Which of the following precautions must be taken before attempting to maintain or repair a surface aerator?

Before attempting to maintain or repair a surface aerator, shutting down the aerator is a critical precaution that ensures the safety of the personnel involved in the maintenance process. When the aerator is operational, it poses several hazards, including the risk of moving parts, electrical components being live, and potential exposure to hazardous gases or chemicals in the aeration basin. By shutting down the equipment, you effectively eliminate these risks, allowing for safer access to the machine and reducing the likelihood of accidents.

While notifying staff, wearing safety goggles, and checking chemical levels are important safety practices in wastewater management, they are secondary steps that should follow the initial action of shutting down the aerator. Notification ensures that others are aware of the maintenance activity, goggles provide eye protection from potential splashes or debris, and checking chemical levels is essential for overall safety and system integrity, but none of these actions can replace the necessity of first ensuring that the machinery is not in operation. Prioritizing the shutdown of the aerator is paramount for safeguarding both the technician and the wastewater treatment process.