Protecting Your Investment in Low Impact Development
Over the past 2 decades, Low Impact Development seminars have been attended by tens of thousands of architects, municipal staffers, developers, landscape architects, civil engineers, contractors and the entire gamut of professionals who depend on development for their livelihood. These professionals hear about the pollutant removal characteristics and the chemical, biological and mechanical processes that make LID practices like bioretention happen, or the hydrologic benefits that help reduce peak discharge rates and all the latest modeling tools that help us quantify those results. We learn to think of LID as a tool box of solutions, that when properly combined, can create an environmentally sensitive project that can lower the overall cost to the developer and increase the project’s value and marketability, while having little adverse impact on the environment. What we rarely hear about is how to implement the design effectively and maintain the system long term, both of which relate back to a good, well thought out design.
I recently had the opportunity to participate on a design team for the American Society of Landscape Architect’s Green Street Project in Washington DC. I was asked to come on board as the Operations and Maintenance consultant based on my 8 years of experience with a variety of Low Impact Development solutions, their installation and ultimately their long term maintenance. Once short listed, five of us flew to DC to compete against 5 other firms from across the nation. The significance of this exercise was that it made me re-focus my thoughts about Low Impact Development, the BMP’s we specify and their Operations & Maintenance.
What I realized when sitting in that room, with some of the brightest landscape architects in the country judging us, surrounded by a group of designers that are the crème de la crème, was that the panel of judges were only able to choose a winning design team from the teams they’d shortlisted. What they weren’t able to do, because the project is a public bid project, was to choose the contractor that bid it or the maintenance group that would maintain it. The only thing within their control was the design team chosen, which means that the design team is ultimately responsible for the success or failure of the project without any control over the construction contractor or maintenance contractor that will ultimately determine its fate.
This is an enormous responsibility for any design team, so it seems clear to me that BMP selection has to be looked at through the lens of maintainability first and foremost. Most will think this is a ridiculous assertion. Millions of dollars have been spent on research to prove the effectiveness of many a BMP system, so why wouldn’t that be the primary criteria, one might ask. The reason this logic seems flawed to me is because in order for the long term success of a solution to truly be sustainable, it must be maintainable, and that maintenance must be simple, effective, and within a price the owner will be willing to pay. If this doesn’t exist, all the owner has is an expensive (at any price) best management practice that is constantly in bypass mode. Even though the designer’s intentions were in the right place, the pollutant removal rates the BMP was designed to produce are not achieved. Remember, there is no such thing as a self-maintaining Best Management Practice.
In your next design, whether trying to use Low Impact Development or Traditional Site Design practices, try looking at your BMP selection through the lens of maintenance first. You will find 3.5 things to be true:
1. The cost of a BMP system is rarely related to the cost to maintain it (Hydrodynamic Separators may be a very expensive to maintain exception, as their maintenance is related to tank size and the gallons of effluent removed from the system during cleanout, the more effluent the higher the cost.)
2. Integrated site design practices (aka, multi-functional landscape features) like LID allow for shared budgets when it comes to maintenance, reducing overall costs to the owner (Biofilters are typically maintained by landscape contractors, for a good example of an inexpensive maintenance regime, check out the FocalPoint Biofiltration System’s O&M Guide)
3. Many popular porous pavement systems don’t have an effective maintenance protocol that will effectively keep/return the product to its original specified flow rate. (The PaveDrain product far exceeds the others and is why we are now proud to represent them.)
3.5. Anytime you can simplify the maintenance process, you raise the odds that effective maintenance will happen. The more complicated the strategy, the more expensive the maintenance (See Sand Filters and Cartridge Filters as primary examples).