Listed in Stormwater Management
Stormwater infrastructure plays a crucial role in protecting roads, the environment, and nearby communities from flooding, erosion, and water pollution. For highway and public works departments, regular inspection of these systems isn’t just good practice, it’s essential for compliance with environmental regulations and for preventing costly failures. Here's a breakdown of the key components that should be on every department’s stormwater inspection radar.
1. Catch Basins and Curb Inlets
Catch basins collect runoff from roads and direct it into underground piping or treatment structures. Inspect for:
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Accumulated sediment or debris in the sump
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Blockages at grates or screens
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Structural damage to the basin or cover
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Evidence of standing water or slow drainage
Tip: Clean out any basin where sediment exceeds one-third the depth from the basin floor to the outlet pipe.
2. Culverts and Storm Pipes
These structures carry stormwater under roads and between drainage areas.
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Look for signs of corrosion, cracking, or joint separation
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Check for blockages caused by debris or sediment
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Confirm water is flowing freely through the pipe
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Inspect headwalls and wingwalls for stability and erosion
Seasonal priority: After major storms and in early spring when freeze-thaw damage may become apparent. Also, see out article on choosing the correct culvert for water flow.
3. Ditches and Swales
Open channels like roadside ditches and vegetated swales are critical for directing surface water.
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Inspect for erosion, scouring, or sediment buildup
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Ensure vegetation is healthy and not overgrown
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Look for signs of improper flow (e.g., ponding or undercutting)
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Ensure that check dams are still functioning properly, and not washed away or inundated with debris
Maintenance note: Mowing schedules and sediment removal should be documented.
4. Dry Wells and Leaching Basins
These systems allow stormwater to percolate into the ground rather than discharge offsite.
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Check sumps for sediment accumulation
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Ensure inflow pipes are not blocked
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Look for ponding that may suggest clogging
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Confirm no illicit discharges or unusual odors
5. Outfalls and Discharge Points
Outfalls are where stormwater exits the drainage system and enters streams, wetlands, or other receiving waters.
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Watch for erosion, undercutting, or collapsed embankments
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Check for signs of pollution (e.g., discoloration, foam, sheens)
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Record flow during dry weather to detect illicit connections
Regulatory alert: Many municipalities are required to visually inspect outfalls under MS4 (Municipal Separate Storm Sewer System) permits.
6. Detention and Retention Basins
These basins slow down and treat stormwater before it's released.
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Inspect embankments for burrowing animals, erosion, or cracks
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Ensure inlet and outlet structures are not blocked
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Look for excessive sediment or algae growth
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Verify that flow control structures are functioning
7. Stormwater Treatment Structures
This includes proprietary treatment units, hydrodynamic separators, and filter inserts.
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Check for clogging or bypass conditions
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Clean filters or screens as per manufacturer guidelines
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Ensure structures are accessible and not buried or forgotten
8. Manholes and Junction Boxes
Often overlooked, these underground features need routine checks too.
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Remove covers and inspect for debris or sediment
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Check structural condition and alignment of pipes
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Confirm no inflow of groundwater or contamination
Why Inspection Matters
Regular inspections:
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Reduce emergency repairs
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Extend the life of infrastructure
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Protect local waterways
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Keep your town in compliance with stormwater regulations
Related Resource:
Download our free Stormwater Inspection Checklist (PDF) to make sure your team is covering all the bases.