FACT SHEET and NPDES WASTEWATER DISCHARGE PERMIT EVALUATION. Department of Environmental Quality Western Region-Salem Office

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1 FACT SHEET and NPDES WASTEWATER DISCHARGE PERMIT EVALUATION Department of Environmental Quality Western Region-Salem Office PERMITTEE: City of Aumsville P.O. Box 227 Aumsville, OR File Number: 4475 SOURCE CONTACT: Steve Oslie Telephone Number: SOURCE LOCATION: North of Aumsville PERMIT WRITER: Tom Fisher PROPOSED ACTION: NPDES Permit Renewal SOURCE CATEGORY: Minor - Domestic TREATMENT SYSTEM: Class I COLLECTION SYSTEM: Class II PERMIT APPLICATION DATE: July 24, 1996 PERMIT APPLICATION NUMBER: BACKGROUND Introduction The City of Aumsville operates a wastewater treatment facility located in Aumsville Oregon. Wastewater is treated and discharged to Beaver Creek in accordance with National Pollutant Discharge Elimination System (NPDES) Permit number The Permit for the facility was issued on April 16, 1992 and expired on March 31, The Department received a renewal application on July 24, A renewal permit is necessary to discharge to state waters pursuant to provisions of Oregon Revised Statutes (ORS) 468B.050 and the Federal Clean Water Act. The Department proposes to renew the permit. Facility Description The wastewater treatment facility consists of a four cell wastewater treatment lagoon. Two primary cells with a total surface area of acres, a secondary cell of 7.80 surface acres and a tertiary cell of 6.33 surface acres. Wastewater from the collection system gravity flows to a influent lift station submerged 23 feet below the ground surface and located just south of the primary cells. The capacity of the pump system is 1260 gallons a minute (1.8MGD). Wastewater is pumped from the lift station through a 6 inch parshall flume into the primary cells. Influent flows are split into two

2 Page 2 eight inch lines to fill both primary cells concurrently. Wastewater is transferred between the primary and secondary cells via a loinch pipeline. After passing through the four cells treated wastewater is discharged from the tertiary cell into a chlorine contact chamber consisting of 180 feet of 60 inch buried concrete pipe. The chamber provides 52 minutes of contact time during maximum flows prior to discharge into Beaver Creek. These facilities have been in operation since the last treatment system upgrade occurred in Based upon the December 1999 inspection, meeting with the source and city engineer, review of source files and the City of Aumsville's March 1999 facilities plan, the renewal permit will include new provisions to address the following items associated with the Collection/treatment system, Infiltration/Inflow, Pretreatment, Chlorine toxicity, Mass loading to Beaver Creek, and wastewater reuse. Biosolids Management and Utilization Aumsville stores all biosolids produced in the treatment lagoon within the lagoon. Due to changes in biosolids regulations, a revised biosolids management plan must be submitted 6 months prior to removing any biosolids from the lagoon. Biosolids will be land applied at beneficial use sites. However, first the Department must approve the application sites and the revised biosolids management plan. Schedule C compliance condition number 4 addresses Biosolids. Inflow and Infiltration (I/I) The volume of Inflow and Infiltration (EI) of storm water into Aumsville's wastewater collection system is unacceptable. Flows to the plant during the months of May through October average 0.29 MGD. In contrast during the months of November through April flows average 0.64 MGD and on occasion flows exceed 1.8 MGD. In the past the pumping capacity of the Influent Pump station has been exceeded resulting in surcharging of wastewater out of manholes onto city streets. In August of 1996 new monitoring equipment was installed at the influent lift station and since, no overflows have occurred. Also the percent removal requirements for BOD are not consistently achieved during storms due to diluted influent with very low BOD concentrations. Schedule C compliance conditions numbers 2,3 and 6 address inflow and infiltration. Pretreatment The permittee does not have a formal pretreatment program. One categorical source Ektron discharges process wastewater to the collection system. The Department is working with the city to determine what pretreatment requirements may apply and a compliance schedule for development of the program has been placed in Schedule C of the proposed permit. The Department of Environmental Quality (DEQ) conducted a joint inspection of Ektron Industries in the City of Aumsville, Oregon, on December 15, The inspection determined that industrial waste subject to Federal categorical pretreatment standards is being discharged into the City of Aumsville's sewerage collection system by Ektron Industries. All owners of sewerage systems that receive such wastes are required by Oregon law [Oregon Administrative Rules (OAR) ] to develop and implement a formal pretreatment program for controlling those industrial contributors. DEQ requires such programs to be consistent with the General Pretreatment Regulations, 40 Code of Federal Regulations (CFR) Part 403. The Federal regulations [40 CFR 403.8(b)] require that an approvable pretreatment program be developed and submitted within no more than one year after written notification from the Department.

3 Page 3 However, Ektron Industries is investigating the possibility of eliminating the categorical waste discharge to the City. If successful, the City would not be required to develop and implement an approved pretreatment program at this time. If categorical wastes continue to be discharged to the City, then under the authority of Section 307(b) and 402(b)(8) of the Clean Water Act, and the implementing regulations (40 CFR Part 403), the City of Aumsville is required to develop and submit an approvable pretreatment program in accordance with a compliance schedule to be incorporated into the City's pending NPDES permit renewal. The terms and conditions of the City's pretreatment program, after being approved by the Department's Pretreatment Program staff, shall be incorporated into and enforceable through the City's NPDES permit. The required components of an approvable pretreatment program are specified in 40 CFR 403.8(f). These regulations require the City to have the "legal authority" to administer the program and to establish "procedures" to carry out specific program responsibilities. A pretreatment program submission is comprised of: an Attorney's Statement (from the City Solicitor or other legal representative) indicating that the City has the enabling legal authority to implement an approved pretreatment program; pretreatment provisions in the City's Sewer Use Ordinance, along with any other applicable legal authorities such as Multijurisdictional Agreements; industrial user survey; Implementation Manual; and technically based Local Limits. The Implementation Manual consists of all documents defining or supporting the City's pretreatment program policies, procedures and implementation including an enforcement response plan or ERP. The manual may also include copies of the City's Local Limits development and legal authorities, which are usually developed as separate documents. In order to track and enhance program development, the following milestone compliance dates for completing all program development documents are included in Schedule C conditions 9 through 14 of the City of Aumsville's NPDES permit renewal: Outfalls Treated wastewater is discharged to Beaver Creek at River Mile 2.5. An additional outfall for wastewater reuse is in the planing stages. Pollutants Discharged The current permit allows City of Aumsville to discharge treated effluent from the wastewater treatment plant from November 1 through April 30 each year. The current permit sets limits on the following pollutants: Five-day Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), Total Coliform (TC) bacteria(wastewater reuse) and, E. coli Bacteria. The discharge is also regulated for ph and pollutant removal efficiency. The permit mass loading limits (winter discharge)are based upon twice the average dry weather design flow to the facility of MGD. This mass loading limits in the existing permit are based

4 Page 4 upon the average dry weather flow and the new limits correct an administrative error made during the last permit issuance. Receiving Streams/Impact Treated wastewater is discharged to Beaver Creek at river mile 2.5. There is very limited data on stream flow of Beaver Creek. However, a CORMLX Mixing Zone Model indicates that the Chlorine Residual Concentration downstream of the outfall exceeds both the chronic water quality criteria at the edge of the regulatory mixing zone and the acute water quality standard within the zone of initial dilution. In addition, in late spring and early fall there may not be enough flow in Beaver Creek to meet minimum dilution standards to maintain Dissolved Oxygen Concentrations in Beaver Creek. With additional wastewater mass discharges during high flows and wastewater reuse, there may adequate storage in the lagoons to stop discharging during low flows. The flow rate of Beaver Creek needs to be established to facilitate the time and volumes of wastewater discharges. The proposed permit requires the City to comply with the minimum design criteria for the Willamette Basin which states that BOD concentrations in the effluent, divided by the dilution factor (the ratio of flow rate in Beaver Creek to effluent flow) shall not exceed one. Schedule C compliance condition number 6 addresses this issue. Groundwater No groundwater impacts are expected from this source when reclaimed water is used in accordance with OAR Stormwater Stormwater is not addressed in this permit. General NPDES permits for stormwater are not required for facilities with a design flow of less than 1 MGD. Compliance History The Permittee has been issued two Notices of Noncompliance (NON) for violation of permit limits during this permit cycle. On July 30,1999 the City was issued a Class II NON for violating the BOD 5 TSS mass load limits. And a Class III NON for failure to achieve BOD 5.and TSS removal efficiency. Another Notice of Non-Compliance was sent to the Permittee on March 31, 1999 for comparable violations. With the new mass loading limits, elimination of more of the Infiltration/Inflow entering the collection system and development of a wastewater reuse site these violations should not be repeated. PERMIT DISCUSSION Face Page The permittee is authorized to construct, install, modify, or operate a wastewater collection, treatment, control and disposal system. Permits discharge of treated effluent to Beaver Creek and by spray irrigation within limits set by Schedule A and the following schedules. All other discharges are prohibited. Schedule A - Waste Discharge limitations: May 1 -October 31: No discharge to state waters is permitted.

5 Page 5 November 1 through April 30: Parameter BODs TSS Average Effluent Concentrations Monthly 30 mg/l 50 mg/l Weekly 45 mg/l 80mg/l Monthly Average lb/day Weekly" Average lb/day Daily" Maximum lbs * Mass load limits based on the design average dry weather flow of MGD. Regardless of Mass load limits, the effluent BOD concentration dividing by the dilution factor cannot exceed one by the expiration of the permit. Calculations: BODs (a) (b) (c) MGD x 8.34 lbs/gal x 30 mg/l monthly average = 170 lbs/day monthly average 170 lbs/day monthly average x 1.5 = 250 lbs/day weekly average. 170 lbs/day monthly average x 2.0 = 340 lbs/day daily maximum. TSS (a) (b) (c) MGD x 8.341bs/gal x 50 mg/l monthly average = 2801bs/day monthly average. 2801bs/day monthly average x 1.5 = 4201bs/day weekly average (rounded) 2801bs/day monthly average x 2.0 = 5601bs/day daily maximum In addition to the concentration and mass load limits for BOD 5 and TSS, the proposed permit requires a minimum monthly average BOD 5 and TSS removal efficiency of 85 and 65 percent respectively in accordance with the federally approved standards for Oregon under 40 CFR A review of the DMR data for the last two years indicates that the facility cannot consistently comply with the current permit limits. The violations occur as a result of excessive Inflow and Infiltration (I/I) within the collection system due to heavy precipitation events. The permittee needs to decrease the amount of EI entering the collection system by correcting the known problem areas. Prior to land application of the reclaimed water, it shall receive at least Level II treatment as defined in OAR Schedule B - Minimum Monitoring and Reporting Requirements In 1988, the Department developed a monitoring matrix for commonly monitored parameters. Proposed monitoring frequencies for all parameters are based on this matrix and, in some cases,

6 Page 6 may have changed from the current permit. The proposed monitoring frequencies for all parameters correspond to those of facilities of similar size and complexity in the state. Schedule B also contains two annual reporting requirements. One condition requires an annual report on inflow and infiltration efforts while the other requires a report on the ability of the system to achieve compliance with the reclaimed water use rules. Schedule C - Compliance Conditions The proposed permit includes fourteen compliance conditions with deadlines. The requirements or mostly standard language conditions concerning: 1) Submittal of an engineering evaluation which confirms the design average wet weather flow or a request to retain the existing mass load limits; 2) Within six months of permit issuance submittal of a request for permit modification specified in condition 1 of this schedule; 3) Submittal by January 1,2004 a mixing zone dilution study for chlorine toxicity which demonstrates compliance with acute and chronic limits or an approvable plan to stop the discharge of chlorine in acute or chronic levels; 4) Submission of a Biosolids management plan six (6) months prior to removal of any Biosoilds from the treatment facilities; 5) Within three (3) months of permit issuance, submission of bypass information, and frequency; 6) Installation within three (3) months of permit issuance, a stream flow gauge on beaver Creek; 7) Submission of a reclaimed water use plan within six (6) months of permit issuance; 8/13 These compliance conditions are all related to pretreatment; 14) and, A condition that the permittee is expected to meet the compliance dates established in this schedule or notify the Department within 14 days following any lapsed compliance date. Schedule D - Special Conditions The proposed permit includes six (6) special conditions. They concern Department approval of plans and specifications prior to any facility modifications or upgrades, a reclaimed water use plan, Maintenance of a grass crop on the irrigation area, operator certification, a spill contingency plan And eliminating requirements for development of a pretreatment program upon removal of categorical wastes from the wastewater facilities.