Two week-long camps for elderly Washington-area residents, particularly those unable to afford vacations, will be held in July in Potomac, Md.

The summer camps, sponsored by SOME (So Others Might Eat), will be July 7-11 and July 14-18 at Mercy Center on Kentsdale Drive, the former retreat house of the Catholic Sisters of Mercy. The sisters are underwriting part of the cost of the SOME sessions, each of which has room for 45 participants.

SOME, a 10-year-old nonprofit ecumenical group at 71 O Street NW, started the camp because "our seniors say they rarely if ever have an opportunity to go on a summer vacation or get out of the city for any length of time," said Sister Becky Gaba, a SOME staff member.

The center, on several hundred acres of woodland, has a swimming pool, gym and recreation rooms as well as bedrooms and a dining room, she said. "Films, arts and crafts, music and just plain relaxation will be offered."

More than 40 elderly residents already have signed up for the two five-day sessions. Reservations, which can be make by telephoning SOME at 797-8806, closes July 2 for the first week and July 8 for the second week.

Participants are asked to donate onlywhat they can afford toward the $10 a day costs of the camp, Sister Gaba said. SOME also wanted to offer camping the last two weeks of July "but lack of funds have forced us to limit it to two weeks," she said. "SOME was unable to get city or private funds for the camp.