Workers for Tricon-Triangle Contractors Inc. of Upper Marlboro spent five months last year trucking 24,000 tons of sand and gravel to an industrial park in Landover to serve as the base for the construction of a new Metrobus garage for Prince George's County.

Then they spent the next six months trucking the material back out, after a Metro engineer warned that the garage might crack or sink if it was built on top of the sand and gravel.

The dispute has indefinitely delayed construction of the garage, originally scheduled to open this summer, and the lot is still vacant.

Because of the delay, Metro officials rejected the bids they had solicited for the actual construction of the garage, estimated to cost about $9 million.

"The thing would be well under construction right now if they hadn't had to reject the bid," said Dee Allison, transit administrator for Prince George's County. "It's kind of a disgrace what's been happening out there. It's been a lot of earth-moving that has gone on."

Richard B. Casey, whose firm was awarded a $2.4 million contract to prepare the site, contends that the material was an "ideal" base for the building.

Allison said that Metro employes told her that the material "did not compact to standards" and that, "with the improper fill material, the building would definitely sink."

Casey, who said he plans to sue Metro over the dispute, said he had agreed to replace the sand and gravel with the crushed concrete and other materials called for in the Metro contract.

Metro spokeswoman Marilyn Dicus, citing Casey's lawsuit threats, said Metro officials would not comment on the controversy.

In addition to the $2.4 million fill contract -- of which all but $400,000 has been paid, according to Casey -- Metro has spent $2.2 million to acquire the 19-acre parcel, $817,000 on a design and $105,930 on an environmental impact study.

The future of the bus garage is expected to be considered by the budget committee of the Metro board next month when the staff presents its recommendations on capital improvement projects.

The garage is planned to replace a deteriorating facility in Coral Hills, on the District line.

A 1977 study estimated that the new facility would save Prince George's $1 million annually because the garage would be in a more central location. This will reduce the number of miles that buses need to travel, and thereby cut the subsidy the county pays each year to Metro.

Casey, whose company has worked for Metro on the bus garage near White Flint and the Huntington, Braddock, Shady Grove and Grosvenor subway stations, said he is "finished" with working for the transit authority once the Landover contract is completed. "I wouldn't build a doghouse for them," he said.