One of the state's biggest oil spills in several years threatened wildlife near the Patuxent River in southern Prince George's County yesterday as cleanup crews worked to contain a leak from a power plant pipe.
Officials of Potomac Electric Power Co. said that the 130,000-gallon spill at the company's Chalk Point Generating Station was contained shortly after it was detected Friday night, but added that restoration of the affected wetlands could take months.
While the pipeline rupture did not send oil into the neighboring Patuxent River, it did foul 45 acres of marshland. Pepco and government officials said cleaning up the swampy terrain will be significantly more difficult than skimming oil from the surface of open water.
Bill Sim, Pepco's group vice president for generation, said, "What you can't see is stuff that gets in among the vegetation. That's what we've got to address."
Pepco officials said damage to wildlife appeared to be limited, but state officials were worried about the consequences of such a large spill in an ecologically valuable area. The area is northeast of Hughesville, around the tiny community of Eagle Harbor, just north of Charles County.
"What they're finding [is] about 25 animals affected, dead or dying -- mostly muskrats. At least one otter," said Susan Woods, a spokeswoman for the Maryland Department of the Environment. "We expect before this is over to find many more -- turtles, snakes, etc. It's a bad thing."
Propane cannons were readied to scare off birds, but wildlife experts said rapidly changing weather and high winds yesterday kept the birds away.
"Anytime you have oil and water in the environment, it is of concern," Woods said. "This is one of the more severe [oil spill] incidents."
The spill, equivalent to 3,000 barrels of oil, is unusually big by area standards. Woods said it was the region's largest "in at least the past four years."
"Typically when we have a spill it's usually a tanker truck or car. We really haven't had pipeline breaks like this," Woods said.
Pepco officials said the accident did not affect operation of the power plant or drinking water.
The cause of the leak was not immediately known. The underground carbon-steel pipeline, which has walls a quarter-inch thick, was inspected two years ago and thought to be in sound condition.
"We know we have it contained. We know we've got it stopped. Now we've got to investigate," Sim said.
The pipeline starts at the ST Services terminal at Piney Point and carries oil to Chalk Point and other area destinations. While Pepco owns the pipeline, ST Services operates it.
Flushing the pipe
Sim said that at the time of the leak, the pipeline was being flushed in preparation for its annual maintenance. The pipeline normally carries a heavy, residual oil. The system was being flushed with a lighter substance, similar to diesel fuel.
About 5 p.m. Friday, Pepco personnel noted that a small pipeline-cleaning device, known as a "pig," was not as far along in the pipeline as it should have been.
Pepco conducted an aerial surveillance and noticed a telltale sheen in the area of the pipeline. The company said it immediately stopped pumping through the pipeline and began putting out booms -- long, shallow plastic foam-and-rubber curtains designed to contain oil slicks. By 8 p.m., the spill was contained, the company said.
Finding the leak
Pepco pumped spilled oil from the area into large mobile storage tanks yesterday. Approximately five miles of booms have been laid out to keep oil from spreading to the river or across more land.
The company will next pump air through the pipeline in order to determine the exact location of the leak.
Pepco, based in Washington, has 700,000 customers in the District of Columbia and in Prince George's and Montgomery counties.
The Chalk Point facility -- where visitors are greeted with a sign reading, "There is no such thing as a little unsafe" -- serves customers from West Virginia to southern Pennsylvania.
Sun staff writer Marcia Myers contributed to this article.