Minnesota Department of Transportation

Location: Twin Cities Metro Area | Client: Minnesota Department of Transportation (MnDOT) | Consulting Team: MN Best Inc. and Water in Motion | Attributes: Basins, Filtration/Infiltration Report, BMP Audit


The Minnesota Department of Transportation (MnDOT) is responsible for Minnesota’s safe and efficient multi-modal transportation system. Officially created back in 1976, legislature determined MnDOT to be the primary agency in charge of organizing, administrating, and implementing transportation services for the entire state.

Providing Minnesotans with the safest transportation systems is MnDOT’s number one priority. However, the agency also acknowledges the importance and value of the state’s environment – mainly how daily transportation impacts Minnesota’s natural resources. For example, next time you drive down a Minnesota highway, look for an infiltration basin – chances are you drive by one nearly every day!

Earlier this spring, MnDOT appointed both Water in Motion and MN Best Inc. to perform a visual inspection of 25 different infiltration basins located across the Twin Cities Metro Area. The entire project was divided into three parts:

  1. Inspect the infiltration basins for the presence of both noxious weeds and native plants.
  2. Examin all basins for slope failures, drainage issues, and overall structure.
  3. Verify that the basins are functioning as designed.



Identifying predominant noxious weeds and native plants for all 25 basins was the first step for this project. In order to distinguish the difference between a noxious weed and a native plant, Water in Motion followed MnDOT’s Minnesota Noxious Weeds Manual. Additionally, any woody plant material, regardless of whether it was native or invasive, was considered undesirable within these basins.

After pinpointing native and invasive plant species in each of the basins, Water in Motion provided furnished recommendations for future vegetation management. For instance, due to the delicate nature of these infiltration basins, Water in Motion recommended management of vegetation should be kept at a minimum. Heavy machinery was suggested to stay out of the basins in order to prevent compaction and reduce subsequent infiltration failure. Furthermore, our company also included instructions specifically for noxious weed eradication for each individual basin.


Step two involved evaluating each basin’s overall structure and its ability to perform properly and efficiently. Our team searched for slope failures, drainage issues, erosion damages, and many other areas of potential problems. The following is a small example of the inspected results:

  • 4 out of the 25 basins were not functioning as designed
  • 10 out of the 25 basins had erosion issues
  • 4 out of the 25 basins were experiencing drainage failures

Similar to the vegetation inspection, Water in Motion furnished recommendations based on its findings. Suggestions to correct basin bottom drainage included subsoiling, removal of sediment, growing healthy vegetation and the removal of noxious weeds. Additionally, it was advised to take corrective action upon basins experiencing areas of erosion. This could include compacting and then reseeding, installing erosion blankets or installing check dams.

Any type of active water basin needs to be regularly maintained and thoroughly inspected to reassure full efficiency. Removing invasive plant material, correcting areas of erosion, and fixing any structural damages are just some of the ways these basins need to be taken care of. Contact Water in Motion for our professional and expert assistance with your next water basin project.