Wastewater plant raises a stink

23:03, Nov 26 2012

Foul smells from Palmerston North's wastewater treatment plant could undermine business for the Manawatu Racing Club and be a disaster for the city's image.

Already grappling with the breach of a discharge consent for harming river life downstream, and cleaning up a wetland pond that oozed black sludge into the Manawatu River this month, the city council now has a stink to address as well.

Club committee member Adrian Broad, who is also a city councillor, said the smell was particularly bad at a small race meeting, affecting about 1000 people, a couple of weeks ago.

But he was worried that if the smell from the Totara Rd plant happened during a large race meeting or important conference attended by thousands of visitors, it would reflect badly on the city.

"My concern is if that odour continues in a strong easterly, it blows straight into the grandstand, where we have conferences attended by people from out of town and major race meetings with thousands of people.

"From a public relations point of view, for the city, that could be particularly bad."


It would harm the club's business if it happened on a major cup or carnival day, Cr Broad said.

Complaints about the smell have prompted Horizons Regional Council to issue the city council with a formal warning for breaching the terms of a rule controlling the way it carries out the permitted activity.

City council waste and water services manager Rob Green said staff believed they had come up with a relatively low-cost solution. He will take a proposal to the council's finance and performance committee in two weeks' time, but was not prepared to go into details before councillors were briefed.

The reason offensive smells had wafted from the plant to the Awapuni racecourse and surrounding neighbourhood more than usual this year was not entirely understood.

"It seems to be related to peculiar weather, with hot, still days."

The smell was caused when natural gases in wastewater were released into the air. It was unavoidable that when the flushings from the city's toilets arrived in a concentrated burst at the wastewater plant, there was a bad smell.

The smell continued to be released through the plant, particularly through the sedimentation process, aeration ponds and lagoon.

Mr Green said none of the proposals being reported to a city council meeting on Wednesday was designed to address the odour problems. He had already completed the update on changes proposed to alleviate the adverse effect of the city's discharge on the river before smell became an issue.

The action plan involves experiments, further monitoring, and greater use of alum to reduce phosphorus in the discharge. It could cost the city up to an extra $1.127 million a year.

The most expensive part of the plan could be removal of sludge that has built up in the aerated ponds, at $700,000, although the cost could be avoided if a trial injecting cultured bacteria to break down the organic matter was successful.

Increasing the number of days and river flow levels when the discharge is treated to remove phosphorus could cost between $100,000 and $300,000 a year.

Manawatu Standard