County engineer recommends $150,000 short-term repairs for S. Bridge; longer-term replacement could cost millions

Valley County engineer Dan Goetz told the Board of County Commissioners on March 24 that the S. Bridge is functionally constrained by narrow deck width, abrasion of the driving surface and corrosion of in-water piles, and recommended a short-term repair program he estimated at about $150,000.

Goetz said the bridge currently measures about 22 feet between inside curbs; removing about a foot of curb on each side would provide roughly 24 feet of roadway, and removing curbs entirely would expose about 26 feet. He warned, however, that the bridge has steel piers in the water showing corrosion and “significant abrasion” of the deck that has exposed rebar. He also noted two pressure sewer lines serving Tamarack are attached beneath the structure and that power or communications lines run across the bridge, meaning any work must be coordinated with utility and sewer authorities.

The short-term package Goetz proposed would include sawing back portions of the curbing to gain width, tapering approaches, repairing guardrail connections and applying an epoxy or protective spray to the deck and remaining curb to reduce further salt and water intrusion. Goetz said that work could likely be staged so that only part of the bridge is closed at a time: “I’m hoping that we could do it half at a time so it would be flagged,” he said. He estimated the short-term work at about $150,000.

Why it matters: the bridge carries traffic toward Tamarack, and Goetz told commissioners that traffic is slowly increasing from that direction. Full closure for replacement would require a roughly 4.5-mile detour over Norwood and Cheline roads, currently gravel and in poor condition; upgrading the detour routes could cost on the order of $250,000, Goetz said. A full replacement or major long-term reconstruction, he said, could cost in the millions and would require federal approvals and a feasibility study.

Goetz described three time horizons: a short-term repair and protective coating (the $150,000 option) to extend service over a couple of winters; a medium-term “bridge over bridge” solution in which a new superstructure is placed over (and effectively outside) the existing bridge — reducing environmental impacts while preserving the existing footprint — which Goetz estimated would add roughly $500,000 beyond the short-term work in his high-level estimate; and a long-term total replacement that could be in the tens of millions, depending on final design and permitting.

Goetz cautioned against adding substantial overlay weight without more detailed foundation analysis because of corrosion in the piles. He also flagged safety concerns where the bridge rail is detaching from its anchors and said that any curb cutting could affect guardrail attachments until the work is engineered. He noted that jurisdictions now sometimes use a bridge-over-bridge technique to limit wetlands impacts and that Idaho Transportation Department and LTAC personnel have discussed that approach with the county.

Commission discussion touched on the condition and the need to coordinate with Tamarack sewer officials. One commissioner challenged an early characterization by saying, “Your first statement was incorrect. The bridge is not in good repair,” and Goetz clarified he meant the structural elements are sound but the bridge is becoming functionally obsolete because of width and other deterioration.

No formal action was taken at the meeting. Goetz said he supports pursuing the short-term repairs this year and bringing cost and schedule details back to commissioners during budget discussions; he also said a feasibility study would be appropriate before pursuing federal funding or an RFP for major replacement.

Discussion points: the bridge carries pressure sewer lines to Tamarack that must remain continuous during any work; the Norwood–Cheline detour is gravel and needs upgrades to carry detour traffic; medium-term “bridge over bridge” work could reduce environmental impacts by leaving existing piers in place; long-term replacement likely requires FHWA approval and significant federal/state funding.

Outlook: Goetz recommended moving forward with a short-term plan this year, staged to avoid full closure if possible, and using results from that work and a planned feasibility process to determine whether to pursue the medium- or long-term options.