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HomeMy WebLinkAboutA001 - Council Action Form dated May 25, 1999 ITEM # 33 DATE May 25, 1999 COUNCIL ACTION FORM SUBJECT: SURCHARGE PROGRAM REVISIONS BACKGROUND: In 1985, the City adopted a high-strength sewer surcharge as required by the federal construction grant for the new Water Pollution Control Plant. The purpose of the surcharge program is to provide an equitable means of assessing each contributor the cost of treatment for high-strength wastewater. Parameter concentrations of normal domestic wastewater are defined in the City Code, Section 28.302. Concentrations above that definition are considered high-strength and are subject to the surcharge. The 1985 surcharge rate was based on projected operating cost of the new Water Pollution Control Plant. Implementation of the surcharge began in 1989 when the new plant was completed. Staff is now proposing to update the surcharge rate and the implementation procedure as follows: 1. Update the surcharge rates based on current treatment costs 2. Reduce program implementation and sampling costs 3. Adopt a more flexible approach based on 10 years of actual experience 4. Provide for more frequent review and update (i.e. every 3± years) The proposed surcharge rates have been calculated using the last three years (FY '97 - FY'99) of actual treatment costs. This will more than double the 1985 rates, but it represents approximately a five percent per year increase. Reviewing these rates more frequently(i.e. every three or four years) will minimize future increases. Five industries have been involved in the surcharge program in the last four years. Total average annual revenues (1995-1998)generated from these industries have been approximately$12,000 to$13,000. Due to the rate increase, the 1999 revenue will be approximately$32,000 to $33,000 from those industries. However, two of the industries are expected to be eliminated from the surcharge program because of process and sampling changes. This would bring the estimated surcharge revenue down to approximately $16,000 to $17,000 for the 1999 calendar year. The proposed changes increase program flexibility by allowing the use of regularly scheduled pretreatment sample sets to calculate surcharges rather than a separate 72-hour sample set. This decreases sampling costs by $350 per required sample set. The revisions also allow the use of more than three days of data for surcharge calculations. This will help facilities with variable surcharge parameter concentrations to even out the highs and lows for a surcharge calculation more representative of their total flow. Attached is the updated Implementation Procedure to replace the Council-approved 1985 procedure. The updated procedure provides more flexibility to work with each contributor to more effectively determine appropriate surcharge requirements. Also attached is the revised ordinance to update the surcharge program. Both of these items have been reviewed with past and present surcharge program participants. Staff have received written or verbal concurrence for these proposed changes. ALTERNATIVES: 1. Approve the revisions to the surcharge program and rates; adopt code revisions to implement these updates. 2. Do not approve the revisions. MANAGER'S RECOMMENDED ACTION: It is the recommendation of the City Manager that the City Council adopt Alternative No. 1. COUNCIL ACTION: CITY OF AMES, IOWA Procedure for Implementation of High-Strength Sewer Use Surcharge April 1999 Purpose The following procedure is to establish an equitable and feasible method of assessing the surcharge to be billed to contributors identified through wastewater sampling who discharge wastewater that is higher in 5-day Carbonaceous Biochemical Oxygen Demand (CBOD5), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), Ammonia (NH3) or Total Kjeldahl Nitrogen (TKN) than normal domestic wastewater. Background In order to obtain federal grant money for the construction of the City of Ames Water Pollution Control facility(WPC),the City was required to comply with numerous federal regulations. Section 204(b)of the Clean Water Act and 40 CFR 35.2140 required the City to adopt a sewer use ordinance which included a surcharge system to recover the actual cost of treating wastewater that is higher in strength than maximum normal domestic wastewater. The strength of the wastewater is determined by the concentrations of CBOD5, COD, TSS, NH3, and TKN. The current surcharge system has been in the city sewer use ordinances since 1985. The new Water Pollution Control facility began operation in 1989 at which time the current surcharge system went into effect, and the City began billing and collecting surcharges for high-strength wastewater. Normal domestic wastewater is defined in the City Code, Section 28.302. The parameters and concentrations used for surcharge program implementation are shown on the table below. CBOD5 and COD are both measures of oxygen demand. For any sample, the COD includes the CBOD5 Therefore, the COD value will be greater than or equal to the CBOD5 value. The COD analysis is simpler and less time-consuming to perform than the CBOD5 analysis and can be completed within an hour. The CBODS analysis requires a five-day incubation period before the results can be determined. Because of the above, some contributors may prefer to test the COD only. In such cases, the contributor will be billed at the CBOD5 rate for COD concentrations. NH3 and TKN are both measures of the nitrogen content of the wastewater. For any sample, the TKN include the NH3-N. Therefore, the TKN concentration will be greater than or equal to the NH3-N concentration. When proteins break down in the treatment process, they are converted to ammonia; however, at the industrial facility's discharge point to the city sanitary collection system, the breakdown of proteins has often not occurred yet. Therefore, for waste streams that have a high protein content (i.e. blood, egg wastes, meat offals, etc.), TKN would better represent the nitrogen concentration that would be treated at the WPC facility. TKN concentration will be used to assess surcharge except in cases where NH3-N is determined to be a more appropriate method. 1 Current treatment costs at the WPC facility, including the costs for operation, maintenance, and replacement, are included in the table below. These treatment costs will be used to determine the surcharges to be paid by contributors discharging wastes higher in strength than domestic wastewater. The costs for wastewater treatment at the WPC facility will be re-evaluated at least every three years so that the surcharge billings accurately reflect the true costs associated with treating the high-strength wastewater. Domestic Wastewater Strength and Cost of Treatment City of Ames Water Pollution Control Plant Maximum Normal Cost of Treatment Surcharge Rate Parameter "Domestic"Wastewater, per pound, $/Ib per mg/L milligrams per liter(mg/L) Extra-Strength, $/100 cu ft CBOD5/COD 250 0.20 0.00125 TSS 300 0.35 0.00219 NH3/TKN 40 0.70 0.00437 Note: Ibs/day = concentration in mg/L x 8.34 x flow in million gallons per day (mgd) Implementation Customers identified through wastewater sampling as contributing wastewater with strengths greater than domestic wastewater for any of the identified parameters (CBOD5, COD, TSS, NH3, or TKN) shall pay a monthly surcharge based on that customer's discharge strength and monthly mE�tered wastewater volume. If metering is impractical, estimates of flow may be used. This surcharge will be in addition to the standard sewer use charge which is based on volume. The surcharge rate applies only to the extra strength (i.e. total concentration minus normal "domestic" concentration) for each parameter. Parameters with concentrations below normal "domestic" wastewater concentrations will be assessed the standard sewer use charge. No credit will be given for a wastewater with one or more parameter concentrations below the maximum normal domestic concentrations. The total surcharge rate is the sum of the surcharge rates for each individual parameter. The process of establishing a monthly surcharge will be done at least annually for those facilities whose wastewater exceeds domestic strength. The sample sets used for surcharge calculations can also be used to help fulfill the monitoring requirements of the industrial pretreatment program. Sampling duplications will not be required where a sample can be used for more than one purpose. The City will work with each contributor to minimize monitoring expenses. However, either the City or the contributor can request additional sampling if either feels that the data currently being used to assess the surcharge are not representative of wastewater discharge quality. If the contributor modifies its operations, such as through a plant expansion or elimination of a product line, either the City or the contributor can request a new sampling set to determine a new database on which to base future surcharge payments. The 1997 average cost for performing three days of surcharge 2 sampling was approximately $350. All costs associated with the surcharge sampling and/or evaluation will be assessed to the contributor. For the purposes of the following section, a surcharge sample is defined as a composite sample (either time-based or flow-proportional) collected from a facility that is representative of a 24-hour period during a typical work week. Samples shall be collected during typical work weeks so that the samples will be representative of the average wastewater flow from the facility. Samples collected during weekends or shutdown periods will not be accepted. Samples must be collected in accordance with 40 CFR 136 laboratory practices and shall be analyzed for pH and other domestic wastewater parameters. If an individual sample (pretreatment or surcharge) indicates that the contributed wastewater has a higher than maximum normal "domestic" strength, one of the following processes (A, B, C, or D) will be followed. Process A: Facilities having at least two years of representative sampling data containing surcharge parameter analyses may use a rolling average to determine the monthly surcharge rate. The rolling average shall be determined by calculating the average surcharge parameter concentrations for the prior 12 months or prior three successive sampling events, whichever results in the most sample analyses available for averaging. The average concentration for each surcharge parameter will be used to calculate the facility's monthly surcharge rate. The surcharge rate calculated using Process A will be assessed monthly to the facility beginning in the billing cycle following the last surcharge sample. The surcharge will be evaluated at least once in 12 months but no more frequently than once in six months. Process B: Facilities for which representative surcharge parameter analyses are not available or are not representative of the current processes (new facilities or facilities which have implemented recent process modifications) should perform or have performed a three-day surcharge sampling event. The three-day surcharge sampling event will consist of three successive surcharge samples being collected in as close of a time frame as possible. The average of the surcharge parameter concentrations for the three samples will be used along with the metered monthly flow data for the facility to calculate a monthly surcharge. The surcharge rate determined by Process B will be billed monthly to the facility beginning with the billing cycle following the last surcharge sample. The surcharge will be used for 12 months or until results from a new three-day surcharge sample event are submitted or until adequate data are available to use Process A. Process C: With the city's approval, facilities self-monitoring for surcharge parameters on a daily or weekly basis may submit the results of the analyses to the City on a monthly basis. City staff will 3 use the average of the submitted results and the metered monthly flow to calculate the monthly surcharge. The calculated surcharge will be billed during the billing cycle it is calculated, The surcharge rate determined by Process C will only be valid for the month it was calculated with and must be evaluated monthly. Process D: If agreed upon by the facility and the City, less than three samples may be used to calculate monthly surcharge rate. Monthly surcharge rates calculated using Process D will be billed monthly (based on metered or estimated flow) to the facility beginning the billing cycle following the evaluation. The surcharge will be evaluated at least once in 12 months but no more frequently than once in six months. 4