Minnesota Department of Transportation

511 Travel Info

Regulated Materials

people planting a tree

Waste Parts Washer 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 Services for additional information or legal requirements.


MnDOT currently uses petroleum and aqueous-based solvents in parts washers. MnDOT approved parts washer solvents must have a flashpoint above 140 °F and do not contain any MPCA targeted F-listed solvents. Using solvents that meet the above criteria minimize the regulatory requirements in managing the waste solvent produced by the parts washing process. Changing the type of solvent may require compliance with additional regulations. Therefore, before using a different solvent or parts washing system, contact RMU for assistance in determining if additional regulations are applicable.

General Guidance on Parts Washer Operation

The following information can be useful in minimizing waste production from the parts washer and meeting applicable regulations:

  • Use the washer only for cleaning oil-contaminated parts. If used for cleaning other materials call OES for assistance for proper management.
  • Don’t use aerosol cleaners over or near the parts washer sink. Introduction of other cleaning products in the parts washer system will likely result in the waste washer solvent having to be managed as a hazardous waste.
  • Regularly clean sludge build-up.
  • Keep washing units closed and turned off when not in use to eliminate solution loss through evaporation.
  • Follow parts washer manufacturer’s instructions on changing filters and other maintenance requirements.
  • The used parts washer waste must be generated from MnDOT maintenance activities. Used parts washer waste must not be accepted from home, public, or private parties.

Parts Washer Waste Management

The management procedures discussed below applies only to wastes produced by parts washing systems using petroleum and aqueous-based solvents to clean oil from parts. Contact RMU personnel for additional assistance in managing any waste materials that do not appear typical compared to past waste materials or if the parts washing practice has deviated from the recommended procedure described above.

Waste Filters, Oil & Sludge

Waste parts washer filters, sludge and skimmed oil may be managed as follows as long as the washer is only used to clean oil from parts:

  • Recycle used fiber filters with burnable used oil sorbents.
  • Recycle used metal-cased filters with used vehicle oil filters.
  • Recycle sludge from filtering process with burnable used oil sorbents.
  • Place oil from skimmer in used oil storage tank for recycling.

Note: If the parts washer system has been used to clean other items such as paint brushes, herbicide/pesticide equipment, or if aerosol cleaners or other solvents are used over or near the parts washer sink, the filter, oil, and sludge need to be containerized separately and treated as a hazardous waste. Contact the District Safety Administrator for assistance in managing used solvent suspected of being a hazardous waste.

Waste Petroleum Parts Washer Solvent

Option 1 - If the facility is a Very Small Quantity Generator or a Minimal Generator, certain petroleum-based parts washer solvents can be added to used oil in an on-site used oil burner or combined with used oil and transported off-site for recycling. To do so, the parts washer solvent must meet the following conditions:

  • Verify parts washer fluid flashpoint is above 140 °F. This can be done by looking at the SDS or call OES for assistance.
  • Sampling and analysis was performed to show that the parts washer used solvent is not hazardous for lead. Documentation of this testing must be kept at the facility and resample every 5 years. If needed, contact OES for this documentation.
  • Gasoline must not be added to the waste solvent. Therefore, gasoline should not be used for cleaning parts in a manner that could result in gasoline entering the parts washer system.
  • To ensure that no undesirable chemicals have been introduced to the parts washer system or used oil, no chlorinated solvents or MPCA Flisted solvents can be stored or used in the facility with the exception of chemicals characterized as F003. Contact the district safety administrator for assistance with this determination. See list of MnDOT approved aerosol cleaners and liquid degreasers.
  • Not used for paint-related for cleaning paint related items.
  • The used oil mixture can only contain up to 10% waste solvent by volume.
  • Only MnDOT employees can add waste parts washer solvent to used oil.
  • Records must be maintained for three years following the date of blending waste parts washer solvent and used oil.

Option 2 - When washer solvent is no longer usable:

Waste Aqueous Parts Washer Solvent

Recent studies have demonstrated that MnDOT waste aqueous parts washer is non-hazardous if the solvent is replaced within one year. The used solvent may be disposed of in the sanitary sewer where it will eventually be treated at a Publicly Owned Treatment Works (POTW). To discharge waste aqueous solvent to the sanitary sewer system, the waste solvent must meet the following conditions:

  • There must be laboratory testing that demonstrates the solvent in the District is non-hazardous. Keep records in file.
  • The used solvent must be filtered to remove oil and particulates prior to placing into the sanitary sewer system.

Containerization, storage, transport, and record keeping

Follow waste handling guidance.