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Home My WebLink About~Master - Sewer Rate Setting Computations to Meet Iowa DNR Requirements ORDINANCE NO. 3013 AN ORDINANCE TO AMEND THE MUNICIPAL CODE OF THE CITY OF AMES, IOWA BY ADDING THERETO NEW SUB- SECTIONS 28.39(9) AND 28.39(10) FOR THE PURPOSE OF ADDING A REFERENCE TO FEDERAL REGULATIONS AND SAMPLE RATE SETTING COMPUTATIONS TO MEET REQUIRE- MENTS OF THE IOWA DEPARTMENT OF NATURAL RESOURCES. BE IT ORDAINED, by the City Council of the City of Ames, Iowa: Section One. The Municipal Code of the City of Ames, Iowa shall be, and the same is hereby amended by adding thereto new sub-sections 28.39(9) and 28.39(10) as follows: (9) The user charge ordinance shall take precedence over any terms or conditions of agreements of contracts which are inconsistent with the requirements of Section 204(b)(1)(A) of the Act and 40 CFR Part 35 dated February 17, 1984. (10) The sewer rates established and stated herein are deter- mined by the system for development of proportional user charges set out, with representative computations, as Appendix M to the Ames Municipal Code. Section Two. The representative computations attached hereto are hereby adopted as Appendix M to the Ames Municipal Code. Section Three. This ordinance .shall be in full force and effect from and after its passage and publication as required by law. Adopted this 14th day of June 1!)38 Nancy Gibbons, City Clerk Larry R. rti s, Mayor Pro Tem APPENDIX M TO USER CHARGE ORDINANCE - AMES, IOWA For Initial Year of Plant Operation FY 1988-1989 I. Annual Expenses A. Treatment Plant Only (from Table A-2, Facilities Plan Addendum) Labor $ 497,000 Energy 164,000 Repairs & Maintenance 128,000 Equipment Replacement (see note below) 181,000* Solids Handling 16,000 SUBTOTAL $ 986,000 B. Related Administration (not including billing & collection) Finance Administration 59,000 General Administration 37,000 SUBTOTAL 96,000 C. Billing & Collection (Finance Department) Specific Charge for Billing & Collection 121,000 D. Sewer System Costs In Public Works Department 565,000 E. Debt Service Retirement of Bonds 3,300,000 GRAND TOTAL $5,068,000 'Note: Annual expense of $181,000 for equipment replacement represents a sinking fund calculation of the amount which, with accrued interest, would provide adequate funds for complete replacement of half the plant equipment during the 20-year reference period ending in the year 2010. 2. Allocation of Annual Expenses Allocation of Annual Expenses to Categories Flow 26% BOD 21 S. Sol . 42 Ammonia 11 TOTAL 1'U6% A. Treatment Annual OM&R Dollars to Transport & Treat Flow = 0.26 x Treatment plus Related Adminis ration = 0.26 x $1,082,000 = $ 281 ,000 Annual OM&R Dollars to Treat BOD = 0.21 x Treatment plus 1-eTated Administration = 0.21 x $1 ,082,000 = 227,000 Annual OM&R Dollars to Treat S. Sol . = 0.42 x Treatment plus RTaTed Administration = 0.42 x $1 ,082,000 = 455,000 Annual OM&R Dollars to Treat Ammonia = 0.11 x Treatment plus - alb Administration = 0.11 x $1,082,000 = 119,000 TOTAL $1,082,000 3. Annual Loadings Estimated Wastewater Flow, gallons per year Wastewater - Ames customers 1,200 million gallons Wastewater - ISU, NADC, Kelley 600 n " Infiltration/Inflow 600 to " TOTALS million gallons/yr Estimated BOD Loading Est. 8,000 lbs/day x 365 days = 2.92 million lbs/yr Estimated S. Sol . Loading Est. 9,000 lbs/day x 365 days = 3.29 million lbs/yr Estimated Ammonia Loading Est. 1 ,600 lbs/day x 365 days = 0.58 million lbs/yr 4. Unit Costs A. Treatment OM&R including Related Administration Unit Cost for Flow $281,000/2,400 mil . gal . = $0.117/1 ,000 gal . Unit Cost for BOD $227,000/2.92 mil . lbs. = $0.078/lb. Unit Cost for S. Sol . = $445,000/3.29 mil . lbs. = $0. 138/lb. Unit Cost for Ammonia = $119,000/0.58 mil . lbs. = $0.205/lb. B. Sewer System Costs Unit Cost for Sewers = $565,000/1,200 mil . gal . = $0.47/1,000 gal . (Note: This is applied to Ames customers only.,) C. Debt Service Unit Cost for Debt Service = $3,300,000/1,800 mil . gal . _ $1 .83/1 ,000 gal . (Note: This is applied to wastewater flows only, not including I/I. ) 5. Minimum Charge (Service Availability Charge) Annual Billing 3 Collection Expense (Finance Dept. ) $121,000 Annual Cost to Treat (Pump) Infiltration/Inflow = $0.117/1,000 gal . x 600 mil . gal . 70,200 TOTAL ANNUAL MINIMUM COST $191,200 Number of Users = 10,800 Number of Bills = 10,800 x 12 mo. = 129,600/yr. Minimum Charge per Month per User with No Wastewater Flow Allownace = $191,200/129,600 bills = $1.48/mo. 5A. Calculation of "Actual" Estimated Wastewater Strength for Ames as contrasted to "NormaStrength as stated in rate or finance Wastewater Flow without I/I = 1,800 mil . gal ./yr. = 4.93 mil . gal ./day BOD Load Estimated to be 8,000 lb/day By formula: lb/day = (mg/1 ) x (8.34) x (mil .gal ./day) mg/l BOD = 8,000 lb/day - 195 mg/l x 4.93 mg S. Sol . Load Estimated to be 9,000 lb/day mg/l S. Sol . = 9,000 lb/day = 219 mg/l 8.34 x 4.93 mg Ammonia Load Estimated to be 1,600 lb/day mg/l Ammonia = 1,600 lb/day = 39 mg/l 8.34 x 4.93 mg 0 w 6. Residential User Unit Charge for OM3R Including Related Ad stration Residential User Unit Charge per 1,000 gallons will be the sum of unit charges for Flow, BOD, S. Sol ., and Ammonia. Unit Charge for Flow = $0. 117/1 ,000 gal . Formulas for Strength Factors: lb/1,000 gal . = (mg/1) x (.00834) and $/1,000 gal . = (lb/1,000 gal .) x ($/lb) Unit Charge for BOD (195 mg/1T x (.00834) x ($0.078/lb) = $0. 127/1 ,000 gal . Unit Charge for S. Sol . = (219 mg/1T—x--FX0834) x ($0.138/lb) = $0.252/1,000 gal . Unit Charge for Ammonia (39 mg/1)x TF6834) x ($0.205/lb) = $0.067/1,000 gal . TOTAL RESIDENTIAL USER UNIT CHARGE $0.563/1 ,000 gal . Proof: 1,800 mil . gal ./yr. wastewater billed as RUUC @ $0.563/1,000 gal . _ $1,013,000 600 mil . gal ./yr. I/I billed as part of Minimum Charge @ $0. 117/1 ,000 gal . 70,000 TOTAL BILLING $1 ,083,000 (Agrees with Annual Expenses of $1 ,082,000) 6A. Residential User Charge for Sewer System Costs Residential User Unit Charge for Sewer System Costs, as calculated in Step 4B above = $0.47/1,000 gal . 7. Residential User Unit Charge for Debt Service Residential User Unit Charge for Debt Service, as calculated in Step 4C above = $1 .83/1,000 gal . 8. Sample Calculation of Residential Sewer User Charge By statistical evaluation of customer water use records, typical single-family (3-person) water use in Ames in approximately 50 gpcd, or 4,500 gal ./month. Minimum Charge per Month (from Step 5) _ $1 .48 (for no wastewater contribution) Unit Charge for OM&R including Related Administration (from Step 6) $0.563/1,000 gal . x 4,500 gal . = 2.54 Unit Charge for Sewer System Costs (from Step 6A) $0.47/1 ,000 gal . x 4,500 gal . = 2. 12 Unit Charge for Debt Service (from Step 7) $1 .83/1 ,000 gal . x 4,500 gal . - 8.24 TOTAL RESIDENTIAL SEWER USER CHARGE $14.38/month 9. Extra-Strength Users According to the ordinance, "'Normal Domestic Wastewater' shall mean wastewater that has a BOD concentration of not more than 250 mg/l average and 400 mg/l maximum; and a suspended solids concentration of not more than 300 mg/1 average and 450 mg/l maximum; and an ammonia concentration of not more than 40 mg/l average and 60 mg/l maximum." Applicable Unit Rates and Factors are: Minimum Charge per Month (from Step 5) = $1 .48/month Residential User Charge for OM&R (from Step 6) = 0.563/1,000 gal . Residential User Charge for Sewer System (from Step 6A) = 0.47/1 ,000 gal . Residential User Charge for Debt Service (from Step 7) = 1 .83/1,000 gal . Unit OM&R for BOD = $0.078/lb BOD Unit OM&R for S. Sol . = 0. 138/lb S. Sol . Unit OM&R for Ammonia = 0.205/lb Ammonia r 10. Sample Calculation of Sewer User Charge for an Extra-Strength User Assume: 20,000 gal ./month BOD of 500 mg/l S. Sol . of 500 mg/l Ammonia of 40 mg/l ("Normal") Minimum Charge per Month (from Step 5) _ $ 1.48 Residential OM&R Charge (from Step 6) $0.563/1,000 gal . x 20,000 gal . = 11 .26 Residential Charge for Sewer System (from Step 6A) $0.47/1,000 gal . x 20,000 gal . = 9.40 Residential Charge for Debt Service (from Step 7) $1 .83/1,000 gal . x 20,000 gal . ; = 36.60 RESIDENTIAL USER CHARGE $58.74 Surcharge for BOD = 20,000 gal . x $0.078/lb. x (500-250) mg/l x .00834 = 32.53 Surcharge for S. Sol . = 20,000 gal . x $0.138/lb. x (500-300) mg/l x .00834 = 46.03 TOTAL SEWER USER CHARGE PER MONTH $137.30