County opts for lower‑cost 'deep patch' for 92nd Avenue slide; DOT to fund majority

County staff and consultants briefed commissioners on options to repair recurring landslides on 92nd Avenue near Little Mo campground. After reviewing alternatives — including a full structural repair with piles and tiebacks estimated at roughly $20 million or more — the county and the state DOT agreed to pursue a lower‑cost "deep patch" alternative as a long‑term maintenance solution.

Jordan Ellis described the deep patch as a 5–7 foot subcut with multiple geogrid layers intended to reduce ongoing maintenance even though it would not fully correct the largest instability in the area. He told the board the deep patch option is estimated at about $2 million total. Under the ER funding approach described by staff, the federal/department share would cover roughly 80% of eligible costs and the county about 20%.

Staff said the county submitted 90% plans to the DOT and received draft environmental approval earlier this year; final DOT and Corps reviews remain pending. The target is to have the project bid‑ready by late 2026 or spring 2027, with construction anticipated in the fall of 2027. To reduce recreation impacts, staff recommended requiring a full road closure and instructing contractors not to begin work until after Labor Day; estimated construction duration is about six weeks.

Commissioners pressed staff on whether the repaired segment would be paved or remain gravel. Consultants advised keeping the roadway gravel in most cases because paving on an unstable slope risks higher future repair costs, though the south slide might be suitable for paving. Commissioners reiterated safety is the primary rationale for the repair.

Staff will return with any DOT or Corps responses and firm bid dates as reviews are completed.