Inspection and sanitation of water tanks are no joke. The need to sandblast the interior of a water tank is a rare occurrence (once in 20 years), but if a city has multiple water tanks, the need for maintenance becomes once every two years.
It’s a six-week process, which begins with sandblasting interior surfaces to remove all the rust in the tank. The top of the tank is most susceptible to rust, as it gets exposed to water and air alternately on a constant basis.
Crews start the process by blasting the old paint from the tank’s floor and bottom rings. Using a lift system, they work their way up the tank, traveling as much as 50 feet vertically.
Armed With Blasters
Tools and equipment for sandblasting on hand, crews climb through a narrow opening in the tank. As blasting commences, the dust and debris fill the narrow area, reducing visibility almost completely. Blasting hoods that are worn by employees source clean air from outside the tank, while ventilation equipment attached to roof hatches circulate air continuously.
Once the sandblasting process is done, the crew starts coating the exposed interior metal with paint. A zinc coating is applied first, paying attention to seams and other connections. Second and third coatings of epoxy are applied. Protocols dictate a significant depth of coat is applied.
After seven days, the surface is primed for flushing the tank with water to wash out all residual sand and debris. The tank is disinfected using chlorine, followed by analysis of water samples for sanitation purposes. After that, the tank is prepped for re-activation.
The job is certainly tough, but maintenance of water tanks are essential to keep water supply lines safe and potable. The next time you drink some clear tap water, thank the stars that water tank cleanup crews aren’t claustrophobic.