The task of selecting the proper stormwater BMP for your site can be tedious. There are thousands of choices; from drainage swales and silt fences to hydrodynamic separation and storm water filtration systems. All of them have their place in a well written BMP Plan, but none of them will work without maintenance. During my time as a state stormwater regulator, I have seen many BMPs and BMP Plans. On paper, most of them are great. They tell you everything that will be done to protect water quantity and quality. Yet, even a well written and executed BMP Plan cannot have a positive environmental and economic impact without proper maintenance.
Stormwater BMPs can be classified as "structural" (devices installed or constructed on a site) or "non-structural" (modified landscaping practices). Recently, there has been a big push for more non-structural BMPs to be implemented instead of the traditional structural BMPs. There seems to be a perception that these BMPs can be installed and left alone, with very little to no maintenance. That couldn’t be further from the truth.
Let’s think about what happens to a bioswale; a simple, non-structural BMP, after install. Rain events occur and the bioswale functions as specified. Stormwater flows to the site by natural drainage and slowly infiltrates and evapotranspirates; depositing sediment, trash, and debris on the surface of the bioswale. Over time, the bioswale plants begin to grow. The trash and debris keep accumulating at the site. The bioswale cross-section begins to change, as sediment deposits in different locations of the swale. Eventually, the bioswale no longer functions properly.
Depending on the location and the amount of stormwater flow to the bioswale, the Department of Water Quality for the State of Oregon recommends that bioswales be inspected seasonally and after ever major rain event, to avoid failure. It may also need to be reshaped, due to large sediment deposits, and plantings need regular maintenance and irrigation during dry spells. The time it takes workers to maintain the swale now has a huge impact on the upfront cost savings you had during installation. The cost of the bioswale does not seem so economical after you include hours of labor intensive maintenance.
When writing your BMP Plan:
- Research the BMP/product you intend to specify.
- Call the manufacturer, engineer, or contractor to get a list of recent installs so you can contact the user for a recommendation.
The cost for a great BMP may be a little higher on the front end, but can save you thousands in the long run if the maintenance is simple and fast. There are many similar BMP products in the marketplace. Don’t assume they are all the same, especially when it comes to maintenance. With thousands of products in the market, maintenance is the key to cost savings in the long run.