Safety is a key concern in the design, operation and maintenance of all process plants. The failure of process plants has produced a number of disasters leading to large loss of life, including the Union Carbide plant at Bhopal and West Fertilizer plant at Waco. While study of large scale disasters produce headlines and industry-wide learnings, small plants and plants not processing hazardous goods may also contain considerable risk.
Process plants can affect safety for a diverse group of stakeholders. Technicians maintaining and operating the plant are at the forefront of risk, however the general public and downstream users can also be affected. Often hidden from view are the flow on effects to families, with emotional and financial hardship that may linger for more than a decade after the incident (OSHA 2015).
In the water industry, risks can manifest in many forms. Process plants in water treatment performs many and varied tasks, including operations on solids, liquids and gases. Many well known risks to operation and maintenance staff include:
• electrical hazard
• contact with hazardous chemicals
• rotating and moving equipment
• gaseous hazards
• microbial hazards
• confined spaces
• slips, trips and falls
• fall from heights
There are many methods for identification and assessment of risks. In the design of the process plant, these steps are often conducted using HAZOP and FMECA assessments. It is important that identification and assessment of risks is a continuous process, with consultation between management, operators, maintenance staff and designers to ensure that new and subsidiary risks are identified and controlled.
Figure 1 The risk management process (Safe Work Australia, 2017)
Some risks are obvious on their surface, although assuring safety with confidence often requires in depth knowledge of the design and failure modes of the plant. One such example, is contact with hazardous chemicals. A deep understanding of the system, including materials, joint construction, interlocks, isolation and valve operation is required to understand when a lack of containment of a hazardous chemical may occur. This knowledge on its own is not sufficient to assess the risk - an understanding of the properties of the chemical, including interactions with water, air and other chemicals is key.
Other risks are often unassuming, even if well publicised, leading to designers, operators and maintenance staff to take the risk for granted. Slips, trips and falls are often paid only lip service. Designers may often consider controlling moist and wet conditions the responsibility of front-line staff, while constructors and operators may not consider the slip resistance of surfaces until an accident occurs. Slips, trips and falls are often overlooked, however they were responsible for 386 deaths in Australia between 2003 and 2015 (Safe Work Australia, 2017).
Figure 2 Hierarchy of risk controls (Safe Work Australia, 2017)
Not all risk control measures are made equal. The control of risks is best understood in terms of the 'hierarchy of risk control'. Risk controls should first look to eliminate the hazard, with sole reliance on PPE as a last resort.
Consultation, open communication, regular review and an action-oriented approach are key to managing risk in your treatment plant. For guidance assessing and controlling hazards in your treatment plant, don't hesitate to call Viridis for assistance.
OSHA 2015, Adding Inequality to Injury: The Costs of Failing to Protect Workers on the Job, US Department of Labor, Washington D.C.
Safe Work Australia 2017, Slips, trips and falls, viewed 21 September 2018 <https://www.safeworkaustralia.gov.au/slips-trips-falls>
Safe Work Australia 2017, Identify, assess and control hazards, viewed 21 September 2018 <https://www.safeworkaustralia.gov.au/risk>