GETTING DIRTY WITH OUR CATCH BASINS
The amount of sediment and debris generated during rainfall is substantial. More than you can imagine, and certainly more than I ever thought possible. The graphic and summary included herein is based on a study completed by Mineart & Singh in 1994, and it—as well as other similar studies—is summarized in this white paper prepared for the Association of Washington Cities and Washington Department of Ecology in 2013. In short, the volume of sediment and debris captured in a storm drain or catch basin varies depending on road width and surrounding land use, as well as other environmental factors. On average, catch basins in industrial areas generate four times the volume of debris relative to catch basins in heavy residential areas. Commercial areas tend to generate 3 times the debris of that generated in residential areas. Whether catch basins should be cleaned annually or more frequently depends on site-specific information, but, at a minimum, they should be cleaned annually. Without proper cleaning, the effectiveness of a catch basin drops dramatically, and all that dirt and debris—as well as the chemicals and bacteria captured along with it—flows right to our waterways. And that, dear audience, gets really expensive to treat.