Legionnaires’ Disease is a severe (and sometimes fatal) form of Pneumonia. Caused by Legionella bacteria that is found in air handling and air conditioning systems or hot water systems, Legionnaires’ Disease is preventable if the correct measures are taken.
This guide broadly discusses the arrangements associated with the control of Legionnaires’ Disease, including cooling towers, risk management plans, the control of bacteria in water systems, Legionnaires’ Disease notification, and working with soils, compost and potting mix.
What is the Risk Management Plan?
A Risk Management Plan should be developed and implemented to address the risks associated with:
- stagnant water, including lack of circulation in cooling tower system;
- nutrient growth, including biofilm, algae and protozoa;
- water temperature within the range that will support the rapid growth of microorganisms;
- the exposure of the water system to direct sunlight;
- poor water quality, including the presence of solids, Legionella, and high level of micro-organisms;
- deficiencies in the cooling tower system, including in design, condition and maintenance;
- the location and access to a cooling tower system, including the potential environmental contamination of the system and the potential for the exposure of people to aerosols of the system.
Effective action should be implemented for any identified risk, as listed above.
Installing Cooling Towers
Measures should be in place to ensure that cooling towers are:
- designed, installed and commissioned in accordance with Australian Standard AS 3666.1; and
- operated and maintained in accordance with Australian Standard AS 3666.2.
Cooling tower systems, water-cooling systems, and warm-water systems must be registered with the authorities, as required by legislation in each jurisdiction.
The Cooling Tower Risk Management Plan should also be reviewed and, if necessary, updated:
- at least once a year;
- if Legionella is detected;
- if directed by the authority; or
- if there is a significant change in any of the environmental conditions under which the system operates or in the operation of the system
Full records should be kept of all repair, maintenance and testing work carried out on the cooling tower system. Records should be kept for at least 7 years.
An approved auditor should audit the risk management plan at least once a year. Effective corrective action must be implemented for any deficiencies identified in the audit.
All plans, maintenance manuals and other documentation related to the cooling water system must be kept in a readily accessible place and made available for inspection on request by an officer from the authority.
Control the Bacteria in Water Systems
Measures should be put in place for the control of microbial growth in water systems. This should deal with systems, including their associated equipment and fitting, as follows:
- air-handling systems;
- evaporative cooling systems;
- hot-water systems;
- humidifying systems;
- warm-water systems;
- water-cooling systems.
The following are measures aimed at the prevention of Legionnaires’ Disease caused by the presence of Legionella bacteria in water systems:
- systems should be designed and installed strictly in accordance with the arrangements of legislation and the relevant Codes of Practice;
- where required, approval from the appropriate authorities should be obtained, prior to construction;
- cooling towers should be inspected, cleaned and maintained at least once a month; this must be carried out in accordance with a controlled schedule and full records must be kept;
- water systems and particularly cooling towers must be disinfected with an oxidising biocide at a frequency as recommended by the manufacturer;
- where required, an automatic biocide dosing device must be fitted to the cooling water system and measures must be in place to ensure it operates effectively at all times while the system is in operation;
- where required, drift eliminators must be fitted to cooling tower systems; and
- sampling for Legionella bacteria must be conducted routinely by qualified and trained personnel and corrective action must be taken if the concentration of Legionella is considered to present an unacceptable risk to the health of personnel.
Working with Soils, Compost and Potting Mix
To prevent Legionella infection, personnel who are required to work with potting mix, compost, soil, peat, and mulch should consider adopting the following precautions:
- open potting mix bags with care to avoid inhaling airborne potting mix;
- moisten the contents of the bag on opening – make a small opening and insert a garden hose to dampen the potting mix;
- wear gloves to avoid transferring potting mix from hand to mouth; and
- always wash hands after handling potting mix, even if gloves have been worn.
What if we find Legionnaires Disease?
Where required by legislation, any instance of identified Legionnaires’ Disease must be immediately reported to the appropriate authority.
In the event of a Legionnaires’ Disease outbreak, managers should also ensure full cooperation with authorised officers from the authority investigating the occurrence.
General advice warning
The information on this site is of a general nature only. It does not take your specific needs or circumstances into consideration. You should look at your own situation and requirements before making any decisions.
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