Coolclean managing director, Darren Driscoll, explains why industry should stop trying to identify the source of the five confirmed cases of Legionnaires' disease that were recently discovered in the Melbourne CBD.
Focusing on the source of the recent outbreak of Legionnaires’ disease in the Melbourne CBD shouldn't be the main focus for industry.
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 onus is on industry to look after cooling towers correctly to help prevent future outbreaks, that should be the focus.
Because it is a safety issue the emphasis should be on doing everything possible to protect the public. At present, water treatment is the main focus in relation to managing Legionella; how the cooling tower performs mechanically tends to be overlooked.
Insufficient mechanical maintenance can lead to higher bacteria levels (Legionella) and the increased possibility of outbreaks.
There should be two lines of defence against Legionella: the first line of defence is water treatment while the second line of defence should be mechanical.
Components such as the fill pack, water distribution system, fan drives, air intake louvres and most importantly, drift eliminators, require maintenance.
Drift eliminators are the most critical component in a cooling tower relating to health and safety. If water treatment fails on a site, which is what happened, then industry should ensure that drift eliminators are working properly to 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.
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.
In our experience within Victoria, if drift eliminators are enclosed behind an access hatch or are difficult to access, seven 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. While Coolclean has been committed to safety and performance over the past 28 years, but when it comes to the wider industry we've noticed a drop in maintenance standards.
When we began 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 in a bid 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.
Industry is often dealing with the past when responding to an incident. In the Melbourne case all 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 during that period of time.
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.
Combining water treatment together with correct mechanical maintenance provides the best means of Legionella prevention.
The best solution is to destroy the bacteria with water treatment, and control the spread of Legionella with well-maintained drift eliminators among other cooling tower components.