Section 15-9-111 - When plan modifiable and effective(a) An urban renewal plan may be modified at any time. If a plan is modified after the lease or sale by the municipality of real property in the urban renewal project area, the modification may be conditioned upon the approval of the owner, lessee or successor in interest as the municipality deems advisable. The modification is subject to any rights at law or in equity as a lessee or purchaser, or his successor or successors in interest, are entitled to assert. (b) Upon the approval by a municipality of an urban renewal plan or of any modification thereof, the plan or modification is deemed to be in full force and effect, and the municipality may then cause the plan or modification to be carried out in accordance with its terms.