Prowers County Receives Bridge Assessment

Ryab Nataluk Details Bridge Assessment in County

The majority of bridges in Prowers County are in pretty good shape, according to Senior Structural Engineer, Ryan Nataluk of Stantec Consulting.  Nataluk provided an overview for the Prowers County Commissioners and Mark Dorenkamp, County Road and Bridge Supervisor, on Thursday, September 8. 

What structural problems the bridges are encountering stems from the streams and canals that they span said Nataluk in his summary.  Erosion, rust and corrosion are the three main factors the road and bridge crew has to contend with regarding degradation of the bridges ability to support a load. 

Soil erosion at the base of piles and support foundations are a constant factor to deal with.  Nataluk said if the erosion is not corrected, some future problems will develop.  One way to prevent the continuation of erosion is with large sized rocks and stone for rip-rap at the base of support piles and columns.  “This form of scouring is the number one bridge failing mechanism in the world,” he added.  Another problem area specific to agricultural areas is ag chemicals and natural alkali in the soils.  Nataluk provided photos of corrosion along metal retaining walls where paint below the waterline was just eaten away to bare metal, allowing the steel to rust off in sheets.  Other areas where water has been a problem develops when corrugated, load-bearing metal decking, sitting on support beams, isn’t water-proofed where they overlap.  He said corrosion begins to eat away at the metal and the beams.  Another problem area develops where ditch riders may burn away piles of accumulated tumbleweed or tree limbs underneath a bridge and the fire scorches and burns off the protective paint and the bare metal starts to rust away.  Another problem area features dirt piling up on top of bridges and along the safety guard rails.  Nataluk pointed out that when the dirt, usually scraped off to the side by a road grader, accumulates to reach the bottom rail, a slope has developed.  He said this prevents the rail from blocking a vehicle from going over the rail, but does the reverse, acting as a ramp where the vehicle could clear the rail. 

The Off-System Bridges Overview is part of a CDOT assessment provided to counties throughout the state.   Nataluk said Dorenkamp’s crew has done a good job of repairing those areas they are aware of, and their recommendations for additional repairs can be handled without extraordinary measures. 

By Russ Baldwin