How did concrete mysteriously turn up in Seattle sewer pipe
SEATTLE Managers at a construction site just 30 feet from a Seattle sewer pipe that is mysteriously blocked by 80 feet of concrete say it’s possible their
subcontractor is at fault, but that several things just don’t add up.
Seattle Public Utilities investigators are examining all the evidence, including the concrete inside the pipe, and intend to charge at least $350,000 in repair costs to whoever is at fault. They believe
whoever forced the concrete inside the pipe did so unintentionally.
The massive Troy Block construction project is among the biggest office towers in South Lake Union. A 90 foot pit at the site uses tie backs to hold up subterranean walls. Those tie backs, according to construction managers for Lease Crutcher Lewis, were drilled safely under the sewer pipe beneath Fairview Avenue, as shown in sewer maps provided by the city, and that drillers can sense when a pipe or rock is nicked.
Utility officials said they’ve had meetings with Lease Crutcher Lewis and its subcontractor, Malcolm
Drilling, and say the tie backs are intended to be three feet below the sewer line. Yet the city and the construction firm say utility maps can be inexact.
The blockage was first noticed October 16 when the basement of a nearby building was flooded with several feet of raw sewage. The utility quickly rerouted the flow of sewage to resume full service to all buildings in the area.
Repairs are blocking one to three lanes between Thomas and Harrison on the heavily traveled Fairview Avenue but mostly restricted to overnight hours to lessen the impact on traffic.
To solve this whodunit mystery, the Seattle Public Utilities’ concrete lab is examining the evidence. A large contraption called a Universal Testing Machine makes a deafening noise as it presses up to 400,000 pounds of pressure per square inch, crushing a concrete core sample into pieces. Their trained staff can make visual assessments of
concrete and look at the microscopic ingredients in the concrete to determine who made it and where it was used.
The lab has dozens of soil, cement and concrete samples lined up in tidy rows. It has a giant door that slowly swings open to reveal a high humidity locker storing
dozens of concrete core samples. It even has chunks of concrete that came from inside pipes in other similar episodes elsewhere around the city.
Read says the research done by his team will help find the party responsible for the Fairview incident. "Let the science take you where it needs to go," he said.
SPU said it has found more concrete inside a side sewer extending from the main line leading directly toward the Troy Block construction site, putting the mystery concrete within only a few feet
of the subterranean walls. Yet SPU is emphatic that it is not making allegations and has not yet finished its investigation.
"We have had progress or construction meetings with Lease Crutcher Lewis and their
subcontractors," said SPU civil engineer Jeff Williams.
The Lease Crutcher Lewis constructions managers said these incidents are not uncommon. But it rarely causes traffic congestion in an already congested city.Articles Connexes：
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