Dealing with our wastewater

On the eve of the former Christchurch Drainage Board’s centenary in 1975, the then secretary of the board, M.J.Horne, told The Star that “people tend to forget the drainage board exists — until they find their property underwater, or worse still, that their lavatories won’t flush.”

Sewerage is not often the subject of dinner party conservation, or in fact any sort of conversation. Most of us just flush the toilet, empty the bath or tip out the dirty bucket of water and that’s where it ends — out of sight, out of mind, so to speak.

For the City Council however, that’s where it all begins.

Underneath our streets and roads is a vast, efficient network of sewer pipes, pumping stations and flush tanks, which continuously convey wastewater to the Christchurch Wastewater Treatment Plant for processing.

Maintaining and upgrading the city’s sewerage system is a major responsibility of the City Council. The draft community plan has budgeted $18.99 million for the treatment and disposal of wastewater for the 2004/05 financial year. That works out to be about $1.89 per week (based on rates for the average residential property value of $164,170). About 136,000 households in Christchurch are connected to the city’s wastewater system. The city is however growing and there is continuing demand being placed on its sewer system.

City Council city water and waste manager Mike Stockwell says the Council has in place an asset management plan for the valuable wastewater pipeline and treatment assets.

“The plan provides a strategy to meet the demands of expected city growth well into the 21st century to maintain the pipe assets and to upgrade the level of service where appropriate,” he says.

Three major projects are under way around the city to not only help improve the ability of the city’s wastewater system to cope with this growth, but also to further improve the way Christchurch treats its wastewater.

“This programme of works has been planned to ensure the city’s sewerage system can cope with expected city growth to around 425,000 residents in 2050,” says Mr Stockwell.