In the nearly 20 years that I’ve spent immersed in stormwater management matters (I’ve only actually gone in a couple of times), I’ve pondered many head-scratchers. The proliferation of flawed policies, poor assumptions, questionable data and lack of enforcement have all been commonplace. However, I have always been comforted by the fact that we have collectively, albeit slowly at times, taken gradual steps forward in advancing the state of the art, bringing us seemingly closer to restoring and protecting our receiving waters. If there wasn’t any progress to speak of, I’m guessing I’d have run out of motivation to keep doing this long ago. Given my desire for progress, I have grown increasingly befuddled over the last year or two with what I would deem a growing disregard for BMP maintainability.
I’m likely not issuing breaking news by saying that we have generally done a terrible job to date of maintaining our installed stormwater infrastructure. There are a few programs serving as exceptions, but in most parts of North America the majority of installed stormwater BMPs are not maintained with sufficient frequency, if at all. At best, neglected BMPs cease to function as intended and their ability to reduce pollutant loads and/or runoff volume is drastically diminished or eliminated. Worse yet, is the potential for neglected BMPs to concentrate pollutants at potentially toxic or otherwise harmful levels, further exasperating the heavy financial burden we must bear to restore functionality to our long-neglected infrastructure. On a positive note, we’re finally starting to collectively see maintenance as a priority and identify solutions for addressing the problem.
What I find most concerning is the growing deployment of BMPs that are very difficult, or in some cases essentially impossible to maintain. Not maintaining BMPs because you don’t have the time, money or expertise to do so is one thing, but installing BMPs that are inaccessible or will eventually require extensive site excavation to restore their functionality seems unacceptable.
There are now a variety of stackable crate-like structures used to detain and/or infiltrate runoff that are not readily accessible to remove accumulated pollutants. I still remember my surprise when asking a manufacturer of one of these systems how to clean them and without missing a beat they responded with, “you don’t”. We also commonly rely on low profile chamber systems wrapped in geotextile to filter runoff. These types of systems can be accessed with special equipment to remove some pollutants, but eventually they will need more extensive maintenance. The published guidelines for one such system explain that eventually the system may need to be partially excavated so a person can be sent inside the 30-inch tall chambers to cut away the geotextile and weld a new one in place. Last, and perhaps worst in class, is a system being marketed as an underground biofiltration solution that can’t be accessed for maintenance once installed. Biofiltration is great and all, but in this system, the filtration bed is not accessible for maintenance without site excavation. Last time I checked, all types of biofiltration systems require regular maintenance. Some programs have reported that their traditional biofilters are requiring monthly maintenance during the rainy season. How many times a year are we planning to dig up our sidewalks and parking lots so we can clean out otherwise inaccessible biofilters?
Meeting stormwater standards in urban areas is not an easy task and we need innovative solutions, including underground BMPs, in our toolbox. However, we can’t ignore the big picture for check the box permit compliance. We can and should do better at ensuring that all BMPs not only meet our water quality goals when first installed, but also continue to do so over time by maintaining them as needed. Willfully installing infrastructure that can’t be reasonably maintained and restored to full functionality is a waste of our limited stormwater dollars. We have a number of highly effective BMPs, including those developed specifically for use underground in constrained urban areas that are also readily maintainable. Moving forward, we must remain mindful that the BMPs we implement to meet water quality goals need to also be reasonably accessible for maintenance. Additionally, we must continue to develop innovative BMPs that effectively address pollutants of concern, are maintainable, and operate at the lowest possible lifecycle cost.