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Ice Pigging: New Water, Sewer Pigging Method Offers Unique Benefits
Also, he added, ice pigging could provide water systems the first opportunity to clean service lines. “There isn’t any good technology that exists for water systems to clean the service line from the water main to the meter,” he explained. “This technology will travel from the water main through the service line without issue.”
The greatest benefits of ice pigging relate to operations, Ervin continued.
Ice pigging technology can enter and exit from any two-inch or larger connection to the main, he explained. Typically live hydrants without modifications are used, but access can be made through air valve connections and even smaller corporation cocks. No excavation or special launching or extraction stations are required.
Water main ice pigging
Ervin describes the steps in cleaning a segment of potable water main with ice pigging:
“First we stage the delivery tank at the entrance hydrant and then put the flow analysis unit at the exit hydrant to monitor flow, pressure, conductivity, temperature and turbidity.
“For a potable water main, the hoses and connections are disinfected and connected to the water main. The flow analysis unit (FAU) is connected to a dechlorination unit to flush water displaced during the process. While the operator at the FAU monitors the water main, system operator personnel would perform a shutdown of the water main.
“The FAU operator is in communication with the delivery unit operator, and confirms when the main is isolated. Before the water pressure in the main drops below 20 psi the ice delivery pump is started to deliver ice to the main. Both operators would communicate to control the ice injection rate and pressures in the main.
“A prescribed amount of ice would be delivered to the main. The delivery unit and FAU then close the hydrants, and the upstream mainline valve is opened. This step would provide some additional ‘packing’ to make the ice slurry a little more solid. The FAU operator then opens the exit hydrant allowing the system pressure to push the ice pig to the exit station while dechlorinating the displaced water. He controls the flow and pressure in the main.
“When the ice pig arrives at the exit, the conductivity will spike due to the salt. At this point, the operator reroutes the waste stream to the sanitary sewer or waste tanker to dispose of the water, sediments and biofilms removed from the main.