The Justice Department asked a U.S. district judge yesterday to impose sanctions on the District for its failure to improve conditions at Forest Haven, a Laurel facility for mentally retarded adults.

The 35-page petition alleges that Forest Haven officials have ignored three consent orders to provide adequate medical care and services at the facility, and that residents have been subjected to "harmful and dangerous conditions."

In April, U.S. District Judge John H. Pratt handed down an order that requires the D.C. government to gradually move the estimated 230 Forest Haven residents to privately operated facilities by October 1991 or face fines of $10,000 plus $100 a day per resident. The city so far has met that schedule, the petition said.

But the petition alleges that medical care is inadequate to the point of being needlessly life-threatening to residents; that residents are neglected by staff members and are not given adequate therapy; that staff members are inadequately trained; and that the facility is not being properly maintained.

The petition did not specify what sanctions should be imposed. Officials of the Department of Human Services, which administers the facility, could not be reached for comment.

The Justice Department's petition quoted Regina Yando, a doctor who toured the facility in June, as being distressed at seeing "at least four residents who had stick-like arms and legs . . . . The lack of muscle on their frames was reminiscent of posters of starving children from underdeveloped countries."

Between May 1989 and January of this year, eight residents died at the facility. The circumstances of those deaths have never been made public.