LITTLE ROCK — It may be a while before federal regulators are ready to approve restarting the oil ExxonMobil pipeline that ruptured in March, spilling thousands of gallons of crude oil into a Mayflower neighborhood, the former head of the federal pipeline regulatory agency said Tuesday.

Brigham McCown, who once led the Pipeline and Hazardous Materials Safety Administration, said he has been to the oil spill site twice and spoken to a number of officials at the federal agency.

"They told me this line is not going to be restarted until the federal government is fully satisfied that it’s safe, and that may take a while," he said during a speech at the Clinton School of Public Service.

McCown also said people should not jump to any conclusions about the cause of the spill or whether it will have long-term effects until the federal investigation is complete.

Exxon’s Pegasus pipeline ruptured in Mayflower on March 29, releasing an estimated 147,000 gallons of oil. The company has provided financial relief to 66 families in the neighborhood, about a third of whom had to leave their homes after the spill. Three of the families have been able to return home.

Some local and federal elected officials have accused the company of being less than forthcoming with information about spill and the condition of the pipeline, and some have called on the company to move the pipeline from the Lake Maumelle Watershed, which provides drinking water to much of Central Arkansas.

McCown said federal investigators "are looking through voluminous data to determine exactly what caused that incident and how it can be prevented in the future."

"I believe … it’s important not to rush to judgment," he said. "The investigation process is comprehensive and deliberative, and deliberately slow in order to arrive at a root cause analysis. If done correctly, it will result in lessons learned that can be applied to the future."

McCown said early indications were that the pipeline "experienced an upset, triggered by a seam crack."

"What nobody knows is exactly why," he said. "Caution and restraint should remain the watch words."

During his speech, McCown, a proponent of the controversial the Keystone XL pipeline project, said federal regulations are key in making pipeline safety in the United States the best in the world. He also discounted criticism that aging pipelines that crisscross the country are a risk to the public and environment because some are 50 years or older.

"Pipelines aren’t actually gallons of milk with expiration dates stamped on them," he said. "A correctly installed, well maintained pipeline can function safely for an indefinite period of time. Inspections are important for determining if problems do exist and if they do, making sure the changes are made to correct any deficiencies."

After the speech, the Little Rock Mayor Mark Stodola asked McCown if there is a way to determine if the same type of leak that occurred in Mayflower could occur somewhere else in the Lake Maumelle Watershed.

McCown said the same type of pipe used in the Pegasus pipeline is in use "everywhere in the country today" and makes up about 40 percent of all transmission pipelines.

A device known as a "pig" was run through the Mayflower section of the pipeline within the past year looking for potential problems and found none, he said. However, more advanced inspections tools, such as ultrasonic, are available and can find circumference cracks as well as longitudinal cracks, like the one found at Mayflower, he said.

The problem, McCown said, is that those inspections gather a lot of data and it takes too long — nine months or more — for all data to be analyzed. That time period must be shortened, he said.

"I’m still waiting for the investigation to come out" on what caused the Mayflower rupture, he said. "The other piece the jury is still out on is, even though there was a seam weld that gave way, we still don’t know what caused that and whether or not it was related to the manufacturer of the pipeline,. the operation of the pipeline or some other third party. Until we have those facts, I’m kind of withholding judgment on what really happened."