Re-use of regional waste in sustainably designed soils

Author(s):

David Saftner, Meijun Cai, Adam Whitcomb

April 2022

Report no. MnDOT 2022-10

Topics:

Environment

This project explores the potential re-use of waste materials/by-products as a soil amendment in northeastern Minnesota. The project team identified 23 waste/by-products and collected 15 of but only analyzed 11 because of the possible content of persistent chemicals in some of the materials or the unwillingness of the owner to participate. Peat screenings, peat scrapings, tree bark, harbor dredge sediment, coarse and fine taconite tailings, and street sweepings were characterized in physical, chemical, and biological properties through lab tests. The results showed that none of the studied materials were defined as hazardous based on RCRA (Resource Recovery and Conservation Act) metal levels and contained minimal or undetectable Polychlorinated biphenyls (PCBs), Polycyclic Aromatic Hydrocarbons (PAHs) or Volatile Organic Compounds (VOCs). Peat by-products were efficient in removing metals from stormwater runoff. The relatively high phosphorus content of peat by-products provided sufficient nutrients to plant growth but could be released when mixed with low-phosphorus runoff. Dredge sediment and street sweeping had low organic contents but could remove 90% or more of the copper from the runoff. Tailings could remove 50% or less of the metals. Radish or oat can successfully grow in 28 days with individual materials or a blend of materials, except for fine tailings, which are in a clay form and thus don?t filter water well.

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