William H. Laverty, of Alexandria, who went undercover to help the U.S. Customs Service stem the flow of narcotics into the United States, has been named one of five recipients of the "Excalibur Award" honoring excellence in federal government service.

Laverty, 38, and two other undercover customs agents received the award last week for their participation in Vice President George Bush's South Florida Task Force, set up to curtail drug traffic into that state. They infiltrated a marijuana smuggling scheme operating out of Colombia.

About 20 federal workers have been honored for outstanding public service since the Excalibur Award was established by Rep. Michael D. Barnes (D-Md.) in 1979.

Laverty moved to Alexandria last fall after being promoted to senior special agent at customs headquarters here.

Other award recipients included Laverty's two customs co-workers, John Gottenborg, of Minneapolis, and Thomas Mitchell, of Glynco, Ga.; Joel Halop, of Barstow, Calif., a Navy Department engineer who invented a new and safe method of removing hazardous asbestos from ships; and Yvonne Cartier, of St. Paul, Minn., a career Internal Revenue Service employe who developed a nationwide program to help people with special needs understand complex federal tax laws.