The State of Virginia asked a federal court in Alexandria yesterday to reject a dual wage scale that the Labor Department has imposed on construction of Interstate Rte. 66 inside the Capital Beltway.

Under a department ruling, Virginia is required to pay a sharply higher wage to workers preparing a culvert in the highway's median strip for possible Metrorail use than it is paying workers on the highway.

The ruling will add $4 million to costs of the highway project, said Virginia Attorney General J. Marshall Coleman at an Arlington press conference yesterday. "It's a classic case of federal bureaucrats making an arbitrary decision that creates a hardship on the taxpayers of Virginia," he said.

The Labor Department's wage appeals board ruled recently that work on the culvert located in the highway's median strip should be classed as "heavy construction" and paid at a rate higher than for highway construction in the state. The ruling means that unskilled laborers would be paid $9.68 an hour for working on the culvert instead of the $4.50 an hour workers on the highway earn, Coleman said.

Virginia authorities have insisted that all workers on the project should be paid at the lower scale. Coleman said the wage ruling will cost the state $400,000, since the federal government pays 90 percent of the highway's costs.