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Stormwater - Filtering with muck, peat and taconite

Woman in lab kneels to fill white tube with dirt
September 23, 2016

Pollutants in runoff from roads can get into watersheds if not captured and filtered. Bioslopes and bioswales constructed with compost and sand are a standard filtering procedure that works pretty well at removing heavy metals, sediment and excess nutrients, to keep the pollutants out of streams and wetlands.

Now, a potentially better idea is being tested at NRRI that will filter using local waste resources.

NRRI Scientists Kurt Johnson and Meijun Cai are experimenting with mixtures of muck (heavy on the clay and some organic material), peat that was stockpiled after a road construction project, and taconite tailings waste rock. Each material has its advantages and disadvantages, so the researchers are experimenting with which “recipe” works.

“It has to support vegetation and it has to filter chemicals in the stormwater,” said Johnson. “And, of course, they have to be native plants, so I’m looking at the biology and plant growth potential.”

Cai is an environmental engineer, so she’s working on the chemical efficiency side of the materials. Another part of the team is with UMD’s Civil Engineering Department to develop the water storage requirements for the materials.

“We’re comparing our mixes to the standard compost/sand mix,” said Cai. “If it works and the performance is good, we can use these local waste resources for local projects.”