Author(s)

M.S. West, J.M.P. Debenham & P.J. Collett

Abstract

Environmental and legislative significance of ephemeral concentration peaks in effluent mixing zones M.S. West," J.M.P. Debenham," P.J. Collett* " WS Atkins Ltd., Water and Environment Group, Woodcote Grove, Epsom, Surrey, KT18 5BW, UK * South West Water pic, Environmental Section, Engineering Services, Peninsula House, Rydon Lane, Exeter, EX2 2HR, UK ABSTRACT Recent water quality surveys and numerical modelling studies for South West Water Services Limited have highlighted the existence of short-lived, high concentrations of components of waste water in receiving waters adjacent to effluent discharges. The areas affected are relatively localized and may be considered mixing zones in which Environmental Water Quality Standards may be exceeded for limited periods of time. The paper presents a synthesis of field observations of such 'ephemeral peaks', their representation in numerical models and their significance with reference to the environment and

Keywords