Rena's Waikato Dumping Ground14-Oct-2011
Rena's Waikato Dumping Ground
Matt Bowen and Jonathan Carson
October 14, 2011
SPECIAL TREATMENT: The Hampton Downs landfill which is equipped to take toxic waste and has the capacity to deal with the quantity of oil from the Rena.
The sticky black, toxic oil spilling from the stricken container ship Rena is destined to be dumped in a Waikato tip, with the first consignment due today.
The oil-drenched sand being scooped from Bay of Plenty beaches will be trucked about 150 kilometres to the Hampton Downs landfill, about 50km north of Hamilton.
Oil cleanup crews have been scrapping the coastline as tonnes of leaked oil from the Rena wash ashore this week.
Most of the sandy waste will be transported in lined, leak-proof truck-and-trailer units.
Nick Smith, in his "worst" week as environment minister, said the dumping ground was the most suitable location – and giving the muck back to its owners was "impractical".
"The Hampton Downs landfill is the closest landfill capable of safely taking these types of waste," he said.
"It has sealed liners and the capacity. It's [the Rena oil] very similar in toxicity to the heavy oil used for bitumen and the most important thing is [that] we get it off the beach and sensitive environments."
Maritime New Zealand and Tauranga City Council contracted EnviroWaste Services for the task. EnviroWaste spokesman Carl King expected the loads to keep coming for at least a month.
"Even if we get 10,000 tonnes per week, it's not a problem."
The landfill is Waikato's biggest, built on 386 hectares. It receives about 600,000 tonnes of waste a year, making the estimated 10,000 tonnes of sandy waste to be collected in the Bay of Plenty a small portion of its intake.
The load would be taken to a special landfill, where it would have to be immediately covered by soil or waste.
While the large amount of material wouldn't make a lot of difference to their daily operations, the waste would need to be buried right away because it was volatile material with a strong odour, Mr King said. "We don't want our staff to come into contact with it. It'll be basically tipped off into a hole then buried.
"There are also precautionary measures around personal protective equipment required."
The sand would be placed in a cell with three protective layers – a compacted clay liner, a geotextile liner, and a thick high-density polyethylene liner.
"It's a special engineered landfill that can deal with this type of waste."
The cell could take two million tonnes of waste and would be sealed in about a year.
"When we are finished and up to the right height, we seal it off with 2.3 metres of clay and topsoil."
Mr King said that the site was extensively monitored, with water and soil tested regularly to ensure it did not become contaminated.
Hamilton Land Care Research soil microbiologist Jackie Aislabie said the oil was a heavy, toxic substance that could take up to 100 years to break down.
"It could be there for years and years and years. We could be talking 50 to 100 plus. Especially if it's low in oxygen, [with] not much water, very little nutrients. This isn't an ideal environment for microbial breakdown."
However, she was confident that Hampton Downs could deal with the oil. "We know that this landfill has dealt with this kind of material before, they have the expertise."
Maritime New Zealand said 95 tonnes of solid waste, including oily sand, and six tonnes of liquid waste had been collected so far.
- Waikato Times