The land on 535 Union Avenue (Parcel ID 101-52-8023-000), the current site of the Callahan Center, and other properties that may be developed for this use, shall be used exclusively as a senior center, unless approved to change by the Mayor upon the recommendation of the Council on Aging as well as a two-thirds vote of the City Council. Short-term use (a single meeting or repetitive activity lasting no longer than 30 days, such as a class or workshop, etc.) of the Callahan Center, as well as any other properties that may be developed for this use, for other purposes may be authorized by the Mayor upon that recommendation by a majority vote of the Council on Aging. In the event of an emergency in the community where time is of the essence, the Mayor or the Mayor's designee, in their discretion, may authorize the use of the Callahan Center, or other properties developed for the same use, for up to 72 hours to assist in managing said emergency in consultation with the Council on Aging Chair and/or the Emergency Management Director, as appropriate.