Managing Cooling Tower Risks in a Changing Environment

December 6, 2016

The potential risks to public health associated with cooling tower systems and Legionella are well publicised. The regulatory requirements for the management of cooling tower systems are different across the States and Territories and some are also currently under review. As such, it is important to understand both the regulatory requirements as well as what a best practice risk management framework is for these systems.

The Australian Standard AS/NZS 3666-2011 (Parts 1 to 4) defines requirements for the design, installation, commissioning, operation and maintenance of water systems of buildings for the purposes of microbial control. State and Territory regulations detail the administrative requirements around the management of Cooling Towers and these vary in approach and in the extent of prescribed activities. In the absence of more detailed statutory requirements, it is recommended that building owners and their managers should consider a Risk Management Plan (RMP) approach to better identify and manage operational risks, and help ensure the discharge of minimum general Duty of Care obligations.

Visual inspection of a cooling tower
Visual inspection of a cooling tower

Risk Management Plan Template

The Victorian Government Cooling Tower System Risk Management Plan template can be regarded as a Best Practice model within Australia – in terms of identifying the specific risks associated with the ownership and operation of a cooling tower system, and establishing an appropriate risk management and reporting regime. Key aspects of this RMP template include:

  • Site and Key Contact information
  • System description and arrangement information
  • Assessment of critical risks
  • Risk Assessment grading methodology
  • Water treatment operational regime nomination
  • RMP monitoring and review and management process
  • Communication and consultation process
  • Water Sampling, Testing and response flow charts
  • Summary of operational and improvement recommendations relating to the specific cooling tower system, and
  • Recommendations status summary table for tracking activities

Overview of Critical Risks

While an assessment of all potential risks should be undertaken, the following is a list of critical risks which should be considered:

Stagnant water: Areas of stagnant water should be minimised. This involves the removal or activation of dead legs, or installation of circulating pumps or other arrangements for idle systems.

Nutrient growth: Eliminate factors that stimulate microbial growth. These include exposure to sunlight, system corrosion, introduced contaminates, and elevated system water operating temperatures.

Poor water quality: Water quality should be managed through a structured treatment and testing program to deal with microbial growth, corrosion and contaminates.

Deficiencies in the cooling tower system: With potential changes to system operation and as system components age and wear, the design fitness for purpose should be reviewed. This should include an appraisal against the requirements of AS 3666, and an assessment of the current condition of key elements including cooling tower drift eliminators and fill, operational regimes and cleaning and maintenance arrangements.

Location and access: Risk mitigation can be assisted through recognising and or limiting potential exposure. Systems located in close proximity to large numbers of people or to potentially immunosuppressed people (e.g. near hospitals) require special attention. Additionally controlling access to the cooling tower system and its surrounds is also important.

Audit of RMP

Once an RMP is in place, it requires regular review to ensure any changes in circumstance are identified and addressed. Evidence based auditing should be used to assure that the risk management and maintenance regime remains appropriate and effective.

Monitor Regulatory Changes

It is strongly recommended that building owners and managers stay fully abreast of the current statutory requirements and prepare in advance for any changes in local obligations.

The Victorian Government Guide to Developing Risk Management Plans for Cooling Tower Systems can be downloaded from the Department of Health & Human Services website: health.vic.gov.au.

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