Prioritizing maintenance for best management products
In the nearly 20 years that I have spent immersed in storm water management, I have pondered many head-scratchers; the proliferation of flawed policies, poor assumptions, questionable data and lack of enforcement have all been commonplace. However, I always have been comforted by the fact that we have collectively, albeit slowly at times, taken gradual steps forward in advancing innovation, bringing us closer to restoring and protecting our receiving waters. If there was not any progress to speak of, I am guessing I would 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 best management product (BMP) maintainability.
Places to Improve
I likely am not issuing breaking news by saying we generally have done a terrible job of maintaining our installed storm water infrastructure. There are a few programs serving as exceptions, but in most parts of North America, the majority of installed storm water 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 or runoff volume is drastically diminished or eliminated. Worse yet is the potential for neglected BMPs to concentrate pollutants at harmful levels, further exasperating the heavy financial burden we must bear to restore functionality to our long-neglected infrastructure. On a positive note, we are 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 difficult or essentially impossible to maintain. Not maintaining BMPs because you do not 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 now are a variety of stackable crate-like structures used to detain 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, he or she responded with, “you don’t.” We also commonly rely on low-profile chamber systems wrapped in geotextile to filter runoff. These 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 the system eventually may need to be partially excavated so a person can be sent inside the 30-in. tall chambers to cut away the geotextile and weld a new one in place.
Lastly, a system marketed as an underground biofiltration solution cannot be accessed for maintenance once installed. Biofiltration is great, 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 require monthly maintenance during the rainy season. How many times a year are we planning to dig up our parking lots to clean out otherwise inaccessible biofilters?
Using Valuable Resources
Meeting storm water standards in urban areas is not an easy task. We need innovative solutions, including underground BMPs, in our toolbox; however, we cannot ignore the big picture for 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 with maintenance. Willfully installing infrastructure that cannot be reasonably maintained and restored to full functionality is a waste of limited storm water dollars. We have a number of highly effective BMPs available, but moving forward, we must remain mindful that the BMPs we implement also must 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.