South Santiam River, McDowell Creek Road Bridge
Linn County Road Department
Capital Improvements
South Santiam River, McDowell Creek Road Bridge
Project Description:
The bridge on McDowell Creek Drive over the South Santiam River in its current configuration was constructed in 1958. From 1930 to 1958, the bridge consisted of timber covered bridge spans. The timber spans were replaced with steel girders with cast-in-place concrete deck spans. The main piers on each bank of the river were reused to support the new spans. The pier on the south bank (Pier 3) has experienced scour issues over the years. In 1969, the pier was retrofitted with drilled in place steel piling and a larger footing cast around the existing concrete footings. Unfortunately, the scour issues remained. In 2009 the Linn County Road Department maintenance crew constructed a small concrete apron at the NW corner of the Pier 3 footing in an effort to correct the scour issue. This worked for a few years, but the 2019 bridge inspection report indicates that a small scour pocket has returned to the same corner. Pier 3 supports the 155-foot main span that crosses the South Santiam River. It is important to correct the reoccurring scour problem to ensure this bridge can remain open to the traveling public that depend on it. This bridge provides access for the public and the timber industry, and is it is vital that it remains open.
The proposed solution is to drive steel sheet piling in around the 3 exposed sides of the footing to protect it from future scour. Due to the steel girders above the footing, the length of the piles is limited by clearances for the sheet lengths and pile driving equipment. Once the sheet piling has been driven, the space between the new sheet piling and the existing footing would be filled with a 3' thick layer of concrete.
Funding:
- Source: State
- Preliminary Engineering: $190,000.00
- Right of Way: $10,100.00
- Construction: $526,500.00
- Total Project Cost: $726,600.00
- County Share: $74,621.82
Schedule of Funding Obligations:
- Preliminary Engineering: FFY2026
- Right of Way: FFY2026
- Construction: FFY2026
County Facility Number: BR0729-0286
Project Number: CB2402
ODOT Key Number: KN23138.
Please email roads@co.linn.or.us if you have any comments or questions regarding this project.