|dc.description.abstract||General site maintenance is important for keeping a well functioning swale; however, it is
not always easy to determine how well a site is currently functioning. Swale performance can be
evaluated by measuring its hydraulic residence time (HRT), because a HRT of at least nine
minutes has been found to be most effective at removing stormwater pollutants (Metro, 1992).
Yet, determining the performance of an existing facility based on its HRT is also not easily
accomplished. The first part of this study, therefore, attempts to develop an easy method for
evaluating performance by relating easily measured swale characteristics to HRT.
The second part of this study is intended to remedy the lack of information on stormwater
maintenance practices by examining and quantifying the benefit of mowing on pollutant removal
in swales. This study also explored whether mowing more than once during the growing season produces better removal efficiencies. Determining the effect of mowing on swale water quality
can help guide planning for future maintenance needs and potentially save money that could be
used to address other maintenance concerns.
Identifying the practices and characteristics that influence biofiltration swale performance
is important to modifying current practices to alternatives that could provide greater benefit.
Determining the real value, if any, of mowing for vegetation cover and pollutant removal could
save much time, money, and effort without compromising swale performance. In addition, being
able to quickly evaluate a swale’s current performance based on a few readily measurable
features could focus retrofitting efforts on the sites that are likely performing the worst.||en_US