What do roadway work, curb-and-gutter installation, and early-phase grading all have in common? Sediment-laden runoff.
These projects all risk failed inspections if you allow sediment to move directly into storm drains. Once it’s entered a municipal storm system, the responsibility doesn’t disappear, either. You’ll likely need to engage in corrective action and costly cleanup.
It’s all preventable, though. Curb inlet protection solutions like curb inlet filters, curb bags, and curb sacks keep your stormwater runoff clear of erosion-related debris — but you’ve got to match the solution to the inlet. The questions you’ve got to answer are: “When do I need curb inlet protection on-site?” and “How do I choose the right inlet protection solution?” A few minutes now will help you stay compliant and keep the work moving.
When Is Curb Inlet Protection Required?
Curb inlets are common along streets and developed areas where runoff flows horizontally before entering the storm system. During construction, those same pathways carry sediment from disturbed soil straight to the drain opening.
Under most stormwater permits, including NPDES construction requirements, inlets that could receive sediment-laden runoff must be protected as part of temporary erosion and sediment control. The EPA identifies storm drain inlet protection as a standard best management practice (BMP) used to prevent sediment from entering storm sewer systems during construction activity.
Per the EPA, inlet protection is typically required when:
- Soil is exposed near curb and gutter systems
- Grading or excavation directs runoff toward street inlets
- Utility or paving work disturbs stabilized surfaces
- A storm event is likely to mobilize loose sediment
In urban and municipal projects, curb inlet filters are often expected as soon as adjacent areas are disturbed. If you wait until after the first rain event, it’s usually too late.
Curb Inlets Differ From Other Inlet Types
Curb inlets require specific protection solutions because they differ from other inlet types like drop inlets or grated storm drains (generally located in open areas). An open area inlet has to deal with vertical flow from above. Curb inlets, on the other hand, collect water that’s moving laterally along pavement or gutter lines. That flow can become a fast and concentrated river, especially in heavy rain.
It’s for these reasons that conventional drain inlet protection, which is designed for flat grates, may not be effective — and is certainly not optimal — at a curb opening. Curb inlet protection must account for:
- The size and geometry of the curb opening
- The expected flow rate along the gutter line
- The sediment load coming from upstream disturbed areas
The EPA also notes that inlet protection practices must allow adequate drainage in addition to trapping the sediment. If protection restricts flow too much, water can bypass the device entirely by running right over it, or it could act like a dam and cause pooling in the roadway.
With that said, if it allows too much flow through without slowing it, sediment is likely to pass directly into the system.
The right approach must balance filtration with flow capacity.
Common Misconceptions About Curb Inlet Protection
Perhaps the most common stormwater solution assumption is that one product fits every curb. In reality, curb openings can have immense variations in width, height, and configuration. An undersized or poorly fitted device will often create gaps where runoff bypasses protection entirely.
Another misconception is that installation alone equals compliance. Inlet protection must also be inspected and maintained throughout the project. Sediment buildup will gradually reduce capacity and increase ponding. This leads to safety concerns along busy roadways.
According to EPA guidance, inlet protection practices require routine inspection and sediment removal to remain effective. One of the primary reasons installations fail during inspection is that the contractor or site manager has neglected maintenance of inlet filters.
4 Things Contractors Can Do to Get It Right
Contractors tend to follow a few practical steps to avoid the most common rework and inspection issues.
1. Install Early!
Curb inlet protection should be in place before any significant grading or disturbance begins. Weather can be hard to predict. Certainly don’t wait to install after sediment has already reached the gutter. This would defeat the purpose and invite inspector scrutiny.
2. Match the Device to the Conditions
Consider flow direction, sediment volume, and curb dimensions. High-traffic urban areas may require extra durable solutions to make sure they don’t shift or collapse under pressure.
3. Maintain Protection Throughout Your Project
Inspect protection after every rainfall event. Remove accumulated sediment before it restricts flow. Replace or reset devices that have shifted.
4. Get to Know Inspection Expectations
Are you familiar with how an inspector evaluates stormwater inlet protection? If not, it’s best to get acquainted. Inspectors will often focus attention on function, fit, and maintenance (not just whether you have inlet protection at all).
Stay Ahead of Problems With Dandy
Curb inlet protection works best when planned ahead of time. A last minute fix can invite mistakes. Curb bags and curb sacks are a priority preventive measure to protect downstream systems and keep your projects on schedule (and on the right side of site inspections).
Dandy curb inlet solutions are constructed from the highest quality geosynthetic fibers for challenging worksite conditions. Contractors trust the orange Dandy solutions to manage sediment right at the curb. Explore your options today to prevent storm-related setbacks.
