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April 2017 MEDIA RELEASE: Legionella outbreak in Melbourne – How to help prevent future outbreaks

April 27th, 2017

April 27 2017

Summary: How to help prevent legionella outbreaks: One critical element is the correct cleaning of cooling towers.

MELBOURNE: The recent outbreak of Legionnaires’ disease in Melbourne CBD, where 5 cases were identified, highlights the importance of controlling Legionella bacteria in cooling towers.

It is very unlikely that the source of the outbreak will be confirmed, as all cooling towers in the suspect area were immediately disinfected to kill off any bacteria.

“The source of the outbreak cannot be the main focus. The onus is on the industry to look after cooling towers correctly to help prevent more outbreaks,” says Coolclean Managing Director, Darren Driscoll.

For the industry, it is a public safety issue – the emphasis should be on doing everything possible to protect the public from the outset.

At present, water treatment is the main focus in relation to managing Legionella; how the cooling tower performs mechanically tends to be overlooked. Insufficient cooling tower mechanical maintenance can lead to higher bacteria levels (Legionella) and increased possibility of outbreaks. “There should be two lines of defence against Legionella: the first line of defence is water treatment; the second line of defence should be mechanical,” says Mr Driscoll.

Mechanical components include fill pack, water distribution system, fan drives, air intake louvres and the most important, drift eliminators.

“Drift eliminators are the most critical component in a cooling tower relating to health and safety. If the water treatment failed on a site, which it did, the industry should ensure that drift eliminators are working properly to also help protect the public.”

If water treatment fails, drift eliminators are the last line of defence against Legionella, because they prevent bacteria escaping the cooling tower via the force of the fan. Each droplet of ‘drift’ has the potential to hold many Legionella bacteria and can be inhaled by persons within a 2 km radius.

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Are your drift eliminators being maintained? If so, photographic evidence should be provided by your service provider. 

Drift reduction is a major benefit and safeguard against Legionella

Current Victorian government regulations do not include a procedure for ‘cleaning’ a cooling tower – therefore there is no legal obligation to remove, inspect or clean drift eliminators. Darren Driscoll says: “In our experience within Victoria, if drift eliminators are enclosed behind an access hatch or are difficult to access, 7 times out of 10, they are not maintained regularly, if at all.”

It is also important to correctly maintain other mechanical components such as fill pack, the water distribution system, air intake louvres and fan drives, as all these components have an impact on drift loss and on the water treatment program.

Coolclean’s approach to cooling tower cleaning, inspection and repair is thorough. “We understand the importance of this and conduct comprehensive cleans on our clients’ cooling towers,” says Mr Driscoll. “Over the last twenty-eight years we’ve held our focus our safety and performance – while lately we are seeing maintenance standards dropping in the wider industry.”

“Twenty-eight years ago, no one specialised in cooling tower cleaning and maintenance. Most cooling tower basins were simply flushed out by site personnel when they were absolutely filthy – we named them ‘the basin flushers’. We believe that 28 years later, the ‘basin flushers’ are making a strong comeback to reduce costs. Now, some sites are even going back to using untrained personnel to carry out cooling tower cleaning work.”

“We challenge the industry to show that they are inspecting and cleaning cooling towers correctly, by taking photos of the access hatches open, and the drift eliminators out while they are removed for cleaning. This is what Coolclean does as standard practice.”

Response to legionella outbreaks

“The industry is always dealing in the past in response to legionella outbreaks,” Mr Driscoll says. “The five people would have contracted Legionella 5-7 days before they presented to a doctor/hospital. Finding the offending cooling tower is a near impossible task as so much would have changed in the cooling tower after 5-7 days.”

Immediately on discovering the outbreak, the Health Department investigates and narrows the search to a suspect area. All cooling towers in that area are then disinfected.

This approach results in all the cooling towers being rendered safe in the area, giving the Health Department time to investigate the outbreak without placing further people at risk.

Prevention – the best means of Legionella control

Combining water treatment together with correct mechanical maintenance provides the best means of Legionella prevention.

Solution: Destroy the bacteria with water treatment, and control the spread of Legionella with well-maintained drift eliminators among other cooling tower components.

Mr Driscoll adds: “It isn’t costly to have a program of correct cleaning (incorporating mechanical inspection) at regular intervals. In addition to reducing Legionella risk, the advantages are that the cooling tower performs better and more efficiently, reducing energy costs.”

To date, 26 cases of Legionnaires’ disease have been notified from across Victoria in 2017, compared to 21 cases for the same period last year.

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