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Scott G. Winterton, Deseret News/KSL Chopper 5
Work continues at Liberty Park to clean the oil out of the water and off the shoreline on June 14, 2010.

SALT LAKE CITY — Chevron Pipeline has spent $75 million to clean up a pair of spills in 2010 that dumped a combined 1,050 barrels of oil into the soil near Red Butte Garden and into the creek, turning the lake at Liberty Park into an oil slick and killing off all the fish.

The price tag is continuing to mount, too, as remediation continues and the most extensive sampling of soils and the creek to date will begin Aug. 23.

Signs are being placed at 21 areas along the creek corridor to advise residents and users on how to report any oil residue they might encounter. The sampling will be in the no stone-unturned vein, involving an assessment of the soil along the creek bank, the lifting up of rocks in the creek bed and testing of the water itself, said Rolf Larsen, an environmental health scientist with the Salt Lake Valley Department of Health.

"We're pretty sure all the oil has been cleaned up, but you never know," Larsen said. "Visually, you don't see anything, but this will help determine what is left to do."

The concern is high flows from a rampant and delayed spring runoff may have loosened some residue that had clung to large rocks in the bottom of the creek or washed away soils along the bank that contain contaminants.

Larsen, addressing participants gathered Wednesday at the 2011 Salt Lake Countywide Watershed Symposium, said the tests will run the gamut and deliver a more exact barometer on the health of the riparian waterway.

The spill had far-reaching impacts that continue to play out more than a year later, he said.

All the fish died, as well as some large, old trees at the spill site that had their root system literally flooded with the oil release. All of the aquatic insects that fish depend on to live were wiped out in the spill and have returned to only half their numbers a year later, Larsen said.

Sampling done of late has shown "very few detections" coming in bearing petroleum contaminants, he said, adding the difficulty in determining cleanup success is hard to gauge not knowing if those contaminants are from the spill or come from typical urban storm system runoff.

In this next round of sampling, residents should expect to see teams out over a three to four day period, said John Whitehead, assistant director of the state Division of Water Quality.

"We're hoping to get a good snapshot of where we stand a year and a couple of months later."

While visually the oil appears to be gone, Whitehead said there continues to be certain events that trigger an odor of oil, prompting calls by residents.

"We have had enough reports that know there are odors that come on under certain conditions — when we have a rainfall event or some other event that happens."

Whitehead said this battery of tests will determine what areas may continue to need remediation, what areas can be deemed free of Chevron oil and where it makes sense to continue any cleanup.

The first spill, caused June 11, 2010 during a summer thunderstorm, happened after wind knocked a tree into a power line, sending an arc of electricity down a fence post into Chevron's pipe buried 3 feet down.

The arc left a quarter-sized hole in the pipe, allowing 33,000 gallons of oil — or 800 barrels — to escape into the surrounding soil and into Red Butte Creek. The spill went undetected until the next morning. Federal authorities investigated Chevron's culpability in the incident — and while the pipeline's failure was chalked up to a freak accident — regulators said the oil company needed better leak detection safeguards in place. Chevron was fined $423,600 as a result.

Less than six months later, there was another accidental release of oil about 75 yards away from the first spill involving the same pipeline. Water left over from a power flush of the pipeline system froze a valve during December, leading it to fail. About 500 barrels escaped from the pipeline, although half of it did not leave a deep vault and none of it spread to the creek.

"We were very, very happy it didn't make it to the creek," Larsen said.

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