The pipeline that spilled 20,000 gallons of diesel fuel near the Bear River Migratory Bird Refuge in Utah failed a stress test Monday.
That test, ordered by the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration, must be successfully completed before Chevron Pipe Line Co. can put the 60-year-old line back into full service. But when the company spiked the water pressure to about 2,606 pounds per square inch (psi), the pipe failed after about six minutes.
What caused the pipe to fail in a stretch between Ogden and Willard Bay, Chevron spokesman Gareth Johnstone said, "is still being investigated at this point."
John Whitehead, Utah Division of Water Quality assistant director, said the company and government authorities will discuss the test results and what should happen next on Tuesday.
"We're keenly interested in the pipeline's integrity," said Whitehead, whose agency has issued Chevron a notice of violation for the March 18 spill.
A preliminary investigation determined a 6-foot pipe section split open just outside the Willard Bay State Park's North Marina parking lot. The diesel leaked into the soil and drainage ditches and eventually found its way into the reservoir that draws picnickers and campers to the popular recreation spot.
The biggest casualties have been six sickened beavers whose lodges helped slow the diesel's flow, plus a few dead fish and birds. Water in the reservoir has been mildly contaminated, but not to a level that has water officials concerned.
The North Marina has remained closed while Chevron continues cleaning up the leak.
The pipeline is 760 miles long. It was built between 1949 and 1952 to deliver petroleum products from the five Salt Lake-area refineries to Idaho and Spokane. For the past few weeks, it has been operating at 80 percent of normal pressure.
An integrity-testing plan ordered by the federal pipeline oversight agency has strict requirements. The company must clean the petroleum product out of the pipe and pump water in.
Then it gradually increases pressure, lingering at certain levels for certain periods of time.
In this case, the pipe failed six minutes into the maximum required pressure. To pass the test, the pipe would have had to hold that pressure for 30 minutes, according to the federal agency's protocol. And after the spike, the pipe would have been tested at around 2,395 psi for eight hours. Normal pressure is about 1,870 psi.
Since the pipe was being tested Monday with clean water along a 24-mile section, there's little concern about any leaking during the test, Whitehead said.
"It's a good thing in a way," Whitehead said of the failure during testing. "If there's a weak section, we want to know about it."
Johnstone noted the stress the pipe was enduring at the time it broke was very close to the maximum pressure it was designed to endure. "It's too early to say" how long it will be before the pipe can be retested.