Any such conveyance, contract, lease or other disposition authorized by Section 59-1-19 of any or all such lands described in Section 59-1-17 may be made upon such terms and conditions and for such consideration as may be found to be adequate by the port commission, and approved by the city, in orders or resolutions authorizing same, and the covenants and obligations of the lessee or grantee to make expenditures in determined amounts, and within such time or times, for improvements to be erected on the land, by such lessee or grantee, and to conduct thereon industrial operations in such aggregate payroll amounts and for such period of time or times as may be determined and defined in such lease, deed or other disposition, shall constitute and be deemed sufficient consideration for the execution of any such conveyance, lease, contract or other disposition. Any such instrument shall, however, contain reasonable provisions for the termination of the lease or revision of title to the land, but, unless otherwise agreed to, not the improvements of grantee or lessee, in the event of default on the part of the lessee or grantee of his or its obligations or covenants under any such agreement.