A power outage at Shenango Inc. coke works on Neville Island has caused the discharge of oil into the Ohio River.

The company estimated that between 25 and 40 gallons of wash oil had found its way into the river from a broken cooling system line, creating a sheen that stretched the 5-mile length of the industrial island.

The power outage, which lasted from 1:55 p.m. to 3:35 p.m. yesterday, shut down Shenango's coke making operation and resulted in the leaking pipe, said Jim Birsic, Shenago's vice president for health, safety and environmental law.

"When the power came back on a surge of pressure blew out part of the line in the wash oil cooling system," Mr. Birsic said. "We discovered the leak at about 4:45 p.m. By then it had gone into the sewer system and into the river."

The coking company called McCutcheon Enterprises Inc., of Apollo, to do the cleanup.

Shenango employs about 165 people. Its 56 coke batteries produce about 360,000 tons of coke a year.