January 20, 2014 in City

Greene Street Bridge repair brings end to weight limits

By The Spokesman-Review
 
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Weight restrictions on the Greene Street Bridge were lifted Friday after the city spent $1.7 million to strengthen the bridge with carbon-fiber-reinforced polymer.

Mayor David Condon hailed the project as a way to increase the efficiency of truck transportation at a relatively modest cost. He said a new bridge would cost between $10 and $12 million and disrupt traffic during a year or more of construction.

Under the restrictions in place since 2007, trucks with loads had to divert either to Division Street or Argonne Road to cross the Spokane River.

“This gets freight traffic out of our neighborhoods,” Condon said.

The project was undertaken after haulers asked Condon to do something to remove the load restrictions, the mayor said.

The old restrictions limited crossings for three-axle vans to 25 tons and six-axle trucks to 40 tons.

Steve Robinson, president of Spokane Rock Products, said his drivers were forced into long detours when working on jobs north of the river. His plant at Eighth Avenue near Havana Street is about a mile south of the bridge.

He estimated the detours took an extra 40 minutes and 10 gallons of fuel for each trip north.

“You can see how key this project is to the community,” he said.

But the project became controversial last year when the contractor on the job found more cracks than expected on the bottom side of the bridge deck.

The contractor, Leewens Corp., estimated that the extra work would increase the cost of the project by nearly $1 million, but the city whittled the cost overrun to $520,000. Epoxy injections were used to seal cracks prior to applying the reinforcing fiber, which has 10 times the strength of steel.

Eventually, extension of the North Spokane Corridor to Interstate 90 will provide a primary truck route across the river in that part of Spokane.

Money for the project came through the Spokane Regional Transportation Council and surface transportation program, the city’s real estate excise tax and the city’s arterial street fund.

Country Homes water fix questioned

Dave Ayres, who lives on North Country Homes Boulevard, is challenging county engineers on their estimate of how much water would flow into the boulevard median in front of his home during a 100-year flood event.

The county is planning to spend $2.3 million to replace the paved storm causeway in the middle of Country Homes with a series of infiltration swales sometimes known as rain gardens. A pipe will be buried along the length of the causeway and under the rain gardens to handle runoff from Five Mile Prairie.

Colleen Little, a county engineer on the project, undertook a detailed study of the prairie watershed to come up with an estimate of how much water would flow off the prairie during a storm that could be expected only once in 100 years.

She said that amount is 50 cubic feet of water per second coming to the causeway. The drainage pipe for the project is being sized to handle that flow and slightly more, she said.

“These guys are selling the community a bill of goods,” said Ayres, a retired dam safety coordinator.

Ayres spent dozens of hours and acquired at least 200 pages of public records investigating the county’s engineering work. He has criticized the project on numerous issues. He said when the flood comes, “This whole thing is going to be a mess.”

He pointed out that an earlier government study estimated the potential 100-year flood at 247 cubic feet of water per second.

That study could not be found, Little said, so she conducted a new study and came up with the different flow estimate based on a hypothetical storm that dumps 2.4 inches of rain in 24 hours.

New subdivisions and streets on the prairie are required to hold back stormwater, which is one reason for the reduced flood estimate, she said. Another reason is that technology and hydrologic science have improved since the original study 30 years ago.

Little’s study was accepted by the Federal Emergency Management Agency, which oversees flood control.

Ayres said the biggest risk of a flood will come when rain melts an existing snowpack in a short period of time.

A check with the National Weather Service shows that the rainfall record in Spokane was set in an apparent thunderstorm on June 7, 1888, when 2.22 inches was measured. The second highest amount is 2.15 inches during a thunderstorm on May 21, 2004. Both are below the hypothetical amount used in Little’s study.

“I don’t think there is a fatal flaw in any of my work,” Little said.

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