TAKING ACTION: Did spilled oil sink to the bottom?

SALT LAKE CITY (ABC 4 News) – Ten days since an oil pipeline ruptured at the mouth of Red Butte Canyon, spilling an estimated 33,000 gallons of oil into the valley below, the clean-up continues.

Crews are skimming the surface, collecting traces of oil.

Some of the men and women on the front lines, chest deep in the water, tell ABC 4 they’re finding blobs and slicks of oil at the bottom of Salt Lake Valley waterways, out of sight from the public.

Hundreds watched again today at Liberty Park in Salt Lake City as crews brought out the giant vacuum hoses, shovels and scrub brushes. At the same time, Chevron executives worked to clean up the company image, pledging to finish the job.

"The idea of us walking away and not fulfilling our responsibility just doesn't measure up," said Dan Johnson, Chevron’s manager of state and public affairs for the company’s Rocky Mountain region.

According to some workers on the front lines, who asked not to be identified for this story, estimates of the amount of oil still polluting Salt Lake waterways don’t add up either.

Chevron reports crews have recovered 500 barrels of spilled oil and 100 barrels have evaporated. That's 24,000 to 25,000 gallons. Work crews tell ABC 4 off-camera there's a lot more at the bottom.

The claim would undercut the popular belief oil floats. Chemical engineers know better.

"In certain circumstances oil and water emulsify,” said University of Utah chemical engineering professor Milind Deo, as he explained what petroleum experts call the “fate” of an oil spill.

“It happens especially in turbulent conditions, such as the action of the waves or when the wind whips the water."

Deo would not say whether he thought it could have happened in a fast flowing stream such as Red Butte Creek. He said light weight oil, such as the crude from Colorado that runs through Chevron's Utah pipelines, mixes more readily with water.

"Oil emulsifies and forms what's called a chocolate mousse, essentially, a mousse-like structure, that can sink."

Has emulsified oil sunk to the bottom of the Liberty Park pond? ABC 4 put the question to Chevron.

"Do you know whether anybody has tested the bottom of the pond or the bottom of the Jordan River?" I asked. Johnson’s response was forthright. "I do not know that they've tested the bottom of the pond or the bottom of the Jordan River."

Workers will continue to skim the water's surface until there are no more visible or detectable traces of oil at toxic levels. How long will it take? No one can say. It's a process Chevron concedes could spill in to next year.