In Area F, any #development# on a #zoning lot# with a minimum area of 20,000 square feet shall be eligible for a #floor area# bonus at the rate of one square foot of #floor area# for every two square feet of usable open space. The minimum size of such usable open space on a #zoning lot# shall be 5,000 square feet with a minimum dimension of 50 feet. The usable open space shall be suitably maintained and shall contain landscaping, planting, lighting, sitting areas and, where appropriate, play areas for children. Such usable space shall be located no more than two feet below or five feet above the #curb level#. No portion of the usable open space shall be provided within 30 feet of the Leif Ericson Drive service road, and no portion of the usable open space shall be used for parking or driveways.