DENVER -- A portion of the T-Rex construction project on the Interstate 25 corridor has been put on hold while workers deal with a patch of land contaminated with chemicals.

Work crews discovered the contamination near Interstate-25 and Broadway this week while digging a hole for the expansion of light rail.

Workers said strong fumes suddenly started coming out of the ground.

The fumes were irritating enough that one of the workers sought medical attention. He was not seriously hurt.

T-Rex managers couldn't give the exact name of the chemical, but say it's some type of volatile organic solvent. Officials say it's probably something left over from decades ago when the area was an active industrial site.

It could take one to two weeks to clean up the site, T-Rex officials say.