The public works director, or its city engineer, has determined that the average total suspended solids (TSS) and five-day biochemical oxygen demand (BOD) daily loadings for the average residential customer are two hundred fifty (250) ppm BOD and two hundred fifty (250) ppm TSS. The public works director, or its city engineer, has assessed a surcharge rate for all nonresidential customers discharging wastes with BOD and TSS strengths greater than the average residential customer. The surcharge will be sufficient to cover the costs of treating such customers' above-normal strength wastes. Such customers will pay an additional service charge of twenty-five cents ($0.25) per one thousand (1,000) gallons for each twenty-five (25) ppm over two hundred fifty (250) ppm of BOD and twenty-five cents ($0.25) per one thousand (1,000) gallons for each twenty-five (25) ppm over two hundred fifty (250) ppm TSS. (Ord. 603 (part), 2004)