06) Taguchi, Vinicius J.; Janke, Benjamin D.; Herb, William R.; Gulliver, John S.; Finlay, Jacques C.; Natarajan, Poornima
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    A Field Study of Maximum Wave Height, Total Wave Energy, and Maximum Wave Power Produced by Four Recreational Boats on a Freshwater Lake
    (2022-02-01) Marr, Jeffrey; Riesgraf, Andrew; Herb, William; Lueker, Matthew; Kozarek, Jessica; Hill, Kimberly
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    Golden Lake Phosphorus Release and Alum Dosing Feasibility Study
    (2020-06) Natarajan, Poornima; Gulliver, John S.
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    St. Cloud Pond 52: Assessment of Pond Sediments After Iron Filings Treatment
    (2022-01) Natarajan, Poornima; Gulliver, John S.
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    Quantifying Wave Energy on Minnesota Lakes
    (2022-01) Herb, William; Janke, Ben; Stefan, Heinz; Cai, Meijun; Johnson, Lucinda
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    Detecting phosphorus release from stormwater ponds to guide management and design
    (2021-01) Janke, Benjamin D.; Natarajan, Poornima; Shrestha, Paliza; Taguchi, Vinicius T.; Finlay, Jacques C.; Gulliver, John S.
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    Biofiltration Media Optimization – Phase I Final Report
    (2021-01) Erickson, Andrew J.; Kozarek, Jessica L.; Kramarczuk, Kathryn A.; Lewis, Laura
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    An Experimental and Numerical Study of Long-throated Flumes
    (2020-11) Herb, William; Hernick, Matthew
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    Characterization of Runoff Quality from Paved Low-Volume Roads and Optimization of Treatment Methods
    (2020-09) Gulliver, John S.; Natarajan, Poornima; Weiss, Peter T.
    Vehicular traffic contributes a large fraction of the pollutant load in stormwater runoff from roadways. While runoff concentrations have historically been characterized for urban roads with high average daily traffic (ADT), the runoff quality from paved rural roads that have relatively low ADT is largely unknown. In this study, runoff from low-volume roads (ADT < 1500) in Minnesota was monitored at 10 locations during 174 rainfall events in 2018 and 2019. The initial concentrations of total suspended solids (TSS), total phosphorus (TP), nitrate+nitrite, and heavy metals in the runoff, and the relationship between measured concentrations and site-specific conditions were analyzed. Concentrations were strongly influenced by the surrounding land use and soil type. Sites with agricultural lands had higher mean TSS, TP, and zinc concentrations, and lower nitrite+nitrate concentrations than wooded sites, which can be related to the type of soil that would get transported onto the roadways. When compared to existing urban runoff quality data, the estimated event mean concentrations (EMCs) in rural road runoff were substantially lower for copper and zinc and marginally lower for TSS, TP and nitrate+nitrite. Based on detailed cost-benefit analysis of various roadside treatment options, roadside drainage ditches/swales are recommended for cost-effective treatment of runoff from low-volume roads over ponds, sand filters and infiltration basins. Example road widening projects were also modeled to determine how stormwater management requirements can be achieved using drainage ditches/swales.
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    Detailed Hydrology for Stormwater BMPs
    (2020-03) Herb, William; Johnson, Lucinda; Gulliver, John
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    Transport of Chloride through Silt Loam, Sandy Loam and Sandy Loam with Compost
    (2019-12) Erickson, Andrew J.; Gulliver, John S.; Weiss, Peter T.
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    Riparian Shading Study
    (2018-09) Sparrow, Olivia