Crews began repairs Tuesday on a second small bridge along Littlerock Road Southwest, south of Tumwater.
The structure between 113th Avenue Southwest and 110th Avenue Southwest is known as the L-5 Bridge. It will remain open during the repairs, according to a news release from Thurston County Public Works.
The repairs are scheduled to take about two weeks, and traffic may be restricted to one lane at times, officials say.
“We need to get the water out from underneath the bridge so we can form up and pour concrete where it’s actually scoured underneath,” civil engineer Matt Unzelman said. “ We’re going to be constructing a bypass system, which is essentially a culvert that we’re going to divert the stream into.”
Scouring is when water washes away rock or footing from a bridge’s foundation.
The L-5 is just south of the L-4 Bridge over Salmon Creek off Littlerock Road that was closed Jan. 27 after crews found scour under the center pier. The L-4 underwent temporary repairs but was shut down Feb. 20 – a day after it was reopened.
The four- to five-mile one-way detour for most motorists has caused traffic jams and frustration for commuters and business owners in the area.
County officials said closing the bridge was the only option for public safety.
“Earlier, the L-4 Bridge was closed due to scouring around support piers and significant cracking on the piers,” the county’s news release stated. “After extensive study and deliberation, it was found that the public safety risk at L-4 was too high, due to the potential collapse of the bridge, to allow it to stay open.”
Unzelman later clarified the county’s statement, saying it should have added that the risk of failure was due to use by heavy vehicles.
The L-4 and L-5 bridges were built at the same time, during the 1950s, and are the same design. Both lack reinforcing steel and footings, county officials say.
County officials have applied for a $3.97 million federal grant to remove and replace the L-4 later this year or in 2015.
The cracks and scour found in the L-5 weren’t as severe, Unzelman said.
He did not have an estimate cost for the repairs, but confirmed that crews are checking to see if there are bridges of this type elsewhere in the county.Lisa Pemberton: email@example.com