Infiltration trenches and basins are designed to infiltrate runoff and remove pollutants from the surface water stream through attenuation in soil or media or transport into underlying groundwater at concentrations below drinking water standards. It is difficult to assess the performance of these BMPs, although considering only potential impacts to surface waters, a properly functioning infiltration system is considered to be highly performing.
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.
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.