City, county approve plan to expand bridge
The city and county are working together on a plan to triple the length of the J Street bridge to ensure that the 14-year-old bridge won't cause future flooding.
Both the Madras City Council and Jefferson County Board of Commissioners have approved one of two alternatives in a draft report by Murraysmith, the engineering firm hired by the city to look into mitigation measures to prevent flooding.
The 80-foot bridge over Willow Creek was built in 2005, when J Street was extended to the east — a joint city-county project.
"When that was constructed (2005), we didn't go through the proper FEMA mapping procedure," said Jeff Hurd, director of the Madras Public Works Department, noting that the bridge could constrict the flow of Willow Creek and cause flooding downstream — at The Pines or nearby school properties.
In 2017, when the city began working with the U.S. Army Corps of Engineers to apply to the Federal Emergency Management Agency for a Letter of Map Revision, the corps determined that the J Street bridge construction could cause stormwater to flow over J Street near its intersection with McTaggart Road.
Initially, the city favored Alternative 1, with a flood control levy on the west side of the creek that would have stretched about 750 feet to the south of the bridge.
"The levee would be designed to keep the stormwater in the Willow Creek floodway and not allow it to overtop J Street near its intersection with McTaggart (Road)," the report noted.
Costs for Alternative 1, while lower for construction and engineering at $3,552,000, were much higher over a 30-year life cycle, which was estimated at $4,986,000.
The higher costs were a result of accreditation by FEMA, ongoing maintenance, and regular reviews.
Under Alternative 2, the preferred alternative, the bridge would be expanded about 160 feet to the west in order to pass stormwater flow without causing the creek to rise downstream of the bridge.
The alternative includes grading, relocating the walking path, and an engineered berm with a flow-control structure.
Construction costs for Alternative 2 are estimated at $4,423,000, but annual costs over a 30-year period would be $166,000, compared with $1,434,000 for Alternative 1. Total cost for Alternative 2 would be $4,589,000 over 30 years.
"The commission approved moving forward with the project as estimated by the city," said County Administrator Jeff Rasmussen, adding that at the commission's April 3 meeting, the county agreed to a 50-50 split of costs for the project.
The city, which approved the agreement April 9, will be in charge of the project.
Hurd said that he will be working to acquire a loan for the project, which should be completed by the fall of 2020.