Soil contamination issues recently proved a roadbump for the Coffman Union renovation project.

A commercial waterproofing substance known as coal tar, used to waterproof the union’s original underground garage, leaked into the soil directly above the garage. The garage, located beneath the plaza directly in front of the student union, was built in 1938.

The problem began with the construction on the plaza, prompting the removal of the contaminated soil.

“It was something they did in 1938 not realizing what would happen,” said Jennifer Schulz, senior editor with facilities management. “We found it and we reacted to it.”

Schulz said having the contaminated soil on campus wasn’t the problem, but what happened to it after it left the project was cause for environmental concern.

She said the soil could have contaminated ground water had it been placed in a standard landfill.

Workers recognized the problem and delivered the soil to a landfill specifically designed to handle potentially hazardous waste.

Maggie Towle, director of student unions, said several environmental specialists were brought in to ensure the plaza area was free of pollutants.

“They took soil samples from the entire plaza to make sure the problem was eliminated,” Towle said.

Coal tar is a substance resulting from the carbonization – extreme heating in the absence of air – of coal.

It is still widely used to line pipelines, sewer pipes, manholes and tidal zone areas.

Schulz said in most cases coal tar is harmless to humans.

“It’s the same stuff roofers use, and they don’t even wear masks,” she said.