Arlington County Fire Chief Robert F. Groshon announced last week that he will retire this summer after spending 23 years in the department, five of them as chief.

Groshon, 50, said he is not leaving because of problems with the job but because he feels after five years an administrator's effectiveness is diminished.

"You do what you can and then move on," he said.

Although he has no definite plans yet, Groshon said he is eager to try a new job, probably training firefighters in rescue and firefighting techniques. He said he may, however, just "go fishing" at his summer home in North Carolina.

After serving in the Chevy Chase, Bethesda and Silver Spring fire departments for eight years, Groshon joined the Arlington department in 1954. He was promoted to lieutenant and was made a training officer in 1961. Two years later he was promoted to captain and in 1966 to battalion chief and chief training officer.

Groshon is leaving under an early retirement program for police and firefighters in Arlington that allows retirement at age 50 with 20 years service.

County Manager W. Vernon Ford said that he will advertise for a Groshon's replacement and hopes to have a new chief inplace by the time Groshon retires on July 7.