Calculating stormwater volume and pollutant reductions and credits

The Minnesota Pollution Control Agency is currently working with a Contractor to develop information for volume and pollutant credits for most of the BMPs discussed in this manual. We anticipate this information will incorporated into the Manual by early summer, 2014. Draft versions of this information can be found for the following BMPs.

• Permeable pavement
• Tree boxes and tree trenches
• Green roofs

The Minnesota Pollution Control Agency is also working with a Contractor to develop information on using the Minimal Impact Design Standards calculator to calculate credits for volume, phosphorus and total suspended solids. Drafts of that information can be found for the following BMPs.

• Bioretention
• Green roofs

The Manual also contains information on models that can be used to calculate credits for volume and pollutants. Information on models is found on the following pages.

• Available stormwater models and selecting a model
• The Simple Method for estimating phosphorus export

The original Manual contained credit information for Better Site Design.