MOUNT VERNON — A bridge deck that was improperly built has allowed salt to seep through and heavily rust I-beams on the bridge over Dry Creek on Thayer Road. The damage is so extensive the load limit for the bridge has been lowered to 10 tons.
Replacement I-beams are in stock and repairs will start, weather permitting, as soon as possible, said Knox County Engineer Jim Henry. The plan is to weld new beams along side the damaged beams.
Bridge decks are normally built with corrugated metal over the beams covered with concrete. Then a waterproof barrier covers the concrete to seal out moisture. An asphalt road surface goes on top.
Henry said when this bridge was built in 1987, the corrugated metal was covered with gravel and alspahlt. Over the years water has worked through the bridge floor and corroded the beams. Bridge inspectors found a 30-inch long heavily rusted area in the 18-inch deep I-beams.
The bridge is in Clinton Township and the area falls under the jurisdiction of the Mount Vernon Fire Department for fire and emergency medical services.
Because of the change in load limits for the bridge, none of the MVFD’s equipment can now safely cross the bridges, according to Capt. David Mills. However, an alternate route via Kinney Road would access the area near the landfill and the Knox County Horse Park should services be required.