Vegetated filter strips, also known as buffer strips or buffers, are vegetated land areas between a pollutant source and a surface water body. They can be stand-alone practices or used as a pre-treatment practice to other practices like bioretention or ponds. They reduce the flow velocity of water and filter and infiltrate pollutants such as sediment from stormwater. Vegetated filter strips may be subject to high public visibility, trash loads, sedimentation, pedestrian traffic, and even vehicular traffic or loads.
Vegetated filter strips require dedicated and regular maintenance to ensure proper and long-lasting operation, and in most cases a vegetated filter strip should be designed to be effective for at least 10 years (NRCS, 2010). The most frequently cited O&M concerns for vegetated filter strips include:
The sections below describe best practices to prevent or minimize these common problems.
Designers should design these practices in ways that prevent or minimize O&M issues. Examples include:
Designers should consult and include any local requirements regarding green infrastructure. O&M considerations often depend on whether the practice is located on public land, private land, or in the public right of way. For example, plantings in the public right of way that conflict with any traffic safety considerations could require increased O&M, such as pruning or complete removal.
Designers should also recognize the need to perform frequent maintenance to remove trash or excess sediment, check for clogging, and if necessary perform practice cleaning. Designers can incorporate design solutions to facilitate maintenance activities. Examples include:
The designer should also provide a site-specific O&M plan that includes the following:
For more design information for vegetated filter strips, click here.
Proper construction methods and sequencing play a significant role in reducing O&M problems. Some key items during the construction phase include:
Effective short and long-term operation of vegetated filter strips requires a dedicated and routine maintenance plan with clear guidelines, expectations, and schedules. Proper maintenance will not only increase the expected lifespan of the facility but will improve aesthetics and property value. A maintenance plan clarifying maintenance responsibilities should be required for all practices.
Some important post-construction considerations are provided below along with recommended maintenance standards.
The table below provides an overview and schedule of general maintenance activities.
First Year of Operation | ||||
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Activity | Frequency | Time period | Level of effort | O&M benefita |
Inspect the level spreader for sediment buildup and the vegetation for signs of erosion, bare spots, and overall health. | At least twice after storm events > 0.5 inches | Within the first 6 months | 1-2 hours | 1,5 |
Check for evidence of clogging or failing of the inlet, outlet, and bypass pipes. | At least twice after storm events > 0.5 inches | Within the first 6 months | <1 hour | 1 |
Remove any stormwater diversion or barriers once seedlings are established. | Once | When plants are sufficiently established | 1-2 hours | 1,2,3,4,5 |
Supplemental watering during drier periods, particularly if keeping stormwater offline until plant seedlings are established. | 1/week initially | |||
As needed
During first 2 months 1-2 hours 2,3,4,5,6 First growing season 1-2 hours Mow grass in surrounding area to 3-4 inches As needed During growing season 1 hour 1,2,3,4,5,6 Removal of sediment and debris from the toe of slope or level spreader. Biannually In spring and fall 1-2 hours 1,5 Reseed bare spots as needed. As needed First growing season 2-4 hours 1,2,3,4,5,6 After First Year of Operation
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