Conn. Gen. Stat. § 13a-109

The commissioner or any municipality or other person who has performed any work on any bridge for a portion of the cost of which any other municipality or person is liable shall, within thirty days after the completion of such work, mail to each person liable for a portion of the cost of such work a statement of the total cost of such work, showing the proportionate share assessed against each interested party, and such amount assessed against each interested party shall thereupon become due and, if not paid within thirty days, shall bear interest at the rate of six per cent per annum and shall be collectible in an action at law brought to the superior court for the judicial district wherein such bridge is located.