Construction has begun on a six-story, 130,000-square-foot office building in Fairfax County, the third phase of Tyson-McLean Office Park.

The building, scheduled for occupancy in June, will be located at 1500 Tyson-McLean Drive. It shares a 17-acre park with two other buildings that house the headquarters of the Planning Research Corp. and the Farm Credit Administration.

The owner of the project, Tyson-McLean Joint Venture, was formed by the Hazel/Peterson Cos. of Fairfax and Metropolitan Life Insurance Co. of New York.

Omni Construction has signed an $8 million contract with the owner to build the octagonal-shaped structure. The architect is Davis and Carter P.C. of McLean; mechanical/electrical engineering will be performed by Lee Kendrick of Fairfax, and structural engineering will be done by Martin, Cagley and Associates of Rockville.

Other developments in commercial realty in the metropolitan area:

*Arlington Bank has signed a $1 million lease for 6,000 square feet at 1550 Wilson Blvd. in Arlington with the owner of the building, 1550 Wilson Blvd. Partnership Ltd.

*Shared Medical Systems, a Penn.-based data processing firm, signed a multi-year lease worth about $1 million for 9,000 square feet at Tysons Executive Plaza in McLean. COMMERCIAL REALTY Construction Starts On 3d Phase of Tyson-McLean Park

Construction has begun on a six-story, 130,000-square-foot office building in Fairfax County, the third phase of Tyson-McLean Office Park.

The building, scheduled for occupancy in June, will be located at 1500 Tyson-McLean Drive. It shares a 17-acre park with two other buildings that house the headquarters of the Planning Research Corp. and the Farm Credit Administration.

The owner of the project, Tyson-McLean Joint Venture, was formed by the Hazel/Peterson Cos. of Fairfax and Metropolitan Life Insurance Co. of New York.

Omni Construction has signed an $8 million contract with the owner to build the octagonal-shaped structure. The architect is Davis and Carter P.C. of McLean; mechanical/electrical engineering will be performed by Lee Kendrick of Fairfax, and structural engineering will be done by Martin, Cagley and Associates of Rockville.

Other developments in commercial realty in the metropolitan area:

*Arlington Bank has signed a $1 million lease for 6,000 square feet at 1550 Wilson Blvd. in Arlington with the owner of the building, 1550 Wilson Blvd. Partnership Ltd.

*Shared Medical Systems, a Penn.-based data processing firm, signed a multi-year lease worth about $1 million for 9,000 square feet at Tysons Executive Plaza in McLean.