Dirty water taken from landfill site

Thousands of cubic metres of contaminated water from the Kate Valley landfill has been "quietly" trucked out of the North Canterbury site for disposal in Christchurch over the past three months.

The equivalent of about five Jellie Park swimming pools' worth of tainted water about 11,000cu m triggered monitoring equipment at the landfill in early August, four days after torrential rain and flooding.

Canterbury Waste Services (CWS), which operates the landfill, says no chemicals or heavy metals have leaked from the site in water that has been in contact with rubbish.

Run-off from torrential rain on July 31 overflowed a bund at the top end of the catchment and flowed into a large stormwater pond.

From there, the water was pumped into a secondary drainage system.

On August 4, the water triggered a monitor showing its conductivity levels were higher than normal indicating more ions (atoms or molecules with an electrical charge) than usual in the water.

CWS's Kate Valley landfill manager Martin Pinkham said it might never be known what contaminated the water.

Christchurch City Council tests showed the levels of routinely tested chemicals ammonia, cadmium, chromium, copper, lead, nickel and zinc in the water were not unusual, he said.

"It could have been from material out of the ground," he said.

"And there's a big stand of beech trees to the north of that pool. We noticed it (the water) was really dark, coming out of the ground."

The incident was the first "trigger event" since the site opened in June 2005.

It was reported to Environment Canterbury (ECan) 10 days later, but the Hurunui District Council (HDC) found out about it only in mid-September, a month later.

The HDC environmental services committee discussed the incident last week and wanted answers from ECan and CWS.

Hurunui Mayor Garry Jackson said the council should have been informed as a courtesy.

"We have a wider perspective, advocating and representing the local community," Jackson said.

"If there were any lapses, we should have been told.

"In our view, any leachate is serious. In that regard, it is deserving of further review ... we were concerned enough to say there were more questions that needed to be asked."

The public had a right to know what happened at Kate Valley, he said.

CWS chief executive Gareth James said the company had followed the correct procedure in dealing with the leachate and in informing ECan and not the district council.

"There's no need for them to know about it at all. Somebody is absolutely trying to make a deal out of this. There's a bit of a track record on this.

"I would be annoyed, in fact would probably have to take action, if somebody is suggesting there was leaching from the site."

If there had been a more serious incident, involving a breach of consents, "we would have been out there telling people", James said.

Jackson said "some time in the middle of September" there was discussion from councillors wondering if the Kate Valley landfill was affected by the July 31 to August 1 flooding.

"We called for some update. One of the triggers for that was neighbourhood gossip that they had a leachate issue because of a build-up from the floods and were trucking it off site."

Until recently, two trucks were making up to three trips a day taking the tainted water from Kate Valley to the Bromley sewage treatment plant. One truck is still on the job.

The total cost of moving the contaminated water is believed to be about $220,000.

James said 232mm of rain in six hours, a one-in-500-year event, and the consequent run-off had been hard to manage during the July 31 event.

"We couldn't keep up with what was coming in. That's why we had to store it and get rid of it quietly over a few months.

"When we are in that situation we know we have to monitor what is happening. There's an increasing risk of water coming into contact with the rubbish. It gets to the point where we say the risk is such, it could be possible this water has touched waste and because of that we'll treat it as leachate rather than stormwater."

Asked about the contaminants in the water, James said: "It's very hard to detect at the levels we are talking about. Certainly we never had any leachate leave the site. We err on the side of caution."

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