Originally published in The Hotel Engineer Vol 21 No. 4 Dec/Jan 16/17
Cooling towers have been in the news for all the wrong reasons. After a spate of falls incidents in NSW, Executive Director of SafeWork NSW, Peter Dunphy offered this advice: “We’re urging NSW businesses to review their safety systems so that no more workers are injured.”
There are also problems maintaining the biological safety of cooling towers, too. In November, an expert panel convened by NSW Health recommended strengthening the regulations around cooling tower maintenance in the wake of legionella outbreaks in the Sydney CBD in March and May that left 15 people ill.
High risk and high frequency
OHS risk is measured in terms of the likely seriousness of an injury and the frequency of the hazard. Cooling tower maintenance ticks both boxes, making it very high risk.
Falls from height are in the top three causes of work-related fatalities in Australia and a priority area for many workplace safety regulators.
Invariably located on rooftops, cooling towers are normally reached by climbing ladders and crossing roofs. The entire route from ground level to the area around cooling tower itself presents a risk every time it is accessed for routine checks.
Business owners are expected to have cooling towers inspected every month, cleaned every six months and certified annually – on top of spot checks by inspectors. Health regulations place expectations on workplace controllers both in terms of access and microbiological safety.
Under the NSW Public Health Regulation 2012, air-handling systems, hot-water systems, warm-water systems and water-cooling systems must be
- installed, operated and maintained according to Australian/New Zealand Standard: Air-handling and water systems of buildings —Microbial control, Parts 1 to 4 (AS/NZS 3666.1-4:2011)
- must have safe and easy access for the purpose of the cleaning, inspection and maintenance
- must be equipped with a disinfection procedure that is in operation at all times and that is designed to control microbial growth so that the level of Legionella in the system is not more than 10 colony-forming units per millilitre, and the heterotrophic plate count in the system is not more than 100,000 colony-forming units per millilitre. Where this is exceeded, remedial action must be taken as soon as practicable by a competent person or a person acting under the supervision of a competent person.
Cooling tower safety roadmap: Code of Practice for Safe Design of Structures
The roadmap for the safe access demanded by the Public Health Regulation starts with the Code of Practice for Safe Design of Structures. Its scope includes cooling towers and the Code aims to eliminate hazards with smart design before they are even created. It helpfully details the risk assessment and control process at each stage of the entire lifecycle:
- Conceptual and schematic design phase
- Design development phase
- Review of control measures.
The hierarchy of controls is central to the Code and, in the case of working at heights, the hierarchy is quite prescriptive and favours passive controls such as walkways and platform teamed with guardrails over harness-based controls that require a high level of user training.
While compliance with the Code is not mandatory in itself, it does provide a formal, industry-recognised benchmark for prosecutors establishing negligence under the WHS Act in the event of an incident.
Compliant cooling towers cost less to maintain
The good news is that compliance is bankable. Following the safe access rules by installing passive systems rather than portable ladders or PPE controls also leads to cost savings from both:
- The lower maintenance costs of walkways leading to platforms and reduced administrative costs
- Labour savings
The lifetime cost of passive systems like walkways leading to platforms and guardrails is lower than comparable anchor-based systems, especially when the ongoing administrative burden of inductions, training and recertification is considered.
For the contractors who must walk across rooftops and clamber around the cooling towers, walkways offer stark efficiency gains over harness-based systems. Time is saved at every stage of the job, from the moment they avoid lengthy inductions through to the ease of simply carrying tools to the plant rather than mapping out anchorage locations and juggling tools with ropes.
Added labour savings arise because walkways do not demand special rope access training of hygienists simply to traverse the roof or the doubling up of personnel on standby for rescue.
The sleeping giants have woken
Both the OHS and health regulators have cooling tower maintenance high on their agendas. Both have responded to a spate of problems for the safety of the people who use and maintain buildings. It’s no coincidence.
Equipment that cannot be safely serviced is more likely to fail and, in the case of cooling towers, with potentially lethal consequences.
Ultimately, though, it falls to HVAC manufacturers, architects, building owners, workplace owners and HVAC contractors to make safety a reality. The good news is that getting it right is a step-by-step process that will result in cooling tower maintenance that is safer, more effective, less costly and truly manageable for everyone involved.