By Dennis Box
The Courier-Herald
The city planned to turn the valve christening a new sewer main Monday after six months of intensive work.
The line runs parallel to the old main, which was found to be corroded and collapsed in places. The new line begins at state Route 410 between the Baron Manfred von Vierthaler Winery Restaurant and Myers Road. The pipeline travels down the slope to state Route 162 at Riverside Drive West.
According to Public Works Director Dan Grigsby the new high density polyethylene line replaces the ductile iron line that failed earlier this year.
The project replaced about 8,000 feet of line at a cost of about $2 million.
Along with the new line, vaults were placed in the ground every 750 feet.
“The vaults hold the valves allowing us to divert water if the line breaks,” Grigsby said.
The sewer line problem was discovered Jan. 10 when a septic tank truck broke through the asphalt near the intersection of SR 162 and SR 410 on Riverside Drive West.
The 30-inch sewer main that carried Bonney Lake's sewage to the Sumner treatment plant had collapsed, washing the soil away beneath the street and Bill and Janene Speck's driveway.
Public Works employees discovered portions of the line were corroded due to a gas buildup and the pressure from the earth caused the main to collapse.
About 1.5 mile of line was tested upstream from break in February and problems were found along the entire length.
The collapsed sewer main is about 20 years old. The polyethylene line is expected to have a much longer life than ductile iron and it is not susceptible to corrosion due to gas build up.
A team including Public Works employees, Parametrix, a consulting firm located in Sumner, and DDJ Construction out of Ravensdale joined forces to replace the line.
“It's was a great team,” Grigsby said. “They were able to do the work in about six months.”
The city will attempt to get a loan from the state's Public Works Trust Fund to help pay for part of the cost.
Dennis Box can be reached at dbox@courierherald.com.
