Constructed basins are designed to retain solids and associated pollutants by settling. A typical method for assessing the performance of constructed basins is therefore measuring and comparing pollutant concentrations at the influent and effluent.

An online manual for assessing BMP treatment performance was developed in 2010 by Andrew Erickson, Peter Weiss, and John Gulliver from the University of Minnesota and St. Anthony Falls Hydraulic Laboratory. The manual advises on a four-level process to assess the performance of a Best Management Practice, involving:

  • Level 1: Visual Inspection. Level 1 assessment is recommended at least annually. The website includes links to downloadable checklists for dry ponds, wet ponds, and underground sedimentation basins.
  • Level 2: Capacity Testing. Level 2 testing can be applied to sedimentation practices to estimate sediment storage capacity. If repeat measurements are made over time, the sediment accumulation rate can be estimated.
  • Level 3: Synthetic Runoff Testing. Synthetic runoff test results can be used to develop an accurate characterization of pollutant retention or removal, but can be limited by the need for an available water volume and discharge.
  • Level 4: Monitoring

Level 1 activities do not produce numerical performance data that could be used to obtain a stormwater management credit. BMP owners and operators who are interested in using data obtained from Levels 2 and 3 should consult with the MPCA or other regulatory agency to determine if the results are appropriate for credit calculations. Level 4, Monitoring, is the method most frequently used for assessment of the performance of a BMP.

Use these links to obtain detailed information on the following topics related to BMP performance monitoring:

Additional information on designing a monitoring network and performing field monitoring are found at this link.

Case studies include the following.