* Transportation Dept would study burying pipelines deeper
* Bill would boost fines for pipeline safety violations
* Full House committee to vote on bill after summer recess
By Tom Doggett
WASHINGTON, July 27 (Reuters) - U.S. oil pipelines could be required to be buried deeper when crossing waterways to avoid the kind of leak that polluted the Yellowstone River this month, under a bill approved by a congressional panel on Wednesday.
Pipeline safety has becoming a bigger priority in Congress after Exxon Mobil's (XOM.N) Silvertip pipeline ruptured earlier this month and spilled an estimated 1,000 barrels of oil where it crossed the Yellowstone River in Montana.
The legislation cleared by the House Energy and Power Subcommittee on Wednesday calls on the Transportation Department to determine within one year whether current regulations for pipelines crossing waterways wider than 100 feet (30 meters) are adequate.
Current federal safety rules say pipelines crossing rivers must be buried at least 4 feet under the riverbed or just 18 inches if rock has to be blasted.
Exxon said it plans to replace the section of the Silvertip line that leaked and bury it 30 feet under the Yellowstone River.
The legislation now goes to the full House Energy and Commerce Subcommittee, which is expected to vote on the bill after lawmakers return in September from their summer recess.
"The bill demands improvements in both technology and personnel that can help prevent leaks from occurring in the first place and reduce the damage if they do," said Representative Fred Upton, who heads the full committee.
The House bill is similar to pipeline safety legislation in the Senate, except the Senate bill does not have language on burying pipelines deeper under rivers.
Both bills would raise fines for safety violations from $100,000 a day to $250,000, and from $1 million for a series of pipeline violations to $2.5 million.
They would also require automatic or remote-controlled shut-off valves to prevent oil spills and natural gas explosions, require faster notification to the government of pipeline accidents and leaks and hire more federal pipeline inspectors.
The United States has about 2.5 million miles (4 million km) of pipelines that move oil, natural gas and other hazardous liquids. The death toll from pipeline safety accidents increased from nine in 2008 to 13 in 2009 and reached 22 last year.
Reporting by Tom Doggett; Editing by Lisa Shumaker