Stormwater basins are used to control runoff, prevent flooding and limit pollutants from reaching rivers, lakes and other large bodies of water. MnDOT monitors and maintains more than 400 infiltration and filtration basins statewide, and that number continues to grow. Identifying indicators of needed maintenance will increase management efficiency and basin performance. Field research at 28 basins identified basin age and silt content as two important factors to consider when planning inspections and taking corrective actions.
Continue reading Identifying Factors That Affect Stormwater Basin PerformanceTag Archives: stormwater management
Developing Biochar Specifications for Stormwater Management
Effective stormwater management helps keep roadway contaminants from entering Minnesota’s lakes and streams. Management practices include soil and vegetation in roadside bioretention systems that filter heavy metals and hydrocarbons created by vehicles. Based on other studies, retention and transformation of roadside pollutants should be improved by biochar application to existing or engineered soils. Abundant sources of biomass can be used to produce biochar, a soil amendment with numerous benefits. MnDOT and local agencies identified biochar specifications for effective use in stormwater treatment to support the next phase of testing and development of biochar design guidance.
Continue reading Developing Biochar Specifications for Stormwater Management
Utilizing Recycled Tires to Treat Stormwater
Repurposing old tires as tire-derived aggregate (TDA) is a stormwater management practice that could retain phosphate in underground treatment systems and prevent it from reaching the soil, surface waters and groundwater. However, chemicals from the TDA may leach into the soil and water sources. This project identifies the environmental impacts and cost-effectiveness of deploying TDA to manage stormwater in Minnesota cities and counties.
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Industrial by-products prove sustainable options for managing roadside stormwater
Reprinted from CTS News, March 25, 2025
Roadside soil plays a crucial role in stormwater management. Naturally vegetated roadsides can filter and control runoff, helping to keep pollutants out of bodies of water and minimizing flooding to communities. However, soil left behind from road construction does not adequately support filtration and plant growth unless it’s amended with organic matter—and traditional mixtures for doing so, such as with sand and compost, can be costly and resource-intensive.
To find a more sustainable solution, U of M researchers partnered with MnDOT and the Minnesota Local Road Research Board. Building on previous research, a team led by CTS scholar David Saftner, principal investigator and associate professor in the UMD Department of Civil Engineering, tested sustainable roadside soil mixtures using locally available waste materials and by-products generated from forestry, agriculture, and industrial activities.
In this project, nine materials were selected for testing, including a peat/biochar mix; dredged river sediment; pine and ash sawdust; VersaLime (a by-product of sugar beet processing); lime mud, bottom ash, and degritter (from a pulp and paper mill); and recycled concrete aggregate (RCA). All nine materials proved efficient at removing pollutants, though some were more effective than others. After extensive laboratory testing, the five top-performing materials were selected and used to create three engineered soil blends:
- RCA (80%) and ash sawdust (20%)
- RCA (80%) and peat/biochar (20%)
- Dredge sediment (80%) and degritter (20%)
Field testing of these three engineered soil blends took place in outdoor plots. The team studied infiltration rate, pollutant removal, and plant growth from grass and flower seed. Through a life-cycle assessment, the researchers also evaluated material collection and transport, energy demand, human health and ecosystem impacts, climate change, and water use.
Their research revealed that all three engineered soil blends were effective at capturing and filtering the first inch of excess stormwater runoff, offering a viable alternative to traditional soil mixes. Other key findings:
- Of the engineered soil mixes, organic and coarser materials were better at allowing water to pass through.
- Greenhouse tests showed promising plant growth, while field plots experienced challenges—possibly due to seasonal dryness.
- The dredge sediment and degritter soil mix had substantially higher impacts than the other two soil mixes as well as the most CO2 emissions.
- The RCA and ash sawdust soil mix had the lowest impacts, with the RCA and peat/biochar soil mix producing similar results.
Based on their findings, a design guide was developed for road engineers outlining best practices for using local by-products and waste materials to create engineered soil mixes while still adhering to regulatory standards. These recommendations are designed to be standard, common, and repeatable.
“This was a great project and I’m especially happy with the design guide,” Saftner says. “Determining how to implement new procedures is tougher than using tried-and-true methods. Our hope is that the guide will simplify things for practicing engineers looking for more cost-effective, sustainable, and locally sourced solutions.”
The study results also highlighted many of the benefits of engineered soil mixtures including the reuse of waste materials, reduced spending on sand and compost, lower transportation costs, and fewer environmental impacts of transporting material.
Further research on the reuse of waste materials includes another multi-phased project incorporating biochar. The first phase of that project should be finished this summer, with the second phase kicking off in summer 2026.
—Krysta Rzeszutek, CTS digital editor
Related Resources
- Article: Waste materials go to work as pollutant filter
- Article: Treating stormwater with local by-products reduces road construction costs, minimizes waste
- Re-use of Minnesota Waste Material in Sustainably Design Soils. Part 2
- Reusing Local By-Products to Create Sustainable Roadside Soil
- Re-use of Regional Waste in Sustainably Designed Soils: Part 1
Revised Stormwater Maintenance Guide Updates Common Practices and Offers Innovative Options
Practices for managing stormwater runoff have evolved over the years. Changes to regulations, land use and weather patterns impact how transportation agencies integrate stormwater control options into road and waterway networks. Local agencies have used a stormwater maintenance guide produced by the Local Road Research Board (LRRB) in 2009. Over a decade of new research and the development of new tools for stormwater control necessitated revisions to the guidance document. The updated Stormwater BMP Inspection and Maintenance Resource Guide provides recommendations for enhancing traditional stormwater practices and presents new, innovative strategies and guidance on stormwater best management practices (BMPs).
Continue reading Revised Stormwater Maintenance Guide Updates Common Practices and Offers Innovative Options
Managing Stormwater in a Changing Climate Will Require Updates to Minnesota’s Infrastructure
Reprinted from CTS News, March 21, 2024
—Sophie Koch, contributing writer
Changing precipitation patterns caused by the onset of climate change mean that Minnesota’s stormwater management systems—the ponds, pipes, and other structures meant to control runoff in the event of a heavy rainstorm—are going to need an upgrade.
Continue reading Managing Stormwater in a Changing Climate Will Require Updates to Minnesota’s InfrastructureStormwater Research Sees Practical Application in Twin Cities Metro, St. Cloud
Sophie Koch, CTS News, February 22, 2024
A long-running series of U of M research projects aimed at improving stormwater quality are beginning to see practical application by stormwater specialists from the Twin Cities metro area and beyond.
Continue reading Stormwater Research Sees Practical Application in Twin Cities Metro, St. Cloud
Drainage 101: Understanding and Managing Drainage Issues
Increased regulation and rising levels of precipitation have made stormwater management a more routine and time-consuming issue than in previous decades. A new resource provides guidance and best practices that will help city and county engineers, local officials and private property owners navigate the complex, often public-facing issues related to recurring drainage problems and stormwater management.
Continue reading Drainage 101: Understanding and Managing Drainage Issues
Assessing Stormwater Ponds for Phosphorus Retention
Stormwater ponds and wetlands reduce flood risk and keep pollutants from entering other bodies of water. As ponds age and change, however, they may not perform as designed. Local agencies now have tools to assess whether a pond is likely to retain phosphorus, which can help guide stormwater management efforts.
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New Project: Update of Stormwater Management Best Practices Manual
The Local Road Research Board published the Stormwater Best Management Practice (BMP) Maintenance Resource Guide in 2009, and best practices for stormwater management have since evolved. Much has been learned about the benefits and limitations and inspection and maintenance activities of stormwater ponds, bioretention facilities, underground treatment devices, underground detention, and infiltration. Regulatory requirements have also changed as indicated in the Minnesota Stormwater Manual.
Continue reading New Project: Update of Stormwater Management Best Practices Manual
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