The diversity of sewer sediments and the consequences for sewer flow quality modelling

Abstract

As a consequence of recent EU Directives and a substantial increase in the environmental awareness of the general public, practising engineers and researchers are now more than ever required to collaborate to provide the higher standards of water quality being demanded. The engineers role is to implement a cost effective, practical and sustainable solution; the researcher must provide the engineer with the tools and ‘know how’ to allow this solution to be attained. Recent research endeavours in the UK have resulted in a philosophy known as Urban Pollution Management. This philosophy allows the engineer to solve a drainage catchment problem utilising either simple or complex approaches, depending upon the ability of the receiving watercourse to assimilate discharges from CSOs and WTP's. The backbone of the complex approach is the sewer flow quality model. Consequently for a ‘realistic’ solution to be implemented, the sewer flow quality model must represent reality accurately. Work carried out in the City of Perth, has shown that there are significant limitations to the accuracy of a typical sewer flow quality model; limitations which cannot be attributed to the mathematics or the limitations of the particular package, but are due to the complexity and diversity of the phenomena encountered within sewerage systems, particularly the effects of the sediments. This paper questions whether in fact the recent UK research endeavour has actually provided engineers with a tool/philosophy which can provide cost effective, practical and sustainable solutions to complex drainage catchment problems.