The board shall have the power and it shall be its duty, by resolution to establish and maintain just and equitable charges and rentals as the case may be, for the use of such athletic establishment, and may readjust, amend and modify such charges and rentals from time to time. Such charges and rentals shall be in such amounts that the total thereof shall be at least sufficient in each year for the payment of the proper and reasonable expenses of operation, repair, replacements and maintenance of the athletic establishment, and for the payment of the sums herein required to be paid into the sinking fund. A schedule of the charges and rentals so established shall be kept on file in the office of the board issuing such bonds and also in the office of the committee having charge of the operation of such athletic establishment, if there be such committee.