Provisions satisfactory to the Planning Board shall be made with respect to the ownership, use, preservation, maintenance and operation of all open space, roadways and other common facilities on the overall site. Responsibility for all private common facilities shall be lodged with one or more condominium or property owners' associations, or similar entities, which shall be empowered to levy assessments against property owners to defray the cost of preservation, maintenance and operation and to acquire liens, where necessary, against property owners for unpaid charges or assessments. The Planning Board may require the establishment of a single "umbrella" entity for the overall site if there are open spaces, roadways or other common facilities that are intended for the shared use of the entire site. If the Planning Board determines that such shared facilities are not significant or that an umbrella entity is not required for proper administration, the Planning Board may instead make appropriate requirements, in the form of easements or otherwise, to ensure proper administration.