Ballston’s 1.68 acre Mosaic Park will get a $6.6 million upgrade, paid for by the company behind the nearby Founders Square development.

On Saturday the county board approved a transfer of development rights from the park to the new development, adjacent to Ballston Common Mall.

As a result, Founders Square will now be taller and denser than before. A 15-story office building will become a 20-story office building, a 198-unit residential building will become a 257-unit residential building, and a 164-unit residential building will become a 183-unit hotel.

In exchange, the Shooshan Company, which is developing Founders Square at the corner of Wilson Boulevard and North Randolph Street, will pay $6.6 million for improvements to Mosaic Park, which is now a mostly empty field with some playground equipment.

“Our action today will help realize a long term County goal to provide a high-quality neighborhood park in Ballston,” County Board Chairman Chris Zimmerman said in a statement. “By trading density from the park to Founders Square, the County has secured more than $6 million from the developer that will be used for improvements to Mosaic Park that will benefit the community.”