Upon the acceptance of a bid for any such improvement, the bidder shall, without unnecessary delay, and within thirty (30) days from the acceptance of his bid, enter into contract with the urban county government for such work in accordance with the ordinances and specifications therefor, and shall execute to the urban county government a bond in a sum equal to thirty (30) percent of the total amount of his bid as estimated by the urban county engineer, with some solvent guarantee company authorized to do business in the state as surety, for the full, complete and faithful performance of the contract in every respect, and that the bidder will indemnify the urban county government against any and all loss or damage it may sustain by reason of any injury to persons or property resulting from negligence, carelessness or other act of the contractor, his agent or employees, in the execution of the work as required by the ordinance therefor. If any damage suits are brought against the urban county government for any such injury to persons or property, the contractor shall, immediately upon receipt of notice from the urban county government of such suit, assume the defense of same and bear all expense thereof and satisfy any judgment which may be obtained therein against the urban county government. Such bond shall guarantee the work for a period of five (5) years from completion and acceptance thereof against all defects occurring therein by reason of defective workmanship or material, and that the contractor will at his own expense repair all such defects occurring in such work within such periods; and it shall be a further condition of the contract and bond that if the contractor fails to make any such repairs within twenty (20) days after notice from the urban county government, delivered to him at his last-known address, the urban county government may make such repairs and charge the cost of same to the contractor; and his bondsmen shall be liable to the urban county government for the cost of such repairs.