Like an automobile, a stormwater best management practice (BMP) needs routine maintenance and inspection to keep running at maximum efficiency. The operations and maintence of any stormwater BMP can be broken up into the following key components:
- Inspection: Especially during the first year, it is important to periodically inspect the stormwater practice. BMP function should be verified immediately following installation at the first storm event. If the practice does not behave as intended, the site contractor and designer should be notified to remedy the situation. All BMPs should be consistently checked following any major storm events for debris or other changes.
- Routine Maintenance: All stormwater BMPs should be routinely maintained. Routine maintenance will upkeep aesthetic attractiveness, save money in the long run, and mitigate any damage that could lead to costly major repairs. Depending on the practice and location, this maintenance may be required 2-3 times a year (for a “naturalized detention basin”, for example) or 6 or more times (for a “stormwater bump out” in a highly urbanized setting, for example). In general, practices require more maintenance in their first 3 years after installation than later, largely to keep invasive species at bay until the desired planting palette is established. Each BMP will have its own set of maintenance requirements, but some common things to keep maintained include:
- Removal of invasive species
- Removal of trash and other debris
- Periodic mowing, depending on BMP design
- Removal of sediment deposited in inlets and low-points
- Cutting back and cleaning up perennials and grasses in early spring
- Remove any clogs in drains or inlets
- Loosen any mulch mats and add more (only where necessary)
- Major Repairs: Large storm events, unexpected accidents, or changes in the contributing land cover (like adding large impervious tracts, making the BMP undersized for its drainage area) might require major repairs or system upgrades. More often than not, however, large rehabilitation efforts can be prevented by routine inspection and maintenance, to get ahead of any problems. The cost of major repairs can far exceed the cost of routine inspection and maintenance. If this is needed, it is strongly advised to consult with the original site engineer and contractors to provide instructions for repair and define a clear strategy to avoid repeat failure in the future.
Stormwaterpartners.com offers simple maintenance checklists for a variety of stormwater BMPs.
The Pennsylvania Landscape & Nursery Association offers training and certification for on the topics of horticulture and sustainable landscapes, both of which address maintenance.
Stormwater Treatment: Assessment and Maintenance is an online manual for assessment and maintenance of stormwater treatment practices developed by the University of Minnesota and the Minnesota Pollution Control Agency.
Bioretention Performance, Design, Construction, and Maintenance. A concise treatment of monitoring results on bioretention practices from NC State University’s Biological and Agricultural Engineering Stormwater Engineering Group, this publication discusses some design considerations, and how filter media can be changed to address various nutrients.