Authors

R.Y.G. Andoh, H. Carter, C. Osterrieder, N. Raymond & M.A. Stein

Abstract

Faced with the challenge of addressing Combined Sewer Overflow (CSO) issues, the City of Saco, Maine, adopted an approach which involved improving the transport and management of excess wet-weather flows by implementing a scheme that applied advanced vortex technologies for both flow control and water quality improvement. The application of vortex technology at Saco utilizes vortex flow regulators in the upstream diversion chambers to regulate maximum flows to the existing wastewater treatment plant in order to avoid hydraulic overloading and the diversion of excess combined sewer flows to the new CSO treatment facility. The new facility utilizes an advanced hydrodynamic vortex separator (HDVS) that incorporates a novel non-powered, self-activating and self-cleansing CSO floatables control screening system and accomplishes primary treatment equivalency, disinfection, floatables capture and grit removal all in one vessel. The underflow from the CSO facility comprising sewer debris and solids including grit, sediments, settleable organic solids and floatables, is returned to the headworks at the treatment plant and the clarified, screened and disinfected overflow is discharged to the receiving environment (Saco River) after de-chlorination. The ability to perform several essential unit processes (i.e. Sedimentation, Screening, Disinfection and Grit Removal) all in one vessel resulted in significant savings in the overall project scheme costs on account of the more compact design of the advanced HDVS system coupled with the elimination of additional tanks and vessels that would have been required with the conventional approach. Analytical results from post-construction compliance monitoring have confirmed the efficacy of the system.

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).

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

Robert Y.G. Andoh,Michael G. Faram and Kwabena Osei

Abstract

Globally, the water and wastewater industry faces major challenges, both in developed and developing world regions. The developed world has enjoyed the benefits of the foresight of prior generations, with major strides gained in public health simply from innovations such as the humble sewer which has contributed more to human health than all developments in the medical field. Challenges faced in different regions are diverse in nature, magnitude and scale. Some are local in nature but others such as the impacts of Climate Change are truly global. The paper examines the status and evolution of innovations within urban water management (with particular reference to stormwater management) including impacts of regulation, barriers to innovation, current trends and paradigms. It is argued that there is a need to change the way we approach urban water management challenges, particular if the goal is to achieve more sustainable development in an increasingly urbanizing world.

Authors

M. G. Faram, J. M. Saker & V. M. Story

Abstract

This paper presents a study of UK water industry capital equipment selection, focusing in particular on behaviour in relation to sewerage/combined sewer overflow (CSO) and wastewater-associated investment activities. Valuable new insights into the perspectives of different parties, including water service providers (WSPs), design consultants and construction companies, are provided. Through analysis of over 200 questionnaires, equipment selection is confirmed to be multi-organisational, with different parties dominating different roles. Among the selection criteria, service and quality are found to be valued as parameters worth paying for. Relationships and sustainability considerations are also found to be important, although views on whether sustainability benefits will be paid for are divided. While interparty alignment of views is generally good, there are occasional discrepancies at the individual water region level. It is suggested that optimisation might derive from recognising the significance of intangible components of the supplier offering, and managing relationships to allow these to be capitalised upon.