Authors

Kwabena Osei, Robert Andoh and Lisa Glennon

Abstract

In approving stormwater BMPs, regulators usually review sediment removal data as the basis for their decisions. One factor that is usually overlooked is the ability of a treatment device to retain captured material in the event of high flow rates. Lately, some agencies are requiring vendors to indicate washout prevention of their stormwater treatment systems. However, no standard protocol exists that measures how much of previously captured pollutant is resuspended and carried downstream of the treatment device during high flows.

Authors

R.Y.G. Andoh, A.J. Stephenson and P. Collins

Abstract

The need for a more holistic approach in the development of solutions to wet-weather induced problems in urban drainage systems is advocated. A review of current approaches to resolving problems of premature overflows and flooding is presented outlining a case example of the successful application of non-conventional approaches, techniques and devices that assist in the better management and control of wet-weather flow sources. This involves the seeking of solutions within the upstream portions of drainage systems by intercepting, containing, controlling and treating excess wet-weather flows before they cause hydraulic and water quality problems in downstream areas (sections of the drainage system). These approaches have been found to be more cost-effective than conventional solutions and involve the implementation of distributed/decentralised schemes which in turn offer improved opportunities for wider community and other stakeholder involvement leading to the realisation of amenity and other non-structural benefits.

Authors

Lisa Glennon, Marcus Mumford, Uday Khambhammettu, Robert Pitt

Abstract

Runoff from urban drainage areas is a major source of diffuse pollution containing high concentrations of pollutants such as phosphorus and silts (sediments in the 3.9 to 62.5 μm range). Urban drainage areas such as parking lots, vehicle fueling and maintenance stations, and public works storage areas have been dubbed critical source areas due to the observation that runoff from these areas may contain high pollutant loadings of varying diffuse pollutant classifications, including trash and other debris, coarse and fine sediment, hydrocarbons, toxic trace metals, nutrients such as phosphorus and nitrogen, pathogens, and/or other toxicants (Bannerman, et al. 1993; Pitt, et al. 1995; Claytor and Scheuler 1996). One approach to stormwater treatment is to treat urban runoff at end-of-pipe, once runoff from critical source areas has mixed with runoff from less polluted areas. An alternative approach is to use small-footprint treatment devices upstream at critical source areas before the runoff mixes with larger volumes of less polluted runoff. Treatment devices installed at critical source areas need to incorporate several treatment processes, such as sedimentation, screening, and filtration, to target the different classifications of pollutants and respond to the inherent variability of runoff quality from different types of critical source areas (Pitt, et al. 1999). An upflow filter device equipped with a pre-settling sump and a coarse screening system has undergone a full-scale field evaluation at a site near the City Hall in Tuscaloosa, Alabama as part of a Small Business Innovative Research (SBIR) project funded by the United States Environmental Protection Agency (US EPA). This paper presents results of ongoing comprehensive characterization and performance evaluation of the upflow filtration unit tested under controlled laboratory conditions at Hydro International's hydraulics facility in Portland, ME, and compares the results to the field data collected by the University of Alabama (Pitt, et al. 2005; Khambhammeettu 2006).