Robert Cadden
Water Technologies Pty Ltd.
The pollution of waterways by the operation of urban wastewater systems is an issue of major concern
to communities, regulators and operators. For the last thirty years considerable effort has been directed
at providing treatment facilities at the point of discharge of a wastewater system and remarkable
improvements in effluent quality and pollution reduction have been achieved.
However, at the same time the wastewater collection systems have tended to be overlooked and in
numerous cities the overflow of sewage, particularly during wet weather, is polluting waterways and
negating the good results being achieved by treatment plants.
North Shore City Council is a good example where, despite its efforts to treat its sewage, closure of its
beaches due to pollution considered mainly to be as a result of sewer overflow, is a regular occurrence.
This has become a major issue with the community of North Shore City.
In 1996/97 North Shore City Council embarked on a program to address its beach water quality and
sewer overflow problem with a view to eliminating the need to erect beach closure notices after
rainfall. In 1998 the council formalised this program and commenced Project CARE which was
designed to include all bacteriological beach water quality issues and undertake a comprehensive
review of the operational performance of the wastewater collection system. This was to include the
impacts on the receiving waterways and to develop a cost effective solution that would be acceptable to
the community.
This paper outlines the processes and techniques that are being applied in an integrated approach to
meet the sewer overflow related objectives of Project CARE.
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