It’s important that facilities managers understand how to properly maintain their stormwater management systems, including, but not limited to, catch basins, retention and detention ponds, bioretention cells, rain gardens, permeable pavement, and stormwater vaults.
Facilities Management Advisor’s July 13 webinar, “Exploring Stormwater Best Management Practices across the United States,” featured speaker Erin Zaske, a certified stormwater control measure (SCM) inspection and maintenance professional and chief development officer from session sponsor AQUALIS.
The Purpose of Stormwater Systems
Stormwater systems manage stormwater runoff and are required at developed properties that are 1 acre or larger. Because impervious surfaces can’t absorb rainwater, runoff enters either groundwater or another body of water.
In order to determine a stormwater system’s type and design, engineers look at a property’s average rainfall, surrounding impervious material, and soil drainage.
Stormwater System Laws
Proper stormwater system maintenance is not only the right thing to do but also necessary so organizations follow the law and avoid unnecessary penalties.
“Lack of proper maintenance may lead to a notice of violation, and associated fines on your system if your system is inspected and found non-compliant. Cities and states have the authority to inspect your property and may issue a fine to property owners. Stormwater systems act as a defense against pollution in our waters,” Zaske explained.
Run to Fail vs. Preventive Maintenance
Facilities managers shouldn’t use the run-to-fail method, which means running a system until a failure occurs, Zaske said, adding that because many stormwater management systems are behind buildings or hidden in parking lots or have vegetation around them, some facilities forget about them and therefore unintentionally run their system until failure. Instead, Zaske recommends preventive maintenance for these systems, which includes regular inspections.
“Maintenance can be viewed as an investment that is beneficial for your property in the long term,” she said, adding, “We recommend regular maintenance as it can be budgeted for, whereas full rehabilitation or replacement of your system can be a large, unexpected lump sum impacting your overall facilities management budget.”
Specifically, she explained that system replacements can cost hundreds of thousands of dollars.
Here is a brief explanation of six common types of stormwater systems and how they can be properly maintained:
1. Catch Basins
One of the most popular stormwater systems is the catch basin, which is a storm drain that redirects water to prevent flooding. These are common in paved parking lots and paved streets.
Examine catch basins to check for the possibility of a sinkhole caused by compromised pipes that can destabilize surrounding surfaces and implode paved surfaces. Also, be sure to regularly assess the catch basins’ function, safety, and compliance.
2. Retention and Detention Ponds
Retention ponds permanently store a specific amount of stormwater. They filter it by allowing suspended solids to settle, which improves water quality.
Detention ponds temporarily store stormwater, which should fully drain within 72 hours.
Maintenance for both retention and detection ponds should involve clearing overgrown vegetation and collecting debris. Failure to maintain these ponds can impact water flow and create sentiment accumulation.
3. Bioretention Cells
Typically found in parking lots or roadways, bioretention cells are landscaped depressions that capture and treat the first flush of runoff from impermeable surfaces and then dry out between storms.
Bioretention cells can be maintained in a variety of ways, including hand weeding, removing trash, clipping and pruning vegetation, replacing mulch, supplemental planning, assessing vegetation health, infiltration testing, and removing sediment.
4. Rain Gardens
Rain gardens feature a variety of native vegetation planted in a small depression and are designed to temporarily hold and infiltrate runoff. Unlike bioretention cells, rain gardens have a variety of soil moisture tolerance but aren’t flood- and drought-tolerant.
Rain gardens can be maintained in a similar way to bioretention cells except that rain gardens need watering during dry spouts and require drainage testing.
5. Permeable Pavement
Permeable pavement is a pavement alternative with porous materials that allow stormwater runoff to be absorbed and held in subsurface stone reservoirs. Vehicles can be parked on one area of permeable pavement, and it can be used to grow grass plantings within a grid system in another area.
Maintenance includes percolation testing (to determine the water absorption rate of soil), sediment removal, and replacement of joint aggregate. It can also vary based on manufacturer recommendations.
6. Stormwater Vaults
These large systems accumulate all stormwater runoff and pollutants that runoff carries.
Maintenance of stormwater vaults should include cleaning out debris and trash that could overwhelm the system. Consider using an industrial vacuum and jetting, or the use of high-pressure jets of water.
If stormwater vaults have filters, they should be cleaned and inspected on a regular basis.
During the presentation, Zaske also discussed the differences between gray and green stormwater infrastructure, erosion prevention, and underground pipe inspection services, as well as the differences between stormwater professionals and landscapers and more.
To watch the entire webinar on demand, click here.