- In the last few decades, a lot of studies have been conducted to study about the quality of stormwater runoff from various sites and conditions. Highways, residential areas, and commercial sites are the focus of most of these studies while limited studies have done examination of stormwater from Maintenance and Service (M&S) facilities. The dynamic nature of M&S facilities with unsteady flow and storage of wide range of construction materials and equipment, and maintenance activities done on these facilities is likely to generate stormwater runoff that may have widely different flow and water quality characteristics than from the above mentioned places. While green infrastructure (GI) is becoming popular for stormwater management at these sites, there is also need to understand how it responds to the dynamic environment at M&S facilities.
This research was focused on characterizing the stormwater runoff from an M&S facility, and evaluating the temporal performance of a bioswale in removing pollutants from such runoff. The study site is an M&S facility belonging to Benton County, Corvallis, Oregon. The catchment is 100,000 sq. ft. and is used as parking space, storage site for varieties of construction materials and equipment, refueling station and maintenance, and for repair of equipment. The runoff from the facility is intercepted using an underground tank, and pumped to a bioswale. The runoff entering the swale was characterized using composite flow-weighted sampling with automated samplers for 12 storms. For four of these storms, automated flow-weighted discrete sampling of influent and effluent was also conducted to examine for temporal dynamics in runoff and water quality entering and exiting the bio-swale. Since stormwater quality tends to vary dramatically during a storm event, discrete sampling provided high resolution analysis by delineating the entire pollutograph. The pollutograph was then used to explain the variability of water quality for a range of parameters, including pH, EC, turbidity, TSS, TDS, VSS, PSD, hardness, Cu, Zn, P, and diesel fraction, and at different time periods during a single storm event.