Abstract
Standard roadside vegetated swales often do not provide consistent pollutant removal. To increase infiltration and pollutant removal, bioswales are designed with an underlying soil media and an underdrain. However, there are little data on the ability of these stormwater control measures (SCMs) to reduce pollutant concentrations. A bioswale treating road runoff was monitored, with volume-proportional, composite stormwater runoff samples taken for the inlet, overflow, and underdrain outflow. Samples were tested for total suspended solids (TSS), total volatile suspended solids (VSS), enterococcus, E. coli, and turbidity. Underdrain flow was significantly cleaner than untreated road runoff for all monitored pollutants. As expected, the water quality of overflow was not significantly improved, since little to no interaction with soils occurred for this portion of the water balance. However, overflow bacteria concentrations were similar to those from the underdrain perhaps due to a first flush of bacteria which was treated by the soil media. For all sampling locations, enterococci concentrations were always higher than the USEPA geometric mean recommendation of 35 Most Probable Number (MPN)/100 mL, but there were events where the fecal coliform concentrations was below the USEPA’s 200 MPN/100 mL limit. A reduction in TSS concentration was seen for both overflow and underdrain flow, and only the underdrain effluent concentrations were below the North Carolina’s high quality water limit of 20 mg/L. Comparing results herein to standard swales, the bioswale has the potential to provide greater treatment and become a popular tool.
Highlights
Urbanization is a global trend, with 54% of the total population living in urban areas in 2014 and expected to reach 66% by 2050 [1]
Rusciano and Obropta [18] found a 91.5% removal of fecal coliform bacteria through bio-media columns, Garbrecht et al [46] found E. coli reduction coefficients between 32–91% based on the soil type in the column, and Hunt et al [47] found an average of 69% and 71% removal of fecal coliform and E. coli, respectively, from stormwater runoff treated by a bioretention cell
A total of 15 storm events were sampled for water quality
Summary
Urbanization is a global trend, with 54% of the total population living in urban areas in 2014 and expected to reach 66% by 2050 [1]. Pollutant removal mechanisms employed by standard swales include: sedimentation, filtration, infiltration, and modest amounts of biological and chemical reactions at the soil surface [32,39,40]. Rusciano and Obropta [18] found a 91.5% removal of fecal coliform bacteria through bio-media columns, Garbrecht et al [46] found E. coli reduction coefficients between 32–91% based on the soil type in the column, and Hunt et al [47] found an average of 69% and 71% removal of fecal coliform and E. coli, respectively, from stormwater runoff treated by a bioretention cell. Research is needed to determine how incorporating soil media and an underdrain affect volume reduction and how their pollutant removal mechanisms affect bacteria sequestration and subsequent removal. Water 2018, 10, x FOR PEER REVIEW determine how incorporating soil media and an underdrain affect volume reduction and how their pollutant removal mechanisms affect bacteria sequestration and subsequent removal
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
