(A) (1) Users of the city wastewater treatment works shall be identified as belonging to one of the following classes:
(a) Residential;
(b) Commercial;
(c) Industrial;
(d) Institutional; and
(e) Governmental.
(2) The allocation of users to these categories for the purpose of assessing user charges and debt service charges shall be the responsibility of the City Administrator-Treasurer. Allocation of users to user classes shall be based on the substantive intent of the definitions of these classes contained herein.
(B) Each user shall pay operation, maintenance and replacement costs in proportion to the user’s proportionate contribution of wastewater flows and loadings to the treatment plant, with the minimum rate for loading of BOD and TSS being the rate established for concentrations of 250 mg/l and 250 mg/l TSS (that is, Normal domestic strength wastewater). Those “industrial users” discharging segregated “normal domestic strength wastewater” only, can be classified as “commercial users” for the purpose of rate determination.
(C) User charges for normal domestic strength users.
(1) Calculating billable flows and loadings; measurement of wastewater volume. The charges assessed residential users and those users of other classes discharging “normal domestic strength wastewater” shall be established proportionately according to billable wastewater volume. Billable wastewater volume shall be calculated as follows:
(a) Residential users. Billable wastewater volume for residential users shall be calculated on the basis of metered water usage. The per monthly billable wastewater volume shall be equal to monthly metered water usage as averaged between the first and last months of the calendar year. The city may require residential users to install water meters for the purpose of determining billable wastewater volume.
(b) Nonresidential users.
1. The billable wastewater volume of nonresidential users may be determined in the same manner as for residential users. Except that if the city determines that there are significant variations in the metered water usage of nonresidential users resulting in a proportionate increase in wastewater volume; then billable wastewater volume shall be:
2. Calculated on the basis of monthly metered water usage as recorded throughout the year, or calculated on the basis of wastewater flow meters.
3. The city may, at its discretion, require nonresidential users to install such additional water meters of wastewater flow meters as may be necessary to determine billable wastewater volume.
4. Determination of loadings from metered water usage: the billable amounts of BOD and TSS will be calculated from the volume of metered water usage, as determined above; where the billable quantities will be those attributable to wastewater at a concentration of 250 mg/1 BOD and 250 mg/l TSS (i.e., “normal domestic strength wastewater”).
(2) Determination of user charges for normal domestic strength users. User charges for normal domestic strength users shall be determined as follows:
(a) Calculation of unit costs for treatment of normal domestic strength wastewater:
Un | = | Comr Tbwv | |
Where: | Un | = | Unit cost for operation, maintenance and replacement to treat normal domestic strength: in accordance with Chapter 53 |
Comr | = | (Total annual OM & R costs) - charge collected to treat concentrations greater than normal domestic strength | |
Tbwv | = | Total annual billable wastewater volume in kgal |
(b) Calculation of user charge for normal domestic strength wastewater:
Uc | = | UN x bwv | |
Where: | Uc | = | User charge |
Un | = | Unit cost for operation, maintenance and replacement to treat normal domestic strength, in $/kgal | |
bwv | = | Billable wastewater volume of a particular user in kgal |
(D) User charges for users discharging wastes with concentrations greater than normal domestic strength:
(1) Calculating billable flows and loadings.
(a) Calculation of billable flows. The billable amount of flow will be calculated from the volume of metered water usage, or at the discretion of the city, from the measurement of effluent flow at user’s point of discharge. Measurements shall be according to a regular program prescribed by the city.
(b) Calculation of billable loadings.
1. The billable amounts of BOD and TSS will be calculated by the measurement of these wastes according to a program prescribed by the city in keeping with the latest edition of Standard Methods for the Examination of Water and Wastewater and in accordance with this title of the city code.
2. To ensure compliance with division (C) above, the following procedures shall be followed in determining average loadings per billing period for industrial users:
a. When a particular reading indicates concentration greater than or equal to normal domestic strength, the actual reading shall be entered into the average for billing purposes; and
b. When a particular reading indicates concentrations less than normal domestic strength, normal domestic strength shall be entered into the average for billing purposes.
(2) Determination of user charges for greater than normal domestic strength users.
(a) Calculation of unit costs for treatment of flow, BOD, TSS.
1. For purposes of determining proportionate surcharges, unit costs for treatment of flow, BOD and TSS shall be determined and fixed annually in the sewer service charge system according to the following procedure:
a. Determine the Annual OM & R budget.
b. Allocate total Annual OM & R costs to FLOW, BOD and TSS proportionately; according to the costs of collection and treatment of FLOW, BOD and TSS.
c. Divide the OM & R costs attributable to FLOW, BOD and TSS respectively, by the total annual billable volume and loadings of FLOW, BOD and TSS to arrive at unit costs.
2. For purposes of determining surcharges, the following definitions of unit costs shall apply:
Uf | = | Unit cost for treatment of FLOW in $/kgal |
Ubod | = | Unit cost for treatment of BOD in $/lb |
Utss | = | Unit cost for treatment of TSS in $/lb |
Unit costs are developed from actual cost per kgal. Subsequent calculations of unit costs shall be according to the substantive intent of this SSCS. | ||
(b) Calculation of user charges for treatment of wastewater with concentrations exceeding that of normal domestic strength wastewater:
Uc | = | [Un x bwv] + [Ubod x K x bwv (Cbod-Nbod)] + [Utss x K x bwv (Ctss-Ntss)] |
Uc | = | User charge |
Un | = | Unit cost for the treatment of normal domestic strength wastewater |
bwv | = | Billable wastewater volume of a particular user in kgal |
Ubod | = | Unit cost for treatment of BOD in $/lb |
K | = | 0.00834 |
Cbod | = | Users concentration of BOD in mg/l |
Nbod | = | 250 mg/l (concentration of BOD in normal domestic strength wastes) |
Utss | = | Unit cost for treatment of TSS in $/lb |
Ctss | = | Users concentration of TSS, in mg/l |
Ntss | = | 250 mg/l (concentration of TSS in normal domestic strength wastes) |
(E) Determination of sewer service charges: the sewer service charge for a particular connection shall be determined as follows:
SSC | = | Uc + Cc | |
Where: | SSC | = | Sewer service charge |
Uc | = | User charge | |
Cc | = | Connection charge for debt service |
(2009 Code, § 406.03) (Ord. passed 2-12-1990)