The funds received from the collection of such charges or rentals as hereinafter authorized shall be deposited daily with the Finance Director, and the money so deposited shall be kept in a separate and distinct fund and shall be known as the Sewer Fund, and when appropriated by Council shall be available for payment of the costs and expenses of maintenance, operation, management and repair of the sewer systems, and any surplus in such fund may be used for the payment of the interest of bonds issued and outstanding or which may be issued to provide funds with which to pay the City's portion of the cost of constructing such sewer systems, or part thereofand to retire such bonds when they mature or become callable, and for the enlargement or replacement of the sewer systems . The expense of any extension of the sewer systems into unsewered areas shall be approved in accordance with Section 915.21. (Ord. 47-19. Passed 11-18-19.)