As construction projects move toward completion, one question often comes up: When can temporary Best Management Practices (BMPs) be removed?
It’s common to see construction sites begin removing silt fence, inlet protection, erosion control blankets, and other temporary measures as areas are completed. However, removing these controls too early can expose soil, allow sediment to enter stormwater systems, and create additional compliance issues.
What Are Temporary BMPs?
Temporary BMPs are measures installed during construction to prevent erosion, control sediment, and reduce the potential for pollutants to leave the site through stormwater runoff.
Unlike permanent stormwater controls, temporary BMPs are generally intended to serve a specific purpose during construction and are removed once they are no longer necessary.
Common examples include silt fences, inlet protections, wattles, VTCs, and temporary erosion control blankets. To learn more about each of these, check out our previous blogs. Each BMP serves a different purpose, and the conditions that determine when it can be removed will depend on its location, function, and the progress of construction.
When Can Temporary BMPs Be Removed?
In general, temporary BMPs should remain in place until the areas they protect are adequately stabilized and the controls are no longer needed to prevent sediment from leaving the site.
Under Colorado’s COR400000 Construction Stormwater Permit, temporary control measures must be removed from the construction site once final stabilization has been achieved, except where the BMP specifications allow certain materials, such as biodegradable products, to remain in place.
This means that completing construction activities in one area does not automatically mean all temporary controls throughout the site can be removed.
Before removing a BMP, here are some things to consider:
- Has construction activity in the area been completed?
The first consideration is whether ground-disturbing activities are finished in the area protected by the BMP. If grading, excavation, landscaping, or other construction activities are still occurring, the area may continue to generate sediment.
If additional work is planned, the existing controls may still be necessary to protect surrounding areas and drainage systems.
- Has the area achieved final stabilization?
Under Colorado’s construction stormwater permit, final stabilization is generally achieved when all ground surface-disturbing activities are complete and disturbed areas have either:
- Established uniform vegetative cover with an individual plant density of at least 70% of pre-disturbance levels; or
- Implemented equivalent permanent alternative stabilization methods (paving, gravel, landscaping, etc.)
Simply applying seed or hydromulch does not necessarily mean an area has achieved final stabilization. Vegetation must become established and provide the required level of coverage.
- Are there other areas still contributing runoff?
Even when one portion of a site is complete, runoff from other disturbed areas may still flow through or around it.
For example, a completed building pad may be stabilized, but an adjacent area undergoing grading could continue generating sediment that travels toward the same drainage inlet. BMP removal should consider the entire drainage area, not just the specific location where the control is installed.
- Are permanent stormwater controls in place and functioning?
Temporary sediment controls may no longer be necessary once permanent drainage features, stabilized channels, or other approved controls are installed and operational.
However, permanent stormwater features should be protected during construction. A permanent pond or drainage facility may still require temporary protection until contributing areas are stabilized and construction-related sediment is no longer entering the system.
Final Thoughts
Temporary BMPs are an important part of construction stormwater management, but knowing when to remove them is just as important as knowing where to install them.
Before removing a control, make sure the area it protects is appropriately stabilized, construction activities are complete, and surrounding drainage conditions no longer require that measure. Taking the time to evaluate site conditions and document changes can help prevent avoidable compliance issues during the final stages of construction.
At Summit Services Group, we help Colorado construction teams navigate stormwater requirements through routine inspections, SWMP support, and practical guidance on BMP installation, maintenance, and removal.
Have questions about BMP removal or project closeout? Contact Summit Services Group for help keeping your stormwater management practices aligned with your project’s conditions and permit requirements.