Dairy spill could devastate river life

Workers helping with the clean-up are dwarfed by the lake of lactose product that spewed from a holding tank. Picture / Amos Chapple

A rupture in a giant holding tank that led to about $1 million of dairy byproduct flooding rural land south of Hamilton yesterday could be devastating for aquatic life.

The accident contaminated the Mangaone Stream which feeds the Waikato River.

Water near the spill was a brown-white colour, but further downstream it turned pale yellow as it slowly diluted.

Yesterday it moved more slowly than expected and was not due to reach the Waikato River until early this morning.

The substance spilled was called Mother Liquor and is used as a stock feed. Essentially a combination of sugar and water, it is sticky and emits a putrid odour. It has a high concentration of chemicals and a high biological oxygen demand.

Aquatic life in the stream would be devastated, said Environment Waikato resource manager Chris McLay.

Farmers were alerted that water in the area was unsuitable for drinking or irrigation. But Mr McLay said consumption was not considered toxic to human health.

The accident happened at Civil Whey Distributors, which takes dairy industry waste from Fonterra's nearby Hautapu Dairy Factory.

More than 500,000 litres was estimated to have been lost, with a further 2.2 million litres contained on-site by large earth mounds.

"We've got a lake out there," said Civil Whey managing director David Civil. He and his staff spent all day trying to pump the excess liquid across farmland.

"It's a byproduct of lactose production, and it's pumped from the [Hautapu] factory to our site."

During spring, dairy production hit its peak and Civil Whey therefore received more byproduct than it could distribute. The holding tank stored excess product until the low season.

Although the plastic liners could not be visually checked during testing, their condition and quality was still the responsibility of the supplier, Mr Civil said.

He estimated the lost product was worth around $1 million. But he was not concerned about the financial loss his company would face, which could include fines imposed by the Environment Court.

"All we are worrying about at the moment is containment."

Hamilton City's water treatment station on the Waikato River was on standby to be shut down, said council spokesman Philip Burton.

But the slow-moving nature of the substance meant there was extra clean-up time and it was hoped water treatment would continue uninterrupted.

Mr McLay said Environment Waikato would do a thorough investigation.

The amount lost to the stream and river was equivalent to half an Olympic-sized swimming pool, he said.

Mr McLay said he was pleased with the company's serious response to the situation.

Punishment for a spill of this type attracts a maximum fine of $200,000 under the Resource Management Act, or up to three months' jail.

The big spill

* 500,000 litres of "Mother Liquor", a byproduct of the dairy product lactose, spilled into a stream that feeds into the Waikato River.

* That amount is equivalent to half an Olympic-sized swimming pool.

* Farmers use Mother Liquor as a stock feed.

* An extra 2.2 million litres of product formed a lake around the Civil Whey plant in Hautapu, near Cambridge.

* About $1 million of product was lost.

* The strong concentration of Mother Liquor quickly depletes water of oxygen, killing all aquatic life it comes into contact with.

* It is not toxic if consumed by humans.

* Under the RMA the maximum fine for this type of spill is $200,000 or three months' jail.