Now that about 20,000 deaf youngsters born during the German measles epidemic of 1963-66 have reached college age, their numbers are straining the already limited education facilities for the deaf.

They were victims of the worst outbreak of rubella in U.S. history, which occurred before development of a vaccine to protect pregnant women and their fetuses from the disease and which tripled the number of infants born deaf.

In efforts to handle the increased enrollments expected this fall, Gallaudet College in Northeast Washington, the nation's only liberal arts college for the deaf, is expanding its faculty, classrooms and dormitory capacity.

Gallaudet has acquired and begun renovating the former Marjorie Webster Junior College campus, an 8.7-acre site at 17th Street and Kalmia Road NW.

A federally supported institution sometimes called the "Harvard" of deaf education, Gallaudet enrolls about 1,400 students on its campus at Eighth Street and Florida Avenue NE. But with an unusually large number of applications this year, the college expects to admit about 500 new students this fall--200 more than usual in freshman classes, according to media relations director Donna Chitwood.

"These students are going to require all of the expertise at our disposal," said Chitwood. "In the rubella group an unusually large number of students are multiply handicapped. Ordinarily among the deaf population 25 percent have secondary handicaps; in the rubella group, it's 40 percent."

"In addition to the new physical plant, we are expanding existing programs. We are in the process of hiring more faculty and a new dean has been named to head up the northwest campus," Chitwood said. "Even with these changes, qualified students will be turned away."

Gallaudet and the National Technical Institute for the Deaf, a branch of Rochester Institute of Technology, are the "only two national programs that can gear up for the increased student population," said William Castle, director of the school, located in Rochester, N.Y. He said the institute, which usually enrolls about 350 students but expects 600 this fall, also has been preparing for the influx of rubella victims.

The Webster junior college, a finishing school for women, was established in 1920 and closed in 1971 because of low enrollment. The site has four two-story residences and two other large buildings that house dormitory rooms, classrooms and offices, as well as kitchen and dining facilities, a media center, gymnasium and swimming pool.

Renovation of the northwest campus, as it is called, will cost an estimated $6 million to $8 million. The renovations will include painting, upgrading plumbing and wiring systems, installing central air conditioning, and making specific modifications such as ramps to accommodate the rubella students. The work is scheduled to be finished in August.

Ann Davidson, head of Gallaudet's biology department and director of the associate of arts degree program, has been named dean of the School of Preparatory Studies, the official name for the Webster addition.

About 60 to 70 percent of the students admitted to Gallaudet need preparatory studies. The new facility will provide a year of intensive instruction in basic skills, particularly mathematics and English, for these students, who need extra help before they move to the main campus as freshmen.

Webster was the focus of intense controversy and legal actions during the 1970s when it was owned by the private University Research Corporation, which attempted to use the campus for various training programs and to lease portions of it to other schools.

Neighborhood groups sued to halt the firm's attempts to expand and modify the site, arguing that the new uses would create more traffic and noise in the neighborhood. One suit sought to prevent the training of drug counselors there. The case went to the U.S. Supreme Court, which ruled in September 1973 that a D.C. zoning ordinance bars the use of the land except as the site for a small college.

The Webster campus was used for several months in 1973-74 by the Cortez-Peters Business School, a small, black-owned institution that folded after losing its accreditation.

University Research Corporation eventually sold the property to the federal government, which planned to use it as a training academy for the U.S. Fire Administration, a federal agency created in the early '70s to set national standards for fire control and safety. But the fire administration found the Webster facility inadequate for its needs. Congress granted, but later rescinded, authorization for resale of the campus, before deciding to transfer it to Gallaudet in 1982.

The transfer made "a great deal of common sense," Gallaudet President Edward C. Merrill Jr. said.

"Gallaudet is the national college of deaf persons, and it responds to the needs of deaf people through instruction, research and service," Merrill said. "If the mission of the institution is to be pursued in the future, decisions have to be made now which will permit growth and development to parallel the society in general."