The emerging theory about what triggered the 33,000-gallon Red Butte Creek oil spill goes like this:
Strong winds Friday broke off a tree branch that fell onto a power line going to Rocky Mountain Power's fence-enclosed Research Substation in the foothills east of Salt Lake City. In this case, the power line angled into the ground to enter the substation below the surface.
When the branch hit the above-ground portion of the line, it caused an electrical fault that sent voltage through the ground. That charge hit a metal post supporting the security fence and shot a surge arcing down to Chevron's 1950s-era oil pipeline.
The impact punctured a quarter-size hole in the pipe. The pressure of the flow pushed 50 gallons of oil a minute through that hole.
Chevron raised the possibility of an arc involving power lines and a fence post at a Monday news conference in which company spokesman Mark Sullivan increased the volume of the spill to 33,000 gallons, 57 percent higher than the Salt Lake City Fire Department's original estimate of 21,000 gallons.
The idea is worth checking, Rocky Mountain Power spokesman Dave Eskelsen said later.
"The theory posed by Chevron today about whether the voltage came down through the ground through this fence post is plausible," he said. "There's not enough information yet to verify that, but we're willing to work with Chevron and determine what happened."
Eskelsen knows for sure that Friday at 9:19 p.m. a power outage hit the Research Substation adjacent to Chevron's underground pipeline. The dispatched lineman found a downed branch against the above-ground portion of the line.
"He isolated the damaged section of the [power] termination and restored power in about 40 minutes," Eskelsen said. "At that point, it seemed a pretty typical outage for us."
Saturday morning came along and Rocky Mountain Power got a call about oil coming out of one of its lines going into the ground. A crew was sent, only to arrive and find the Fire Department there already, responding to a much bigger leak, the one initially reported just before 7 a.m. by staff at the Veterans Affairs Medical Center.
If there is a connection between the tree, the power line, the fence post (erected in the early 1980s) and the oil leak, he added, "it would be extremely unusual."
Sullivan characterized the possibility of an arc-related cause a "one in a million" event still being probed by a Chevron-led investigation.
"It is quite unusual that this fence is in the pipeline right of way," Sullivan said, "and we are continuing to investigate that." (The corridor also contains natural gas and water lines.)
While the arc theory might help explain the cause of the rupture, Sullivan acknowledged that Chevron officials remained "quite concerned" that two separate monitoring systems along the line, which funnels crude from northwestern Colorado to the company's Salt Lake City refinery, "did not work in this very unusual circumstance."
Since early Saturday, medium crude has stained the Red Butte Creek corridor in modest and affluent neighborhoods, killed fish and birds, pooled in the pond at Liberty Park and crept into the Jordan River.
"It is difficult to imagine a worse location for this pipeline leak," Sen. Orrin Hatch, R-Utah, said Monday. "Not only did it happen near a beautiful residential area, but it has seriously damaged a treasured riparian area."
Booms have captured much of the leakage, but Sullivan noted a "minimal" amount of oil has created a visible "sheen" on the Jordan. River monitors show no contamination north of 600 North, he said, and no oil has reached the Great Salt Lake, home to a world-class waterfowl flyway. The major spill also has not compromised drinking water.
About 280 birds -- mostly Canada geese and mallards (some as young as a week old) -- were transported from Liberty to Hogle Zoo to be cleansed with Dawn dish soap. Eight or nine birds have died, according to Mike Roach, conservation officer with the Utah Division of Wildlife Resources.
Rodney Lewis, who lives near Liberty Park, smelled the stench from the oil collecting at the park's large pond over the weekend and came to Monday's news conference to get answers.
"Of course they don't know," he said with disgust. "It's a maintenance problem, obviously."
Lewis also wonders whether an electrical arc really is an isolated event. "Why can't it happen to the other pipes?"
Sullivan said the damaged portion of the 10-inch pipeline was removed and sent to a third party for examination. He declined to speculate on whether the arc could have come from lightning or whether the pipe could have been sabotaged.
Cleanup crews have been divided into 18 sections, he said, while workers and equipment along the Jordan have been doubled. A yet-to-be-released plan will detail how crews will clean up each section. Additional field personnel also have been dispatched to the most-saturated portions of Red Butte Creek between Sunnyside Avenue and 1100 East.
"We'll be here to see it through to the end," said Sullivan, reiterating Chevron's commitment to scrub the spill and pay for all the damage.
Already, 1,000 barrels of water mixed with oil have been recovered from the Liberty pond and trucked to Chevron's refinery. Scores of blue, 42-gallon barrels also were visible on the perimeter of the pond.
Sullivan estimated the timetable for a complete cleanup "in the order of weeks." He said initial air-quality tests have not found any acute or chronic toxicity levels that can harm people or pets. At the same time, Sullivan cautioned residents not to attempt any cleanup on their own.
Salt Lake County's animal services division now has taken the lead in the cleansing of birds and their release back to the wild, said Rick Graham, the city's director of public services. Graham encouraged residents to contact their vets if they fear their pets suffered exposure to the spill.
Some neighbors criticized Chevron's response. But on Monday morning, several Liberty Park joggers and cyclists had nothing but praise for the company.
"It seems to be a freak accident," said Robert Sandoval, who walks the park daily. "They seem to be working rather quickly."
Stretching on the grass, Anne Warburton took a break from her bike ride to read about the spill in the newspaper. "Yesterday, I was just crying," she said. "But a Chevron guy told me 70 percent has been cleaned up. People who say Chevron didn't act quickly enough -- they're wrong. It doesn't even smell anymore."
Mayor Ralph Becker said city crews are working 12-hour shifts and some around the clock to address the environmental mess. The mayor, along with City Council members Jill Remington Love and J.T. Martin, went door to door in the Yalecrest neighborhood Sunday to answer questions and distribute fliers.
Becker, who has "no idea" yet on a damage price tag, said so far Chevron's response has been "very satisfactory."
He reiterated the oil giant has pledged to take care of the contamination, cleanup and recovery efforts. The mayor also noted city attorneys are meeting to ensure that happens.
"There's been no wavering on that," Becker said. "We'll certainly hold them accountable."
Key officials -- including Becker, his chief of staff, the city attorney, fire chief and multiple council members -- were out of town when news of the leak surfaced. Becker hopped a plane from a mayors conference in Oklahoma City to return Saturday.
"It caught us all," said Councilwoman Jill Remington Love, who noted the event has proven a good test for the capital city's emergency response. "Overall, it's worked"
Love said she has not seen a crisis of this scale in the city since a 1999 tornado.
Sullivan said it is possible that all 33,000 gallons leaked from the quarter-size hole, but questions remain about how long the oil flowed. Chevron didn't learn of the leak until after city emergency crews were notified Saturday shortly before 7 a.m.
Becker said it is not fair to speculate on the exact time of the leak, though he acknowledged oil could have been spilling all night.
Tribune reporters Judy Fahys and Thomas Burr contributed to this story.
"I have been pleased with early reports that indicate Chevron officials are taking the issue very seriously and have responded accordingly. I intend to work with them to ensure that continues."
-- Sen. Orrin Hatch, R-Utah
"My office will be checking this week to see that safety rules were followed. In the meantime, I asked that [Chevron] be open and forthcoming with local officials and the public."
-- Rep. Jim Matheson, D-Utah
"We need to work with Chevron to ensure that the appropriate parties take responsibility and to guarantee that such an incident will never be repeated."
-- Rep. Jason Chaffetz, R-Utah
Chevron spokesman Dan Johnson says the company has fielded 300 calls to its spill hot line and 14 claim requests. No payments have been made.
Any resident wishing to make a claim can contact Chevron at 1-866-752-6340. Information also is available on the city's website at http://www.slcgov.com.