Abstract
Bioretention and rain garden systems are shallow planted areas designed to capture, retain, or detain stormwater to encourage soil infiltration of water that would otherwise run off over the soil surface. Benefits to the environment associated with rain gardens include: improved water quality, enhanced groundwater recharge, suspended particle reduction, reduced surface flows and associated erosion, and habitat creation for birds, butterflies, and beneficial insects. In 2008, a rain garden system was installed at a container plant nursery in northern Florida to evaluate the effectiveness of bioretention to mitigate irrigation associated nutrient loading to adjacent wetlands, water bodies, and groundwater. Irrigation runoff from an impervious production bed that is 360 ft × 50 ft (109.7 m × 15.2 m) flows into one of two rain gardens that are approximately 25 ft × 15 ft (7.6 m × 4.6 m) in size. The garden soil consists of ASTM C-33 sand and is approximately 34 inches (86.4 cm) deep with under-drains. The gardens are side-by-side, separated by a constructed 3-ft- (0.9 m) wide clay soil partition, with one designated as planted and the other non-planted. Three native plants species, Hydrangea quercifolia (oakleaf hydrangea), Serenoa repens (saw palmetto), and Canna flaccida (canna lily), were installed in the planted garden. Studies are currently under way to monitor nitrogen, phosphorus, and zinc, pre- and post-exposure to the rain garden. It is anticipated that results from this study would supplement current best management practices for container plant nurseries in Florida for associated nutrient loading from bed irrigation runoff.
