Browsing by Author "Olsen, Tyler"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Grace Chain of Lakes Stormwater Retrofit: Assessment of Best Management Practices
    (Resilient Communities Project (RCP), University of Minnesota, 2016) Jaakola, Leena; Earl, John; Barnett, Sarah; Olsen, Tyler
    This project was completed as part of the 2015-2016 Resilient Communities Project (rcp.umn.edu) partnership with Carver County. Carver County was interested in reducing amounts of total suspended solids (TSS) and total phosphorus (TP) in the Grace Chain of Lakes. To determine the best solution, Carver County project lead Tim Sundby worked with a team of students in CEGE 5511: Urban Hydrology and Water Quality. Based on an analysis that used P8 modeling software, the students recommended that the County use a combination of rain gardens, iron-enhanced sand filters, SAFL baffles, vegetated swales, and modified pond dimensions to reduce TSS and TP levels. The students' final poster, presentation, and report are available.
  • Thumbnail Image
    Item
    Phosphorus Dynamics in Stormwater Ponds
    (2017-08) Olsen, Tyler
    Retention ponds are designed to settle particulate phosphorus in the sediments. However, internal loading mechanisms can release bound phosphorus from sediments into the water column, leading to eutrophication conditions in the pond and downstream waterbodies. To understand these mechanisms, twentyone intact sediment and water cores were extracted from four stormwater ponds. Each mesocosm was subjected to different redox conditions and monitored over 30 days. The water column orthophosphate concentrations are used to obtain an overall sediment phosphorus release rate. Phosphorus fractions in the sediment are analyzed to better understand the role of pond sediment characteristics in phosphorus release. Redox sensitive and organic phosphorus concentrations correlated with phosphorus release from the sediments, highlighting the important influence of sediment composition in ponds. These relationships can be used to quantify phosphorus release rates in ponds by fitting regressions to oxygen consumption and sediment P fractions versus the measured phosphorus flux in the mesocosms.