WASHINGTON Jan 2 (Reuters) - An Exxon Mobil pipeline spill into the Yellowstone River in 2011 would have been far less severe if the company had not delayed closing valves, a report issued on Wednesday by federal pipeline regulators said.
Exxon's Silvertip pipeline, which carries 40,000 barrels per day of crude in Montana, leaked about 1,500 barrels of oil into the Yellowstone River in July 2011 after the region suffered heavy flooding.
Had Exxon Mobil Pipeline Company's shutdown procedures required remote controlled valves to be closed immediately after a leak, "the crude oil release volume would have been much less," said a U.S. Pipeline and Hazardous Materials Administration report obtained by Reuters on Wednesday.
Controllers closed some valves and pumps 10 minutes after the spill. But workers then waited about 46 minutes before shutting other valves, the report said. If the company had responded faster the spill would have been about two-thirds smaller.
The report said erosion from the flooding exposed the pipeline to debris that severed it and caused the leak. It did not specify fault or express that Exxon violated any safety regulations. A spokesman said the agency was reviewing the report to determine if enforcement actions will be taken.
The Silvertip routinely transports oil sands crude from Canada which environmentalists have said can corrode pipelines. The oil industry has said the petroleum is no more corrosive than other crude transported in pipelines. Exxon has said no Canadian oil was in the line near the area that was affected by the spill.
After the spill, Exxon had installed a new quarter-mile section of the line at least 40 feet under the river.
An Exxon spokeswoman said the company would not comment on the report until it had more time to review and analyze its findings.