Franklin County proposes short reroute to reopen Old Highway 100 within weeks

Franklin County highway staff told commissioners they plan to reroute Old Highway 100 about 28 feet to the north and reopen the road in about four weeks if utility confirmations and routine preparations go as expected, Highway Department staff said during a county commission meeting.

County highway staff said the proposed reroute is substantially less expensive than fully stabilizing the slide area and would use millings from the existing pavement as base material, with about 10 to 12 inches of base and new asphalt laid on top.

The Highway Department staff said an engineering study and further field work showed the soil north of the existing alignment is substantially more stable than the subsurface beneath Old Highway 100. Staff reported finding an 8-inch high-pressure gas line roughly 3.5 to 4 feet below the current pavement and said they met with the pipeline owner, who “assured us that that is not a conflict” and will provide written confirmation that building over the line is acceptable. The staff member added crews had potholed a telephone line about 18 inches deep but did not expect that to be a critical constraint.

"They're going to give that to us in writing this week yet that they have no conflict with us building on top of that," Highway Department staff said, referring to the pipeline owner. The same staff member said, "If everything goes right, we would be looking at probably opening old 100 up in about 4 weeks." The staff member also described plans to rent a milling machine and reuse the asphalt millings on site rather than hauling them off.

County commissioners and staff discussed protecting nearby utility poles with guardrail, arranging for a contractor to install that guardrail, and talking with the owner of the nearby SECO plant about moving two gates back from the right of way so vehicles are not stopped in a traffic lane while waiting for gate entry. Highway Department staff said much of the preparatory work would be done by county crews once chip-sealing season winds down.

A commissioner noted the proposed fix would likely cost "probably a $100,000," and contrasted that with an earlier, larger stabilization estimate referenced in the meeting. The larger estimate was described by a commissioner as a jump from an earlier figure in the millions. No formal vote or commission order was recorded on the reroute during the meeting; staff presented the options and described the preferred, lower-cost in-house approach.

County staff emphasized the plan still depends on written utility approvals and on-site conditions. Staff said they would notify the pipeline owner when construction begins so the owner can monitor the work. The Highway Department also said it would remove concrete debris left by the slide and excavate and dispose of material that fell into the creek; material still flat on the existing road surface would be milled and reused.

The presentation noted local stakeholders — including the nearby school and the City of Washington — had expressed strong interest in reopening the route. Highway Department staff said they would continue to develop the plan and keep commissioners and the public updated if unforeseen issues arise.

No formal action was taken during the meeting; the discussion was recorded as a departmental report and next steps are contingent on utility confirmations and final field preparations.