FACT SHEET And NPDES WASTEWATER DISCHARGE PERMIT EVALUATION

Transcription

1 FACT SHEET And NPDES WASTEWATER DISCHARGE PERMIT EVALUATION Department of Environmental Quality Western Region - Salem Office 750 Front Street NE, Suite 120, Salem, OR Telephone: (503) PERMITTEE: SOURCE LOCATION: SOURCE CONTACT: PERMIT WRITER: PROPOSED ACTION: SOURCE CATEGORY: TREATMENT SYSTEM CLASS: COLLECTION SYSTEM CLASS: PERMIT APPLICATION DATE: PERMIT APPLICATION NUMBER: City of Junction City PO Box 250 Junction City, OR File Number: /2 mile west of Junction City on High Pass Road Jason Knope Telephone Number: Robert Dicksa Telephone Number: Renewal of a National Pollutant Discharge Elimination System (NPDES) wastewater discharge permit Minor Domestic Level II Level II April 19, BACKGROUND Introduction City of Junction City operates a wastewater treatment facility located in Junction City, Oregon (See Figure 1). Wastewater is treated and discharged to Flat Creek in accordance with National Pollutant Discharge Elimination System (NPDES) Permit number (See Antidegradation Review Sheet Attachment 1). The Permit for the facility was issued on December 19, 2001 and expired on November 30, The Department received a renewal application on April 19, 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.

2 Page 2 Facility Description The City of Junction City owns and operates a wastewater treatment facility and a sanitary sewage collection system. The major treatment process is a two-cell stabilization lagoon. The water surface area of each cell is approximately 23 acres. Under normal operation, the lagoons operate in parallel. The lagoons provide biological treatment to the wastewater prior to disinfection with chlorine gas and then the effluent is discharged during the winter months through Outfall 001 to Flat Creek at River Mile (RM) 9.0. During the summer months, the treated wastewater is beneficially land applied through Outfall 002 at agronomic rates using sprinkler systems on adjacent agricultural land. The original wastewater treatment facility was constructed in 1966/1967. New headworks were installed and completed in November The headworks is located at the north end of the lagoons and consists of a concrete structure containing a sewage grinder, Parshall flume with an ultrasonic flow meter, a composite sampler, ph and temperature monitoring unit, and a distribution structure to split flows between the existing lagoons and future third lagoon. Transfer pipes in the central dike between the lagoons allow the wastewater to flow from the western (primary) lagoon to the eastern (secondary) lagoon. Each lagoon has an outlet structure at the southern end near the central dike. Normally, all treated wastewater is withdrawn from both lagoon cells via gravity to the chlorine contact chamber located immediately to the south of the dike. Effluent flows are measured using a V- notch weir. Disinfected wastewater flows by gravity from the chlorine contact chamber east in a ditch prior to discharging into Flat Creek. During summer operations, the effluent is pumped onto agricultural lands directly from the chlorine contact chamber. The engineer who designed the facility determined the average design dry weather flow. It is the estimated maximum flow during May 1 to October 31 (expressed as a daily average flow), at which the design engineer expects the treatment facility can still consistently meet all effluent limits. The dry weather flows do not include the high levels of infiltration and inflow that are associated with the winter in Oregon. For this facility, the average design dry weather flow is 0.80 million gallons/day (MGD). The current actual dry weather flow for May 1 to October 31, for the past two years, is 0.62 MGD. The Department also determined from the DMRs the monthly average influent loading of lbs/day of BOD to the treatment facility. This number is approximately 1140 lbs/day of influent BOD. Using the standard organic loading value guideline of 35 lbs/day of BOD multiplied by 46 acres of lagoon storage (each lagoon is approximately 23 acres and they are typically operated in parallel), equals approximately 1610 lbs/day of BOD treatment capacity and still meet a 30 mg/l of BOD 5 effluent permit limit. Therefore, 1140 lbs/day influent BOD divided by 1610 lbs/day BOD capacity, equates to the treatment facility being at approximately 71 % capacity. The facility is currently under a Mutual Agreement and Order (MAO) with the Department to complete facility modifications and upgrades that will help resolve past and future compliance issues. The permittee has not been able to comply with all aspects of the MAO due to circumstances beyond their control. Therefore, the Department intends to modify the MAO and reissue the MAO as part of this proposed permit action. The upgrades listed in the current MAO were originally proposed to be completed in three phases. Phase I, the installation of new headworks, has been completed. Phase II, the installation of aerators, removing the biosolids, and leak testing the lagoon cells has been partially completed. The biosolids from one cell have

3 Page 3 been removed. The two existing lagoon cells were leak tested in 2001 and found to have leakage rates within the Department's guideline of less than 1/8 inch per day. The new lagoon cell will be leak tested upon completion of all the upgrades. Phase III still needs to be completed and will be implemented under the compliance schedules of the modified MAO. Phase III will consist of constructing additional lagoon cells, leak testing the new and existing lagoon cells, installing new disinfection and dechlorination facilities, and constructing a new effluent pump station, force main, and outfall to the Willamette River, and a outfall diffuser. The proposed permit will be issued for the existing facility. The Department will modify the permit after approval of the pre-design of the upgrades and modifications because of outstanding issues with the planning and design that cannot be immediately resolved. Biosolids Management and Utilization Waste sludge accumulates in the treatment lagoon. The Department approved the permittee's biosolids management plan in August 2001, which allows the permittee to remove solids from the lagoon cells and land apply the solids as part of Phase II of the wastewater facility upgrades to the treatment facility. The permittee will be required to follow the conditions of the approval letter prior to removing any additional biosolids from the existing lagoon cells. The Biosolids Management Plan will ensure compliance with the federal biosolids regulations (40 CFR Part 503). Pretreatment The permittee does not have a formal pretreatment program, nor is one required for this source. Outfalls Outfall 001 The current NPDES Permit allows the treatment facility to discharge treated effluent into Crow Creek during the winter months at River Mile (RM) 5.5. However, the Department's new GIS tool identifies the receiving stream as Flat Creek and the discharge location as RM 9.0. Therefore, the renewal permit will specify the receiving stream as Flat Creek and will allow the treatment facility to discharge treated effluent through Outfall 001 to Flat Creek at RM 9.0 during the winter months (November 1-April 30). No discharge to state water is allowed from May 1-October 31 without written authorization from the Department. The allowable mixing zone for this outfall is defined as that portion of Flat Creek contained within a band extending from a point five (5) feet upstream of the outfall to a point five-hundred (500) feet downstream of the outfall. However, the receiving stream is considered inadequate and not able to provide enough dilution to assimilate the discharge. The permittee is currently under a MAO to construct a new outfall to the Willamette River and will continue to discharge to Flat Creek during the interim until the new outfall is complete. Outfall 002

4 Page 4 The City owns 60 acres of land for irrigation. During the summer months reclaimed water is beneficially irrigated on a silage corn and seed grass/pasture land. The treated effluent will comply with Oregon Administrative Rules (OAR) pertaining to the Use of Reclaimed Water from sewage treatment plants, OAR Chapter 340, Division 55. The City is proposing to treat the wastewater through secondary treatment and disinfection to Division 55, Level II standards to reduce Total Coliform bacteria to not more than a 7-day median of 23 organisms per 100 ml, not more than 240 organisms per 100 ml in two consecutive samples. Irrigation must conform to the Department approved reclaimed water use plan (RWUP) plan. No discharge from the irrigation area to state waters is permitted. All reclaimed water shall be distributed on land for dissipation by evapotranspiration and controlled seepage by following sound irrigation practices so as to prevent: 1. Prolonged ponding of treated wastewater on the ground surface; 2. Surface runoff or subsurface drainage through drainage tile; 3. The creation of odors, fly and mosquito breeding or other nuisance conditions; 4. The overloading of land with nutrients, organics, or other pollutant parameters; and, 5. Impairment of existing or potential beneficial uses of groundwater. Receiving Streams/Impact The City of Junction City discharges to Flat Creek at River Mile 9.0. The discharge is within the Willamette Basin and Upper Willamette Sub-basin. The designated beneficial uses of the receiving stream are: public and private domestic water supply, industrial water supply, irrigation, livestock watering, fish and aquatic life (including salmonid rearing and migration), wildlife and hunting, fishing, boating, water contact recreation, aesthetic quality and hydro power. The water quality standards for the Willamette Basin (OAR ) were developed to protect the beneficial uses of the basin. Section 303(d) of the Clean Water Act requires the establishment of a Total Maximum Daily Load (TMDL) in water bodies in which the technology based effluent limitations are not stringent enough to implement the water quality standards. The Willamette TMDL was issued on September 21, 2006, and approved by the EPA on September 26, OAR states no wastes shall be discharged and no activities shall be conducted which cause violations of the water quality standards in the Willamette Basin. Flat Creek is not included on the Department's List of Water Quality Limited Water Bodies (also called the 303(d) List) as water quality limited for any parameters at any time of the year. The TMDL does not address Flat Creek specifically because it was not listed for any parameters, however; the TMDL addresses temperature in the portion that includes Willamette Basin tributaries. This is discussed further below. Antidegradation Review

5 Page 5 OAR describes the Environmental Quality Commission's (EQC) Antidegradation Policy for Surface Waters. In summary, the policy is intended to guide the decisions that affect water quality such that unnecessary degradation from point and non-point sources of pollution is prevented. The Department must make certain findings and consider certain issues before renewing the permit. The Department performed an Antidegradation review and has determined that Flat Creek is a High Quality Water during the period of allowed discharge (See Attachment 1). Temperature Water temperature affects the biological cycles of aquatic species and is a critical factor in maintaining and restoring healthy salmonid populations throughout the state. It is the policy of the Environmental Quality Commission (EQC) to protect aquatic ecosystems from adverse temperature changes caused by anthropogenic activities. The purpose of the temperature criteria listed in OAR is to protect the designated beneficial uses that are temperature sensitive, including salmonids in waters of the state. The Department utilizes Fish Use Designation and Salmon and Steelhead Spawning Use Designation maps to identify applicable temperature criteria for each basin. The Willamette Basin maps are contained in OAR , Figures 340A and 360B, respectively. According to the approved use designation maps, no spawning occurs in the area of the outfall. Therefore, the applicable numeric temperature criterion is 18 C. The 303(d) List for 2002 does not list Flat Creek as water quality limited for temperature. In addition, the permittee only discharges to Flat Creek during the winter season when water temperatures tend to be cooler. However, in accordance with the Willamette Sub-basin TMDL, the Department has assessed the discharge from the City of Junction City for temperature impacts to Flat Creek. The Willamette TMDL included Waste Load Allocations (WLA) for discharges to tributaries in Willamette River Sub-basins. Therefore, in accordance with the Willamette Sub-basin TMDL Waste Load Allocations, sources that discharge effluent warmer than ambient temperatures and applicable biologically-based criteria must be evaluated for potential to contribute to exceedances of numeric criteria. Facilities found to have no reasonable potential to warm the receiving water do not require a waste load allocation and are allowed to discharge within their current permit. The City of Junction City's effluent temperature impacts were assessed for the discharge period during April 1 through April 30. The assessment was conducted in accordance with the Sub-basin TMDL Waste Load Allocations by using a flow chart process contained in the TMDL as follows: Does the point source discharge warm the river less than 0.3 C above numeric criterion given 25% of 7Q10 flow? If yes, then the source is assigned an Allocation based on 0.3 C and 25% of 7Q10 low flow or the Department makes a determination of no reasonable potential for temperature increase and therefore, the source may discharge at current level.

6 Page 6 The Department calculated the in-stream temperature increase using the average winter discharge flow rate of 2.06 MGD for the last two years, the maximum observed effluent discharge temperature of 16.1 C, the applicable numeric criterion of 18 C, and 25% of the lowest winter flow in Flat Creek (There is currently no USGS gauging station on Flat Creek. Consequently, the 7Q10 flow is not available. However, the permittee has been recording the winter flows in Flat creek using a staff gauge based on the cross section of the Creek. The Department used 0.74 cfs which is the lowest flow recorded for the last three years. This information was input into a thermal calculator spreadsheet (See Attachment 2) to determine if there is a reasonable potential to warm the river less than 0.3 C above the numeric criterion. According to the thermal calculator spreadsheet, the discharge warms the river less than 0.3 C above the criterion. Therefore, the Department has determined that there is no reasonable potential for a temperature increase above the criteria and the City of Junction City may discharge at the current rate. In addition, the permittee is under a MAO for upgrades to the facility that will include construction of a new outfall pipeline and outfall into the Willamette River. Once the upgrades are complete, the Department will conduct a RPA for thermal impacts to the Willamette River and modify the permit as necessary. Based on the above assessment the Department has also determined that the effluent discharge is in accordance with OAR (2)(d) Temperature Thermal Plume Limitations as follows: Temperature mixing zones and effluent limits authorized under OAR l-0028(12)(b) will be established to prevent or minimize the following adverse effects to salmonids inside the mixing zone: (A) Impairment of an active salmonid spawning area where spawning redds are located or likely to be located. This adverse effect is prevented or minimized by limiting potential fish exposure to temperatures of 13 C or less for salmon and steelhead, and 9 C for bull trout; (B) Acute impairment or instantaneous lethality is prevented or minimized by limiting potential fish exposure to temperatures of 32.0 C or more to less than two seconds; (C) Thermal shock caused by a sudden increase in water temperature is prevented or minimized by limiting potential fish exposure to temperatures of 25.0 C or more to less than five percent of the cross section of 100 percent of the 7Q10 flow of the water body; the Department may develop additional exposure timing restrictions to prevent thermal shock; and, (D) Unless the ambient temperature is 21.0 C or greater, migration blockage is prevented or minimized by limiting potential fish exposure to temperatures of 21.0 C or more to less than 25 percent of the cross section of 100 percent of the 7Q10 low flow of the water body. According to the Oregon Department of Fish and Wildlife (ODF&W) District Biologist, there are no active salmonid spawning redds in the vicinity of the Junction City effluent discharge to Flat Creek. In addition, the measured maximum effluent temperature of the discharge during this period is 16.1 C, which is in accordance with the Thermal Plume limitations listed above. To support the Thermal Plume limitations for C, the Department calculated the in-stream

7 Page 7 temperature increase using the average winter discharge flow rate of 2.06 MGD for the last two years, the maximum observed effluent discharge temperature of 16.1 C, the applicable numeric criterion of 18 C, and 5% of the cross section of 100 percent of the lowest winter flow in Flat Creek. This information was input into the thermal calculator spreadsheet to determine if there is a reasonable potential for the discharge to warm the creek above the criterion (See Attachment 2A). To support the Thermal Plume limitations for D, above, the Department used the thermal calculator spreadsheet to determine the in-stream temperature increase using the same input data above, but using less than 25% of the cross section of 100 percent of the lowest winter flow in Flat Creek (See Attachment 2B). Both spreadsheets indicated that there is no reasonable potential for the discharge to violate the criterion and that the discharge is in accordance with the Thermal Plume limitations. Groundwater In 2004, the Department declared a "Groundwater Management Area" in the Willamette Valley in an effort to address widespread nitrate groundwater contamination. As part of this effort, the Department has been focusing attention of those permits that are being renewed within the management area to evaluate if the facilities could potentially be contributing to the area's groundwater contamination. The City of Junction City is located in the Groundwater Management Area so Department personnel performed a hydrogeologic review of the lagoon areas. The lagoons and spray-irrigation area (site) are located in the SW quarter of Section 36 of T15S, R5W. The two lagoons are lined with in-situ bentonite clay. The primary treatment lagoon is located west of the secondary treatment lagoon. Lagoon water is treated with chlorine prior to discharge to land during the summer months and discharged to Flat Creek in the winter months. The wastewater is land applied by spray irrigation on approximately 20 acres located west of the lagoons. The site is located on Junction City-owned property approximately 2000 feet west of the western edge of Junction City limits. To the north of the site are several tax lots totaling about 200 acres that are slated for future residential development. Based on a conversation with a Junction City Planner, the area north of the site is slated for residential development and City water and sewer will be supplied to that area as development progresses. The area between the City limits and the site has not been annexed, so groundwater is used in that area for domestic purposes. Based on information provided by the City, the sewer collection system is affected by groundwater inflow and infiltration. The site is situated in a swale created by Flat Creek and the site slopes very gently to the north following Flat Creek. The creek appears to have been rerouted to the east side of the lagoons. There were no wells identified directly north of the site, which is the presumed down gradient direction based on surface topography and Flat Creek flow direction. There were 6 public supply wells (City water supply) identified 1 to 1.5 miles east and southeast of the site. These wells are mostly screened below 100 feet within Willamette Valley alluvium. Five additional public supply wells for the Tivoli Mobile Home Park (2 wells), Weyerhaeuser, Kountry Village,

8 Page 8 and Trailer Town are located between 1 and 2 miles southeast of the site. The screened interval is unknown for these wells, but they may be less than 100 feet. The majority of the domestic wells located near the site are screened between 15 and 40 feet bgs, due to the abundance of groundwater at shallow depths. Shallow soils consist of silt from the surface to about 15 ft below ground surface (bgs), which grades into sands and gravels that continue to depths of 40 to 50 ft bgs. Several well logs indicate the presence of a 20 to 30-foot thick clay layer between 60 and 100 feet bgs, which likely acts as a confining unit and may be present beneath the site. Interbedded sands, gravels and silt/clays exist to depths as great as 260 ft bgs. A review of the Oregon Department of Human Services (DHS) Public Water Supply Information for the six City wells is summarized below. City of Junction City PWS (includes all 6 wells): City wells located on 8 th and Front Street, and the Elm Street well have had detections of nitrates as high as 12 mg/l since 1986 and as high as 6.9 mg/l as recently as January The 5 th and Maple well, which is the closest City well to the lagoons has not had any detection of nitrates since The nitrates detected in the Front Street well and Elm Street wells are likely from another source. Coliform was absent in all tests for the City wells, except for a few anomalous detections. The existing wastewater treatment lagoons were leak tested in 2001 and found to have leakage rates with the Department's guideline of less than 1/8 inch per day. The new lagoon cell will be lined with a synthetic liner and leak tested prior to being brought on line as part of the treatment facilities. Public water supplies are located in an apparently up gradient or cross gradient direction of the wastewater treatment facility lagoons. Zoning north of the site is single family residential and will likely remain as such for the foreseeable future. Development north of the site in the presumed down gradient direction will include city water supply to those residences. Several domestic wells are located east of the sites that are not planned for city water hookup. These wells may be potential receptors of groundwater contamination. Because the improvements to the wastewater facilities includes lining of the new lagoon, assessment and repair of the collection system and discharge of effluent to the Willamette River, future impacts to groundwater are limited. On the basis of the hydrogeologic review, the Department is not going to require the City to conduct sampling and monitoring of the groundwater for nitrates at this time. However, the City may consider as part of the wastewater treatment plant upgrade project, including groundwater monitoring wells on the wastewater treatment plant site to collect information for the City's own use. Stormwater

9 Page 9 General NPDES permits for storm water are required for facilities with a design flow of greater than 1 MGD if storm water is collected and discharged from the plant site. This facility's design flow is less than 1 MGD therefore no storm water permit is necessary. Compliance History The monitoring reports for this facility were reviewed for the period since the current permit was issued, including any actions taken relating to effluent violations. The permit compliance conditions were reviewed and all inspection reports for the same period were reviewed. This facility was last inspected on November 11, 2006, and was found to be out of compliance for the following: Exceeding permit discharge limits for E.coli bacteria. Failure to monitor for E.coli bacteria, and failure to report effluent temperature.. The facility is currently under a Mutual Agreement and Order (MAO) with the Department to complete facility modifications and upgrades that will help resolve past and future compliance issues. The permittee has not been able to comply with all aspects of the MAO due to circumstances beyond their control. Specific compliance schedules and dates in the MAO have expired. Therefore, the Department intends to modify the MAO and reissue the MAO as part of this proposed permit action. PERMIT DISCUSSION Face Page The face page provides information abut the permittee, description of the wastewater, outfall locations, receiving stream information, permit approval authority, and a description of permitted activities. The permittee is authorized to construct, install, modify, or operate a wastewater collection, treatment, control and disposal system. Permits discharge of treated effluent to Flat Creek within limits set by Schedule A and the following schedules. All other discharges are prohibited. In accordance with OAR 340, Division 49 all permitted municipal wastewater collection and treatment facilities are to receive a classification based on the size and complexity of the systems. The Department has incorporated the classification of the collection and treatment systems into the NPDES discharge permit. The collection system is currently considered a Class II system while the treatment system is considered a Class I system. Both systems were reevaluated to determine the appropriateness of the current classification for operator certification requirements (See Attachment 3). The Department is proposing to change the classification of the treatment system to a Level II based on the reevaluation of the system. The reevaluation is based on the excessive amount of I/I within the system which contributes to an extreme variation in the strength of the raw waste. The permittee is currently undergoing upgrades to the collection system to reduce the amount of I/I in the collection system. However, the permittee is under a MAO with the Department that requires the permittee to construct upgrades to the treatment facilities. Upon completion of the upgrades, the treatment system would be re-classified as a Level II system. Therefore, Schedule C of the proposed permit will require the permittee to retain a certified Level II operator for the system. However, the

10 Page 10 condition will allow the permittee a reasonable amount of time to obtain a certified Level II treatment system operator. Schedule A - Waste Discharge limitations BOD and TSS concentration and mass limits Based on the Willamette Basin minimum design criteria, wastewater treatment resulting in a minimum of secondary treatment is required from November 1 through April 30. Secondary treatment in Oregon is defined as monthly average concentration limit of 30 mg/l for BOD 5 or 25 mg/l for CBOD 5 and 30 mg/l for TSS. Lagoons are given special consideration in setting concentrations limits for TSS. The monthly average TSS concentration limit can be 50 mg/l with a weekly average limit of 80 mg/l. The Department is proposing concentration limits at least as stringent as the basin minimum design criteria. The proposed monthly average BOD 5 concentration limit is 30 mg/l with a weekly average limit of 45 mg/l. The proposed monthly average TSS concentration limit is 50 mg/l with a weekly average limit of 80 mg/l. The winter mass load limits for the facility are based on the design ADWF of 0.80 MGD and the monthly average BOD 5 or TSS concentration limits of 30 mg/l and 50 mg/l, respectively. The limits are in accordance with OAR l(10)(e). All mass load limitations are rounded to two significant figures. The winter mass limits can be based on design average wet weather flow (AWWF) but the Department considers Flat Creek to be an inadequate receiving stream and will not allow a winter flow based mass load increase at this time. However, the proposed permit does contain a compliance condition requiring the permittee to submit an engineering study after the completion of the new Outfall 001 to the Willamette River that accurately determines the design wet weather flow and to request a permit modification that would allow the winter mass load limits be based on the design wet weather flow. The alternative is for the permittee to retain the existing mass load limits. The proposed permit bases winter mass discharge limits on the monthly average dry weather design flow and are considered interim in accordance with Oregon Administrative Rule (OAR) (10)(d). BOD^ and TSS The limits are: (1) May 1-October 31: No discharge to state waters is permitted. (2) November 1 - April 30: I I Average Effluent Monthly Weekly Daily

11 Page 11 Parameter BOD 5 TSS Concentrations Monthly Weekly 30 mg/l 45 mg/l 50 mg/l 80 mg/l Average lb/day Average lb/day Maximum Lbs Calculations: (1) BOD5 (a) (b) (c) 0.80 MGD x 8.34 #/gal x 30 mg/l monthly avg. = 200 lbs/day 200 lbs/day monthly avg. x 1.5 = 300 lbs/day weekly avg. 200 lbs/day monthly avg. x 2.0 = 400 lbs/day daily max. (2) TSS (a) (b) (c) 0.80 MGD x 8.34 #/gal x 50 mg/l monthly avg. = 330 lbs/day 330 lbs/day monthly avg. x 1.5 = 500 lbs/day weekly avg. 330 lbs/day monthly avg. x 2.0 = 670 lbs/day daily max. BODj and TSS Percent Removal Efficiency A minimum level of percent removal for BOD 5 and TSS for municipal dischargers is required by the Code of Federal Regulations (CFR) secondary treatment standards (40 CFR, Part 133). In accordance with the federally approved standards for Oregon under 40 CFR , certain types of treatment facilities (including trickling filters and facultative lagoons) are eligible for consideration of lower percent removal limits. The proposed permit requires a minimum monthly average BOD 5 and TSS removal efficiency of 85 and 65 percent respectively. ph The Willamette Basin Water Quality Standard for ph is found in OAR The allowed range is 6.5 to 8.5. The proposed permit limits ph to the range 6.0 to 9.0. This limit is based on Federal wastewater treatment guidelines for sewage treatment facilities, and is applied to the majority of NPDES permittees in the state. Within the permittee's mixing zone, the water quality standard for ph does not have to be met. Mixing with ambient water within the mixing zone will ensure that the ph at the edge of the mixing zone meets the standard based on a Department approved ph evaluation spreadsheet that derives mixing zone boundary values for ph (See Attachment 4). Bacteria The proposed permit limits are based on an E. coli standard approved in January The proposed limits are a monthly geometric mean of 126 E. coli per 100 ml, with no single sample exceeding 406 E. coli per 100 ml. The bacteria standard allows that if a single sample exceeds 406 E. coli per 100 ml, then the permittee may take five consecutive re-samples. If the log mean of the five re-samples is less than or equal to 126, a violation is not triggered. The new rule

12 Page 12 states that the re-samples should be taken at four hour intervals beginning as soon as practicable (preferably within 28 hours) after the original sample was taken. The rale also allows for changing the re-sampling timeframe if it would pose an undue hardship on the treatment facility. After discussions with the permittee, the Department is proposing that the five re-samples be taken beginning no later than 48 hours after the original sample was taken. The bacteria limits for irrigation of level II reclaimed water are a 7-day median of 23 organisms/100 ml, with no two consecutive samples to exceed 240 total coliform per 100 ml. Chlorine Residual Disinfection of the effluent with chlorine is the process the permittee uses to comply with the waste discharge limitations for bacteria. The current facility uses chlorine gas to disinfect the treated wastewater. Chlorine is a known toxic substance and as such is subject to limitation under Oregon Administrative Rules. The (OAR (2)) states in part that toxic substances shall not be discharged to waters of the state in concentrations that adversely affect public health, aquatic life or other designated beneficial uses. In addition, concentrations of toxic substances shall not exceed the criteria listed in Table 20 which were based on criteria established by the EPA and published in Quality Criteria for Water (1986), unless otherwise noted. However, OAR (2)(b)(A) states that the Department may allow a designated portion of a receiving water to serve as a zone of dilution for wastewaters and receiving waters to mix thoroughly and this zone will be defined as a mixing zone. The Department may suspend all or part of the water quality standards, or set less restrictive standards, in the defined mixing zone, provided the water within the mixing zone is free of materials in concentrations that will cause acute toxicity to aquatic life as measured by the acute bioassay method and outside the boundary of the mixing zone is free of materials in concentrations that will cause chronic toxicity. Furthermore, 40 CFR (d) states that permit limitations must control all pollutants or pollutant parameters which are or may be discharged at a level which will cause, have the reasonable potential to cause, or contribute to an excursion above any state water quality standard, including state narrative criteria for water quality. The fresh water criteria for chlorine were used to calculate permit limitations. According to OAR , Table 20, chlorine concentrations of 11 pg/l can result in chronic toxicity in fresh waters while 19 pg/l can result in acute chlorine toxicity in fresh waters. Compliance with acute toxicity criteria is required at the edge of the Zone of Immediate Dilution (ZID) and compliance with chronic toxicity criteria is required at the edge of the mixing zone. For the current facility, the Department chose to perform a Reasonable Potential Analysis (RPA) using worst case conditions. The Department used an effluent to stream ratio using the design flow for the facility, and 25% of the lowest winter flow in Flat Creek (There is currently no USGS gauging station on Flat Creek), and the highest measured residual chlorine concentration of 2.2 mg/l. Consequently, the 7Q10 flow is not available. However, the permittee has been recording the winter flows in flat creek using a staff gauge based on the cross section of the

13 Page 13 Creek. The Department used 0.74 cfs which is the lowest flow recorded for the last three years). This data was input into an EPA approved spreadsheet to determine if there is a reasonable potential for chlorine toxicity within the receiving stream (See Attachment 5). The RPA analysis indicated that there is a reasonable potential for chlorine to cause acute and chronic toxicity within the receiving stream during the discharge season. A chlorine limit will be included in the permit (See Attachment 6): Pollutant Total Chlorine Residual Limitations Shall not exceed 0.02 mg/l daily maximum and 0.01 mg/l monthly average In accordance with EPA Region X guidance for establishing water quality based effluent limits (WQBEL) below analytical detection limits; the Department is including the above limits in the permit but is using the promulgated Minimum Level (ML) as the "compliance evaluation level". Daily maximum concentrations below 0.10 mg/l will be considered in compliance with the limitation. The permittee will not be able to comply with the proposed chlorine limits with the current facilities. However, the permittee is currently under a Mutual Agreement and Order (MAO) with the Department. The MAO will be modified and re-issued with the proposed permit. Part of the MAO modifications will include interim chlorine limits with a plan and schedule for meeting the in stream water quality standard for chlorine toxicity. Ammonia The State of Oregon has adopted the EPA 1999 ammonia criteria but the new criteria have not been formally approved by EPA. Until that time, the existing toxicity standards currently contained in OAR Chapter 340, Table 20 from the EPA 1986 Gold Book Criteria are used to evaluate ammonia toxicity to determine if limits are necessary in a permit. A reasonable potential analysis was conducted using the effluent and stream data as described under the "Chlorine Toxicity" section above. Using the highest effluent ammonia data from 3 samples of ammonia, the spreadsheet analysis indicated that there was no reasonable potential to violate the ammonia toxicity standard at the edge of the ZID, however it did indicate there was a reasonable potential to violate the standard at the edge of the mixing zone (See Attachment 7). Therefore, the Department calculated effluent ammonia limits (See Attachment 8) and has included the effluent limitations for ammonia during the winter discharge season in the proposed permit. In addition, monitoring for ammonia-n has been included in the proposed permit during the discharge season in order to provide additional data. The proposed permit limits are listed below: Pollutant Ammonia-N Limitations Shall not exceed 3.0 mg/l daily maximum and 1.6 mg/l monthly average The permittee will not be able to comply with the proposed ammonia limits with the current facilities. However, the permittee is currently under a Mutual Agreement and Order (MAO)

14 Page 14 with the Department. The MAO will be modified and re-issued with the proposed permit. Part of the MAO modifications will include interim ammonia limits with a plan and schedule for meeting the instream water quality standard for ammonia toxicity. Temperature As discussed above, there is no reasonable potential for the discharge to warm the river more than 0.3 C above the criterion. Therefore, the proposed permit will not contain an Excess Thermal Load limit. Mixing Zone and Zone of Immediate Dilution Federal regulations (40 CFR ) allow for the use of mixing zones, also known as "allocated impact zones". When using mixing zones acute toxicity to drifting organisms must be prevented and the integrity of the water body as a whole may not be impaired. Mixing zones allow the initial mixing of waste and receiving water, but are not designed to allow for treatment. EPA does not have specific regulations pertaining to mixing zones. Each state must adopt its own mixing zone regulations that are subject to review and approval by EPA. In States that lack approved mixing zone regulations, ambient water quality standards must be met at the end of the pipe. The Department has adopted the two-number aquatic life criteria and developed mixing zone regulations with respect to that. The regulations are primarily narrative and essentially require the permit writer to use best professional judgment in establishing the size of the mixing zone. Based on EPA guidance and the Department's mixing zone regulations, two mixing zones may be developed for each discharge that reflect acute and chronic effects: 1) The acute mixing zone, also known as the "zone of initial dilution" (ZID), and 2) the chronic mixing zone, usually referred to as "the mixing zone". The acute mixing zone is designed to prevent lethality to organisms passing through the ZID. The chronic mixing zone is designed to protect the integrity of the entire water body as a whole. The allowable size of the mixing zone should be based on the relative size of the discharge to the receiving stream, the beneficial uses of the receiving stream, location of other discharges to the same water body, location of drinking water intakes, and other considerations. More specific guidance is available from the EPA regarding criteria used to in appropriately sizing a ZID. Primarily the ZID must be designed to prevent lethality to drifting organisms. The Department's mixing zone regulations state the mixing zone must be less than the total stream width as necessary to allow passage of fish and other aquatic organisms. Early recommendations regarding the size of the zone of passage originated from the Department of Interior (1968). They recommended a zone of passage of 75 percent of the cross-sectional area and/or volume of flow of the receiving stream. Based on this recommendation, the Department's standard practice is to allow no more than 25 percent of the stream flow for mixing zones. The proposed regulatory mixing zone is modified in this permit from the current permit to be defined as follows: that portion of Flat Creek where the effluent mixes with 25 percent of the stream flow but in no case shall it extend farther than five (5) feet out from the outfall pipe and from a point

15 Page 15 ten (10) feet upstream of the outfall to a point one-hundred (100) feet downstream from the outfall. The Zone of Initial Dilution (ZID) shall be defined as that portion of the allowable mixing zone that is within two (2) feet of the point of discharge. The Department believes that there may not be adequate dilution within the receiving stream and that the beneficial uses of the receiving stream may be affected by this discharge. However, the permittee is under an MAO to eliminate this outfall and build a new outfall to the Willamette River. Once the upgrades to the facilities are complete, the Department may re-open and modify the permit as necessary to describe the new mixing zone within the Willamette River. Groundwater The City of Junction City is located in the Groundwater Management Area. Based on the Department's current information, this facility has a low potential for adversely impacting groundwater quality. Therefore, the permit includes a condition in Schedule A that prohibits any adverse impact on groundwater quality. In addition, Schedule D of the proposed permit states that no groundwater evaluations will be required during this permit cycle. No other groundwater impacts are expected from this source when reclaimed water is used in accordance with OAR Outfall 002-Reclaimed Water Prior to irrigation of the reclaimed water, the discharge must comply with total coliform limits based on protection of human health due to human pathogens. For Level II reclaimed water, the limits include a weekly median of 23 total coliform per 100 mis with no two consecutive samples to exceed 240 total coliform per 100 mis. The application of reclaimed water must be managed in accordance with the approved Reclaimed Water Use Plan. All reclaimed water shall be distributed on land, for dissipation by evapotranspiration and controlled seepage by following sound irrigation practices so as to prevent: a. Prolonged ponding of treated reclaimed water on the ground surface. b. Surface runoff or subsurface drainage through drainage tile. c. The creation of odors, fly and mosquito breeding or other nuisance conditions. d. The overloading of land with nutrients, organics, or other pollutant parameters; all consumptive and agronomic site loadings must be according to the approved RWUP. e. Impairment of existing or potential beneficial uses of groundwater. Specific crops, application rates and buffers will be approved by the Department within the Reclaimed Water Use Plan. The bacterial effluent limitations are achievable through proper operation and maintenance. The permittee is under an MAO to complete improvements to the wastewater facilities. Part of the improvements will require that a new land application site for reclaimed wastewater be obtained. Schedule C, Condition 6, of the proposed permit requires that the permittee submit for review and approval an updated Reclaimed Water Use Plan by no later than December 31,2010. This date will coincide with the completion of the new wastewater facilities.

16 Page 16 Schedule B - Minimum Monitoring and Reporting Requirements Schedule B describes the minimum monitoring and reporting necessary to demonstrate compliance with the conditions of this permit. The authority to require periodic reporting by permittees is included in ORS (5). Self-monitoring requirements are the primary means of ensuring that permit limitations are being met. However, other parameters need to be monitored to collect information when insufficient information exists to establish a limit, but where there is a potential for a water quality concern. In 1988, the Department developed a monitoring matrix for commonly monitored parameters. The matrix was updated in Proposed monitoring frequencies for all parameters are based on this matrix and, in some cases, 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. The permittee is required to have a laboratory Quality Assurance/Quality Control program. The Department recognizes that some tests do not accurately reflect the performance of a treatment facility due to quality assurance/quality control problems. These tests should not be considered when evaluating the compliance of the facility with the permit limitations. Thus, the Department is also proposing to include in the opening paragraph of Schedule B a statement recognizing that some test results may be inaccurate, invalid, do not adequately represent the facility's performance and should not be used in calculations required by the permit. Below is a discussion of some of the minimum monitoring requirements contained in the proposed permit: a. Influent Item or Parameter Total Flow (MGD) Flow Meter Calibration BOD, TSS ph Minimum Frequency Daily Annually Weekly Weekly 3/Week Type of Sample Measurement Verification Composite Composite Grab Treated Effluent Outfall 001 Item or Parameter Total Flow (MGD) Flow Meter Calibration BOD 5 TSS ph Effluent Temperature E. coli Ammonia-N Minimum Frequency Daily Annual Weekly Weekly 3/Week 3/Week Weekly 1 per 2 Weeks Type of Sample Measurement Verification Composite Composite Grab Record Grab Grab

17 Page 17 Quantity Chlorine Used Chlorine Residual Pounds Discharged (BOD 5 and TSS) Average Percent Removed (BOD 5 and TSS) Outfall 002-Level II Reclaimed Water Daily Daily Weekly Monthly Measurement Grab Calculation Calculation Item or Parameter Flow Meter Calibration Total Flow Quantity Irrigated (inches/acre) Quantity Chlorine Used Chlorine Residual ph Total Coliform Nutrients (TKN, N0 2 +N0 3 -N, NH 3, Total Phosphorus) Minimum Frequency Annually Daily Daily Daily Daily 3/Week 1/Week 1 per 2 Weeks Type of Sample Verification Measurement Measurement Measurement Grab Grab Grab Grab Flat Creek e. Biosolids Item or Parameter Minimum Frequency Type of Sample Flow (upstream) 3/Week Measurement The Department approved the permittee's biosolids management plan in August 2001, which allows the permittee to remove solids from the lagoon cells and land apply the solids as part of Phase II of the wastewater facility upgrades to the treatment facility. The permittee will be required to follow the conditions of the approval letter prior to removing any additional biosolids from the existing lagoon cells. Therefore, the permittee will not be required measure sludge depth in the lagoons during this permit cycle. Reporting The reporting period is the calendar month. Discharge monitoring reports must be submitted to the Department monthly by the 15 th day of the following month. The monitoring reports need to identify the principal operators designated by the Permittee to supervise the treatment and collection systems. The reports must also include records concerning application of biosolids and all applicable equipment breakdowns and bypassing. Schedule B of the permit includes the requirement for the submittal of two annual reports. The permittee must submit an annual report on inflow and infiltration reduction activities, and a report on the reclaimed water system.

18 Page 18 Schedule C - Compliance Conditions The proposed permit includes eleven compliance conditions with compliance deadlines. requirements include: The Within 180 days of completing the installation of the new lagoon cell, the permittee shall submit a Leak Test Plan to the Department prior to conducting a leak test on the new lagoon cell. Within 180 days after Department approval of the Leak Test Plan, the permittee shall conduct a leak test on the new lagoon cell and submit the results of the leak test to the Department. Should the results of the leak test show that the seepage rate from the new lagoon cell is greater than or equal to 1/8 inch per day, then within 90 days of Department approval of the results, the permittee shall submit to the Department for approval a plan and schedule to perform corrective action for fixing the new leaking lagoon cell and preventing groundwater pollution from occurring pursuant to OAR By no later than one year after completion of the Outfall 001 pipeline to the Willamette River and all upgrades to the wastewater treatment facilities are brought on-line, the permittee shall submit to the Department either an engineering evaluation which demonstrates the design average wet weather flow and a request for winter flow based mass load limits, or a request to retain the existing mass load limits. A compliance condition requiring the permittee to submit a proposed program and time schedule for identifying and reducing inflow if the permittee requests a permit modification to include higher winter mass load limits based on wet weather flow. By no later than December 31, 2010, the permittee shall submit for review and approval an updated Reclaimed Water Use Plan. The plan shall be in accordance with OAR Six months prior to the removal of accumulated solids from the lagoon, the permittee shall submit to the Department a revised biosolids management plan developed in accordance with Oregon Administrative Rule 340, Division 50, "Land Application of Domestic Wastewater Treatment Facility Biosolids, Biosolids Derived Products, and Domestic Septage". Upon approval of the plan by the Department, the plan shall be implemented by the permittee. By no later than 90 days after permit issuance, the permittee shall submit to the Department a report which either identifies known sewage overflow locations and a plan for estimating the frequency, duration and quantity of sewage overflowing, or confirms that there are no overflow points. The report shall also provide a schedule to eliminate the overflow(s), if any. By no later than June 30, 2008, the permittee will have an operator/supervisor who is qualified at the new plant classification of Level II in accordance with Oregon Administrative Rules (OAR), Chapter 340, Division 49, "Regulations Pertaining To Certification of Wastewater System Operator Personnel".

19 Page 19 Within six months from the date of permit issuance, the permittee shall submit to the Department an approvable plan and schedule for conducting and Industrial Waste User Survey. The final condition requires the permittee to meet the compliance dates established in this schedule or notify the Department within fourteen days following any lapsed compliance date. Schedule D - Special Conditions The proposed permit includes eight special conditions. The requirements include: A condition that all biosolids shall be managed in accordance with the DEQ approved biosolids management plan. A condition that the permit may be modified to incorporate any applicable standard for biosolids use or disposal promulgated under section 405(d) of the Clean Water Act. The permittee must have the facilities supervised by personnel certified by the Department in the operation of treatment and/or collection systems. A condition requiring the permittee to comply with the rales concerning the use of reclaimed water and the Reclaimed Water Use Plan approved by the Department. A condition that requires the permittee to keep a cover crop on the irrigation site at all times unless otherwise approved by the Department in the Reclaimed Water Use Plan. A condition that all reclaimed water used at the treatment plant site for landscape irrigation will be exempt from OAR , provided the reclaimed water receives secondary treatment and disinfection and is confined to the treatment plant site. A condition in that prohibits any adverse impact on groundwater quality. The permittee shall notify the Departments Western Region - Salem Office of any malfunctions so that corrective action can be coordinated between the permittee and the Department in accordance with the General Conditions of this permit. Schedule F, NPDES General Conditions All NPDES permits issued in the State of Oregon contain certain conditions that remain the same regardless of the type of discharge and the activity causing the discharge. These conditions are called General Conditions. These conditions can be changed or modified only on a statewide basis. The July 2005 edition is included as Schedule F of the draft permit. Section A contains standard conditions which include compliance with the permit, assessment of penalties, mitigation of noncompliance, permit renewal application, enforcement actions, toxic discharges, property rights and referenced rales and statutes. Section B contains requirements for operation and maintenance of the pollution control facilities. This section includes conditions for proper operation and maintenance, duty to halt or reduce activity in order to maintain compliance, bypass of treatment facilities, upset conditions, treatment of single

20 Page 20 operational events, overflows from wastewater conveyance systems and associated pump stations, public notification of effluent violation or overflow, and disposal of removed substances. Section C contains requirements for monitoring and reporting. This section includes conditions for representative sampling, flow measurement, monitoring procedures, penalties of tampering, reporting of monitoring results, additional monitoring by the permittee, averaging of measurements, retention of records, contents of records, and inspection and entry. Section D contains reporting requirements and includes conditions for reporting planned changes, anticipated noncompliance, permit transfers, progress on compliance schedules, noncompliance which may endanger public health or the environment, other non-compliances, and other information. Section D also contains signatory requirements and the consequences of falsifying reports. Section E contains the definitions used throughout the permit. PERMIT PROCESSING/PUBLIC COMMENT/APPEAL PROCESS The beginning and end date of the public comment period to receive written comments regarding this permit, and the contact name and telephone number are included in the public notice. The permittee is the only party having standing to file a permit appeal. If the Permittee is dissatisfied with the conditions of the permit when issued, they may request a hearing before the EQC or its designated hearing officer, within 20 days of the final permit being mailed. The request for hearing must be sent to the Director of the Department. Any hearing held shall be conducted pursuant to regulations of the Department.