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Tide turning on Estuary
For the health of the people and the
environment, the City Council should start
planning to build an ocean outfall for its treated
wastewater. That is the opinion of experts who
have been looking at the future of the city’s
sewage treatment. Last month City
Councillors, reporters and
people from interested
groups were invited to hear
the results of studies done
since ECan commissioners
released their decisions on
the Council’s plan to
continue using the Avon-
Heathcote Estuary as its
wastewater outfall. That decision – in effect
telling the City Council to
stop putting its treated
wastewater into the Estuary
as soon as possible – showed a big gap between
what the Council and the commissioners thought
was the state of the Estuary. Two groups of expert scientists were asked to
have another look at all the evidence that had
been gathered so far and give the Council a
second opinion. One group looked at public
health issues, the other concentrated on the
health of the Estuary environment. At last month’s
briefing both groups said the commissioners are
probably right – an ocean pipeline is a better longterm
solution although they did not share the
commissioners’ sense of desperate urgency. The scientists who examined the Estuary’s health
said taking away the wastewater outfall would,
over time, result in a big drop in the amount of
sea lettuce and other green algae growing there.
Sea lettuce is a bother. It smells bad when it rots,
is a nuisance to people in the area, and is thought
to smother other estuary life. They also said the Estuary
would become a healthier
place for fish and other marine
life. The expert group dealing
with public health looked at
evidence and also took into
account new national
guidelines for grading water
quality. They said the Estuary
beaches would improve if the
ocean outfall was built, but to
really lift their ratings the city
would need also to deal with
pollution – much of it bird and other animal
droppings – being washed into the Estuary by the
Avon and Heathcote rivers. The Council has already approved plans for
drastically reducing wet weather sewer overflows
over the next five years as one major step to
meet the targeted improvements. It was impossible to say how much the city’s
population might grow in the next 20 to 30 years
and the best long-term solution was to clean up
the wastewater as much as possible and put the
outflow into the ocean, the experts said. Neither team thought the Estuary’s health was
in immediate danger. City wastewater had been
pumped into it for most of last century and it was
likely to be able to stand a few more years until
the Council did the planning and building needed
to replace its outfall. Christchurch Mayor Garry Moore said people
from the different interest groups had been able
to sit in while the scientific groups did their work.
It was important, he said, that the decision-making
about the wastewater treatment was “open for
everyone to see”. “This is a 100-year issue we’re dealing with,” Mr
Moore said. “They don’t come up every day,
they’re usually incredibly expensive and we’ve got
to get it right. We all have to live with the
consequences of this thing.” One idea behind the Council’s earlier decision
to push for a continued Estuary outfall was its
belief in sustainable development – the idea that
the wastewater could one day be a resource, with
the nutrients and water separated out and reused. Mike Bourke, the Council’s Water and Waste
Operations and Maintenance Manager, said
building a pipeline to the ocean did not cut off
those options forever. For now, however, the
technologies were far too expensive. |