Any accessory shed or other accessory structure shall be built solely to house equipment essential to the operation of the local communication facility and shall be designed, painted, and/or screened by year-round landscaping to blend in with the surrounding environs to the extent possible, as determined by the Planning/Zoning Board. The structure shall be located as close to the antenna support structure as possible and shall not exceed 10 feet in height or 100 square feet in area, unless expressly authorized by the Planning/Zoning Board. Only one such structure shall be permitted per facility user, unless a need is otherwise demonstrated to the Planning/Zoning Board. If feasible, additional land for the equipment needs of future co-locators shall be secured in the purchase/lease of the selected site or be available by lease agreement.