The user charge system shall be based or actual use of the city's wastewater treatment facilities. Each user (user class) shall pay his proportionate share of operation, maintenance and replacement expenses based upon his estimated (actual) contribution to the flow volume and loading of the plant, thereby assuring the fiscal self-sufficiency of the facility over its useful (design) life. The user charge system shall include the following sections 10-1-4-5 through 10-1-4-27 of this chapter. (Ord. 453, 11-29-1990; amd. 2001 Code)