In any district where such a specified community facility use is permitted, and on any zoning lot where one or more buildings occupied by such use exist on the date of application for the special permit, the Board of Standards and Appeals may permit development or enlargements which, only because of the continued existence of such buildings on a temporary basis, fail to comply with one or more of the applicable district bulk regulations, provided that the Board finds that continued use of the existing buildings is essential as a service to the community until the new construction makes it possible to replace the facilities contained therein.

The Board shall prescribe as a condition of such permit that such existing buildings will be removed within a stated period of time not to exceed two years after completion of the development or enlargement.