Construction will begin early next year on Merrifield Plaza, a 254,000-square-foot office complex at the intersection of Lee Highway and Merrilee Drive in Merrifield.

When completed, Merrifield Plaza will consist of two six-story 127,000-square-foot buildings on 5 1/2 acres. The $20 million project is being developed by Weissberg Corp., an Arlington-based developer and builder, and the owner of the land, Lee Madison L.P.

The area of Merrifield, located south of Tysons Corner near Fairfax Hospital, is a mixture of light-industrial and medium-rise office buildings. While Merrifield possesses no true center, a number of major tenants have recently moved into the area, including CACI International Inc., Mobil Corp., Prudential Insurance Co. of America and the Defense Mapping Agency.

"We are excited about this location and our projections indicate the buildings will likely attract many prospective tenants prior to completion," said Richard Gersten, vice-president of Weissberg.

Merrifield Plaza will have a green reflective facade and walls of granite. When completed, the two buildings will be connected on the top floor, according to Susan Goyette, marketing coordinator at Weissberg. The complex will also have four levels of parking.

Weissberg is looking for a large tenant that may want to occupy up to one-third of the space available in each building, Goyette said. "We need to find the right tenant," she said.

Annual lease rates for the project will range from $20 to $22.50 per square foot.

Smallwood, Reynolds, Stewart & Stewart of Atlanta are architects for the project. A general contractor has not yet been named.

Completion of the project is expected in the spring of 1990.

In other developments in commercial realty:

Chevy Chase Federal Savings Bank leased 19,990 square feet at Bethesda Gateway, at 7201 Wisconsin Ave., from Central Properties Inc. Coldwell Banker was the leasing agent.

Decision Sciences Consortium, a risk management firm, leased 16,500 square feet at The Branches Office Park, 1895 Preston White Dr., Reston, from Lee Sammis Associates Inc. Barrueta and Associates Inc. represented the tenant and Coldwell Banker represented the landlord in the transaction.