Wastewater pipe in capital isolated

WELLINGTON: A broken water pipe has been blocked and isolated as Wellington Water races to prevent wastewater spewing into the harbour.

A pipe burst at the intersection of Victoria and Mercer Sts on Monday.

The break is in a 300mm diameter cast iron pipe that was installed in the early 1900s.

Wellington Water chief executive Colin Crampton said yesterday the pipe was reaching the end of its useful life and was in the company's programme for renewal or replacement in two to three years.

``Wastewater comes from businesses and residents and it flows down to the harbour edge, where it's contained in tanks and is pumped back up to the main tunnel that goes to the wastewater treatment plant,’’ Mr Crampton said.

``So, because it's under pressure, it means it gets forced out of that defect and is obviously much more tricky than if it was just a gravity flowing main.''

He said Wellington Water had hoped to complete the repair overnight, but it was more complex than first thought and would now take three days.

The focus changed yesterday morning to digging down in a different place to block and isolate the broken section of pipe, which was successfully completed yesterday afternoon.

This means some pumps can resume removing wastewater from tanks underneath the Michael Fowler Centre and send it to a treatment plant.

Earlier yesterday, Mr Crampton described the situation as having reached a ``very fine line''.

``We're on the cusp at the moment of filling all of our storage up and so if we can't get this stopper put into the pipe and resume pumping during today, we will find it very hard not to cause an overflow into the harbour, he said.

``We see it as a matter of hours now and we have all of our people down there on site ready to get into gear if that was to occur.''

Sucker trucks are on site to help manage the risk.

Some residents and businesses reduced wastewater flow during yesterday by flushing the toilet only if essential and not using inside drains.

Some will have to continue taking these measures, although the affected area of the CBD has been significantly reduced. — The New Zealand Herald