NPDES WASTEWATER DISCHARGE PERMIT EVALUATION

Transcription

1 NPDES WASTEWATER DISCHARGE PERMIT EVALUATION Department of Environmental Quality Eastern Region - Bend Office 475 NE Bellevue Drive, Suite 110; Bend, OR Telephone: (541) PERMITTEE: City of Hood River P.O. Box 27 Hood River, OR File Number: SOURCE LOCATION: 818 Riverside Drive SOURCE CONTACT: Doug Nichols Telephone Number: (541) PERMIT WRITER: Karen Bower Telephone Number: (541) ext PROPOSED ACTION: Renewal of a National Pollutant Discharge Elimination System (NPDES) wastewater discharge permit SOURCE CATEGORY: Major Domestic TREATMENT SYSTEM CLASS: Level IV COLLECTION SYSTEM CLASS: Level III PERMIT APPLICATION DATE: May 7, 2007 PERMIT APPLICATION NUMBER: BACKGROUND Introduction City of Hood River owns a sewage treatment plant located on Riverside Drive in Hood River. Operations Management International (OMI) operates the treatment facility, which serves a population of about 7,550 for the City and county. Wastewater is treated and discharged to the Columbia River at river mile in accordance with National Pollutant Discharge Elimination System (NPDES) Permit number The Permit for the facility was issued on October 25, 2004 and will expire on August 31,2009. The Department received a renewal application on May 1,2007. This permit is being renewed early in order to bring Hood River under the Department of Environmental Quality's new Hood River Basin watershed approach. Under this approach, ail systems within the Hood River Basin will expire during the same year. A renewal of this permit is necessary to allow continued discharge to state waters pursuant to provisions of Oregon Revised Statutes (ORS) 468B.050 and the Federal Clean Water Act. The Department proposes to renew the permit. Facility Description A major upgrade of the Hood River sewage treatment plant was completed in This upgrade included new head works, conversion of the old primary clarifier to an aerated storage basin for waste activated sludge and incoming aerobic sludge from package plants in nearby communities, new diffused air system in both aeration basins, rebuild of one existing secondaiy clarifier so that both are useable, new dewatered sludge handling facility (belt press, solids

2 Page 2 storage building, transport hoick and application equipment), remodel of digester building and replacement of some digester equipment, new emergency power generator and new composite sampling equipment. Tiie actual average dry weather flow from May 1 to October 31, for the past two years was 0.84 MGD. The average design dry weather flow is 2.0 million gallons/day (MGD). The actual average wet weather flow (November 1 through April 30), for the past two years was 1.30 MGD. The highest monthly average daily flow for the past two years was 2.11 MGD in January of Based on this data it does not appear that the City has a serious inflow and infiltration problem. However, an ongoing program to reduce inflow and infiltration is recommended Biosolids The permittee's most current biosolids management plan was approved on August 28,2002. Aerobically digested sludge from package plants in several nearby communities including Cascade Locks, Mosier, Parkdale, Stevenson, Timber-line' Lodge and Zig Zag are hauled to Hood River and mixed with the Hood River waste activated sludge. The solids are then dewatered with a gravity belt thickener and treated in the anaerobic digester at the Hood River facility. The biosolids are then dewatered with a belt filter press and stored as cake. Ultimate disposal is through land application on farmland. The permittee is required to sample its biosolids once per year for total solids, volatile solids, NH 3 -N, NO3-N, & TKN, phosphorus, potassium, and ph. It is also required to sample twice per year for 11 metals, and to report the percent reduction in volatile solids accomplished through stabilization. Records must be kept detailing biosolids application location, date and volume. Groundwater Based on the Department's current information, this facility has a low potential for adversely impacting groundwater quality. Therefore, no groundwater evaluations will be required during this permit cycle. However, the permit still includes a condition in Schedule A that prohibits any adverse impact on groundwater quality. Stormwater Stormwater is not addressed in this permit. Stormwater for this facility is currently covered under a 1200-Z General Permit. This general permit is not a subject of this permit renewal. Compliance History Annual compliance inspections were conducted on March 23,2005, March 7,2006, and April 25,2007. The facility was operating in compliance with the permit. Discharge monitoring reports since the last permit renewal in October of 2004 show compliance with the permit effluent limitations except for the following exceedances: August BOD Weekly Limit: reported level mg/l; permit level - 30 mg/l August BOD Weekly Limit: reported level mg/l; permit level - 30 mg/l TSS Monthly Limit: reported level mg/l; permit level - 20 mg/l January BOD Daily Maximum Limit: reported level -2,154 lbs/day; permit level ~ 1,000 lbs/day TSS Daily Maximum Limit: reported level - 3,210 lbs/day; permit level - 1,000 lbs/day Whole effluent toxicity testing was conducted in December of 2005, December of 2006, and January of 2007, as required in the City's NPDES permit. Based on the weight of evidence from the bioassays, it appeared that the City's discharge did not cause in stream toxicity nor violate 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 hot designed to allow for treatment. EPA does not have specific regulations pertaining to mixing zones. Each state must adopt its

3 Page 3 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 developed mixing zone regulations with respect to the two-number aquatic life criteria: chronic and acute (OAR ). 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 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 necessary to allow passage offish 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 crosssectional 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. Hood River's mixing zone is 100 feet. The width of the Columbia River at the outfall is over 4,000 feet, which means the mixing zone is less than 2.5% of the river's width. A dye study at the outfall from the Hood River wastewater treatment plant into the Columbia River was conducted in August, The study showed that the dilution at the boundary of the zone of initial dilution was approximately 5. The dilution at the mixing zone boundary was approximately 15. These dilution factors were used to calculate reasonable potential analysis and permit limits. PERMIT DISCUSSION Face Page The permittee is authorized to construct, install, modify, or operate a wastewater collection, treatment, control and disposal system. In accordance with OAR all permitted wastewater collection and treatment facilities are to receive a classification based on the size and complexity of the system. The Department has evaluated the proposed systems based upon rule criteria and classifies the systems as Treatment System Class IV and Collection System Class III. The Department has removed Emergency Overflow, Outfall 002 from the permit face page. This overflow is not a permitted outfall. Schedule A - Waste Discharge limitations Two categories of effluent limitations exist for NPDES permits: 1) Technology based effluent limits, and 2) Water quality based effluent limits. Technology based effluent limits have been established by EPA rules. Technology based effluent limits were established to require a minimum level of treatment for industrial or municipal sources using available technology. Water quality based effluent limits are designed to be protective of the beneficial uses of the receiving water and are independent of the available treatment technology. Technology-Based Effluent Limits EPA has established secondary treatment standards for domestic wastewater treatment facilities. The standards are found in 40 CFR Part 133. The ph must be between 6.0 and 9.0. The facility must remove at least 85% of the influent BOD 5 and TSS. In addition, this facility must achieve a biochemical oxygen demand (BOD 5 ) and suspended solids (TSS) monthly average of 30 mg/l and a weekly average of 45 mg/l during the winter months (November 1 - April 30). Also, the Hood River Basin minimum design criteria sets the monthly average effluent concentration at 20 mg/l

4 Page 4 and weekly average concentration of 30 mg/l for both BOD 5 and TSS during the summer months (May 1 - October 31). Water Quality-Based Effluent Limits Pollutant parameters should be limited if there is a reasonable potential for the discharge to cause or contribute to an excursion above any state water quality criteria or standard, Future Total Maximum Daily Loads (TMDL) may assign wasteload allocations to this source that will guide development of permit limits that protect against in-stream violations of water quality criteria. The Department is required to determine whether the discharge has the reasonable potential to cause or contribute to an exceedance of a water quality criterion, EPA has developed a method to make this determination for toxic pollutants called a reasonable potential analysis (RPA). An RPA relies on statistical probability to determine the likelihood that a discharge will violate an instream criterion based on the effluent data, its variability, available dilution, and the receiving water background concentration. The Department has developed an RPA spreadsheet that employs EPA's methodology. BOD and TSS Concentration, Mass, and Percent Removal Based on the Hood River Basin minimum design criteria, wastewater treatment resulting in a monthly average effluent concentration of 20 mg/l and a weekly average concentration of 30 mg/l for both BOD 5 and TSS must be provided from May 1 - October 31. From November 1 - April 30, a minimum of secondary treatment or equivalent control is required, Secondary treatment for this facility is defined as monthly average concentration limit of 30 mg/l and a weekly average concentration of 45 mg/l for both BOD 5 and TSS. The mass load limits are as follows: Summer BOD 5 & TSS Mass Limits (a) (b) (c) 2 MGD x 20 mg/l x L/gal x 1/453,592 Ib/mg = monthly avg. = 330 lbs/day 2 MGD x 30 mg/l x L/gal x 1/453,592 Ib/mg = weekly avg. = 500 lbs/day 330 lbs/day monthly avg. x lbs/day daily max. Winter BOD 5 & TSS Mass Limits (a) 2 MGD x 30 mg/l x L/gal x 1/453,592 lb/mg - monthly avg. = 500 lbs/day (b) 2 MGD x 45 mg/l x L/gal x 1/453,592 lb/mg = monthly avg. = 750 lbs/day (c) 500 lbs/day monthly avg. x 2.0 = 1,000 lbs/day daily max. Also, the facility is required to remove at least 85% of the influent BOD 5 and TSS. This requirement is set by the EPA (40 CFR ) for all similar treatment plants and is used to prevent dilution as a form of treatment. ph The Hood River Basin Water Quality Standard for ph is found in OAR (1). The allowed range is 7.0 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. 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. Bacteria The proposed permit limits are based on the E. coli standard contained in OAR (5). The proposed limits are a monthly geometric mean of 126 E. coli per 100 ml, with no single sample exceeding 406 E, colipqv 100 ml. If a single sample exceeds 406 E. coli per looml, 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

5 Page 5 triggered. The re-sampling must be taken at four hour intervals beginning within 28 hours after the original sample was taken. The proposed limits are taken directly from the Oregon bacteria rule which is found in OAR This rule establishes numeric in-stream water quality standards (OAR (1)), establishes a prohibition against discharging raw sewage, establishes effluent limitations and the methodology for establishing a violation (OAR (5)). Regarding the general condition 6 found in Section B of Schedule F in this permit which prohibits overflows from wastewater conveyance systems, the Environmental Quality Commission (EQC) recognizes that it is impossible to design and construct a conveyance system that will prevent overflows under all storm conditions. The applicant is not seeking permit coverage for overflows and the permit does not authorize such discharges. The State of Oregon has determined that all wastewater conveyance systems should be designed to transport storm events up to a specific size to the treatment facility. Therefore, in exercising its enforcement discretion regarding Sanitary Sewer Overflows, the Department will consider the following: (1) Whether the permittee has conveyance and treatment facilities adequate to prevent overflows except during a storm event greater than the one-in-five-year, 24-hour duration storm from November 1 through May 21 and except during a storm event greater than the one-in-ten-year, 24-hour duration storm from May 22 through October 31. In addition, DEQ will also consider using enforcement discretion for overflows that occur during a storm event less than the one-in-five-year, 24-hour duration storm from November 1 through May 21 if the permittee had separate sanitary and storm sewers on January 10, 1996, had experienced sanitary sewer overflows due to inflow and infiltration problems, and has submitted an acceptable plan to the Department to address these sanitary sewer overflows by January 1, 2010; (2) Whether the permittee has provided the highest and best practicable treatment and/or control of wastes, activities, and flows and has properly operated the conveyance and treatment facilities; (3) Whether the permittee has minimized the potential environmental and public health impacts from the overflow; and (4) Whether the permittee has properly maintained the capacity of the conveyance system. DEQ will review the permittee's determination of the one-in-five-year, 24-hour duration winter storm and the one-in-ten year, 24-hour duration summer storm as described above in the permit holder's facilities plan. In the event that a permit holder reports an overflow event associated with a storm event and DEQ does not have information from the permit holder sufficient to determine whether or not the storm event exceeds storm events as specified in OAR (6) & (7), DEQ will perform the determination using the information contained in Figure 26 of the 1973 NOAA Atlas 2 entitled "Precipitation-Frequency Atlas of the Western United States, Volume X - Oregon". This figure is entitled "Isopluvials of 5-yr 24-hr precipitation in tenths of an inch". The Atlas can be obtained on line at however the file is very large. A scanned version of Figure 26 is available at: DEQ will compare the information in this figure with rainfall data available from the National Weather Service, or other source as necessaty. Chlorine Chlorine is a toxic substance that is harmful to aquatic organisms. The permittee uses ultraviolet light to disinfect the treated effluent. According to the RPA conducted for chlorine, chlorine is not shown to have the reasonable potential to cause an exceedance of water quality criteria at the edge of the mixing zone. However, some chlorine is still used at the facility for maintenance purposes and the effluent that is reused at the plant site is chlorinated. Therefore, the Department proposes to retain the current chlorine limitations, as listed in Schedule A of the proposed permit.

6 Page 6 Toxics The Department reviewed seven sampling events conducted by the permittee over the past three years (shortened permit cycle) for various heavy metals. The results were tabulated and the largest of the seven data points were used to calculate a Reasonable Potential Analysis (RPA) at a 99% confidence level for each respective metal to determine whether the effluent discharge of the pollutants have the potential to cause acute toxicity outside the zone of initial dilution or chronic toxicity outside the mixing zone, (see RPA worksheets, attached). With the exception of silver and arsenic, all metals showed no reasonable potential for excursion of water quality standards. According to the RPA worksheet, silver has the potential to cause an exceedence of water quality criteria at the edge of the mixing zone. Therefore, a limit has been added to the proposed permit for silver. The proposed monthly average concentration limit for silver is mg/l and daily maximum concentration is mg/l. However, the Department feels that the actual problem is not high silver levels; rather, it is a function of extremely poor mixing at the discharge pipe. The Department strongly recommends an upgrade to the sewage treatment plant's Columbia River discharge pipe. If and when an upgrade to the discharge pipe occurs, the Department will use new dilution information from an updated mixing zone study to re-calculate the RPA, If the re-calculated RPA shows no potential to cause an exceedence of the water quality criteria at the edge of the mixing zoiie, the Department may re-open the permit to remove the silver limit and extra monitoring from the permit. Results of all but one of the arsenic samples were below detection limits. However this one data point (0.88 ug/l) was above the human health limits (0.002 ug/l) set for arsenic. In many locations about Oregon, Arsenic is found naturally occurring at levels that exceed human health limits. The geometric mean of the USGS Columbia River Arsenic data collected between 2001 and 2005 put the concentration of arsenic in the Columbia River at ug/l. The Department's Draft Strategy for Implementing Human Health Water Quality Standards in NPDES Permits (Draft Strategy) states that the Department must determine whether the POTW is a significant contributor to the receiving water load for arsenic. The Department determines this by evaluating whether the effluent causes downstream receiving water concentrations to be more than 10% greater than upstream concentrations. If the difference between the two concentrations is less than 10%, the POTW is not considered a significant contributor. It is very difficult to calculate concentrations based on one single result above the detection limit. However, assuming a worst case scenario and an effluent concentration of 0.88 ug/l, and using a dilution factor of 15, the concentration of arsenic at the edge of the mixing zone would be: 0^0= [(0.715 ug/lx 15) ug/l]/ ug/l Percent Difference - [(0.725 ug/l ug/l) / 0.715] x 100 = 1.4% Therefore, a concentration of 0.88 p,g/l arsenic in the effluent would only cause the receiving waters to increase by 1.4% at the edge of the mixing zone. The Hood River STP is not considered a significant contributor to arsenic in the Columbia River. However, in accordance with the Draft Strategy, the Department is increasing the monitoring frequency for arsenic and requiring continued implementation of existing Best Management Practices (BMP's) used at the facility. The Department will also require the permittee to sample the Columbia River for background concentrations, in order to obtain better arsenic data for use in calculations during the next permit cycle. Turbidity The water quality standard for turbidity is dependent on receiving stream turbidity measurements. The standard states that no more than a 10% increase in stream turbidity levels is allowed at the edge of the mixing zone relative to a control point immediately upstream of the discharge. To determine compliance with the turbidity standard, DEQ requested that Hood River STP conduct in-stream turbidity monitoring upstream of the discharge as well as effluent turbidity monitoring. The table below presents the pertinent statistical data for the measured turbidity concentrations.

7 Page 7 TABLE 12: COLUMBIA RIVER AND EFFLUENT TURBIDITY LEVELS Parameter Season Median Turbidity (NTU) 95 th percentile Turbidity (NTU) Effluent Turbidity May 1 - Oct. 31 Nov. 1 - April River Turbidity May 1 - Oct. 31 Nov. 1 - April ~ -- To determine whether there is a reasonable potential for this discharge to exceed the turbidity standard, a mass balance equation was used to determine the resulting increase in turbidity levels at the edge of the mixing zone. The calculation is as follows: Where: Turbidity^ = (Turbidity, * Q e + Turbidity, * Q s ) / (Q 1!1Z ) Turbidity inz is the turbidity concentration at the edge of the mixing zone; Turbidity e is the turbidity concentration in the effluent; Turbidity s is the turbidity concentration in the Columbia River upstream of the discharge Q s is the portion of the Columbia River available for mixing (14) Q inz is the dilution at the edge of the mixing zone (15) Q e is the effluent flow as a ratio to river flow (1) Using the median turbidity levels, the resulting turbidity increase at the edge of the mixing zone is NTU during the diy season (May 1 - October 31) and NTU during the wet season (November 1 - April 30). These values indicate a decrease in turbidity at the edge of the mixing zone, when compared to background turbidity levels. With the 95 th percentile effluent turbidity levels, the resulting turbidity increase at the edge of the mixing zone is 0.35 NTU during the diy season (May 1 - October 31) and NTU during the wet season (November 1 - April 30). Again, this indicates a decrease in turbidity during the wet season. The dry season value represents an increase in turbidity at the edge of the mixing zone; however, the increase is significantly less than the allowed 10% increase from background turbidity levels. Based on this analysis, it is determined that the discharge from outfall 001 has no reasonable potential to exceed the water quality standard for turbidity. Ammonia The Department performed a Reasonable Potential Analysis (RPA) for ammonia to determine if the effluent discharge has the potential to cause toxicity at the mixing zone or zone of immediate dilution boundaries (see RPA worksheets, attached). The results of the RPA showed that there was no potential for ammonia toxicity. Therefore, no ammonia limits have been proposed for this permit. Temperature Since the last permit was issued, the Department has adopted a new temperature standard. However, the temperature criterion for the Columbia River remains at 68 F (20 C). For streams that are listed on Oregon's 303(d) list, prior to the completion of a temperature TMDL or other cumulative effects analysis, the rule states that no single NPDES point source that discharges into a temperature water quality limited water may cause the temperature of the water body to increase more than 0.3 degrees Celsius (0.5 Fahrenheit) above the applicable criteria after mixing with either twenty five (25) percent of the stream flow, or the temperature mixing zone, whichever is more restrictive (OAR (12)(b). The City's design effluent flow is 2 MGD or 3.1 CFS; the Columbia River 7Q10 flow is 80,637 CFS. The ratio of 25 % of the stream flow to the effluent flow is: 6,502 to 1. Dilution at the edge of the mixing zone is 15 to 1. Clearly, dilution at the mixing zone will be the more restrictive.

8 Page 8 The Department uses the following equations to determine compliance with the cold water (OAR (11)) and biologically based criteria (Refer to the attached Excel worksheet): Equation used to calculate AT at edge of MZ: _T e+ (S-l)T a 1 inz r* a Where: AT niz = Change in Temperature at the edge of the mixing zone S = Dilution T e = Effluent Temperature, C T a = Ambient Stream Temperature Criterion, C As indicated in the worksheets, the discharge from the wastewater treatment facility does not cause the temperature of the Columbia River to be increased by more than 0.3 C above the applicable criteria at the edge of the mixing zone, at 25 % of the stream flow, or at 100% of the stream flow. Based on the above analysis, there appears to be no reasonable potential that this facility will cause or contribute to the temperature standards violations in the Columbia River. Thermal Plume Although the above results show compliance with the cold water section of the temperature standard, the thermal plume requirements also apply to the discharge. OAR (d) discusses thermal discharge and is addressed as follows: OAR (d) (A); Impairment of an active salmonid spawning area where spawning redds are located or likely to be located. Hood River discharge: There are no spawning salmon, steelhead, or bull trout in this segment of the Columbia River. This segment of the Columbia River serves as a migration corridor for salmonids. OAR (d) (B): Acute impairment or instantaneous lethality is prevented or minimized by limiting potential fish exposure to temperatures of 32 C or more to less than 2 seconds. Hood River discharge:- Based on daily temperature data submitted on the DMR's, the maximum effluent temperature ever measured at outfall 001 was 25.4 C. Thus, the discharge is not expected to cause an acute impairment or instantaneous lethality. OAR (d)(C)\ Thermal shock caused by a sudden increase in water temperature is prevented or minimized by limiting potential fish exposure to temperatures of 25 C or more to less than 5% of the crosssection of 100% of the 7Q10 flow of the waterbody. Hood River discharge: The mixing zone has been set so that it does not occupy more than 5% of the width of the river. The mixing zone is in fact less than 2.5% the width of the river. OAR l-0053(d)(D): Unless ambient temperature is 21 C or greater, migration blockage is prevented or minimized by limiting potential fish exposure to temperatures of 21 C or more to less than 25% of the crosssection of 100% of the 7Q10 flow of the waterbody. Hood River discharge: The mixing zone has been set so that it does not occupy more than 25% of the width of the river. The mixing zone is in fact less than 2.5% the width of the river. Thus, the analysis indicates that the discharge from the Hood River STP meets the temperature thermal plume limitations in OAR (d).

9 Page 9 The Department has decided to retain the current thermal discharge limitation. This limitation was added to the permit in 2004 and was calculated as follows: TDL = QxT Where: TDL = Thermal Discharge Limitation (gallons per day C) Q - Effluent weekly average design flow rate (gallons per day) = Average diy weather design flow multiplied by 1.5 T = Maximum effluent temperature ( C) 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). Selfmonitoring 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. This matrix has been 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. BOD and TSS Concentration and Percent Removal Monitoring requirements for BOD and TSS Concentration and percent removal are unchanged from those specified in the 2004 permit. Temperature Temperature monitoring of the effluent is required. In addition, the permittee is required to calculate the weekly average temperature of the effluent. Monitoring and reporting for temperature is only required during the months of May-October. Ammonia Ammonia monitoring of the effluent is required on a monthly basis during the summer months. Chlorine Chlorine r monitoring of the effluent is required on a daily basis when chlorine has been in use at the plant and may be present in the effluent. Turbidity The previous NPDES permit did not require monitoring for turbidity. Turbidity monitoring has been included in the proposed permit. Turbidity monitoring must be conducted in both the effluent and in the Columbia River upstream of the outfall, and recorded on the monthly Discharge Monitoring Reports (DMR).

10 Page 10 Toxics Effluent Priority Pollutant Monitoring is required of ail treatment plants with a pretreatment program or an average dry weather design capacity greater than 1 million gallons per day. This information is required for Part D of the EPA renewal application. Monthly silver sampling is required in this permit to determine compliance with the new silver limit. Outfall 002 (Emergency Overflows) This outfall has been deleted from the permit. Therefore, the associated monitoring in Schedule B has also been removed from the permit. Polychlormated Biphenyl's (PCB's) The Columbia River has been listed under section 303(d) as water quality limited for PCB's from river mile 142 to The City of Hood River discharges effluent at river mile The previous permit (issued October 25,2004) required the permittee to sample for PCB's quarterly for at least one year and stated that "if no PCB's are detected, upon written request by the permittee and written approval by the Department, the PCB monitoring may be stopped after one year." Four samples were collected and analyzed for PCB's over a 12 month period ending hi September of All four samples resulted in non-detects at the required detection limit. A Permit Action Letter was written by the Department on November 22,2005 which deleted the quarterly effluent PCB monitoring requirement from Schedule B of the permit. No PCB monitoring is proposed for this 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. For any year in which biosolids are land applied, a biosolids report shall be submitted to the Department by February 19 of the following year that describes solids handling activities for the previous year Schedule C - Compliance Conditions and Schedules No Compliance Schedules have been proposed for this permit Schedule D - Special Conditions The permittee must have the facilities supervised by personnel certified by the Department in the operation of treatment and/or collection systems. The other conditions in this schedule are standard verbiage. Schedule E - Pretreatment Activities The 2004 permit, Schedule E, requires the City to conduct and enforce an industrial waste pretreatment program as approved by the Department and the General Pretreatment Regulations (40 CFR Part 403). The Department is proposing to remove this requirement and effectively de-list Hood River's pre-treatment program. During 2006 Luhr-Jensen, the only categorical industrial user (CUT) discharging to City sanitaiy sewer, permanently terminated production and vacated then* premises in Hood River. This industry originally created the need for the pretreatment program in the late 1990's. The City does have one significant industrial user (SIU) by federal definition which is Full Sail Brewery; however it is a non-categorical SIU. The City has performed a loading evaluation of the industry and has determined that it does not have the potential to adversely impact the POTW. The presence of this industry does not justify the continued requirement for formal pretreatment program. The DEQ recommends that Full Sail Brewery be regulated through a local program under the current authorities when the mandatory program is delisted.

11 Page 11 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. 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 rules 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 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 noncompliances, and other information. Section D also contains signatory requirements and the consequences of falsifying reports. Section E contains the definitions used throughout the permit. The General Conditions were revised in A summary of the changes is as follows: There are additional citations to the federal Clean Water Act and CFR, including references to standards for sewage sludge use or disposal. There is additional language regarding federal penalties. Bypass language has been made consistent with the Code of Federal Regulations. Overflow language has been modified. Formerly the language stated that overflows in response to the five or ten year event would not violate the permit. Now it states that overflows are prohibited. DEQ will continue to exercise enforcement discretion with respect to overflows consistent with the provisions of the Bacteria Rule (OAR ). Reporting requirements regarding overflows have been made more explicit. Requirements regarding emergency response and public notification plans have been made more explicit. Language pertaining to duty to provide information has been made more explicit. Confidentiality of information is addressed.