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Ice Pigging: New Water, Sewer Pigging Method Offers Unique Benefits
“Once the turbidity, conductivity and temperature have started to return to normal, the operator diverts the water back through the dechlorination unit to allow more flushing until all the readings return to normal or better than normal. At this point, all closed valves are reopened and the process is complete.
“A typical project will take less than three hours from mobilization to demobilization.”
Sewer force main ice pigging
The process for cleaning a force sewer main is similar. The pump supplying the force main is shut down and depending on the temperature; the main is flushed with water to cool the pipe. This flushing can be completed simply by running the pump and wet well.
The pipe is accessed on the pressure side of the pump through an air valve or other opening, ice is injected into the pipe and the supply pump activated to push the ice through the pipe to the end of the main.
The ice slurry continues through the system to the wastewater treatment plant.
Ervin said ice pigging was invented by Prof. Joe Quarini of the University of Bristol in the United Kingdom, and patented in the U.S. in 2005. The technology has been used in Holland, United Kingdom, Germany, France, Japan, Spain, Australia, Chile and Saudi Arabia. To date, approximately 175 miles of pipe have been cleaned. The longest single run has been 2.67 miles of a PVC pipe in Wales.
Relatively new to North America, details about ice pigging technology are not widely known in the U.S. and Canada.
“Water operators are very familiar with flushing operations,” said Ervin. “Some operators also realize that flushing is not solving their problems and that a more aggressive solution is required. However, operators are not very familiar with ice pigging as a solution. We are making great strides to educate these operators and have presented numerous presentations, demonstrations, papers at organizations such as AWWA, NRWA and at the 2013 UCT show.”
Ervin describes response to the company’s presentations as “extremely positive” from water systems people and an even larger response from the wastewater industry where options for cleaning force mains are limited.
Summarizing the benefits of the technology and its application, Ervin said ice pigging is a more sustainable technology than other cleaning methods because it uses significantly less water during the operation. The waste can be easily collected and disposed of eliminating contamination of nearby streams or ponds, and the waste stream can be easily identified and quantified.