What to inspect
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When to inspect
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Why inspect
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Examples of how-to inspect
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What to document
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Structural stormwater best management practices (BMPs) including green roofs, permeable pavement, infiltration basins or trenches, raingardens, filtration devices, sand filters, hydrodynamic devices, etc. [Part III.D.6.e.(1)] |
Annually |
To determine structural integrity, proper function, and maintenance needs |
- Identify clogged, overloaded, and full devices, inlets, or outlets
- Identify misaligned inlets or outlets/overflow devices
- Identify materials that are deteriorating and releasing pollution
- Identify erosion/channelization, sedimentation, soil slides, animal burrows, undercutting, displaced riprap, or other problems
- For infiltration practices that should be dry (e.g. infiltration basins, filter strips/swales) identify standing water or wet spots
- If standing water is present, determine if the device is functioning as designed and meeting the 48 hour draw down requirement
- Identify excess or unwanted vegetation (e.g. long-grass, tree growth)
- If vegetation is designed to be present (e.g. bioretention basins, filter strips/swales), determine if the vegetation is healthy, is of appropriate size/density, and free of weeds and invasive species
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- Inspection findings and date [Part III.D.6.h.(1)]
- Dates & description of maintenance [Part III.D.6.h.(3)]
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Outfalls where an MS4 discharges to a receiving water, or the discharge permanently leaves the MS4 [Part III.D.6.e.(2)] |
Once per each permit term |
To determine structural integrity, proper function, and maintenance needs |
- Identify erosion/channelization, scour, or other problems
- Identify displaced, damaged, missing, or clogged riprap
- Identify missing or damaged grates or guards, if applicable
- Identify cracked, undercut, or spalled aprons, if applicable
- Identify unwanted vegetation growth or decay, litter or debris, sediment buildup, or animal dens that may obstruct flow of water
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- Inspection findings and date [Part III.D.6.h.(1)]
- Dates & description of maintenance [Part III.D.6.h.(3)]
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Stormwater ponds [Part III.D.6.e.(2)] |
Once per each permit term |
To determine structural integrity, proper function, and maintenance needs |
- Identify scour, erosion/channelization, sedimentation, litter, animals burrows, undercutting, displaced riprap or other problems at/around the banks, inlets, or outlets
- Identify clogged or overloaded inlets or outlets
- Identify excess or unwanted vegetation (e.g. long-grass, new trees)
- Identify and record materials within the device that are deteriorating and releasing pollution into the stormwater system
- Determine if the vegetation looks healthy, is of appropriate size/density, and free of weeds and invasive species
- Determine if there is evidence of sedimentation or erosion downstream of the outlet
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- Inspection findings and date [Part III.D.6.h.(1)]
- Dates & description of maintenance [Part III.D.6.h.(3)]
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Stockpiles, and storage and material handling areas that are inventoried in the Facilities Inventory [Part III.D.6.e.(3)] |
Quarterly |
To determine maintenance needs and proper function |
- Identify leaking, leachate, or runoff
- Identify undercut, full, clogged, ripped, broken, misplaced, askew, or other BMP maintenance needs
- Install additional BMPs, such as secondary containment, impervious cover, runoff collection areas as needed
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- Inspection findings and date [Part III.D.6.h.(3)]
- Dates & description of maintenance [Part III.D.6.h.(3)]
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Illicit discharges (Part III.D.3.c.&f.) |
During the structural stormwater BMP; outfall; pond; and stockpile and storage and materials handing inspections |
To identify and eliminate illicit discharges to the MS4 |
- Identify and characterize any dry weather flow
- Describe the material (color, odor, sheen, froth, etc.), its effects (e.g. corrosion, pipe etching), or, if appropriate, analyze chemically
- Investigate potential upstream sources that may be contributing non-stormwater flow
- Record clear, unpolluted dry weather flows. If present, the discharge may be coming from unregulated sources
- Inspect areas that you've identified as priority areas likely to have illicit discharges (e.g. business/industrial areas, where illicit discharges have been identified in the past)
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Date(s) and location(s) of IDDE inspections conducted [Part III.D.3.h.(1)]
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Construction activity |
At the frequency identified in the Construction Site Inspection procedure for your MS4 |
To prevent and minimize erosion to reduce the amount of sediment from entering your MS4 |
- Inspect for items required by the MPCA construction stormwater permit and your regulatory mechanism, some examples include:
- Are erosion and sediment control and vehicle tracking BMPs effective, in good working condition, and able to perform their intended function?
- Are soils stabilized where needed?
- Do pipe outlets have energy dissipation?
- Are inlets protected?
- Are solid and hazardous wastes contained, stored, and properly disposed of?
- Is the contractor conducting the required site inspections?
- Is the permanent stormwater BMP designed appropriately and protected?
- Are temporary sedimentation basins used and with BMPs?
- Is dewatering discharging to a sediment basin or preventing nuisance conditions?
- Identify any potential pollution problems related to stormwater runoff or infiltration into the groundwater
- Determine if any additional BMPs may be appropriate
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Checklist or other written means to document what was inspected for [Part III.D.4.h.(1)]
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