LONDON AVENUE CANAL STORMWATER TREATMENT FEASIBILITY STUDY

City of New Orleans in southern Louisiana is uniquely situated between Lake Pontchartrain to the North and Mississippi River to the south. Due to an average ground elevation below the water surface elevation in the surrounding large water bodies, the City is protected by levees both to the north and to the south. The City's drainage infrastructure consists of multitude of interconnected ditches and box culverts. The levees, while protecting the City from the Lake and the River, pose drainage discharge problems, which is overcome with the use of drainage pump stations. Lake Pontchartrain is a designated primary contact recreation area. Nonpoint source pollution entering the drainage canals are eventually discharged into the Lake. This has adversely affected the Lake's health. Concerted efforts of Lake cleanup from Lake Pontchartrain Basin Foundation has reversed this trend. However, source control of this nonpoint pollution was not adopted for study and implementation until the City of New Orleans secured a grant from LDNR/NOAA to conduct a feasibility study of stormwater pollution treatment in London Avenue Canal. Hartman Engineering, Inc. along with their sub-consultants Brown and Caldwell, Inc. (BCI), Essential Environmental Engineering, Inc. (E3) and Citywide Testing and Inspections, Inc. (CWTI) were contracted by the City to conduct this study and recommend appropriate solutions. The project team accomplished this task via literature search, multiple site visits, technology search, and multiple field implementation of selected technology. The initial project focused on devising constructed wetland utilizing submerged aquatic vegetation (SAV) to treat fecal coliform and floatables in the stormwater of London Avenue Canal. Due to the strong potential of impeding flow in the drainage canal, the constructed wetlands concept was eliminated from consideration during the course of the project, with the objective being amended to determine feasibility of floatables treatment only. Canal hydraulic parameters were measured under various conditions - dry weather, wet weather with no pumps running, wet weather with pumps running, north wind, no wind, and south wind. Multiple techniques were identified and evaluated for feasibility of floatables treatment in London Avenue Canal. A matrix was developed for evaluation and prioritization of selected techniques. The selected technique of floatable boom and catch basket combination underwent multiple field implementations. Individual project trial runs netted upwards of 125 pounds of floatables material within five hours or less without impeding flow in the drainage canal. The selected technique was determined to be easy to install and operate, fairly inexpensive, free of hindrance to flow in the drainage canal, and environmentally friendly. Further long term experimentation at multiple locations along selected canal, in other drainage canals of the City, during various times and seasons, and at various stages of pumpage are recommended future actions to develop a comprehensive database of stormwater pollution and recommended treatment methods for Citywide applicability and master planning purposes.