Water‐Quality Performance of a Constructed Stormwater Wetland for All Flow Conditions¹

Abstract

Wadzuk, Bridget M., Matthew Rea, Gregg Woodruff, Kelly Flynn, and Robert G. Traver, 2010. Water‐Quality Performance of a Constructed Stormwater Wetland for All Flow Conditions. Journal of the American Water Resources Association (JAWRA) 46(2):385‐394. DOI: 10.1111/j.1752‐1688.2009.00408.x Abstract: Results from a multiyear study demonstrate that a constructed stormwater wetland (CSW) improves urban stormwater runoff quality mitigating downstream impacts. Best management practices, such as CSWs, can comprehensively treat the various scales of stormwater runoff issues. Discrete sample analysis was used to investigate the CSW effect for storm events and base‐flow periods on water‐quality parameters [i.e., total suspended solids, total dissolved solids, total nitrogen, phosphorous (total and reactive), chloride, heavy metals (zinc, lead, and copper), and Escherichia coli]. The primary finding was that stormwater sediment load was removed through the CSW for all flow conditions during all seasons. The mechanisms responsible for the removal of suspended solids, including slower flow velocity, longer retention times, and vegetative contact, also reduced the mass of nutrients discharged downstream throughout the year. Exceedance probabilities were used to evaluate the expected pollutant reductions of nutrients and to incorporate the effect of natural flow variation on quality. Other findings included the observation that there was no significant difference in the performance of the CSW over two‐year‐long periods four years apart, indicating that a CSW is effective for an extended period.

Nutrient and Escherichia coli Attentuation in a Constructed Stormwater Wetland in the North Carolina Coastal Plain

“…Constructed stormwater wetlands (CSWs) are often advantageous over other BMPs in that they tend to maintain a continuous flow, involving base flow and storm flow whereas other BMPs (retention ponds, etc.) may only be functioning as a treatment mechanism during and post storm events (Wadzuk et al, 2010).…”

“…Wetland performance in treating stormwater is a function of numerous factors including, but not limited to hydraulic loading rate, detention time, storm intensity, runoff volume, wetland size (Carleton et al, 2001), season (Yousef et al, 1986;Hvited-Jacobsen et al, 1989), maintenance intensity (Hunt & Lord, 2007), and vegetative species and placement (Jenkins & Greenway, 2005). While most studies have shown that stormwater wetlands are effective at reducing nutrient and pathogen influent concentrations, the reported treatment efficiencies are often variable because of the many factors which influence pollutant treatment (Line et al, 2008;Hathaway et al, 2009;Wadzuk et al, 2010 ).…”

Adapting the Relaxed Tanks-in-Series Model for Stormwater Wetland Water Quality Performance

“…Volume reductions in CSWs are typically negligible [8,12,52]; however, some systems have experienced significant reductions (24-55%) due to seepage and evapotranspiration [8,50,53,54]. Consequently, CSW designs based on this model would provide conservative area recommendations, and further refinements to the model could include water balance calculations to evaluate CSW performance and sizing on a mass loading basis.…”

Comparing Green and Grey Infrastructure Using Life Cycle Cost and Environmental Impact: A Rain Garden Case Study in Cincinnati, OH

“…When assessed from a “triple bottom line” perspective, one that assesses social and environmental benefits in addition to the financial, GI is shown to have significant additional benefits (Wolf, ; Neukrug and Camp, ; Wise et al ., ). GI can complement or replace existing infrastructure, improving functionality or reducing costs (Bedan and Clausen, ; Wadzuk et al ., ; Opperman et al ., ; Steffen et al ., ). GI primarily benefits the environment by eliminating the need for traditional grey infrastructure and its associated environmental impacts.…”