For each Best Management Practice (BMP) in the Manual, a page was created explaining how to apply that BMP in the Minimal Impact Design Standards (MIDS) calculator. These pages provide a discussion of the requirements, recommendations and information for using that BMP in the calculator. Each page also contains an example application for the BMP. Links to those pages are shown in the table below.
| BMP (MIDs Calculator, Version 3.0) |
Requires input dimensions? |
Pollutant Reductions (%) | |||
|---|---|---|---|---|---|
| Volume | TSS | Total particulate phosphorus (TPP) |
Total dissolved phosphorus (TDP) |
||
| Green roof | Yes | 45 | 96 | 0 | 0 |
| Bioretention Basin (w/o underdrain) | Yes | Lookup table1 | |||
| Bioretention Basin (w/ underdrain) | Yes | Lookup table1 | 60 | 0-803 | 0-603 |
| Infiltration basin/ Infiltration Trench | Yes | Lookup table1 | |||
| Underground Infiltration | Yes | Lookup table1 | |||
| Permeable pavement | Yes | Lookup table1 | 74 | 82 | 0 |
| Tree Trench (w/o underdrain) | Yes | Lookup table1 | |||
| Tree Trench (w/ underdrain) | Yes | Lookup table1 | 68 | 0-803 | 0-603 |
| Swale Side Slope | Yes | Lookup table1 | |||
| Swale Main Channel (w/o underdrain) | Yes | Lookup table1 | 68 | 73 | 0 |
| Swale Main Channel (w/underdrain) | Yes | Lookup table1 | |||
| Wet swale | No | 68 | 0-453 | 0-603 | |
| Harvest and Re-Use Cistern | Yes | Calculated2 | |||
| Imperviousness Disconnection | Yes | Lookup table1 | 68 | 0 | 0 |
| Sand Filter (Not-Enhanced) | No | 85 | 85 | 0 | |
| Sand Filter (Enhanced) | No | 85 | 85 | 40 | |
| Constructed Wetland | No | 68 | 55 | 0 | |
| Stormwater Pond (Level 1) | No | 60 | 62 | 0 | |
| Stormwater Pond (Level 2) | No | 84 | 84 | 8 | |
| Stormwater Pond (Level 3) | No | 90 | 90 | 23 | |
| Other | No | User-defined4 | |||
| Individual vs. lumped BMPs The MIDS calculator was developed as a site tool. Thus, BMPs are typically entered as individual entities rather than lumped together. For example, if a site has three bioretention BMPs, each BMP would be entered individually in the calculator. However, BMPs can be lumped in the calculator. In this example, the three bioretention BMPs could be combined and treated as a single BMP. Lumping BMPs has the advantage of simplifying complex site and may be useful when using the calculator for larger areas where several BMPs are implemented. Lumping BMPs can introduce errors in the calculations if the BMPs are not properly sized, since lumping smoothes out these sizing differences. The following document provides an example comparing calculator results for a site where BMPs are treated individually and lumped. |
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| 1 "Lookup Table" indicates removal calculated from MIDS P8 modeling lookup tables. 2 “Calculated" indicates volume reduction is calculated based on user inputs for cistern reuse / irrigation scheduling. 3 TPP and TPD reduction variable based on design input parameters. 4In conjunction with the University of Minnesota street sweeping crediting study, the MCPA contracted with TetraTech to assess if or how street sweeping could be incorporated into the Minimal Impact Design Standards Calculator. Based on the available data types and quantity, MPCA does not recommend incorporating street sweeping into the MIDS calculator. |
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