Sewer main collapses near Sumner and strands septic truck
By Dennis Box
The Courier-Herald
Some days it goes and some days it breaks.
Around 4 p.m. Jan. 10, as a septic tank truck left the home of Bill and Janene Speck at 7208 Riverside Dr. W. - near the intersection of state Route 162 and state Route 410 East - the asphalt broke open under the left, front wheel of the truck.
A 30-inch sewer main carrying all of Bonney Lake's raw sewage to the Sumner plant collapsed and the gray water washed the soil away beneath the concrete, causing the asphalt to give way beneath the truck.
The line carries 3,200 gallons per minute of raw sewage or about 4 million gallon each day.
Pubic Works Director Dan Grigsby said the city's sewer crew, led by Curt Roundtree, was first to respond to the scene followed by City Engineer John Woodcock, DDJ Construction and Parametrix.
Complicating an already messy matter were two Williams Northwest natural gas pipelines crossing the sewer line and a Qwest fiber optic line encased in concrete running parallel to the line.
Grigsby said the quick response of everyone involved saved the utilities from any damage.
The first order of business was getting the truck out of the caved-in area, then figuring out what happened.
The crews and a tow truck company were able to place steel plates on the ground and move the truck out of the site.
Once the truck was moved, DDJ dug down and found the busted line.
The sewer main is made of concrete and is about 20 years old.
“Gas builds up in the line and acts like an acid corroding the concrete inside the pipe on the upper half,” Grigsby said. “Eventually pressure from the ground breaks the pipe from the top.”
The city will replace the line between two manholes, about 180 feet, which, according to the city, will cost about $100,000. The funds will be drawn from a contingency fund used to pay for city emergencies.
Grigsby said no sewage was spilled into the street, although considerable debris fell into the line and went into Sumner's wastewater treatment plant.
Sumner's Public Works Department reported there would be no problems at the plant with the extra debris.
Kevin Aalmo, a foreman for DDJ, spent the night Jan. 10 monitoring the site.
“We couldn't take the chance of contamination getting into the yard,” Aalmo said. “We didn't have a problem.”
DDJ crew members pumped the sewage from one manhole to the next one beyond the collapse, which contained the problem.
Grigsby said the city will need to decide how to assess and treat future failures in the line.
Dennis Box can be reached at dbox@courierherald.com.
