Sewer overflows in eastern England: a general survey for environmental investment

A survey has been undertaken in East Anglia, UK, to assess the environmental impact of 51 combined sewer overflows and emergency overflows where investment is being considered. Using the combined sewer overflow (CSO) assessment procedure, 26% of the overflows were assessed as having an unsatisfactory or very unsatisfactory environmental impact, and at six sites there were environmental problems unrelated to the overflows. The results were formatted into a matrix based on the CSO assessment procedure, general quality assessment (GQA) aesthetic classes, the presence of trade effluent and the dilution available within the watercourse. This matrix provides useful guidance to prioritize action. The survey has proved to be a useful source of information and analysis, providing considerable opportunities to improve management of the environment, while using the limited economic resources available more cost-effectively.