More Woes At Denver Airport -- Runways Cracking As Wet Soil Expands

DENVER - Cracked runways, the latest dilemma for Denver's long-delayed new airport, will raise maintenance costs for the runways' entire 40-year life span unless they are dug up and fixed right, according to a soils expert.

Fu Hua Chen said the fissures are "a good indication that in the future, we'll have serious problems with these runways."

The $3.7 billion Denver International Airport was built 23 miles northeast of the city after officials decided that Stapleton International Airport could not be expanded to accommodate increased air traffic.

The airport was supposed to open in October 1993. That date was pushed back four times by construction delays and problems with the high-tech baggage system, which loses or chews up bags.

The airport is built on one of the country's worst areas for soils that expand when wet and crack even the strongest concrete.

Before the runways were laid, the top six feet of soil was scraped away and the area was leveled. Then the soil was replaced and the top 12 inches mixed with lime to reduce expansion.

Since the cracks appeared - some 10 to 20 feet long - workers have ground down thousands of square yards of uneven concrete and patched fissures with glue.

More than seven gallons of epoxy was injected into one monster hole on one of the runway aprons, said Graham Barber, supervisor for the contractor Bangert Bros.

The Federal Aviation Administration, which must certify the runways, does not allow runway slabs to be ground down more than half an inch.

Peter Stokowski, DIA's senior engineer for runways, said the problems have been fixed to the satisfaction of the city and the FAA.

Chen, 82, is an adjunct professor at the University of Colorado at Denver, in the Expansive Soil Research Center. He wrote the textbook "Foundations on Expansive Soils," which Stokowski said he studied before working on the airport.