Minnesota Department of Transportation

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Regulated Materials

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Waste N-Propyl Bromide Solvent and Sludge Management

This guidance document is prepared by MnDOT personnel and is intended only for use on MnDOT projects, including partnership projects, and MnDOT Maintenance Operations.

MNDOT has prepared this guidance document to provide its internal procedures and requirements for work performed on MnDOT rights of way, including MnDOT-owned facilities.

This document should not be construed as a full description of all regulations pertaining to the subject matter. Contact the Regulated Materials Unit in the MnDOT Office of Environmental Stewardship for additional information or legal requirements.


MnDOT Materials Laboratories use N-Propyl Bromide solvent for asphalt extraction for aggregate counts. The purpose of this guidance document is to assist in determining the appropriate management practices for the waste solvent and asphalt sludge produced following the cleaning process.

N-Propyl Bromide solvent has a flashpoint above 140° F and does not contain certain MPCA listed solvents and is not hazardous when used for asphalt extractions. For other uses the waste solvent may need to be treated as a hazardous waste. Contact your District Waste Management Coordinator if using for another purpose or if doing asphalt extractions using another product.

Use Categories

  • Used in asphalt extraction testing: Waste N-Propyl Bromide and associated filters and sludge generated from asphalt extraction testing do not have to be managed as a hazardous waste. Instead, the waste materials may be managed as follows:
    • Used fiber filters - recycle with burnable used oil sorbents
    • Used metal-cased filters - recycle with used oil filters
    • Sludge from filtering or distillation operation - recycle with burnable used oil sorbents or dispose of as nonhazardous waste disposal through MnDOT’s hazardous waste contractor located at under the heading Waste Handling and MnDOT approved list of waste contractors link.
    • When solvent is no longer usable, containerize and dispose of as nonhazardous waste through the hazardous waste contractor
  • Used for other cleaning purposes: Waste N-Propyl Bromide solvent or solvent mixtures and associated waste filters, sludge or other materials generated during cleaning activity must be managed as hazardous waste unless approved by Office of Environmental Stewardship, Regulated Materials Unit as non-hazardous.

Containerization, storage, transport, and record keeping of Waste Solvent and Sludge