World Environmental & Water Resources Congress 2008; May 12-16, 2008, Honolulu, Hawaii Loffill et al., 2008 Storm Water Best Management Practices into the Existing Urban Landscape – Systems for Controlling Sediments Ed Loffill 1 , David Phipps 1 , Rafid Alkhaddar 1&4 , Robert Andoh 2 and Mike Faram 3 (1) The Liverpool Centre for Environmental Technology, Liverpool John Moores University, The Peter Jost Centre, Byrom Street, Liverpool L3 3AF, UK (2) Hydro International, 94 Hutchins Drive, Portland, ME, 04102-1930, USA (3) Hydro International, Shearwater House, Clevedon BS21 7RD, UK (4) Corresponding Author: r.m.alkhaddar@ljmu.ac.uk ABSTRACT The operation of an ‘advanced’ hydrodynamic vortex separator (AVS) designed for stormwater sediment interception has been examined using particle capture and retention efficiency testing and dye tracer testing. For retention efficiency in particular (referring to the efficiency with which a chamber retains pollutants following capture) the results are compared with those for other configurations, including simple vortex and gravity separation devices. The results show how the collection and retention efficiencies of the AVS are enhanced through the presence of a quiescent zone in the base where solids are stored. A simple model of system operation is considered, based on the surface loading rate of the active region and the particle sedimentation velocity. It is concluded that a comprehensive model of system performance needs to take into account a variety of factors, including the detailed characteristics of the sediment material and the hydrodynamic characteristics of the specific separation device in question. KEYWORDS Hydrodynamic vortex separator; retention efficiency; sediment; stormwater treatment INTRODUCTION Hydrodynamic vortex separators are high rate separation systems that have been utilized for a number of applications, including wastewater treatment (Faram et al., 2004), combined sewer overflow (CSO) treatment (Andoh, 1998) and stormwater treatment (Deahl & Faram, 2002). Their application for stormwater treatment is particularly valuable with urban run-off which contains entrained sediments that have been identified as a source of pollution (Pitt et al., 1995; Sansalone and Buchberger, 1997). Given their high efficiency and compact footprint, together with a low head-loss, they are applicable to both new construction and retrofit applications. The system described here, an ‘Advanced Vortex Separator’ (AVS) has been developed over a number of decades, with a clear understanding of the factors affecting its efficiency. METHODOLOGY The small-scale prototype AVS that formed the focus of the studies (overall diameter 375mm, operating volume approximately 60 litres excluding any connecting pipe work) was constructed of transparent Perspex™. This was based on the system shown in Figure 1. World Environmental and Water Resources Congress 2008 Ahupua'a © 2008 ASCE