Do it once, do it right
Date: 13 March 2015
The Causeway Alliance is currently raising and widening the Northwestern Motorway in Auckland as part of the Western Ring Route road of national significance – but an unexpected find last year brought one work site to a halt.
During routine pre-construction work for the 4.8 km section of the NZ Transport Agency’s State Highway 16 upgrade, the Causeway Alliance in Auckland dug test pits along the Rosebank Domain embankment. They would be constructing additional westbound lanes, and were to excavate in preparation for stormwater and drainage reticulation, plus carry out landscaping, including pits for nine native trees and a large sign.
Previous contamination investigations had focused on hydrocarbons and heavy metal contaminants. There was no reason to expect asbestos contamination, and initial investigations revealed none. It was a surprise, therefore, when a team member uncovered broken asbestos cement fragments and other construction waste as excavation commenced in May 2014. All work was halted immediately.
The alliance budget had included some allowance for unexpected contamination, but Mark Evans, SH16 Causeway Alliance project manager, knew immediately it would not be enough to cope with this discovery. Initial estimates for specialist contractors to remove the asbestos safely were nearly $1.5 million, and a decision was made to manage the process internally.
SITE-SPECIFIC REMOVAL PLAN
As safety, health and environment advisor for the project, Brigitte Dunbar was tasked with ensuring all legal and safety requirements were identified and met. “We needed to do it once and do it right,” she says. “We had to develop a process that met all legal requirements and would be approved by WorkSafe NZ, without delaying the project more than was absolutely necessary.”
Over the next three months, Brigitte developed a site-specific removal plan in consultation with the alliance’s operations team and the environmental and safety team, together with external parties including Auckland Council, WorkSafe NZ, the NZTA, land owners, haulage contractors and a contaminated land specialist. Work to clear the contaminated soil began in August and was completed by October.
Brigitte says they quickly learned that legislation seemed to have been written with the expectation that asbestos would be found in the building industry, rather than in soils or an earthworks project.
All waste containing asbestos must be sealed before it can be disposed of to an appropriately certified landfill, and no fibres can escape to the air. When asbestos is old it can become brittle, and the deadly lightweight fibres can escape if not handled correctly.
Although the type of asbestos found at this site was proven not to be airborne, all workers in the area needed to wear specialist personal protective equipment at all times.
MANAGING THE SITE
The challenge for the project was to manage a large volume of excavated material with small quantities of contaminant mixed in with it. Vehicle movement was carefully managed.
Empty trucks approached the scaffolding lining station, where a thick plastic lining was installed in the empty bins by hand, and secured in place with sandbags. The station was designed to allow the specially trained workers to easily access the bins.
With its cab and driver safely sealed inside, trucks next approached the excavator to receive their loads, and then proceeded slowly to a second scaffolding station to seal it – contaminated soil needs to be kept damp to ensure any friable asbestos particles cannot escape.
Trucks were finally checked for any external contamination, including tyre soiling, and washed down if necessary. All such water was captured in a lined bund for subsequent treatment and disposal.
Two decontamination units were created, and five air monitors were installed to ensure air quality – within the excavator itself, at the bin liner sealing station, immediately adjacent to and downwind of the excavation, and on the work boundary. Workers were decontaminated whenever they left the site. All plant remained inside the work area and was decontaminated once all work was completed.
Every aspect needed to be recorded, monitored and certified by a qualified certificate of competence officer to ensure all requirements within the Hazardous Substances and New Organisms Act 1996 and the Health and Safety in Employment Act 1992 were met.
It was a sign of their quality of research and procedures that WorkSafe NZ offered only minor suggestions and no improvement notices once the removal commenced – something Brigitte and the Causeway Alliance team are justifiably proud of.
NATIONAL DATABASE NEEDED
The asbestos cement pipes and tiles found amongst the other construction waste and excavation material on the causeway site had apparently come from a central city construction site in the early 1990s, in an area known amongst older contractors as ‘Asbestos Mountain’.
Following the discovery, the alliance found no information on where other such waste is buried, although it would have presumably been logged at the time with the appropriate authority.
Asbestos had been a popular material for insulation, brake linings and building materials, as well as for lining pipes, because it is resistant to heat, fire, and chemical or biological degradation. Asbestos products had been manufactured at the James Hardie factory in Penrose between the 1930s and 1970s, with waste dumped throughout the Auckland region by private contractors.
In the late 1990s, developers building houses on former farmland in Flat Bush, Manukau, encountered a similar problem. Officially, nobody seemed to know asbestos-contaminated waste had been dumped there, although in 1963, Paul Cavanagh QC had unsuccessfully sued the then-Manukau County Council for asbestos dumping in the area.
“The country really needs a national database of contaminated sites that is freely available to everyone,” says Brigitte Dunbar.
A GREY AREA
Alan Edge, president of the New Zealand Demolition and Asbestos Association (NZDAA), agrees record-keeping of asbestos dump sites and contaminated soils has not been all it could be, and neither has the management of asbestos within buildings.
“Since 2011, regulations have tightened considerably,” he says. “But as for who keeps a register of where asbestos is found – that’s very much a grey area.”
Alan Tresadern, acting chief engineer, infrastructure and environmental services, for Auckland Council, says, “Auckland property owners or others with an interest in a specific site can make an enquiry through the manager of regional environmental control at the council’s licensing and compliance services department, whose team can access legacy land use databases that may include information about asbestos in soils.”
If asbestos is suspected on a specific site, Auckland Council doesn’t usually charge to report on this – although they do charge for LIM and property file requests.
Neither does there seem to be national agreement about how long land use information should be kept, although 40 years seems to be acceptable to some official bodies, for a product that never breaks down.
“There are numerous legacy systems for land use consent-related data, and details for each are different,” explains Marcus Herrmann of Auckland Council. “Generally speaking, historic records relating to asbestos in soils would remain accessible with no time limit.” Which means the council can search records for contamination on a single specific site if they’re asked.
FORMALISING PROCEDURES
The NZDAA is lobbying hard for New Zealand to adopt similar legislation to Australia’s, where all buildings and infrastructure over a certain age are assumed to contain asbestos and are managed accordingly.
“Where possible, the presence of asbestos should be marked clearly on building plans,” they say. “These plans should be made available to employees, including tradespeople, and to outside contractors.”
The Health and Safety Reform Bill currently before Parliament is expected to formalise some procedures around asbestos management, when the report is returned in March.
- Corrie Cook NZ Construction News