The Chadron City Council has awarded a $7.6-million dollar contract to a South Dakota firm for repairs and repaving of the runways and taxiways at the Chadron airport.

Upper Plains Contracting of Aberdeen was about $750,000 under the next lowest bid and about $1.9-million under the estimate of project engineer Curt Christianson of Olsson Associates. The city has already been approved for a $7.5-million dollar federal grant for the project.

Christiansen says the main runway and taxiways need repaving because the concrete from a similar project in 2000 has developed serious cracking and disintegration problems by ASR, an unexpected chemical reaction involving the silica sand used in the cement mix.

Project and runways in other cities with the same concrete formula…used successfully in a wide range of projects for more than 50 years at the time…have developed similar problems. Christiansen says a slight change in formula and greater testing should avoid any ASR problems this time.

The project will be completed in phases with Upper Plains Contracting having 287 working days to complete it. Christianson says the only time the airport will be fully closed is when the project reaches the intersection of the two runways…and it can be close for just 15 days without penalty.

Upper Plains will be removing some 83,000-square yards of concrete and 71,000 square yards of asphalt while using more than 1,800 tons of concrete to lay over 90,000 yards of new paving.