Two combination office and residential complexes in the Ballston area were approved this week by the Arlington Planning Commission, another step in the redevelopment of the once declining area.

The larger of the projects is a $100 million development proposed by the Oliver T. Carr Co. that includes a one-acre park.

The development, called Stuart Park, is between the Ballston Metro and the new Ballston Common shopping center. It takes up three-fourths of a block facing North Fairfax Drive between North Taylor and North Stuart streets. Plans call for a 15-story office building and a 22-story residential building with 255 units.

The second project, called Quincy Street Station, is made up of an eight-story office building and a 10-story residential building with 202 units on Fairfax Drive between North Randolph and North Quincy streets. The John G. Shooshan Co. is the developer.

When Carr unveiled its proposal last fall, a company official said the county would not be asked for height or density bonuses in exchange for the park. But the proposal submitted to the Planning Commission asked for both height and density bonuses.

The building was made taller and slimmer to increase the acreage available for the park, according to a county staff report. However the park's size still falls short of the 1.5-acre goal the county board has said it wanted for a park.

Thomas A. Carr, the firm's vice president for suburban development, said the additional density would allow the firm to add more office space and compensate for the high expense of building the park. Park plans call for elaborate landscaping and an outdoor dining area.

"The park we've planned is the centerpiece of Ballston," Carr said. "The total cost of the park is $1.6 million. That's $1.3 million over what we typically spend on a plaza."

The commission approved the height bonus but balked at giving a density bonus as well. "How many times are you asking the county to pay for how much park?" asked commission member Carrie Johnson, who added that the county is also being asked to pay a yet-to-be-set annual fee for the park's maintenance.

The height bonus is 30 feet and will raise the office building's height to 200 feet or 15 stories. The standard allowable height in the zoning area is 170 feet, said county planner Ricki L. McKenzie. However, county policy allows the granting of the additional 30 feet if a developer "contributes to a community facility," such as a park, McKenzie said.

Decisions by the Planning Commission are advisory. The projects still must be approved by the Arlington County Board, which is scheduled to consider them July 11.

There was also a dispute over whether the Carr Co. should provide a tunnel from its project to the Ballston Metro station. County Public Works Director Henry S. Hulme Jr. spoke in favor of the requirement, saying "we feel it's important to have as much access to Metro as possible." Hulme estimated the cost of the tunnel to be around $500,000. Carr Co. officials said the cost would be closer to $700,000.

However, the commission, noting that the Carr Co. is providing a park, voted to let the firm make a $100,000 contribution to a county fund to improve pedestrian access to Metro rather than requiring the tunnel.

The plans for Quincy Street Station did not cause as much controversy.

Civic activist Bernard Berne noted that the project site holds four two-story apartment buildings that will be demolished. He asked the commission to find a way to require developers in the future to replace such moderate-cost housing in their projects.

Jonathan C. Kinney, an attorney for the developer, said the tenants in the apartment buildings have been offered generous relocation packages and said the new residential building would be rental housing.

Commissioner Helen Hedges said state codes do not give the county the legal means to require the replacement of such housing.