The areawide trend to condominium conversion continues in Alexandria, where two fully occupied, moderate-to-expensive rental complexes are slated to go next.

Documents have been filed with the Virginia Real Estate Commission in Richmonmd for permission to convert the 283-unit, high-rise Marina Towers on the northern Old Town waterfront and the 263-unit Canterbury Square garden apartment complex at 5201 Duke St. In both cases, tenants have been told by the developers that there will be aid for those who wish to relocate elsewhere.

Jim Comparato, who heads Marina Towers Inc., the developing firm, said the 13-year-old Marina Towers apartments would be offered at prices ranging from $49,000 for efficiencies to $130,000 for three-bedroom units (with good views).

Comparato said the Marina development plan includes setting aside 53 rental units for elderly and handicapped tenants who may continue to rent for five years at prices within 12 percent of the current rent, but with a pass-through provision for any tax or assessment increases. Units not taken by older persons will be allocated to other current tenants on the basis of seniority.

The relocation plan allows for paying $300 to $420 to tenants who decide to move, or 50 percent more than that if they stay until their units are sold.

For tenants who elect to buy their apartments at Marina, Comparato cited discounts of 15 to 19 percent off prices offered the general public. He said 63 tenants already have made preliminary $1,000 deposits toward purchasing their apartments.

Comparato bought the Marina building two years ago from Chase Manhattan Bank. He recently acquired separately the six acres on which the building stands from Slater and Jacqueline Lamont. The waterfront building was built by Washington developers Alan Kay and Allan (Buddy) Rozansky.

A member of a Rochester, N.Y., family involved in realty investments and development for two generations, Comparato recently moved his family to the McLean area. His interests in Virginia include shopping centers near Lake Barcroft and Richmond and a small group of townhouses in Alexandria.

At Marina Towers, tenant association president James Moody said that "the developer sincerely wants to work with us." Depending on interest rates, which have not yet been set, Moody said he plans to buy the apartment he and his wife now occupy. He said the "as-is" price is about $73,000 for the two-bedroom unit, which they are renting for $520 a month.

Carol McCracken, former tenant association president and now a member of Alexandria's tenant-landlord review board, said she will be unable to buy the one-bedroom apartment she occupies. While McCracken was president of the Marina tenant group last year, she led tenant opposition to rent increases that some tenants considered unreasonable and higher than the 12 percent voluntary guidelines legislated in Alexandria.

WMAL disk jockey Tom Gauger, a bachelor who lived 3 1/2 years at Marina, she he moved out recently because he chose not to buy the two-bedroom unit he had rented for $520 a month. His apartment would sell for about $100,000, he said, and he and he ended up buying a fairly new townhouse in Southwest Washington for about $80,000. Gauger said he did not feel his rent at Marina was unreasonable, "considering the fabulous waterfront view."

Rep. Manuel Lujan (R-N.M.) who has rented at Marina Towers for two years, said he was not seriously concerned by the plan to go condo but would reserve his decision about buying until mortgage rates are determined. Lujan said he would prefer to remain a tenant at $565 a month. Currently, rates for mortgages on condo purchases range above 16 percent Rep. Ron Marlene (R-Mont.) and Elwood Hilis (R-Ind.) also rent in the building.

At Canterbury Square, meanwhile, the conversion will be unusual, in that builder-owner Melvin J. Berman will have a major role along with consultant-developer Albert C. Schneider. Berman said he chose to remain as a developer because of his long association with the 16-year-old complex.

Most owners have sold their buildings to developers planning conversion, in order to take a long-term capital gain. Berman said the sale to Canterbury Square Development Corp. is expected to provide capital-gain status for himself while also enabling him to be "active at both ends of the process."

At the seven-building Canterbury Square complex, where rents range from $365 to $400, residents were told that they will receive discounts of $6,000 to $12,000 off public purchase prices. Senior citizens and severely handicapped tenants will get an additional $1,500 discount.

Canterbury's prices to the public will range from about $45,000 for efficiencies to $70,000 for three bedrooms. A few tenants also will be given long-term leases, and others who decide not to purchase or to remain as tenants will be given financial assistant for relocations. Berman said the Alexandria landlord-tenant board gave Canterbury a commendation for exceeding voluntary guidelines to aid tenant-buyers and those who move out. Lewis & Silverman will handle sales at Canterbury.

In Arlington County, an affiliate of Potomac Investment Associates called Cardinal House Associates Inc. has signed a contract to purchase the 232-unit Cardinal House apartment complex on Spout Run Parkway in Arlington. The four-wing building, built in 1959, will be converted to condominium ownership, according to letters mailed recently to tenants.

Under Arlington County guidelines, Cardinal House tenants have been promised discount prices, a special rental program and monetary assistance in moving.

In Montgomery County, First Condominium Development Co. of Chicago this spring inauguarated an "early-intention" purchase program and three-year rental-continuance plan for elderly tenants at the high-rise Willoughby in Friendship Heights. This week First Comdominium reported that 458 residents of the 814-unit complex have put down $500 each to make reservations to buy at established prices, and 120 elderly tenants have taken advantage of the rental plan.

Also, the Willoughby developer said nearly 1,200 outsiders have indicated interest in buying the 236 apartments not reserved for present tenants. It had been announced earlier that the new owernship of the Willoughby did not plan to begin settlements on condo ownerships until next Feburary, anticipating lower mortgages rates then. Willoughby prices to tenants range from about $26,000 to $141,900. CAPTION: Picture 1, Marina Towers on the waterfront in Alexandria, is going condominium. Picture 2, Prices for outside buyers at Canterbury Square will range from $45,000 to $70,000. By Douglas Chevalier -- The Washington Post