01 September 2015

Tom Clarke

Engineering Insight: Explosive Mix

  • Demolition machines lifting the collapsed building to expose the engine room. Photo: Bob Nelligan.
  • Aerial view of the fire scene. A burnt out fire engine is in the centre foreground. Photo: Bob Nelligan.
  • Rack of refrigeration compressors where the leak occurred. Photo: Bob Nelligan.
  • Compressor rack removed for examination. Photo: Bob Nelligan.

A highly flammable refrigerant, a leaking joint in a gas pipeline and a primary school gala – the 2008 Icepack coolstore fire was so dangerous it led to legislative change. What lessons have been learned from this?

Two reports into the fatal Icepak Coolstore fire near Hamilton in 2008 have resulted in changes in the way the Fire Service operates during emergency callouts and in the way large refrigeration plants are managed and operated. It has also impacted on how forensic engineers conduct their responsibilities in such events.

While it is unlikely these changes will reduce the high number of fires that occur in coolstores, they should reduce the risks of a repeat of the Icepak blaze, which killed one fireman and injured seven others.

Fire and Mechanical engineer, Bob Nelligan, of consulting engineering firm, R.J. Nelligan & Associates Ltd, says coolstores are one of the most common types of commercial buildings to be damaged by fire with about one occurring every month.

The fire scene

The Icepak drama began on 5 April 2008, triggering an automatic fire alarm at the plant at Tamahere, which summoned the Hamilton Fire Service. The Icepak Coolstore, which contained large quantities of dairy-based products, is just off State Highway 1 between Hamilton and Cambridge, 150 metres from a rural primary school and a function centre.

When the two fire trucks and eight crew arrived, there was no sign of fire and an automatic gas detector at the complex had not been triggered. Nor were there signs warning them (or anyone else) that the complex was using a refrigerant called Hychill Minus 50, a blend of propane and ethane. It is a highly flammable hydrocarbon-based refrigerant commonly known as Liquid Petroleum Gas (LPG).

Mr Nelligan says LPG has a boiling point that is ideal for refrigeration use, and doesn’t affect the ozone layer or global warming. “It’s a great refrigerant and its properties had been well understood for years, except that it is incredibly explosive.”

A Fire Service report found the crews looked for but couldn’t locate an alarm indicator panel. They had begun a search of the exterior of the buildings when they noticed vapour escaping from a plant room. With some difficulty they were able to access the building and found a leaking joint in a gas pipeline. Just as they were about to tighten the joint there was an explosion that created a fireball and blew out sections of the building, which was totally destroyed in the inferno that followed.

Seven firefighters caught in the blast were badly injured – one later dying as a result of his injuries; the eighth suffered lesser injuries. A number of possible ignition causes have been identified, with the Fire Service report suggesting there may have been an electrical fault in an unprotected switchboard.

The blaze spread quickly. Within minutes, it was beyond control, engulfing almost the entire complex.

Fortuitously, the nearby Tamahere School was hosting a gala. Because of its proximity to Waikato Hospital, the parents of many of the children attending were trained medical staff, including a St John paramedic, several nurses, an anaesthetist and a specialist intensive care doctor, who were on the scene within minutes to provide medical assistance. They were able to rescue two fire fighters trapped in the wreckage of the building and cool their burns with water from the fire trucks’ tanks until help arrived.

Mr Nelligan says had it not been for the presence of the medical specialists, the number of deaths could have been higher.

Dealing with the fallout

After the fire, a Department of Labour report revealed a long list of shortcomings in the coolstore’s operation. It noted the installation did not meet safety or legal requirements, the refrigeration engineer involved did not have the knowledge or experience to construct and run the plant safely, and there were no signs on the property to warn that an LPG-type refrigerant was being used.

It recommended changes to the way the Fire Service operates to reduce risks to front-line staff, and that legal action be taken against the companies and directors involved.

Mr Nelligan says the use of LPG on the site was not illegal, although there is a widely held misconception it was the wrong refrigerant to be using. In his view, two major lessons were learned from the tragedy.

One is that when refrigerants such as Hychill are introduced, there need to be stringent conditions put in place along with a high level of involvement with the Fire Service, as it is the organisation that will be involved if something goes wrong.

The second is the importance of co-ordinated control at the fire scene, which is likely to involve a broader range of interests than emergency services alone. In the case of the Icepak fire, it was unclear who was in charge; furthermore, Mr Nelligan says there was open animosity between the Fire Service, the Police and the Department of Labour at times. Altogether, there were about 40 people involved, all representing interested parties concerned about recovering their financial losses, which amounted to tens of millions of dollars.

“When you have a serious incident like this, an enormous number of people descend on the scene in addition to emergency services,” Mr Nelligan says. “The insurance industry relies heavily on investigators reporting on the cause and origin of such incidents and the moment something like this occurs, a whole lot of people – generally ex-Fire or ex-Police – arrive with the need to secure the scene and establish what happened.

“Forensic engineers like me generally work under the radar and behind the scenes, but the insurance industry and the legal industry rely very heavily on us to be able to do our work.”

He says when the Department of Labour took control of the site, it re-alised there were a number of specialist engineers on the scene who could help, but needed full access to the site. A week after the fire, it was eventually agreed one “Cause and Origin” specialist would act for everyone involved and co-ordinate the removal and classification of wreckage from the site.

Mr Nelligan says the incident was also a wake-up call for the insurance industry, which had relied on the Fire Service to protect their assets. “There is a recognition amongst those working in the fire industry that the Fire Service now won’t enter a building constructed using expanded foam polystyrene – unless there is a risk of someone being inside – until it’s absolutely clear there’s no risk to the crew.

“The Fire Service learnt a lesson at Icepak and won’t go charging in to try and save a building – they’ll stand back and watch it burn – and who can blame them? They’re quite rightly saying if you want to protect your assets, put in fire detection and sprinkler systems, and don’t expect us to do it for you.”

New law

Legislative changes following the fire now require better identification of on-site hazards. Any new installation using a hazardous substance involves the Hazardous engineers to review how incidents will be handled.

Mr Nelligan is a believer in the need for regulation because he believes allowing industries and companies to self-regulate doesn’t work.

“At the time of the Icepak fire, plants had a requirement to self-regulate without any real enforcement clout,” he says. “This incident made it clear that if you allow people to self-regulate, they will do the absolute minimum they have to do.”

Advice for engineers

Following the fire, the Institution of Professional Engineers New Zealand (IPENZ) initiated a review of the engineering design of cold storage facilities with particular emphasis on refrigeration fluids, insulation techniques, sprinkler technology and structures. The Institution convened a group of engineers and others with expertise in these disciplines and worked in collaboration with the Fire Service to produce an IPENZ Practice Note on coolstore design.

More awareness of HAZCOM needed

Fire engineer, Carol Caldwell, who has extensive international experience, believes New Zealand engineers need to be more aware of hazardous materials issues. Ms Caldwell says the fire engineering community tends to treat the subject as the responsibility of the Hazardous Substances and New Organisms Act, but they need to step up and take more responsibility. She also believes individual fire brigades need to be more proactive in meeting their legislative responsibilities to be aware of the potential hazards that exist in their response areas.

“It works both ways,” she says. “If somebody is using hazardous materials, they also have a legislative responsibility to inform people like the Fire Service – they can’t sit back and wait for the Fire Service to come to them.”