In order that the chief engineer may make immediate cash payment to laborers and in other instances where, in his or her judgment, it is advantageous or necessary for the conducting of the work supervised by the chief engineer to make such payments, the state treasurer shall deposit in a bank in the city and county of Denver, Colorado, from the state highway fund, the sum of twenty-five thousand dollars, which must be made payable upon order of the chief engineer in the form of a voucher check, the voucher to show to whom and for what payment is made. A duplicate of all such vouchers shall be retained in the office of the chief engineer. An amount equal to the checks returned and found in proper form shall thereupon be deposited by the state treasurer to the credit of such special fund from the state highway fund. Voucher checks drawn upon the special fund shall not be used to pay salaries of officers or regular employees of the department.