DEQ. National Pollutant Discharge Elimination System PERMIT EVALUATION AND FACT SHEET November 8,2006

Transcription

1 ^m~m^< DEQ State of Oregon Department of Environmental Quality National Pollutant Discharge Elimination System PERMIT EVALUATION AND FACT SHEET November 8,2006 Oregon Department of Environmental Quality Western Region 1102 Lincoln Street, Suite 210 Eugene, OR (541) Permittee: Current Permit: Source Information: Source Contact: Proposed Action: Permit Writer: Veneta, City of PO Box 458 Veneta, OR File Number: NPDES Permit Number: EPA Reference Number: OR Issue Date: March 27,2002 Expiration Date: December 31,2006 City of Veneta Wastewater Treatment Facilities SerticRoad, Veneta Latitude, 44 05' 15" North, Longitude ' 23" Kyle Schauer Public Works Superintendent Telephone Number: NPDES Minor Domestic Permit Renewal Application Number; Date Received: June 7, 2006 Julie M. Berndt Phone: West BACKGROUND Introduction The City of Veneta operates a wastewater treatment facility located in Veneta, Oregon, Wastewater is treated and discharged in accordance with National Pollutant Discharge Elimination System (NPDES) Permit number The Permit for the facility was issued on March 27, 2002, and is scheduled to expire on December 31, In accordance with OAR , the applicant has filed a completed renewal application. The Department proposes to renew the permit. Facility Description The original treatment system was constructed in 1970 and consisted of a single cell, 3.86 acre facultative lagoon followed by chlorination and discharge during the winter to the Long Tom River at River Mile (RM) 33. The

2 Page 2 facility was expanded in 1976 to include two facultative lagoons with a total of acres, a submerged rock filter, and a larger chlorine contact chamber. In 1982, the City began summer spray irrigation of treated effluent on nearby farm land purchased by the City. A pipeline was constructed from the chlorine contact chamber to the irrigation fields and an effluent pump was installed in the chamber. The existing sewage treatment facility was constructed in 2002 and is a lined earthen lagoon activated sludge system known as a BIOLAC system. The headworks consists of an influent Parshall flume, an influent pump station, headworks with one in-channel rotary type mechanical screw and screening and a manually cleaned bar screen bypass, There is a three million-gallon lined earthen surge basin to equalize high flows that go over the bypass. A rotating drum screen, a screw conveyer and press, and a grit container all provide primary treatment prior to wastewater entering the BIOLAC system. The system has a maximum design flow of 1.25 million gallons per day (MGD) based on the capacity of the screw pumps. The BIOLAC system is an activated sludge technology that uses moving aeration chains which suspend submerged fine-bubble diffusers within two large earthen activated sludge basins. This type of system operates in an extended aeration mode which provides a longer sludge age or solids retention time (SRT) which enables the system to achieve lower BOD, complete nitrification and better nutrient removal. The BIOLAC system consists of two earthen lagoon activated sludge treatment units with integral secondary clarifiers consisting of five bioflex headers accommodating 150 diffuser tubes per basin, Disinfection is provided by a low pressure UV disinfection system. There are two facultative sludge lagoons totaling that can hold 920,000 gallons where waste sludge is stored until land application. Flow is measured by an effluent Parshallflumewith an ultrasonic flow meter. Treated wastewater is pumped in the summer months to a holding pond and then through a pump station that pumps to an irrigation area of approximately acres utilizing poplar trees, and also a 40 acre parcel of grass pasture. In the winter flow is discharged through an outfall pipe with a single port diffuser to the Long Tom River at River Mile 33. J S2^"--i #, zm^^s^i k*k == % 4 (ft ^ir-'v r^ O «P Veneta /<_,.» _.._ J\l - 'i%0'!l &''& i : a / 4r/ffM ^ZZYZCj^ X "X "' '.' ««i?jl»m4s7l/ III "T^I^KtQ^Zm Wf 4 Ji ij> Imi.Miij :«m b n -nj rnr^mmwmm-wmmmmmmim^mifmli -.t1?-i!i.~ --. ~*T~ t/.-.-.-«t 'HUSOS?

3 Page 3 Treatment Plant Flows The engineer who designed the upgraded facilities made a determination that the average dry weather design flow (ADWDF) of the plant is 1.25 MGD. This is based on the capacity of the influent screw pumps to convey water to the BIOLAC system. Flows above this are generally diverted to the surge basin until they can be treated, The ADWDF is the estimated maximum flow expressed as a daily average flow, at which the design engineer expects the treatment facility can still consistently meet all effluent limits. For this facility, the current actual average dry weather flow to the plant (May 1 - October 31) for the period November, 2003 to October, 2005 (which was used as a representative period) is MGD (See Attachment #1). The City irrigates wastewater in the summer months. The City irrigates an average of MGD onto the irrigation sites, The current actual average wet weather flow (November 1 - April 30) for this same time period 0.59 MGD with a maximum daily flow of MGD. Flows above 1.25 MGD are diverted to the surge basin for later treatment and disposal. Based on these current flows, the Permittee has sufficient capacity available in the treatment facilities. The mass load limits in the current and proposed permit(s) are based on an average wet weather design flow (AWWDF) of 0,524 MGD which was the wet weather design flow of the former plant. Wet Weather Capacity Issues The permittee is requesting that discharge be allowed through Outfall 001 to the Long Tom River when occasional heavy precipitation during the months of May and October result in very high influent flows to the treatment plant. During these infrequent periods, discharge to the Long Tom River is not permitted, However, the heavy precipitation on the irrigation fields (Outfall 002) results in saturated soil conditions, ponding, and eventual runoff into surface waters should the permittee irrigate onto the fields during those times. Adverse impacts to groundwater from these types of conditions is also of concern. During the plant upgrades, a surge basin was designed and built to hold high flows during these periods which is later directed to the treatment plant and then disposed of through Outfall 001 or 002. Flows in the Long Tom River are very high during these periods as a result of the precipitation, Veneta was historically allowed a discharge during the month of May in past NPDES permits; this was changed in the permit renewal issued in 1996, Since that time, the City has requested permission from the DEQ to discharge outside of the permitted season, both in May and October when heavy precipitation has occurred. Part of the treatment plant upgrades completed in 2002 were done to increase the capacity of the treatment plant itself to deal with high wintertime flows and to expand the irrigation fields to provide adequate land for irrigation during the summer months. The City completed these requirements as follows: The City purchased new land and planted some of it with poplar trees to increase the uptake of nutrients and treated wastewater and expand the available land for irrigation; The City has developed and implemented an aggressive inflow and infiltration (I/I) identification and removal program to reduce extraneous water from entering the collection system during wet weather thus increasing the effective capacity of the treatment plant. The program has been adequately funded every year and annual reports outline the work that has been completed as well as the work that is planned for the next year; and, The City constructed a new surge basin designed to store flows above the design capacity of the plant for later treatment and/or for irrigation. The city also constructed a holding pond from which water is irrigated to the approved sites. Despite these upgrades and efforts to effectively deal with occasional high wet weather flows to the treatment facility, the City may still occasionally be faced with certain periods of time during May and October when discharge from either outfall is not permitted, and holding capacity has been used up due to high precipitation.

4 Page 4 The City has requested that the permit renewal allow discharge during these times based on certain conditions. These conditions would include high stream flows in the Long Tom River, accompanied by saturated irrigation fields. The Department agreed to evaluate whether this is a viable alternative and whether all water quality standards could be met under this scenario. These evaluations are presented later in this report. Inflow and Infiltration (W) The City's collection system has historically had very high inflow and infiltration. The City received a wintertime mass load increase during the last pemiit renewal on the condition that they implement a plan for inflow removal from the collection system, The City has complied with the plan and has removed a significant amount of inflow from the system, They have also done substantial work on identifying and removing infiltration from the collection system by TV-ing lines, installing sewer cleanouts for increased monitoring and replacing components of the piping over time. The City has submitted annual reports on progress made during the past year and plans for work in the upcoming year on schedule as required in the permit, The proposed permit will contain a condition that requires the permittee to continue implementing a plan for inflow removal as part of the condition for the wintertime mass load increase. Biosolids Management The permittee has an approved biosolids management plan. This plan is necessary prior to land apply sludge from the treatment system. The Department approved the biosolids management plan as part of the current permit when it was issued in The plan is adequate and will remain in effect for this permit action. Schedule D requires the permittee to submit an updated plan if any significant changes are planned in biosolids application. The permittee wastes sludge to the facultative sludge lagoons (FSL). Operation of the lagoons is rotated on approximately a yearly basis. The frequency of land application of biosolids should be annually from one lagoon each year after the initial filling. Biosolids were recently land applied during the summer of 2006 for the first time. Land application will be at beneficial rates on authorized application sites. The City will submit a report including amount applied and analytical results in February as required in the permit. Pretreatment The Veneta sewage treatment system does not have a formal pretreatment program. There are no categorical industries discharging to the system and the facility is not experiencing toxic upsets. Therefore, there is no industrial pretreatment survey recommended for this permit renewal. Groundwater A Groundwater Prioritization Evaluation was completed as part of this permit evaluation (see Attachment #2) The permittee uses a lined earthen lagoon, a lined earthen surge basin, and two lined earthen sludge lagoons for treatment of the wastewater. A compliance condition in Schedule C of the current permit required the City to conduct a leak test on the newly constructed lagoons in order to demonstrate that they are not leaking in excess of the rate allowed by the Departments groundwater rules. A Department hydrologist reviewed the results of the leak tests and determined that there is no leakage above DEQ acceptable rates for lagoons. No further action regarding groundwater concerns is required in this permit renewal. At the next permit renewal, potential groundwater impacts will be evaluated and the permit may require that another leak test to be performed Schedule A of the proposed permit prohibits adverse impacts to groundwater. A condition in Schedule D states that no groundwater evaluations will be required during this permit cycle.

5 Page 5 Stormwater Stormwater is not addressed in this permit. General NPDES permits for stormwater are not required for facilities with a designflowof less than 1 MGD, Compliance History The facility was last inspected on July 2, 2005 and was found to be operating in compliance with permit limitations and conditions. The monitoring reports and files were reviewed for the period that this current permit has been in effect. No complaints were documented during this permit cycle. There have been no informal or formal enforcement actions issued during this permit cycle. The facility is considered to be in substantial compliance with all permit limitations and conditions. Outfalls Outfall 001 During the winter months, all wastewater discharged from the wastewater treatment plant is discharged through Outfall 001 to the Long Tom River. The outfall discharges at RM 33. In the current permit, the allowable mixing zone for this outfall is defined as that portion of the Long Tom River contained within a band extending out twenty feet from the east bank of the river and extending from a point fifteen feet upstream of the outfall to a point one-hundred-fifty feet downstream of the outfall. The Zone of Immediate Dilution (ZID) shall be defined as that portion of the allowable mixing zone that is within fifteen feet of the point of discharge. Evaluation of the current mixing zone is discussed later in this report Outfall Reclaimed Water The City owns approximately 112 acres of land where poplar trees are planted on the majority of the land. Reclaimed water is beneficially irrigated in the summer months from Outfall 002 in accordance with the Department approved Reclaimed Water Use Plan and Oregon Administrative Rules (OAR) Chapter 340, Division 55. The reclaimed water meets Level II reclaimed water standards in order to reduce Total Coliform bacteria to not more than 240 organisms per 100 ml in not more than two consecutive samples, and a 7-day median of 23 organisms per 100 ml. No discharge from the irrigation area to state waters is permitted. All reclaimed water will be distributed on land for dissipation by evapotranspiration by following sound irrigation practices so as to prevent: Prolonged ponding of treated wastewater on the ground surface; Surface runoff or subsurface drainage through drainage tile; The creation of odors, fly and mosquito breeding or other nuisance conditions; The overloading of land with nutrients, organics, or other pollutant parameters; and, Impairment of existing or potential beneficial uses of groundwater. During 2005, the permittee irrigated a total of 37.7 million gallons from May - October, They removed 44,000 lbs of hay from the grass growing portion of the site. The permittee's reclaimed water use plan has been approved by the Department. The annual reports describing the effectiveness of the reclaimed water system have been complete and submitted on time. Any changes to the approved plan will follow the procedures outlined in Schedule D,

6 Page 6 Pollutants Discharged The current permit allows the City of Veneta to discharge treated effluent from the wastewater treatment plant to the Long Tom River from November 1 through April 30 each year and to land irrigation from May 1 - October 31. The current permit sets limits on the following pollutants for discharge to the Long Tom River: Five-day Biochemical Oxygen Demand (BODS), Total Suspended Solids (TSS), and R coli bacteria. The discharge is also regulated for ph and pollutant removal efficiency. The permittee is requesting that the discharge season be extended to include times when the precipitation is high and the irrigationfieldscannot yet be used. The assumption is that during these times, theflowin the Long Tom River would be high enough to provide adequate mixing with the treated effluent to meet the water quality standards. Mixing Zone Analysis 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 waterbody 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" (ZED), 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 upon 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 EPA regarding criteria used 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 necessaiy 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 current permit provides for a mixing zone that is defined as that portion of the Long Tom River contained within a band extending out twenty feet from the east bank of the river and extending from a point fifteen feet upstream of the outfall to a point 150 feet downstream of the outfall. The Zone of Immediate Dilution (ZID) shall be defined as that portion of the allowable mixing zone that is within fifteen feet of the point of discharge. The permittee completed a mixing zone study during facilities planning for the new plant (Long Tom River Effluent Mixing Study March 12, 1996, Systems West Engineers, Inc.) that showed that at critical low flow

7 Page 7 (7Q10) in the Long Tom River, the river width could be as small as 33 feet. Therefore, the mixing zone should be changed to reflect that no more of 25% of the river width can be used for mixing instead of the twenty feet that is currently allowed, The ZED should also be modified to generally be no more than 10% of the mixing zone area. Based on this evaluation, the Department proposes to amend the existing mixing zone and include a ZID as follows: The allowable mixing zone is that portion of the Long Tom River contained within a band extending out 1/4 the width of the stream from the east bank and extending from a point fifteen feet upstream of the outfall to a point 150 feet downstream from the outfall. The Zone of Immediate Dilution (ZED) is defined as that portion of the allowable mixing zone that is contained within a band one and one-half (1.5) feet upstream, two feet toward midstream and fifteen feet downstream of the point of discharge. Receiving Stream Water Quality Treated wastewater is discharged to the Long Tom River at RM The discharge is within the Willamette basin and Upper Willamette sub-basin. Applicable water quality standards for the Long Tom River are found in OAR A. Included in Table 6 as beneficial uses for the Willamette Basin are: Public domestic water supply, Private domestic water supply, Industrial water supply, Irrigation, Livestock watering, Fish and aquatic life (including salmonid rearing, passage and spawning), Wildlife and hunting, Fishing, Boating, Water contact recreation, Aesthetic quality, and Hydro Power 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. Water quality standards are based on protection of beneficial uses designated for that water body. The Department has established a list of water bodies that do not meet one or more water quality standards during the year in accordance with Section 303(d) of the Clean Water Act. The Willamette TMDL was issued on September 21,2006, and approved by the EPA on September 26, The Long Tom River in the area of the outfall 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. Fern Ridge Reservoir, which is downstream of the discharge and is part of the Long Tom River system is listed on the 303(d) List) as water quality limited for the following parameters during the discharge period: Waterbody Name ' Ri^^ffle J PiiruiiiL-tL-i '-\ Season! 1'cm Ridge Resei\oir/Lor.g lorn River. 2'!.2lo3l.8 Fecal Coliform Wintcr/Spring/Fall Fern Ridge Reservoir/Long Tom River 24.2 to 31.8 Turbidity Year Round

8 Page 8 The TMDL did not address the Long Tom River above Fern Ridge Reservoir because it was not listed for any parameters. The TMDL did address turbidity and bacteria in Fern Ridge Reservoir which is downstream of the point of discharge. Anti-degradation Review 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 nonpoint sources of pollution is prevented, The Department must make certain findings and consider certain issues before renewing the permit and/or allowing an extension of the discharge period to the river, This is to be in accordance with the Department's "Antidegradation Policy Implementation Internal Management Directive for NPDES Permits and Section 401 Water Quality Certifications (March, 2001)". The Department is obligated to review the request in relation to other alternatives to the request, beneficial uses which may be impacted, and the potential impacts to the water quality of the receiving stream. The Long Tom River has been determined to be High Quality Waters during the period of discharge, as described in this policy; therefore, the level of water quality in the water body shall be maintained and protected. An activity is considered likely to lower water quality if it would likely result in any measurable change in water quality away from conditions unimpacted by anthropogenic sources (outside the existing mixing zone). Measurable change will be based on criteria specified in OARs and/or on professional judgment based on the type of discharge. An Anti-Degradation review was done with this proposed permit renewal to ensure that the proposed permit meets the intent of the policy and rule. For this type of domestic discharge, dissolved oxygen and temperature were evaluated for a lowering of water quality (measurable change). As described below, these and other individual parameters were evaluated to ensure the policy and rule was being met (See Attachment #3). Dissolved Oxygen (DO) Based on OAR (3)(d), an activity that results in less than 0.1 mg/l decrease in DO will not constitute a lowering of water quality. During the facilities planning for the new treatment facility, the City and DEQ engineers evaluated the effects of the discharge from the new treatment facility on DO levels in the Long Tom River. A Streeter-Phelps Model was used to predict instream DO levels (sag) at various conditions including low flow conditions during the permitted discharge period (See Attachment #4). This information was also used to determine when discharge through Outfall 001 would be proposed outside the previous discharge season based on dilution provided by the river, A low flow analysis of the Long Tom River was done using flow data from the USGS gauging station number , Long Tom River near Noti, Oregon. This gauging station is located at RM 37.4, 2.4 river miles upstream of the discharge location and measures flow for an approximate drainage area of 89.3 square miles (mi 2 ). The estimated monthly 7Q10 (lowest average week flow for a ten year return period) for the month of November in the Long Tom River was measured to be 24 cubic feet per second (cfs) or 16 million gallons per day (MGD), The discharge flow rate from the facility is based on the estimated Design Average Wet Weather Flow (DAWWF) for the facility of MGD. Therefore, the Department used the DAWWF and the 7Q10flowfor November for the Long Tom River to determine the ultimate dilution ratio of approximately 32:1, receiving stream to effluent. All of the model runs demonstrated that the estimated maximum DO sag created by the WWTP discharge was less than 0.1 mg/l. It is important to note that all of the model runs used higher pollutant loading than are proposed in the permit for the mass loading discharge limitations.

9 Page 9 In October and May when discharge is proposed to be allowed during certain high river flows, the proposed discharge limits would be 10 mg/l for BOD and TSS with the mass loads reduced to 1/3 of the normal discharge season. This would effectively result in 1/3 less pollutant loading at the same riverflowsthat do not result in a DO sag above the 0.1 mg/l standard, Therefore, this would be less loading than the conservative estimates used for the existing discharge season. In addition, to be very conservative, the flow in the Long Tom River will be required to be at a minimum of 50 cfs, which is essentially twice times the river flow at the 7Q10 for November. It is anticipated that the facility can use other means of disposal when the riverflowis less than this because the plant can store and irrigate during tunes of drier weather, which equates to lower stream flows. Temperature Issues Based on OAR l-004(3)(c), an activity that results in less than a 0.3 C temperature increase at the edge of the mixing zone will not constitute a lowering of water quality. 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 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 Designations maps to identify applicable temperature criteria for each basin. The Willamette Basin maps are contained in OAR , Figures 340A and 340B, respectively, According to the newly approved use designation maps, spawning is not a designated use for the Long Tom River and therefore, the applicable numeric temperature criterion is 18 C for rearing and migration. Winter Discharge Season The Department's List of Water Quality Limited Water Bodies (also called the 303(d) List) for 2002 indicates the Long Tom River is not water quality limited for temperature at any time during the year. Because the stream is not listed for temperature and the TMDL for the Willamette basin has been completed, all sources taken together cannot cause a maximum impact more than 0.3 C above the ambient temperature in the Long Tom River. In lieu of the practicality of performing that evaluation, the Department uses a spreadsheet to perform a reasonable potential analysis for each source using either: 1) 25% of the stream; or, 2) the dilution at the edge of the mixing zone. Both have been calculated for this source. However, according to OAR (1 l)(c), the cold water protection requirements do not apply (the source is not limited to a 0.3 C increase) if: a. There are no threatened or endangered salmonids currently inhabiting the water body. b. The water body has not been designated as critical habitat. c. The colder water is not necessary to ensure that downstream temperatures achieve and maintain compliance with the applicable temperature criteria. The Long Tom River does not have T&E species, has not been designated as a critical habitat, and the river below the point of discharge is designated for cool water temperature criteria. Despite the exemption, and to be ultra conservative, the evaluation was done using the cold water criteria. The Department calculated in-stream temperature increases (see Attachment #5) using the existing facility design flow of MGD, a maximum effluent temperature of 20 C (higher than that which has been reported to be conservative), 25% of the 7Q10 stream flow during the month of November (critical low flow), and the stream temperature criteria of 18 C. Based on the spreadsheet calculations, the in-stream temperature increase is smaller than the allowable increase. Therefore, this facility has no reasonable potential to violate the

10 Page 10 temperature standard. Based on this analysis, an Excess Thermal Load limit has not been included in this permit. This also demonstrates no lowering of water quality from temperature. 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 for ammonia toxicity limits that might be necessary in a permit. A reasonable potential analysis (See Attachment #6) was conducted using the effluent and stream data as described under the "Temperature" section above. Using the highest effluent ammonia data from eight samples for ammonia, the spreadsheet does not show that there is a reasonable potential to violate the ammonia toxicity standard at the edge of the mixing zone and ZID. Therefore, no limit is included in this permit. m The proposed effluent limits for ph remain unchanged at 6,0 to 9.0 for the facility. The Willamette Basin water quality standards for ph are established in OAR The allowed ambient range is 6.5 to 8.5, The proposed permit limits ph to the range of 6.0 to 9.0. An evaluation of ph at the edge of the mixing zone shows that the facility will not cause a violation of the standard with a range of 6,0 to 9,0 (see Attachment #7). This limit is in accordance with Federal wastewater treatment guidelines for sewage treatment facilities (in 40 CFR (c)) and is applied to the majority of NPDES permittee's in the state. Within the permittee's mixing zone, the water quality standard for ph does not have to be met. The Department considers the proposed permit limits to be protective of the water quality standard. Turbidity Fern Ridge Reservoir fails to meet minimum water quality standards for turbidity and is therefore included on the 303(d) list. The Long Tom River itself is not listed for turbidity. The turbidity standard is established to protect the beneficial uses of salmonid rearing (trout), resident fish and aquatic life, and fishing. Internal sources of turbidity in the reservoir are a result of re-suspension of previously settled solids which are mostly storm related. These external sources of turbidity are caused by storm related inflows of solids due primarily to bank erosion and upland loads due to surface runoff. The recently completed TMDL for Fern Ridge Reservoir identifies Amazon and Coyote Creeks, which contain excessive loads of suspended solids, to be the main contributors of turbidity problems in Fern Ridge. There is no mention of point sources (including the City of Veneta) as contributors to these instream violations in the TMDL. The Long Tom River contribution to turbidity violations in Fern Ridge is also not considered significant and is not part of the TMDL allocation. Load allocations made in the TMDL for turbidity-causing suspended solids have been established for Coyote Creek and for Amazon Creek. Veneta's wastewater treatment facility produces very high quality effluent with very low total suspended solids (TSS). It is very unlikely that this point source is contributing to any instream violations of turbidity in Fern Ridge Reservoir. The current and proposed permit limit of 130 lbs/day monthly average has been taken into consideration in the TMDL, No restriction of this load is proposed, E. coli bacteria (Fecal Bacteria) The Long Tom River in the area of the discharge is not listed on the 303(d) list for fecal bacteria. Fern Ridge reservoir below the discharge is listed for this parameter. The bacteria standard is established to be protective of the beneficial use of water contact recreation.

11 Page 11 Chlorine Toxicity The upgrades to the new facility included installation of an Ultraviolet (UV) disinfection system instead of the use of chlorine. Therefore, chlorine toxicity will not be a problem to the in-stream water quality. Summary and Recommendations It is the Department's opinion that expanding the discharge season into spring and early summer when river flows exceeds 50 cfs and heavy precipitation precludes land irrigation, should not cause a measurable decrease in the DO concentration or a measurable increase in the temperature of the Long Tom River or Fern Ridge Reservoir. Likewise, allowing for discharge in October when stream flows exceed 50 cfs should not cause a measurable decrease in the DO concentration of the Long Tom River. All water quality standards will be met at the edge of the mixing zone or as otherwise required and therefore, it is assumed that all beneficial uses for the receiving water body are being protected. It is recommended that the discharge season for the NPDES permit be modified as follows: October 1-31 and May 1-31: Discharge only allowed when stream flow in the Long Tom River is at a minimum of 50 cubic feet per second (CFS), the treated effluent storage pond is near its capacity, and the approved land application sites are saturated which would preclude irrigation of treated wastewater. Mass load limits based upon the design average wet weather flow to the facility of MGD and the Willamette Basin standard of 10 mg/l BOD and TSS. PERMIT DISCUSSION Face Page The face page provides information about the permittee, description of the wastewater, outfall location, 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 the Long Tom River at RM 33.0, and by spray irrigation 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. In the current permit, the treatment and collection systems are considered Class II systems. Both systems were reevaluated to determine the appropriateness of the current classification for operator certification requirements (see Attachment #8). The evaluation of the current plant operations resulted in system classifications remaining the same at Level II. Schedule A - Waste Discharge limitations: The permittee has requested in their pennit renewal application an extension to the existing discharge season in accordance with OAR l-004(3)(a) for the facility. The request is proposed to be approved based on the findings in this report and in Attachment #3.

12 Page 12 The proposed permit limitations for BOD 5 and TSS are: a. Treated Effluent Outfall 001 (1) June 1 - September 30: No discharge to waters of the State (unless approved in writing by the Department) (2) November 1 - April 30 Parameter BOD5 TSS Average Effluent Concentrations Monthly Weekly 30 mg/l 45 mg/l 30 mg/l 45 mg/l Monthly* Average lb/day Weekly* Average lb/day Daily* Maximum lbs Winter mass load limits based upon design average wet weather flow to the facility equaling MGD. (3) October 1-31 and May 1-31: Parameter BOD5 TSS Average Effluent Concentrations Monthly Weekly 10 mg/l 15 mg/l 10 mg/l 15 mg/l Monthly* Average lb/day Weekly* 0 0 Average : lb/day < v/ypaily*oooo. Maximum XYY'MYfY Discharge only allowed when stream flow is the Long Tom River is at a minimum of 50 cubic feet per second (CFS), the treated effluent storage pond is near its capacity, and the approved land application sites are saturated which would preclude irrigation of treated wastewater. Mass load and concentration limits based upon the design average wet weather flow to the facility of MGD and the Willamette Basin standard of 10 mg/l BOD and TSS. Calculations: (1) BOD5 and TSS (June 1 - September 31) (a) (b) (c) MGD x 8.34 lbs/gal x 30 mg/l = 130 lbs/day monthly average 130 lbs/day monthly avg. x 1.5 = 200 lbs/day weekly avg. 130 lbs/day monthly avg. x 2.0 = 260 lbs/day daily maximum (2) BOD5 and TSS (October 1-31 and May 1-30) (a) (b) (c) MGD x 8,34 lbs/gal x 10 mg/l = 44 lbs/day monthly average 41 lbs/day monthly avg. x 1.5 = 66 lbs/day weekly avg. 41 lbs/day monthly avg. x 2.0 = 88 lbs/day daily maximum hi addition to the concentration and mass load limits for BOD 5 and TSS, the proposed permit requires a minimum monthly average BOD and TSS removal efficiency of 85 percent.

13 Page 13 EH The proposed permit discharge limits for ph are the same as the current permit. The Willamette Basin Water Quality Standard for ph is found in OAR (2)(d). The allowed range is 6,5 to 8.5. The proposed permit limits ph to the range of 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. It is the Department's belief that mixing with ambient water within the mixing zone will ensure that the ph at the edge of the mixing zone meets the standard, and the Department considers the proposed permit limits to be protective of the water quality standard. Fecal Bacteria The current and proposed permit contains limits on E. coli limits for Outfall 001 that are based on the surface water quality bacteria standard approved in January The 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 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. Chlorine The treatment facility uses ultra-violet light to disinfect the treated wastewater. No chlorine or chlorine compounds may be used for disinfection purposes for discharge through Outfall 001 and no chlorine residual will be allowed in the effluent due to chlorine used for maintenance purposes. Mixing Zone The current pennit provides for a mixing zone that is defined as that portion of the Long Tom River contained within a band extending out twenty feet from the East bank of the river and extending from a point fifteen feet upstream of the outfall to a point 150 feet downstream of the outfall. The Zone of Immediate Dilution (ZED) shall be defined as that portion of the allowable mixing zone that is within fifteen feet of the point of discharge. The permittee completed a mixing zone study during facilities planning for the new plant (Long Tom River Effluent Mixing Study March 12, 1996, Systems West Engineers, Inc.) that showed that at critical low flow (7Q10) in the Long Tom River, the river width could be as small as 33 feet. Therefore, the mixing zone should be changed to reflect that no more of 25% of the river width can be used for mixing instead of the twenty feet that is currently allowed. The ZID should also be modified to generally be no more than 10% of the mixing zone area. Based on this evaluation, the Department proposes to amend the existing mixing zone and include a ZID as follows: The allowable mixing zone is that portion of the Long Tom River contained within a band extending out 1/4 the width of the stream from the east bank and extending from a point fifteen feet upstream of the outfall to a point 150 feet downstream from the outfall. The Zone of Immediate Dilution (ZID) is defined as that portion of the allowable mixing zone that is contained within a band one and one-half (1.5) feet upstream, two feet toward midstream andfifteenfeet downstream of the point of discharge. Raw Sewage Overflows No overflows are allowed from this source unless the cause of the discharge is due to storm events as allowed under Schedule F.6.b. as described earlier in this report. Groundwater Based on the Department's current information, this facility has a low potential for adversely impacting groundwater quality. The permittee was required construct a lined holding pond that should be protective of groundwater beneath this source. Following construction of the lined lagoons, the Department required that leak tests be conducted on the new lagoons, A Department hydrologist reviewed the results of the leak tests and determined that there is no leakage above DEQ acceptable rates for lagoons. No further action regarding groundwater concerns has been required,

14 Page 14 It is not anticipated that the treatment process and discharge to surface waters is currently causing groundwater impacts. The facility is not included in the designated Groundwater Management Area, Therefore, no groundwater investigation will be required for this permit renewal. This will be evaluated again at the next permit renewal. A groundwater evaluation sheet is included in this report as Attachment #2. Schedule A 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. Outfall Reclaimed Water The utilization of treated effluent for agricultural purposes is regulated under OAR Prior to irrigation of the reclaimed water, the discharge must comply with bacteria 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. Treated wastewater shall be distributed on land, for dissipation by evapotranspiration and controlled seepage by following sound irrigation practices so as to prevent: Prolonged ponding of treated reclaimed water on the ground surface. Surface runoff or subsurface drainage through drainage tile. The creation of odors, fly and mosquito breeding or other nuisance conditions. The overloading of land with nutrients, organics, or other pollutant parameters; all consumptive and agronomic site loadings must be according to your approved RWUP. 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. Schedule B - Minimum Monitoring and Reporting Requirements Schedule B describes the minimum monitoring and reporting necessaiy 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: Influent and Outfall 001 (Treated Effluent) Daily monitoring of effluent flow when discharging and calibration of the flow meter annually is required in this permit. Monitoring of the influent and effluent for BODS and TSS is retained at once per week when discharging. Pounds of effluent BODS and TSS must be calculated at the same frequency. Federal secondary treatment standards require municipal sources to achieve a specific BOD5 and TSS removal efficiency as a monthly average. Reporting of the removal efficiencies is required in the current permit and no changes are proposed.

15 Page 15 The proposed permit requires bacteria monitoring of the effluent for E. coli bacteria once per week, Monitoring for E. coli must be performed in accordance with one of the methods approved by the Department. Monitoring of the influent and effluent for ph is required two times per week as in the current permit in accordance with the monitoring matrix, Temperature monitoring of the effluent is also required two times per week. The intensity of UV radiation passing through the water column will affect the systems ability to kill organisms. To track the reduction in intensity, the UV disinfection system must include a UV intensity meter with a sensor located in the water column at a specified distance from the UV bulbs, This meter will measure the intensity of UV radiation in mwatts-seconds/cm2. The daily UV radiation intensity shall be determined by reading the meter each day. If more than one meter is used, the daily recording will be an average of all meter readings each day. Flow is required to be monitored in the Long Tom River during the months of October and May if discharge is to occur through Outfall 001. The flow is to be reported as measured at the USGS stream gauge No, on the Long Tom River near Noti, Oregon, at R.M Outfall Level 2 Reclaimed Water The following monitoring is required when irrigating wastewater from Outfall 002: Item or Parameter Flow Meter Calibration Quantity Irrigated (inches/acre) PH Total Coliform UV Radiation Intensity Nutrients (TKN, N0 2 +N0 3 -N, NH 3, Total Phosphorus) Minimum Frequency Annually Daily 2/Week Weekly Daily Quarterly Type of Sample Verification Measurement Grab Grab Reading Grab Biosolids The permittee has an approved biosolids management plan. This plan is necessary prior to land apply sludge from the treatment system. The Department approved the biosolids management plan as part of the current permit when it was issued in 2002, The plan is adequate and will remain in effect for this permit action. Schedule D requires the permittee to submit and updated plan if any significant changes are planned in biosolids application The permittee wastes sludge to the facultative sludge lagoons (FSL). Operation of the lagoons is rotated on approximately a yearly basis. The frequency of land application of biosolids should be annually from one lagoon each year after the initialfilling.biosolids are currently in the process of being land applied during the summer of 2006 for the first time. Land application will be at beneficial rates on'authorized application sites. The City will submit a report including amount applied and analytical results required in February as required in the permit. Reporting The reporting period is the calendar month. Discharge monitoring reports must be submitted to the Department monthly by the 15th 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 three annual reports. The conditions are standard language requirements concerning: Annual report which details progress towards reducing inflow and infiltration. Annual report describing the reclaimed water use activities. For any year in which biosolids are land applied, a report shall be submitted to the Department by February 19 of the following year that describes solids handling activities for the previous year and includes, but is not limited to, the required information outlined in OAR (6)(a)-(e),