8/2/2011
Reed Hollinshead
ITD Communication
208-334-8881
reed.hollinshead@itd.idaho.gov
UPDATE: Washout repairs near Marsing expected to finish Thursday
BOISE - Repairs to a culvert that failed July 24 on Idaho 55 near Marsing are expected to finish Thursday (Aug. 4) with the reopening of that section of new road. The aging culvert's failure caused the washout of a 20-foot section of highway about a half-mile west of Marsing near the junction with U.S. 95.
The replacement pipe is currently being installed. It was received Friday, but crews found an older pipe buried under the one that had failed. Removing that second pipe and building the area up so that it was ready for the new pipe delayed repairs by a few days.
The replacement culvert, manufactured by a Nampa company, is a reinforced concrete pipe made specifically for deep installations. The pipe will be placed about 20 feet under the roadway surface.
A less-expensive metal pipe cannot be used because the composition of the soil would eventually corrode and eat away the metal, causing another failure. Aluminum, in that quantity and shape, is more expensive and difficult to find.
To handle greater water-flow volumes, the new culvert also will be 48 inches in diameter rather than the 36-inch diameter of the corrugated metal culvert that failed.
Crews first constructed a gravel-and-dirt “bench” from which to use an excavator. From the bench, ITD removed the remains of the old pipe and created a diversion channel in order to have a relatively dry area to work while replacing the culvert. The new concrete pipe is then installed and the joints sealed. The diversion pipe will be removed and the excavation filled to near roadway level. The roadway base will then be graded, compacted and the roadway repaved. It will be reopened to traffic following the repaving.
Northbound traffic on U.S. 95 bound for Idaho 55 is routed east on Pershal to Idaho 78 then north to Idaho 55. There is no increase in mileage for northbound traffic on U.S. 95 headed to Idaho 55, but southbound traffic on U.S. 95 going to Idaho 55 has a two-mile increase. Southbound traffic on Idaho 55 is routed north on Edison Road to Thompson Road, west to Bunt Rock Road then south to U.S. 95. This adds three miles to the commute.
Message boards are in place to help direct motorists. A 12-foot maximum width restriction is in place on the detour route, and oversize loads are also restricted.
Repairs are estimated at $30,000. Because the failure was within the highway right-of-way, ITD will pay for the repairs through its maintenance funds.
According to 2010 data, approximately 3,300 vehicles use that section of highway each day, especially agricultural traffic.