| This study will evaluate bioretention systems' ability to remove microbial pollutants in both the laboratory and field settings, while also providing essential background on urban stormwater, pollutants, treatment options, and water regulation. Increased urbanization has increased the quantity of pollutants carried by stormwater. Conventional stormwater systems assist in the mitigation of stormwater pollution but can have an adverse effect on natural hydrology. Low impact development (LID) strategies incorporate engineering designs that address pollutants at the original source while also providing some aesthetic value to the community, LIDs are multiuse best management practices (BMPs). Since unmanaged microbial pollution can result in degraded public health and the spread of disease, literature has suggested a need for quantifying microbial removal efficiencies from LID practices. There are numerous studies describing the removal efficiencies of bioretention cells for non-microbial pollutants illustrating the benefit of LID systems.;This study will quantify removal efficiencies of E.coli, enterococci, and coliphage in filter media with and without fly ash amended soil incorporating column experiments and field experimentation. Column experiments using soil cores from the sand layer of established bioretention cells give mean removal efficiencies of 67%, 71%, and 64% for E.coli, enterococci, and coliphage respectively in sand only filter media. The fly-ash amended media showed mean removal efficiencies of 64%, 83%, and 41% for E.coli, enterococci, and coliphage respectively. These removals do not consider other layers within the bioretention system, only the filter media layer. Additionally, the second component of this study involves field experiments from three bioretention cells sites in Grove, Oklahoma. These sites were monitored and mean removal and concentration change of microbial indicators calculated. The mean removal efficiency for each of the three sites sampled in the field study are site 1 (87%, 80%, 78%), site 2 (35%, 95%, 81%), and site 3 (43%, 97%, 46%) for E.coli, enterococci, and coliphage, correspondingly. Finally, the third component of this study is the development of bioretention cell design criteria that specifically targets microbial removal and destruction. This microbial removal bioretention design criteria is based on recommendations found in literature from laboratory and field studies from 2008 to current. |
