Commercial stormwater credit application
Required materials
Maps, plans, and diagrams
You must include maps, plans, and diagrams showing the drainage for the entire site. This includes:
- Drainage area delineations to each stormwater management facility.
- Impervious area for each delineation and facility.
You also need all related infrastructure to the stormwater management facilities. This includes:
- Pre-treatment
- Inlets
- Outlets
- Storm pipes
- Maintenance holes
- Underdrains
You must show any connection points to the City of Minneapolis stormwater system.
Modeling and calculations
You must provide modeling and calculations to prove that credit criteria are met.
Water Quality Credit
Provide water quality model inputs and results using one of these models:
- P8 (version 2.4 or newer)
- WinSLAMM (version 9.4 or newer)
- MIDS Calculator
Rate control credit
Provide rate control credit model inputs and results using one of these models:
- HydroCAD
- XP SWMM
- EPA SWMM
Volume control credit
Provide the calculation in conjunction with HydroCAD.
Operations and maintenance (O&M) plan
You need to include pollution prevention practices for the properties, such as covering material storage areas.
Basic salt management plan (Basic SMP)
To complete a Basic Salt Management Plan, you’ll need to:
Both of these trainings must be documented on the Basic Salt Management Plan form.
Advanced salt management plan (Advanced SMP)
If you are applying for the advanced SMP credit type, you must provide an advanced SMP. This is separate from the basic SMP. This must show that winter maintenance practices are reducing or ending salt use in applicable areas.
Additional resources
Types of stormwater credit
| Credit type | Description | % of stormwater charge | Applied to |
|---|---|---|---|
| Chapter 54 | Meet the minimum standards for water quality treatment, peak discharge rate control, and volume control of Chapter 54 as a part of development approval. | 10% | Property area meeting the standard. |
| Advanced salt management plan (SMP) | Implement a SMP that demonstrates winter management salt reduction. | Up to 30% | Portions of property where winter site management is required. |
| Voluntary/unregulated |
Voluntary BMPs (not required as a part of development) meeting water quality treatment, peak discharge rate control, and volume control standards as outlined in Chapter 54. Water quality treatment: remove at least 75% of the total phosphorus (TP) on an average annual basis. |
Up to 30% | Property area meeting the standard. |
| Above and beyond (20%) | Volume reduction: Capture and retain on-site 2.0” of runoff from impervious surfaces. | 20% | Property area meeting the standard. |
| Above and beyond (60%) | Peak discharge rate control: Maintain peak discharge rates at or below the pre-settlement rates for the 10-, and 100-year storm events. | 60% | Property area meeting the standard. |
| Equity | Credit added for implementing stormwater best management practices on properties located in Green Zones. | 10% | Property area meeting the standard. |
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