The New Orleans Redevelopment Authority (NORA) owns and manages hundreds of vacant lots located throughout New Orleans and experienced a sharp increase in the number of these properties since 2005 as a direct result of Hurricane Katrina. Subsequently, the City needed an innovative strategy for management of properties that had become overgrown. Addressing this issue is vital to preserving the City’s historic character and unique aesthetic, particularly due to the concentration of these vacant properties within the dense, urban core of New Orleans. Transforming vacant lots into green infrastructure sites was determined to be a viable and sustainable solution that solved issues of repetitive losses due to localized flooding, increased pollutant loads in runoff, and the lack of green open space in these neighborhoods.
Dana Brown & Associates designed detention basins on five vacant lots dispersed throughout the neighborhoods of New Orleans. The sites are envisioned as urban greenspaces that accept large volumes of stormwater runoff from the neighborhood. Most of the water is collected from the impermeable streets utilizing a custom designed concrete runnel as an inlet. As the runoff collects, the runnel is designed to direct it through depressed planted areas which increases opportunities for onsite bioremediation and groundwater recharge prior to the water exiting through a custom designed drain outlet. This outlet allows the detained stormwater to slowly exit the site and enter the municipal drainage system. By design, the site is completely drained of runoff within 48 hours, by way of the custom outlet box, which mitigates potential for mosquito larvae habitat.
Each lot manages an average capacity of 34,000 gallons of runoff water from streets. The lots are designed to be multifunctional, serving as green infrastructure demonstrations, eliminating blighted, vacant property, increasing green space in dense, urban areas, and reducing localized flooding from rainstorms.