By: TrueNorth Steel
Located a few miles outside the Coeur d’ Alene Resort, the rural country side of Post Falls provides a subdued lifestyle for both full and part time residence. W. Riverview Dr provides access for residence to and from local shopping resources just a few miles away. Closing the road was not an option because the alternate route didn’t make sense, since the drive was too far for the residence to travel. Rehabilitating the existing structure made perfect sense.
An older four side concrete arch was quickly approaching its useful service life, when the Post Falls Hwy District approached TrueNorth Steel for potential solutions. In the early stages, the owner thought it was best to match the existing profile and was considering a TrueSteel Liner by TrueNorth Steel to match the profile.
The Hwy District Hired a local engineer RUEN-YEAGER & ASSOCIATES, INC. a 
nd they determined that the hydraulic flows were less and the original four sided concrete arch was over designed. The engineer worked with TrueNorth Steel to find a viable and cost effective solution in Polymeric Coated Spiral Rib. The next challenge was to figure out a shape that would handle the flows and fit the profile of the existing structure. A 10% ellipse fit the bill and was selected with beveled ends and a toe plate on the inlet to prevent undermining and piping.
Northwest Grading was hired to install the spiral rib pipe, form the pipe ends and flow fill the lightweight cellular concrete with perforated PVC tubes as backfill for the annulus space.