Enhanced degradation of stormwater petrochemicals within the rhizosphere of rain garden bioretention cells

Project overview

Traditional approaches to stormwater management, such as curb and gutter, fail to provide infiltration or water quality improvements and can act as conduits for pollutants. More municipalities and developers are turning to Low Impact Development (LID), which promotes on-site infiltration as alternative stormwater management approaches. Rain gardens (small, on-site, vegetated depressions to which runoff is directed) as a popular Best Management Practice (BMP) for urban stormwater quality. However, there is concern that contaminants present in the runoff may accumulate and cause pollution of soil or groundwater. Little research has been done to examine the fate of hydrocarbons in alternative stormwater systems or to understand rain gardens as a pollution control device. In order to truly be effective as a pollution control BMP, a rain garden must not only trap and detain, but degrade petrochemicals routed to them. Because most rain gardens are vegetated, It is also vital to understand the role of plants in pollution control applications of rain gardens.

We propose to create simulated rain garden systems in columns and analyze the fate of benzene and toluene (gasoline components), and to determine what effects varying vegetation have upon the degradation capacity of these hydrocarbons. It is our hypothesis that legumes, which possess an enhanced microbial community in the rhizosphere of their roots, will facilitate an environment leading to greater biodegradation of these compounds.