Tonnes of asbestos from Christchurch are being trucked through North Canterbury to the Kate Valley Landfill. What risk is this bringing to North Canterbury? KIM NEWTH travelled with a load of asbestos to find out. 

Along the ridge from the Kate Valley landfill is a recreational walking area that is very popular with local families like ours. Called the Tiromoana Bush Walkway, the land through which this walkway passes was actually set aside by Transwaste for public use when the landfill was first established. A major conservation and bush-restoration programme is being carried out there.

Yet the recent news that 5000 tonnes of toxic asbestos from old sewerage pipes (to add to the growing pile from other demolition sites across Christchurch) was to be dumped at the adjacent landfill took the edge off our enthusiasm for this particular spot.

This 5000-tonne payload was originally going to be disposed of at the Burwood Resource Recovery Park, but opposition from concerned Parklands and Waimari Beach residents in May saw it diverted out to Kate Valley. It was good news for the city, but it left me wondering the downsides to this decision for those of us to the north.

While I'd heard assurances about safety, I had only a limited understanding of how asbestos is actually being removed, transported and disposed of and that concerned me.

Just how robust is the whole asbestos disposal process? How do they get it from demolition site to dump truck?

I also wondered about the dump trucks themselves and how well set up they are to ensure the asbestos is safely sealed away. And, above all, what happens at the tip face to prevent potentially harmful asbestos fibres getting airborne?

Canterbury Waste Services general manager Martin Pinkham agreed to let me ride with a dump truck out to Kate Valley so I could see for myself how asbestos gets to the landfill. The journey began in the heart of the city, Cathedral Square, where the Grant Thornton building is just starting to be demolished.

Inside the red zone, Cera debris and waste manager Luke Austin says those most at risk from asbestos are the demolition workers themselves.

"That is why there is such a big emphasis on keeping them safe and why we have so many protocols in place about its removal." Only contractors certified by the Department of Labour can legally carry out asbestos removal, in accordance with set guidelines.

The 1970s Grant Thornton building is a 12-storey reinforced concrete building with an additional rooftop lift machine room - and it also happens to be one of the most dangerous buildings still standing in the central city.

It has suffered considerable earthquake damage and the engineering advice is a strong aftershock - or the demolition process itself - could cause "a global collapse". So I wear a hard hat.

A team of six from Bricon Asbestos Removal Ltd have been working at the top of this building to remove a membrane containing asbestos that was originally applied for waterproofing.

The asbestos also acts as a fire retardant.

While at work, the team remains harnessed to the main hook of a crane via safety lines, while "a dog man" rigger keeps a watchful eye and guides the crane driver from within "a man cage".

This cage is where they will all run to in the event of a major aftershock.

Everyone wears disposable protective gear - masks, overalls, gloves and boots.

"The asbestos membrane is stuck down with tar," says Bricon operations manager Tania Manderson.

 

"What we've been doing is hammering and chiselling away at it and then bagging it up."

In fact, double-bagging it, each bag being 200 microns thick. Manderson doesn't believe in taking any chances.

There are many types of asbestos - here it's mostly chrysotile white - but to Manderson "asbestos is asbestos" and as far as she's concerned it's all "friable". That means liable to release asbestos fibres into the air if pierced or broken up and so dangerous to health.

Breathe in too many asbestos fibres and asbestosis can develop, although it may take 20 years or more for symptoms to show.

"Asbestos doesn't kill you straight away, but I'm quite satisfied that in 20 or 30 years I won't be diagnosed with asbestos disease. We have taken all the right precautions," she says.

They spray their overalls with water while up on the building, then when they finish work, rip them off and bag them up. Once they're back at ground level, they remove masks, gloves and gumboots and bag them, too.

So far they've removed four tonnes of asbestos material from the top of this building. It ends up in a bin, lined with thick plastic (250 microns), which is then sealed at the top and covered with a tarpaulin.

With the asbestos under wraps for its journey to Kate Valley, it's hard to see how any fibres could escape the double-bagging and bin- liner seal.

Pinkham says: "The Department of Labour are all over this. They did a review last year and were comfortable with what was happening, apart from saying the thickness of the plastic bin liners should be increased - that has now happened. In the end, it's the individual operator that's licensed, and it's their livelihood at stake. If they do something wrong, then they will lose their licence and they haven't got a job any more."

There is the bigger question of how to handle any remaining asbestos that may be inside the building once demolition is fully underway.

It is not thought any will be found, but site supervisor Wayne Rowley, of Mackay Leighs Demolition, says they need to be prepared just in case some is still hidden in ducting.

A plan is in place so that if the crane operator comes across any suspected asbestos material, it will first be sprayed with water - the cranes are equipped with spray units - placed in "a designated location", sprayed down again and covered with plastic. A five-metre perimeter will then be put in place.

We have to leave the red zone before the dump truck arrives to collect the asbestos, so Pinkham gives me a lift to the end of Marshlands Road to connect with the Kate Valley-bound container waste truck.

Container Waste is one of only a few independent operators taking waste to the landfill daily.

Driver Tony Tavendale says he makes two trips a day of "special waste" that covers not just asbestos but other waste like treated sludge or rotten food.

He is amused by his friends' horrified reaction when he tells them he regularly takes asbestos to Kate Valley. They think it's like a death sentence. In truth, he's much more concerned about the risks posed by the crazy driving he sometimes sees on the state highway.

With 42 tonnes on the road, our trip by truck is bouncy and slow, especially on the steep road up to the landfill, but we survive the crazy drivers and the asbestos stays covered the whole way.

To offload the asbestos, a permit is required and Tavendale also has to fill out a special waste manifest sheet detailing his load. It is impossible to get into the landfill without this permit.

At the landfill we are met by landfill technician Paul Ryder, who tells me that, as of May, 800 tonnes of asbestos material have been disposed of at Kate Valley, mostly from the city's CBD.

It is all buried deep in the landfill, still wrapped in plastic.

Ryder drives me to the final resting place of our asbestos load: a four-metre-deep hole that, in turn, is 4m above a triple lining (clay- impregnated material sandwiched between plastic and topped with an additional layer of gravel) to prevent any contamination of the surrounding soil.

The GPS position is recorded so it's not accidentally dug up again. While still bagged and wrapped in the bin liner, the asbestos is tipped into the hole. A load of treated sludge goes on top and then the whole lot is covered with soil.

No asbestos fibres go flying around. The toxic asbestos from the roof of the Grant Thornton building is now safely resting in double plastic bags wrapped in a bin liner topped with sludge. It's a strange, but safe, conclusion to my journey.

I'd be happy now to take the kids up to the Tiromoana Bush Walkway again some time soon.

 

ASBESTOS

* Asbestos is the fibrous form of mineral silicates belonging to the serpentine and amphibole groups of minerals - loose fibre broken down from the mined rocks.

* Asbestos means: Amosite, chrysotile, crocidolite, fibrous actinolite, fibrous anthophyllite, or fibrous tremolite.

* The only known types of asbestos used in New Zealand are: Chrysotile (white), Amosite (brown), crocidolite (blue).

* Asbestos fibre means a particle of asbestos that is not less than five micrometers in length, and is less than three micrometers in width, and has a length to width ratio of not less than 3:1

* The types of asbestos-containing materials, which may be encountered in a building or other structure and are of most concern from a health perspective include: sprayed-on fireproofing/ soundproofing/thermal insulation, acoustic plaster soundproofing, insulation, decorative coatings such as textured ceilings, flooring such as some vinyls, lagging.

 

* Kim Newth is a North Canterbury writer.

- © Fairfax NZ News

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