The Underground Construction Co. of Virginia, a McLean firm, has agreed to pay a $2,500 fine for a safety code violation on a sewer construction site in Reston.

The firm had been cited several times for constructing a 15-foot-deep unshored trench at the Sperry-Rand construction site in Reston. Under federal regulations set by the Occupational Safety and Health Administration, builders are not permitted to work in trenches deeper than five feet without shoring or sloping.

No trench-related injuries were reported at the Underground Construction site.

Two months ago a Harpers Ferry man was killed on a construction site in southern Fairfax County when an unshored trench caved in on him. Virginia safety officials have proposed a fine of more than $6,000 against the William B. Hopke Construction Co. in that case -- the highest such fine on record in the state. The maximum allowable fine is $10,000.

Richard Raeon, an attorney representing Underground, said the firm had agreed to pay the $2,500 fine with the understanding that the fine could be reduced after state scrutiny of the firm's financial condition. State safety officials had originally proposed a $3,500 fine against Underground, which the year-old firm had fought on grounds of financial hardship.

A spokeswoman for the firm told a reporter last week that Underground was averaging $38,000 to $40,000 a month in profits. "We're doing very well," said Louise Alsip, the firm's comptroller.