Diving In: Underwater Work Saves Cities Money & Water
By Warren Tenney
It seems unlikely that divers would be in demand in the middle of the Sonoran Desert, but cities call on them regularly to help keep their water treatment plants operating reliably and efficiently. Don’t picture these professional divers in goggles with air tanks on their backs swimming among fish. These contractors operate more like construction crews who happen to work underwater.
Here are a few ways commercial divers help your city save water and money.
- Make equipment repairs and do maintenance while all or most of the treatment plant continues to operate.
- Avoid the cost of trenching and boring to reach pipes and valves buried deep underground.
- Complete inspections, cleanings and repairs in a multi-million gallon reservoir without draining it.
- Plug a small section of a pipe to create a dry and safe place for maintenance and construction crews to reroute a line or add a pump.
- Find and quickly plug leaks within a water delivery system. Stopping leaks saves water for all of us and helps to keep water utilities within the 10 percent maximum water loss allowed by the state of Arizona.
Professional divers are called for routine jobs at water and wastewater treatment plants and in cases of emergencies. Their work is heavily regulated. These divers are in sanitized dry suits that cover them seamlessly from face and head to toes. These suits protect the divers from pathogens that could be in untreated wastewater and protects drinking water from possible contamination from divers’ suits or exposed skin. For example, Arizona Commercial Diving Services (ACDS), Inc. has worked for all AMWUA member cities as a contractor or subcontractor. The company maintains separate sets of suits, tools and even trucks for jobs in raw water, wastewater and drinking water plants.
These commercial divers don’t use tanks at water treatment plants, but receive air to breathe through a tube located on the surface, known in the business as an “umbilical.” This provides the diver with an unlimited air supply. Federal rules require a four-person team to be on hand at treatment plant dives. There is a diving supervisor, a lead diver and a standby diver in case the lead diver gets into trouble. A “tender” watches over the air flow through the umbilical. The diver is in constant video and voice communication with the team.
These divers can work in a reservoir holding 20 million to 30 million gallons of water or squeeze into a 24-inch water pipe. (Divers pull themselves through the pipe using their hands and knees.) Work in a small space or “a confined space dive” requires a six-person team including a second “wet tender,” who is suited up and in the water at the point of entry.
Professional divers need to know more than how to dive. For example, ACDS divers sometimes send a remotely operated vehicle (ROV) into the water first to inspect the problem. Then divers work with plant employees to create a fix. Once under water, divers need to be experts with special underwater equipment and tools. These tools allow divers to weld, cut through steel, saw through and core concrete, seal a bulk head or use ultrasonic equipment to gauge the thickness of a steel gate or pipe and assess degradation of the infrastructure.
Water utilities often call in divers to quickly fix emergencies. For example, gates and valves control the processes and the flow of water through treatment plants as the water or wastewater gets cleaner at each step. Sometimes a shaft that operates a gate breaks and the gate is stuck open or closed. A professional diver can fix the gate, disassemble the gate, or plug the hole created by the open gate. At a wastewater plant, heavy monsoon rains can inundate the bar screens at the entry to the plant with debris and rock threatening to slow down the intake of wastewater. The debris must be cleared before basins overflow.
Divers keep a reliable supply of safe drinking water flowing into homes and businesses and keep wastewater moving though underground pipes and treatment plants. Divers save cities money and water - even in the middle of a desert.
For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit amwua.org.