The town of Somerset last week agreed to a method proposed by the Metro transit authority to clean up oil that leaked from a bus garage in Northwest Washington into the Little Falls Branch creek from the mid-1970s to 1981.

Metro's proposal was one of the settlement terms of a suit filed in U.S. District Court against Metro by the town, civic organizations and the Mazza Gallerie shopping mall at Wisconsin and Western avenues NW.

Oil from the garage ran off into storm drains that emptied into the creek. Documents from the Maryland Water Resource Administration, which were filed in the case, said Metro also dumped diesel fuel-tainted water into the creek without a permit.

The cleanup, devised by Engineering Science, a Fairfax environmental consulting firm, involves blocking off portions of a half-mile stretch of stream bank that has oil in the sand. A water jet will be used to stir up the sand and separate it from the oil, said Roger Hassett, senior utilities engineer for Metro.

Workers will soak up the oil with absorbent blankets, similar to those used on large-scale oil spills. The water jet is a novel approach to oil cleanups, Hassett said.

Hassett said Metro could not estimate the cost of cleaning up the creek because the approach is so new. He said he hopes to complete the work in several weeks.

Metro already has taken many steps as part of the settlement to prevent more oil from flowing into storm drains, said Ralph Smith, director of general maintenance for Metro. He said workers have cleaned the drains, retrieved oil that drained into the parking garage at nearby Mazza Gallerie and added oil separators in the Metro garage to prevent oil from reaching storm drains.

Smith said Metro's garage currently is being renovated, and the slope of the bus parking area is being changed to prevent drainage of oil into the street.

"We've taken all the action we can to prevent drainage. The only thing that's left is the stream bed restoration itself," Smith said.

Metro attorney Frank Filiatreau, who handled the suit, could not estimate the total cost of the lawsuit to Metro, except that it was "substantial."

Metro has hired Engineering Science to study all the Metro bus sites to prevent further problems, Hassett said.