Minnesota Department of Transportation

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Project development

Environmental process | Environmental review

Contaminated Materials


The purpose of the contaminated materials group is to identify and document known or suspected contamination (in soil, groundwater, soil vapor, etc.) within existing and proposed right of way, and in adjacent properties.

When to use this subject

There are four types of work activities that trigger a Contaminated Materials review, which may include a Phase I and Phase II Environmental Site Assessment (ESA) to investigate for the presence of contaminated materials. 

These triggers are:

  • Acquisitions of new right of way such as temporary or permanent easement, Commissioner’s temporary orders, and all other acquisition types in accordance with MnDOT Policy OP009 Environmental Due Diligence (EDD) for Property Acquisition (see Minnesota Statutes, section 115C.021, subdivision 3a and Minnesota Statutes, section 115B)
  • Grading and/or excavation
  • Work in commercial/industrial areas
  • Work in areas with shallow groundwater that require temporary or permanent dewatering

For current staff and district responsibilities, see the website.

How this subject fits into the overall project development process

The Environmental Investigation Unit (EIU) project review starts in the scoping phase and the Early Notification Memo (ENM) summarizes the triggers listed in the previous section. Following this process results in formal reviews, responses, and recommendations for additional evaluation by EIU to the Project Manager, Environmental Document Writer, and the District Design contact, as specified in the ENM. The contaminated material additional evaluation typically takes 12 to 18 months; P6 baselining will determine the project-specific schedule.

Identifying areas of contamination early in the project allows MnDOT time to assess and manage the risk and liability related to acquisition of right of way, make changes to design if necessary, and prevent delays during construction.  Allowing time to obtain regulatory liability assurances on property acquisitions protects MnDOT’s long-term liability and limits the potential contaminant investigation and cleanup costs.

Proactively identifying areas of contamination within the project limits during preliminary design allows the project team to:

  • Make any necessary changes
  • Establish liability protections
  • Establish bid items
  • Notify contractors through special provisions
  • Properly manage contamination in regulatory compliance
  • Prevent construction delays and cost increases

All activities related to contaminated materials must be finished in the final design phase.

For specific process information, see the other guidance page and/or contact the individuals on the contacts page.

Organizations involved