Permit Evaluation Report

Transcription

1 Permit Evaluation Report Oregon Department of Environmental Quality Western Region Office, Salem 750 Front St Salem, OR Permittee: City of Florence 250 Highway 101 Florence, OR Existing Permit File Number: Information: Permit Number: Expiration Date: November 30, 2010 EPA Reference Number: OR Source Contact: Rick Mumpower, Source Location: LLID: Receiving Stream/Basin: Proposed Action: Source Category: Sources Covered: Permit Writer: Wastewater Supervisor 794 Rhododendron Drive Florence, OR Lane County D Receiving Stream: Siuslaw River Basin: Mid-Coast Sub-basin: Siuslaw Renew Permit Application Number: Date Received: June 1, 2010 NPDES Minor Domestic Treated municipal wastewater Steve Schnurbusch Senior WQ Permit Analyst Date Prepared: November 12, 2013 Page 1 NPDES Permit Evaluation Report City of Florence

2 Table of Contents 1.0 Introduction Permit History Issuance, Renewal and Modifications Compliance History Proposed Revisions to Permit Facility Description Wastewater Facilities Description Outfalls Sewage Collection System Recycled Water Wastewater Solids Storm Water Groundwater Industrial Pretreatment Receiving Water Designated Uses Receiving Stream Water Quality Mixing Zone Analysis Overview of permit development Types of Permit Limits Existing Permit Limits Overview of Whole Effluent Toxicity (WET) Analysis Whole Effluent Toxicity Analysis Biosolids Antidegradation Permit Draft Discussion Face Page Permit Limit Derivation Technology-Based Effluent Limits (TBELs) Water Quality-Based Effluent Limits Schedule A. Waste Discharge Limits Schedule B Minimum Monitoring and Reporting Requirements Monitoring Requirements Schedule D - Special Conditions Schedule E - Pretreatment Schedule F - NPDES General Conditions Next Steps Public Comment Period Response to Comments Modifications to Permit Evaluation Report and Fact Sheet Issuance...19 Attachment #1: Operator Certification Review Attachment #2: Reasonable Potential Analysis Attachment #3: Antidegradation Review Sheet Page 2 NPDES Permit Evaluation Report City of Florence

3 1.0 Introduction The Department of Environmental Quality (DEQ) proposes to renew the National Pollutant Discharge Elimination System (NPDES) wastewater permit for the City of Florence. The proposed permit allows and regulates the discharge of treated municipal wastewater to the Siuslaw River. The proposed permit also allows the city to process, apply to land, dispose of or beneficially reuse wastewater solids. The purpose of this permit evaluation report is to explain and provide justification for the permit. The Federal Water Pollution Control Act of 1972 (also known as the Clean Water Act) and its subsequent amendments, as well as Oregon Revised Statutes (ORS 468B.050), require a NPDES permit for the discharge of wastewater to surface waters. This proposed permit action by DEQ complies with both federal and state requirements. 2.0 Permit History 2.1 Issuance, Renewal and Modifications The current NPDES Permit was issued on December 21, 2005 and expired on November 30, DEQ received renewal application number from the city on June 1, Because the permittee submitted a renewal application to DEQ in a timely manner, the current permit will not expire until DEQ takes final action on the renewal application as per OAR Compliance History The wastewater treatment plant was last inspected on August 24 th, No violations were noted during the inspection. No violations have been documented since the last time the permit was renewed. 3.0 Proposed Revisions to Permit The proposed permit contains the following substantive changes from the 2005 permit: Schedule A includes a new interim and final effluent limits for ammonia, a new limit on enterococcus bacteria and a more stringent limit for fecal coliform bacteria. Schedule B includes Siuslaw River monitoring for copper, dissolved zinc, free cyanide, total thallium, total mercury and inorganic arsenic. Schedule D includes a requirement to develop a mercury minimization plan and to perform an industrial user survey. 4.0 Facility Description 4.1 Wastewater Facilities Description The Florence sewage treatment plant is an activated sludge plant that was upgraded in The average dry weather design flow is 1.3 million gallons per day (mgd). The current dry weather flow is around 0.76 mgd. The treatment plant has the following processes: Headworks: The headworks consists of a perforated plate spiral screen and a grit removal system, consisting of a grit chamber, grit pump, grit concentrator and grit washer. A carbon-packed odor control scrubber draws air from the covered influent channel on a continual basis. Aeration Basins: The aeration basins consist of five aeration cells with an anaerobic selector zone, blowers, an anaerobic zone mixer and automatic dissolved oxygen control. The aeration basins are equipped with fine bubble diffusers. Page 3 NPDES Permit Evaluation Report City of Florence

4 Secondary Clarifiers: There are two 65-foot diameter secondary clarifiers, four return activated sludge (RAS) pumps and a scum pump. RAS is automatically controlled based on plant flow. Disinfection: Disinfection consists of a Trojan UV4000 medium pressure UV system utilizing two banks with five modules per bank. Each module contains two medium pressure UV lamps. The system is automatically controlled based on the effluent flow meter. Gravity Belt Thickening: A gravity belt thickener provides for thickening for the waste activated sludge (WAS). WAS fed to the gravity belt thickener is measured before passing through an upstream grinder. Polymer is added to enhance water release of the sludge. Thickened WAS is pumped to the thickened sludge storage tank prior to anaerobic digestion. Anaerobic Digestion: The anaerobic digester digests thickened WAS in a 38-foot wide, 30-foot high mesophilic digester. The digester holds 265,000 gallons of sludge and has a hydraulic retention time of twenty-two days at design flow. The digester is gas mixed and heated with a water-to-sludge spiral heat exchanger. The boiler heating the digester is fueled by digester gas with fuel oil backup. Digested sludge overflows to the digested sludge holding tank prior to mechanical dewatering. The holding tank capacity is 90,000 gallons. Centrifuge Dewatering: An Alfa Laval solid bowl centrifuge dewaters digested sludge. The centrifuge is capable of dewatering up to 500 pounds of sludge per hour using polymer to enhance dewatering. The dewatered cake is conveyed to a drop box via two screw conveyors while the concentrate is pumped back to the head of the aeration basins. Treatment Plan Figure 1: Facility Location Page 4 NPDES Permit Evaluation Report City of Florence

5 4.2 Outfalls Outfall 001 is a 36-inch diameter pipe located on the right shore (facing downstream). The outfall consists of a 150 foot long staged multiport diffuser with sixteen 6 inch duckbill style ports. The first port is about 275 feet from the shore. The outfall is located at approximately river mile Sewage Collection System Sewage collection systems are designed to collect and transport raw sewage from residences and businesses to the municipality s wastewater treatment facility. The City of Florence has a collection system that uses 38 lift stations. Sewage is pumped to the treatment plant through either the Ivy Street pressure main or the Rhododendron Drive pressure main. There are 16 stations that pump into the Rhododendron Drive main. All others pump to a location where gravity lines take the sewage to the Ivy Street Station. About two thirds of the entire flow goes through the Ivy Street pump station. Both of these mains are constructed of HDPE pipe. The Ivy main is 12" and the rhododendron line is a combination of two lines of varying sizes for future use. All of the stations are connected to the WWTP SCADA system and all alarms are tested 3 times a year. Maintenance records are kept at the treatment plant and all pump repairs are done by city employees. The ratio of wet weather to dry weather flows measured at the treatment plant is an indication of how much inflow and infiltration is occurring in the collection system. The average effluent flow during the summer months (May October) over the past three years is 0.77 mgd. The average flow during the winter months is 0.86 mgd. The ratio of winter to summer flow is 1.1. This demonstrates the City does not have an I/I issue. 4.4 Recycled Water The permit holder does not currently operate a recycled water program and does not intend to do so during the term of this permit. 4.5 Wastewater Solids The City owns and operates a covered aerated static pile (CASP) biosolids composting program utilizing a GORE cover system that produces class A biosolids. The GORE fabric is used as a replacement to buildings for covering the compost. The covered piles are aerated via semi-permanent aeration piping above grade using approximately 0.5 horsepower blowers. Blower capacity is approximately 380 cubic feet per minute. Air is delivered to the compost pile via two 6-inch diameter high density polyethylene (HDPE) pipe placed directly on the pavement. Composting takes place by means of controlled pressurized aeration in the encapsulated GORE cover. The cover keeps wind and precipitation out while allowing CO2 and water vapors to escape. The cover also prevents odors from escaping the compost pile. Yard debris mulch and biosolids from the wastewater treatment plant are mixed at about a 3-4:1 ratio (yard debris:biosolids based on volume). The mixture is then placed into a pile over the HDPE pipe and covered with the GORE cover. The composting process typically takes days or more to meet the pathogen reduction and vector attraction reduction requirements. The compost is then remixed with a front-end loader and recovered for an additional 14 days. It may be remixed followed by another 10 to 14 day compositing period. The final composted biosolids are tested to meet pathogen density requirements and will be either sold, given away, or stored at the treatment plant. If necessary the City can dispose of their sewage sludge at the Short Mountain Landfill or transport it to Heard Farms for processing. Page 5 NPDES Permit Evaluation Report City of Florence

6 The permit holder has developed a comprehensive biosolids management plan and land application plan to address their new process. These plans are considered part of the proposed permit and are open for public comment. 4.6 Storm Water The City directs their plant site storm water into their treatment system. General NPDES permits for stormwater are not required for wastewater treatment facilities with a design flow of greater than 1 MGD when stormwater is collected, treated, and discharged as part of its treated wastewater. 4.7 Groundwater The existing treatment system consists of concrete treatment units with little to no potential to leak and impact groundwater. 4.8 Industrial Pretreatment Municipalities that receive wastewater from certain categories of industries must have in place approved pretreatment programs. These programs are designed to reduce the discharge of pollutants from identified industries that the treatment plant is not able to treat. These pollutants can interfere with treatment plant operation, reduce the value of wastewater and biosolids for reuse, cause worker health or safety concerns, and pose a risk to the public or the environment. The wastewater treatment plant s average dry weather design flow is 1.3 million gallons per day (mgd). Facilities with design flows greater than 1 mgd are required to perform an industrial survey to determine if there are any significant industrial users discharging wastewater to treatment plant. The proposed permit requires the city to perform an industrial survey. This requirement is contained in schedule D. 5.0 Receiving Water 5.1 Designated Uses DEQ is required to identify the beneficial uses of every water body in Oregon as required under the Clean Water Act. The intent of this requirement is to insure that the water quality standards DEQ develops are consistent with how the waterbody is used. Permits issued by DEQ must in turn reflect the water quality standards that apply to the basin in which permits are issued. Florence discharges to Siuslaw River at river mile 3.7. The following beneficial uses have been identified for the Mid Coast Basin: industrial water supply, fish and aquatic life (including salmonid rearing and migration), wildlife and hunting, fishing, boating, water contact recreation, aesthetic quality, commercial navigation and transportation 5.2 Receiving Stream Water Quality The city s outfall discharges to the Siuslaw River at river mile 3.7. This portion of the river is tidally influenced. The Siuslaw River exceeds water quality standards near the city s outfall for some parameters. The parameters are listed Page 6 NPDES Permit Evaluation Report City of Florence

7 in Table 1 below. When a stream exceeds water quality standards for a particular parameter it is deemed to be water quality-limited for that parameter. When a stream is water quality limited, an analysis needs to be performed for the stream to determine what the sources of pollution are for that pollutant and then a plan needs to be developed to reduce those sources of pollution. This plan is called a total maximum daily load (TMDL). No TMDLs have been completed for the Siuslaw River. Table 1: Water Quality Limited Parameters Waterbody Name River Mile Parameter Season Siuslaw River 0 to 106 Temperature Year Round 5.3 Mixing Zone Analysis Permits issued by DEQ sometimes specify a regulatory mixing zone. Mixing zones are allowed under both state and federal regulation. They are areas in the vicinity of outfalls in which all or some of Oregon s water quality standards can be suspended. DEQ allows mixing zones when the overall impact, evaluated with respect to Oregon s mixing zone rule (OAR ) appears to be negligible relative to the overall receiving stream. Two mixing zones can be developed for each discharge: 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 ZID is a small area where acute criteria can be exceeded as long as it does not cause acute toxicity to organisms drifting through it. The mixing zone is an area where acute criteria must be met but chronic criteria can be exceeded. It must be designed to protect the integrity of the entire water body. The city s permit specifies a mixing zone as follows: The allowable mixing zone is that portion of the Siuslaw River contained within a band extending out 700 feet from the north bank of the river and extending 210 feet upstream and downstream from the outfall. The Zone of Immediate Dilution (ZID) shall be defined as that portion of the allowable mixing zone that is within 21 feet of the point of discharge. The City submitted a mixing zone study dated September 15, 2011 with an update dated December 21, The study consisted of collecting ambient data near the outfall and then using that data to simulate the discharge using a computer model. The study indicates that the combination of the outfall design and the location within the estuary provide rapid initial mixing. Model predictions indicate dilution is lower in the winter because ambient stratification traps the plume below the surface preventing full vertical mixing. The report states the winter dilution estimates are conservative due to the linear density stratification that was assumed. The City may collect addition ambient data and update the mixing zone study in the future. Following is a summary of the predicted dilutions at the edge of the ZID and mixing zone. Table 2: Mixing Zone Dilutions Season Mixing Zone (chronic aquatic life) ZID (acute aquatic life) Mixing Zone (human health) Summer Winter These dilutions are applicable for the protection of aquatic life criteria. The average of the winter and summer mixing zone dilutions (420) is applicable for the protection of human health criteria because human health criteria are based on long term exposures over the course of the entire year (summer and winter). Page 7 NPDES Permit Evaluation Report City of Florence

8 6.0 Overview of permit development 6.1 Types of Permit Limits Effluent limitations serve as the primary mechanism in NPDES permits for controlling discharges of pollutants to receiving waters. Effluent limitations can be based on either the technology available to control the pollutants or limits that are protective of the water quality standards for the receiving water. These two types of permit limits are referred to as technology-based effluent limitations (TBELs) and water quality-based effluent limits (WQBELs) respectively. When a TBEL is not restrictive enough to protect the receiving stream, a WQBEL must be placed in the permit. More explanation of each is provided below. TBELs: o The intent of TBELs is to require a minimum level of treatment of pollutants based on available treatment technologies, while allowing the discharger to use any available control technique to meet the limits o o TBELs for municipal treatment plants, also known as federal secondary treatment standards, have been developed by EPA for the following parameters: biochemical oxygen demand measured over 5 days (BOD 5 ), total suspended solids (TSS) and ph. These are found in the Code of Federal Regulations (CFR). Oregon is unique in that its rules contains narrative language for establishing mass load based TBELs for sewage treatment facilities based on the design capabilities of the treatment plant [OAR (9)(b)]. WQBELs: o o The intent of WQBELs is to ensure the water quality standards of a receiving stream are met. The water quality standards are developed to protect the beneficial uses of the receiving stream such as swimming and fishing. In many cases TBELs are not restrictive enough to ensure the receiving stream meets water quality standards. In these cases, WQBELs need to be established to protect the receiving stream. Oregon is unique in that it has minimum design criteria for BOD 5 and TSS that are only applicable to sewage treatment plants. These design criteria vary by watershed basin and were developed to protect water quality in their respective basins. These are often times more stringent than the federal secondary treatment standards during the summer period [OAR (4)(a)]. When this is the case, the basin standards supersede the federal standards. Each time a permit is renewed, the permit writer evaluates the existing limits to see if they need to be modified as a result of changes to technology based standards or water quality standards that may have occurred during the permit term. The more stringent of the existing or new limits must be included in the renewal permit with some exceptions. 6.2 Existing Permit Limits The existing permit limits are as follows: Page 8 NPDES Permit Evaluation Report City of Florence

9 Table 3: Existing Effluent Limits - Outfall 001 May 1 October 31 Average Effluent Concentrations Monthly* Average Weekly* Average Daily * Maximum Parameter Monthly Weekly lb/day lb/day lbs BOD 5 20 mg/l 30 mg/l TSS 20 mg/l 30 mg/l November 1 - April 30 Average Effluent Concentrations Monthly* Average Weekly* Average Daily * Maximum Parameter Monthly Weekly lb/day lb/day lbs BOD 5 30 mg/l 45 mg/l TSS 30 mg/l 45 mg/l * Average dry weather design flow to the facility equals 1.3 MGD. Mass load limits based upon maximum flows to the facility with a two year recurrence interval and the capability of the treatment works at those flows. Year-round (except as noted) Limitations Fecal Coliform Bacteria (See Note 1) Shall not exceed 126 organisms per 100 ml monthly geometric mean. No single sample shall exceed 406 organisms per 100 ml. (See Note 2) ph Shall be within the range of BOD 5 and TSS Removal Efficiency Shall not be less than 85% monthly average for BOD 5 and 85% monthly for TSS. 6.3 Overview of Whole Effluent Toxicity (WET) Analysis Once the permit writer has determined the appropriate TBEL or WQBEL permit limits (described in the previous section) for the facility, the permit writer must determine whether there is reasonable potential for the discharge to cause toxicity due to combinations of chemicals that may be present in the effluent. This is done via Whole Effluent Toxicity (WET) testing. WET testing involves controlled laboratory experiments in which aquatic organisms are exposed to samples of effluent at different dilutions. EPA recommends running WET tests using an invertebrate, vertebrate, and a plant test organism, and has developed WET test protocols using freshwater, marine, and estuarine test species that measure both acute and chronic effects. Depending on the test, the measured effect may be fertilization, growth, reproduction, or survival. For facilities that have mixing zones, an acute WET test is considered to show toxicity if significant mortality occurs at effluent concentrations less than that which is found at the edge of the zone of immediate dilution (ZID). A chronic WET test is considered to show toxicity if significant adverse affects occur at effluent concentration less than that which is known to occur at the edge of the mixing zone. If the facility does not have a mixing zone, the tests are conducted using 100% effluent. The permit holder must submit the results of WET tests as part of the permit application process. If the permit writer determines, based on the results of these tests that there is a potential for the effluent to cause toxicity in the receiving stream, the permit writer will include WET test requirements in the Special Conditions section of the permit. These conditions in the permit will describe followup requirements in the event that the WET tests indicate toxicity. Page 9 NPDES Permit Evaluation Report City of Florence

10 At this time, DEQ generally uses this Special conditions approach rather than numeric limits; however, if the permit writer elects to include WET requirements in the permit as numeric limits, the permit writer should consult EPA s Technical Support Document for TSD for possible approaches. For more detail on WET testing, see Appendix E of the following: Whole Effluent Toxicity Analysis Whole Effluent Toxicity (WET) refers to the toxic effect to aquatic organisms from all pollutants contained in a facility's wastewater. WET tests are performed in a laboratory where they measure the wastewater's effect on specific aquatic organisms' ability to survive, grow and reproduce. The organisms are placed in tanks that contain varying concentrations of wastewater (e.g 100%, 50%, 25%). Their ability to survive, grow and reproduce would be measured over time to determine the effect of the wastewater on the organisms. These tests are designed to look at short term (acute) and longer term (chronic) effects. The WET test is passed if there is no statistically significant acute impacts at wastewater concentrations present at the edge of the zone of initial dilution and no chronic impacts at wastewater concentrations present at the edge of the mixing zone. The City conducted WET testing on four different species on four separate occasions during the past permit cycle. Four acute toxicity tests were conducted on the water flea and four on the fathead minnow. Five of those eight tests resulted in no adverse affects at a 100% wastewater concentration. The other three tests resulted in no adverse affects at a 50% wastewater concentration. The lowest dilution achieved at the edge of the ZID is 12 as reported in the mixing zone study. This equates to a maximum wastewater concentration of about 8% at the ZID. Since the acute WET tests demonstrate no adverse affects at a wastewater concentration of 50%, there should be no acute toxicity to organisms at the edge of the ZID where the maximum wastewater concentration is 9%. The City conducted four chronic tests on the topsmelt and four on a mussel. The topsmelt results indicate there are no adverse affects at a 50% wastewater concentration. The mussel results indicate there is no adverse affects at a 9% wastewater concentration. The lowest dilution achieved at the edge of the mixing zone is 33. This equates to a maximum effluent concentration at the edge of the mixing zone of 3%. Since the chronic tests demonstrate no adverse affects at an effluent concentration of 9%, there should be no chronic toxicity to organisms at the edge of the mixing zone where the maximum effluent concentration is 3%. DEQ has included annual WET testing in the proposed renewal permit. Details of the WET testing can be found in Schedule D of the proposed renewal permit. 6.5 Biosolids OAR requires facilities that are proposing reuse of biosolids by application to the land to maintain a biosolids management plan and land application plan. The biosolids management plan describes how the facility will meet the permit limits for biosolids land application; the land application plan identifies locations where biosolids land application may occur. Conditions in the biosolids management plan and land application plan are enforceable permit conditions. Approval of an updated biosolids management plan and land application plan is proposed with this permit action. The biosolids management plan has been updated to reflect the new Class A composting facility. This plan describes the biosolids process, the required testing to meet vector attraction reduction and pathogen reduction requirements and describes how the biosolids will be land applied. The plan is a separate document and available for review. Page 10 NPDES Permit Evaluation Report City of Florence

11 6.6 Antidegradation As part of renewing a permit, DEQ must demonstrate that the discharge does not lower water quality from the existing condition. DEQ is required to make this demonstration as required under Oregon s antidegradation policy for surface waters found in OAR DEQ performed an antidegradation review for this discharge. The proposed permit contains the same discharge loadings as the existing permit. Permit renewals with the same discharge loadings as the previous permit are not considered to lower water quality from the existing condition and therefore this renewal is protective of the designated beneficial uses as listed in Section 5.1. These uses are very broad and include fish and aquatic life, fishing, boating, and water contact recreation. DEQ is not aware of any existing uses present within the waterbody that are not currently protected under the designated beneficial uses. Therefore, DEQ determined that the proposed discharge complies with DEQ s antidegradation policy (see antidegradation review in Attachment #3). 7.0 Permit Draft Discussion 7.1 Face Page The face page provides information about the permittee, description of the wastewater, outfall locations, receiving stream information, permit approval authority, and a description of permitted activities. The permit allows discharge to the Siuslaw River within limits set by Schedule A and the following schedules. It prohibits all other discharges. In accordance with state and federal law, NPDES permits will be effective for a fixed term not to exceed 5 years. Upon issuance, this permit will be effective for no more than 5 years. DEQ evaluated the classifications for the treatment and collection systems (see Attachment #1). The treatment system is currently considered a Class III system and the collection system is considered a Class III system. The addition of the City s Class A biosolids processing facility raised the treatment system to Class IV. 7.2 Permit Limit Derivation Technology-Based Effluent Limits (TBELs) EPA has developed concentration-based TBELs for municipal wastewater treatment facilities as discussed in section 6.1. These are listed in the table below. Table 4: Technology Based Effluent Limits TBELs Parameter 30-Day Average 7-Day Average BOD 5 30 mg/l 45 mg/l TSS 30 mg/l 45 mg/l ph (instantaneous) % Removal 85% BOD 5 and TSS OAR (9)(b) contains narrative language for establishing mass load-based TBELs for sewage treatment facilities based on the design capabilities of the treatment plant. These limits were calculated as follows: The BOD 5 and TSS mass limits are based on the two year recurrence flows and the capability of the plant at those flows. The summer period flows and treatment plant capabilities are 2.3 MGD and 11 mg/l for monthly averages, 2.6 MGD and 11 mg/l for weekly averages and 2.8 MGD and 24 mg/l for the daily maximums. The winter period Page 11 NPDES Permit Evaluation Report City of Florence

12 flows and treatment plant capabilities are 3.0 MGD and 11 mg/l for monthly averages, 4.0 MGD and 15 mg/l for weekly averages and 4.8 MGD and 33 mg/l for the daily maximums. The limits are in accordance with OAR (9)(b). All mass load limitations are rounded to two significant figures per the calculations below. The limits are the same as in the existing permit. (1) Summer (May Oct) BOD 5 and TSS (a) (b) (c) 2.3 MGD x 8.34 #/gal x 11 mg/l monthly avg. = 210 lbs/day 2.6 MGD x 8.34 x 11 mg/l weekly avg. = 240 lbs/day weekly avg. 2.8 MGD x 8.34 x 24 mg/l daily max. = 560 lbs/day daily max. (2) Winter (Nov Apr) BOD 5 and TSS (a) (b) (c) 3.0 MGD x 8.34 #/gal x 11 mg/l monthly avg. = 280 lbs/day 4.0 MGD x 8.34 x 15 mg/l weekly avg. = 500 lbs/day weekly avg. 4.8 MGD x 8.34 x 33 mg/l daily max. = 1300 lbs/day daily max Water Quality-Based Effluent Limits DEQ performs an analysis to determine if there is a reasonable potential to cause or contribute to violations of instream water quality criteria. This analysis is conducted for various types of pollutants present in wastewater including temperature, ph, ammonia and other toxics. DEQ has developed its own methodology for ph and temperature. DEQ adopted EPA s methodology for performing a reasonable potential analysis (RPA) with respect to toxics. This methodology was developed primarily for acute and chronic criteria but can be adopted to other criteria based on different frequencies and durations (i.e. human health criteria). This RPA takes into account effluent variability, available dilution (if applicable), and receiving stream water quality. If the RPA results indicate that there is a potential for the discharge to cause or contribute to exceedances of water quality standards, the methodology is then used to determine permit limits to ensure the discharge does not cause or contribute to violations of water quality standards. ph The Mid-Coast Basin standard for ph is a range from This range needs to be met at the edge of the mixing zone. DEQ uses a ph analysis tool that takes into account mixing zone dilution, ambient and effluent, ph, alkalinity and temperature to determine the ph at the edge of the mixing zone. The ph analysis demonstrates there is no reasonable potential for the ph TBEL to exceed the basin standard (see Attachment #2). A ph limit of is being applied to this permit. There is no change from the previous permit. Temperature The Siuslaw River does not consistently meet the temperature criterion of 18 ºC as discussed above in section 5.2. OAR (12)(b)(A) allows a 0.3 ºC increase above the criterion at the edge of the mixing zone when a stream is water quality limited for temperature. A temperature analysis was conducted to determine whether the discharge has the potential to exceed 0.3ºC at the edge of the mixing zone. This analysis was performed during the summer months when the waterbody exceeds the temperature criterion. The analysis demonstrates the discharge does not exceed 0.3ºC at the edge of the mixing zone. A spreadsheet is used to perform this analysis and a copy is included as Attachment #2. The discharge was also evaluated for compliance with the thermal plume restrictions found in OAR (2)(d). Discharges must be regulated so as to prevent or minimize the following adverse effects to salmonids inside the mixing zone: Page 12 NPDES Permit Evaluation Report City of Florence

13 (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 o C or less for salmon and steelhead, and 9 o C for bull trout; (B) Acute impairment or instantaneous lethality is prevented or minimized by limiting potential fish exposure to temperatures of 32.0 o 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 o 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 o C or greater, or minimized by limiting potential fish exposure to temperatures of 21.0 o 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 DEQ s fish use maps for the Mid Coast basin, no salmonid spawning occurs in the vicinity of discharge. Requirement A above is satisfied. The maximum effluent temperature during the last two summers was 21.0 o C. The discharge temperature is less than the 32.0 o C and 25 o C thresholds in B and C above. The maximum effluent temperature is 21 o C and will immediately be reduced to temperatures below 21º C as it mixes in the estuary. Requirements B, C and D above are satisfied based on this temperature analysis. Page 13 NPDES Permit Evaluation Report City of Florence

14 Figure 2: Shellfishing Locations (source: ODFW) Bacteria The discharge pipe is located in the Siuslaw River estuary. Two bacteria criteria apply at this location: fecal coliform and enterococci. The fecal coliform bacteria criterion is designed to protect human consumption of shellfish (e.g. oysters and clams). This does not include crabs. The fecal coliform criterion limits median concentrations to 14 organisms/100 ml with no more than 10% greater than 43 organisms/100 ml. Page 14 NPDES Permit Evaluation Report City of Florence

15 The map in figure 2 shows where crabbing and clamming takes place relative to the location of the outfall. The outfall is located with the crab harvesting area but not within any clamming areas. DEQ has fairly recent fecal coliform data for the Siuslaw river at three stations in the vicinity of the outfall (river mile 1.1, 5.2 and 6.7). The median value of this data is 20 organisms/100 ml. This data indicates the river is slightly above the standard of 14 organisms/100ml. DEQ has determined there is no assimilative capacity in the river based on this data so no dilution is available for fecal coliform. Therefore, the fecal coliform permit limit will be a monthly median of 14 organisms/100 ml with no more than 10% of the samples exceeding 43 organisms/100 ml. The enterococci criterion is designed to protect humans who may ingest small amounts of water while recreating in it (e.g. swimming, surfing, water skiing). The enterococci criterion limits the geometric mean to less than 35 organism/100 ml. The proposed permit contains an enterococci limit of 35 organisms/100 ml. Ammonia Ammonia exists in two forms in natural waters: ionized and un-ionized. The un-ionized ammonia form is toxic to fish. A greater percentage of the un-ionized form is present at higher ph and temperature concentrations. DEQ s acute and chronic ammonia criteria are therefore dependent upon ph and temperature. DEQ performed an analysis to determine if there was a reasonable potential for the discharge to exceed the ammonia criteria at the edge of the ZID and mixing zone. The analysis takes into account the ZID and mixing zone dilutions and the temperature, ammonia, ph and alkalinity levels in the effluent and the receiving water. The analysis determines if the ammonia concentrations at the edge of the ZID and mixing zone are greater than the acute and chronic criteria respectively. DEQ uses a spreadsheet to perform these calculations per EPA guidance. The City collected effluent ammonia data in 2006 and 2007 and routinely measured effluent ph and temperature over the past permit cycle. This data was used in the analysis. DEQ has two ambient sampling stations upstream of the outfall where ammonia, temperature and ph were measured. This data was also used in the analysis. The data was parsed into summer and winter seasons and analyses were conducted for each season. The maximum effluent ammonia values were used for the analysis. 90 th percentile values were used for effluent ph and temperature and ambient ph, ammonia, and temperature. The analysis indicates the aquatic life ammonia criteria are met in both seasons. A copy of the spreadsheet showing the various input parameters is included in Appendix 2. Toxics The City of Florence was required to test their treated wastewater for about 100 toxic pollutants during the last permit cycle. The City performed these tests in 2006, 2007 and 2010 for a total of 3 data sets. Most pollutants were not detected in their effluent. Only copper, cyanide, thallium, zinc, arsenic and mercury were detected in the effluent. These detected pollutants were all tested for the total recoverable fraction of the pollutant. However, DEQ recently adopted new criteria and the copper and zinc water quality criteria are now based on the dissolved fraction, the cyanide criteria is based on free cyanide and the arsenic criteria is based on inorganic arsenic. An analysis of these pollutants indicates the total recoverable fraction of these pollutants has the potential to exceed the dissolved and inorganic fractions in the final effluent prior to mixing in the Siuslaw River. In order to determine if the effluent has the reasonable potential to exceed the water quality criteria at the edge of the mixing zone for these pollutants, the effluent needs to be tested for the appropriate fraction (e.g. dissolved vs total) that corresponds to the criterion. In addition, pollutant concentrations within the Siuslaw River are needed as well. Thallium and mercury are based on the total recoverable fraction. An analysis conducted on these pollutants indicates they have the potential to exceed their respective criterion within the final effluent prior to mixing within the estuary. DEQ considers pollutants that have the potential to exceed criterion in the final effluent pollutants of concern that warrant additional monitoring. Page 15 NPDES Permit Evaluation Report City of Florence

16 Additional effluent and stream monitoring is being proposed for dissolved copper, dissolved zinc, free cyanide, inorganic arsenic, total thallium and total mercury within the first two years of the permit. This data will be used to determine if there is a reasonable potential to violate any of these water quality criteria at the edge of the ZID or mixing zone. In addition, the permit requires sampling of all toxic pollutants towards the end of the permit cycle. This data will be used for the next permit renewal to assess compliance with water quality standards. In addition, because mercury was detected in the City s final effluent, the proposed permit requires the City to implement a mercury minimization plan. DEQ s mercury human health criterion is based on mercury concentrations present in fish tissue. Almost all waterbodies in the state exceed the fish tissue mercury criteria so DEQ s policy is to require any discharge with mercury present in their effluent to implement a mercury minimization plan. The plan will be submitted to DEQ for review as outlined in Schedule D. Attachment 2A contains a copy of the reasonable potential analysis spreadsheets. Only those parameters that were detected are included on the spreadsheet. 7.3 Schedule A. Waste Discharge Limits The proposed permit limits are included in Schedule A of the permit. The numeric limits in Schedule A are reproduced below. These limits are the result of the analyses described in Section 7.2. Table 5: Proposed Effluent Limits Outfall 001 May 1 Oct 31 Average Effluent Monthly Weekly Daily Parameter Concentrations, mg/l Average Average Maximum Monthly Weekly lbs/day lbs/day lbs BOD TSS November 1 April 30 Parameter Average Effluent Concentrations, mg/l Monthly Weekly Monthly Average lbs/day Weekly Average lbs/day Daily Maximum Lbs BOD TSS Year-round Limits BOD 5 and TSS Removal May not be less than 85% monthly average for BOD 5 and TSS Efficiency Fecal Coliform Bacteria Monthly Median concentration may not exceed 14 organisms per 100 ml. No more than 10% of the samples collected in a calendar month may exceed 43 organisms per 100 ml. Enterococcus Bacteria Monthly geometric mean may not exceed 35 organisms per 100 ml. ph May not be outside the range of 6.0 to 9.0 S.U. 7.4 Schedule B Minimum Monitoring and Reporting Requirements Monitoring 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 limits are being met. Other parameters may also need to be monitored when insufficient data exist to establish a limit, but where there is a potential for a water quality concern. Page 16 NPDES Permit Evaluation Report City of Florence

17 DEQ has developed monitoring and reporting matrices that establish monitoring and reporting frequencies based on the size and complexity of the facility. These matrices were used to establish the monitoring and reporting requirements for the proposed permit. The frequencies are the same as the existing permit. In addition to monitoring and reporting requirements, Schedule B includes the following: Requirements to develop and implement a Quality Assurance/Quality Control (QA/QC) program What to do if QA/QC requirements are not met. Requirements pertaining to reporting procedures. These include: o The correct use of significant figures o Reporting of detection levels and quantitation limits o Calculating and reporting mass loads. Supplementary monitoring is being required for total copper, dissolved zinc, total thallium, inorganic arsenic and total mercury. Monitoring for these pollutants in the effluent and the receiving stream is required twice per year for the first two years after permit issuance. This data will then be used to determine if there is a reasonable potential to exceed any of these criterion at the edge of the ZID or mixing zone. The permit may be reopened if there is a reasonable potential to exceed any of the criterion. The proposed permit requires effluent toxics characterization monitoring to be completed toward the end of the permit cycle. Effluent monitoring is required for about 100 toxic parameters as listed in Schedule B. This data will be reviewed at the next permit renewal. Whole effluent toxicity (WET) testing is being required in this permit as in the previous permit. The proposed permit requires four wet tests be conducted in a different quarter over the first four years of the permit. Biosolids Monitoring Requirements and Monitoring Frequency OAR requires the permittee to monitor biosolids for pollutants, nutrients, and conventional parameters. The permittee is also required to monitor appropriate parameters to demonstrate compliance with pathogen reduction and vector attraction reduction standards. The frequency of biosolids monitoring is based on the total quantity of biosolids land applied or produced for sale to distribution to the public. Samples must be representative of biosolids and the process used to produce biosolids. Specific details on biosolids monitoring must be provided in the Biosolids Management Plan. 7.5 Schedule D - Special Conditions The following conditions are included in Schedule D: 1. Inflow and Infiltration: It is important for the permit holder to assess and take steps to reduce the rate of infiltration and inflow of stormwater and groundwater into the sewer system. Consistent with this, Schedule D of the permit requires the permit holder to undertake activities to track and reduce I/I in the sewer system. 2. Emergency Response and Public Notification Plan: Municipal wastewater treatment facilities are required, under General Condition B.8. in Schedule F, to have an Emergency Response and Public Notification Plan. Information on what DEQ looks for in such plans can be found in DEQ s Internal Management Directive on Sanitary Sewer Overflows at: 3. Exempt Wastewater Reuse at the Treatment System: Schedule D exempts the permit holder from the recycled water requirements in OAR , when recycled water is used for landscape irrigation at the treatment facility or for in-plant processes, such as in plant maintenance activities. Page 17 NPDES Permit Evaluation Report City of Florence

18 4. Biosolids Management Plan: This condition requires the permittee to have an approved biosolids management plan for processing distribution of their biosolids. 5. Wastewater Solids Transfers: This condition allows the facility to transfer treated or untreated wastewater solids to other in-state or out-of-state facilities that are permitted to accept the wastewater solids. The permittee is required to monitor, report, and dispose of solids as required by the permit of the receiving facility. Wastewater solids that are transferred out-of-state must meet all requirements for the use of disposal or wastewater solids as required by both Oregon and the receiving state. 6. Hauled Waste Plan: This condition states the permittee may accept hauled wastes at discharge points designated by the POTW after receiving written DEQ approval of a hauled waste control plan. 7. Whole Effluent Toxicity (WET) Testing: The language in this section of the permit describes the test WET test procedures to be followed. 8. Operator Certification: This condition requires the permittee to have a certified operator consistent with the size and type of treatment plant covered by the permit. The language in this section of the permit describes the requirements relating to operator certification. 9. Industrial User Survey: This condition requires the permittee to conduct an industrial user survey and report the findings to DEQ by no later than November 15 th, The purpose of the survey is to identify whether there are any categorical industrial users discharging to the POTW, and ensure regulatory oversight of these discharges to state waters. 10. Mercury Minimization Plan: This condition requires the permittee to submit a mercury minimization plan to the DEQ by March 1, Schedule E - Pretreatment The permittee does not have a DEQ-approved industrial pretreatment program. Based on current information, no industrial pretreatment program is needed. 7.7 Schedule F - NPDES General Conditions These conditions are standard to all domestic NPDES permits and include language regarding operation and maintenance of facilities, monitoring and record keeping, and reporting requirements. The General Conditions for all individual permits issued by DEQ were substantially revised in August Minor modifications have been made since then. 8.0 Next Steps 8.1 Public Comment Period The proposed NPDES permit will be made available for public comment for at least 35 days. Public notice and links to the proposed permit will be posted on DEQ s website, advertised in newspapers (major sources), and sent to subscribers to DEQ s pertinent public notice lists. A Public Hearing will be scheduled if requested by 10 or more people, or by an authorized person representing an organization of at least 10 people. If a public hearing is to be held, then an additional public notice would be published to advertise the public hearing. Page 18 NPDES Permit Evaluation Report City of Florence

19 8.2 Response to Comments DEQ will respond to comments received during the comment period. All those providing comment will receive a copy of DEQ s response. Interested parties may also request a copy of DEQ s response. Once comments are received and evaluated, DEQ will decide whether to issue the permit as proposed, to make changes to the permit, or to deny the permit. DEQ will notify the permittee of DEQ s decision. 8.3 Modifications to Permit Evaluation Report and Fact Sheet Depending on the nature of the comments and any changes made to the permit as result of comments, DEQ may modify this permit evaluation report and fact sheet. DEQ may also choose to update the permit evaluation report and fact sheet through memorandum or addendum. If substantive changes are made to the permit, then an additional round of public comment may occur. 8.4 Issuance The DEQ mails the finalized, signed permit to the permittee. The permit is effective 20 days from the mailing date. Page 19 NPDES Permit Evaluation Report City of Florence

20 Attachment #1: Operator Certification Review Page 20 NPDES Permit Evaluation Report City of Florence

21 Page 21 NPDES Permit Evaluation Report City of Florence

22 Page 22 NPDES Permit Evaluation Report City of Florence

23 Attachment #2: Reasonable Potential Analysis Temperature Reasonable Potential Analysis Facility Name: City of Florence Date: 2/2/2014 Enter data into white cells below: Mixing Zone Dilution = 807 7Q10 = na cfs Effluent Flow = 1.3 mgd Applicable Temperature Criterion 18 ºC Effluent Temperature 22 ºC Equation used to calculate T at edge of MZ T mz T e + ( S 1) T = S Equation used to calculate thermal load limit a T TLL = Q S T C ρ e a all p Allowable increase = 0.3 ºC Where: Qe = Effluent Flow in mgd S = Dilution Dilution at 25% Stream Flow = na Τ all = Allowable temperature increase at edge of MZ ( C) T at edge of MZ= 0.00 ºC No Reasonable Potential Cp = Specific Heat of Water (1 cal/g C) T at 25% Stream Flow= na ºC ρ = Density of Water (1 g/cm 3 ) Thermal Load Limit = N/A Million Kcals = Flow conversion from mgd to m 3 /day Page 23 NPDES Permit Evaluation Report City of Florence

24 Ammonia Reasonable Potential Analysis Facility Name: City of Florence Date: 2/2/2014 Dilution Values? (Y/N) y calculated Summer data Effluent Stream Mixed Low Flow ZID (1Q10) 45 * ZID MZ Low Flow MZ (7Q10) 807 * ph * = ( ) Low Flow MZ (30Q5) * * Temp * = C High Flow ZID (1Q10) 11 * Alkalinity = High Flow MZ (7Q10) 33 * Salmonids Present? (Y/N) n/a y High Flow MZ (30Q5) * * Salmonid Spawning? (Y/N) n/a n Enter data below if no dilution data is available Fresh Water? (Y/N) n/a n Data to estimate dilution Summer Winter Salinity (ppt) Effluent Flow (mgd) = * * Winter data 1Q10 (CFS) = * * ph * = ( ) 7Q10 (CFS) = * * Temp * = C 30Q5 (CFS) = * * Alkalinity = % dilution at MZ = * * Salmonids Present? (Y/N) n/a y % dilution at ZID = * * Salmonid Spawning? (Y/N) n/a n Fresh Water? (Y/N) n/a n Confidence Level = 99% Salinity (ppt) Probability Basis = 95% Calculated Maximum Maximum WQ CRITERIA # of Highest Coef. of Maximum Background Conc. at Conc. at Acute Chronic PARAMETER Samples Conc. Variance Conc. Conc. ZID MZ (CMC) (CCC) REASONABLE POTENTIAL? mg/l mg/l mg/l mg/l mg/l mg/l mg/l ACUTE CHRONIC ZID MZ Low Flow Season CHLORINE * * * * * * * * * AMMONIA - Freshwater * * * * * * * n/a n/a * * AMMONIA - Saltwater NO NO ZID MZ AMMONIA - Proposed 1hr/4day * * * * * * * * * AMMONIA - Proposed 30day* * * * * * n/a * n/a n/a n/a * High Flow Season CHLORINE * * * * * * * * * AMMONIA - Freshwater * * * * * * * n/a n/a * * AMMONIA - Saltwater NO NO ZID MZ AMMONIA - Proposed 1hr/4day * * * * * * * * * AMMONIA - Proposed 30day* * * * * * n/a * n/a n/a n/a * Page 24 NPDES Permit Evaluation Report City of Florence

25 Toxics Reasonable Potential Analysis: Aquatic Life RPA Run Information Facility Information Facility Name: City of Florence 1. Are there dilution #'s from mixing zone study? (Yes/No) Yes 2. Is the receiving waterbody fresh water? (Yes/No) No 3. If Question 1 = "No", then fill in the following table Eff. Flow Rate MGD N/A Calculated dilution Factors Stream Flow: 7Q10 CFS N/A ZID N/A Stream Flow: 1Q10 CFS N/A MZ N/A % dilution at ZID % 10% % dilution at MZ % 25% 4. If answered "Yes" to Question #1, ZID (from study) na then fill in dilution values MZ (from study) na Color Key: "*" = Enter data 5. Enter Water Hardness. Ambient: Effluent mg/l CaCO 3 25 Intermediate Calc.s 7Q10. Effluent: default of 25mg/l. Up-stream mg/l CaCO 3 25 "--" = Will calculate Calculation Results Min/Max mg/l CaCO3 ZID boundary mg/l CaCO 3 N/A MZ boundary mg/l CaCO 3 N/A Translation Factor off 6. Please enter statistical Confidence Level % 99% Confidence and Probablity values Probability Basis % 95% (note: defaults already entered) Identify Pollutants of Concern Determine In-Stream Conc. Det. Reasonable Potential Pollutant Parameter Highest Max Total Max Total WQ Crit: WQ Crit: Is there Evaluation # of Coefficent of Est. Max RP at end Ambient Effluent 1 Hour 4 Day Reasonable Required? Sample Variation Eff. Conc. of pipe? Conc. Conc. ZID RMZ (CMC) (CCC) Potential to Exceed? (Yes/No) (Yes/No) (µg/l) Default=0.6 (µg/l) (Yes/No) (µg/l) (µg/l) (µg/l) (µg/l) (µg/l) Acute Chronic General Parameters Conventional and Nonconventional Pollutants Required to be Tested by Existing Discharges if Expected to be Present (equivalent to Table IV) Phosphorus (as P), Total TBD * * * METALS, CYANIDE, AND TOTAL PHENOLS (equivalent to Table III Other Toxic Pollutants) Cadmium (as total) Yes No * Copper (as total) Yes Yes * Lead (as total) Yes No * Mercury (as total) Yes Yes * Nickel (as total) Yes No * Selenium (as total) Yes No * Silver (as total) Yes No * Zinc (as total) Yes Yes * Oregon State Water Quality Criteria Arsenic III (trivalent) Yes No * Cyanide (as free) Yes Yes * Chromium VI (Hexavalent) (as Total) Yes No * Page 25 NPDES Permit Evaluation Report City of Florence

26 Toxics Reasonable Potential Analysis: Human Health RPA Run Information Facility Information Facility Name: City of Florence 1. Do I have dilution values from a mixing zone study? (Yes/No) Yes 2. If answered "No" to Question 1, then fill in the following table Eff. Flow Rate MGD N/A Calculated dilution Factors Stream Flow: Harmonic M CFS N/A Harmonic Mean N/A Stream Flow: 30Q5 CFS N/A 30Q5 N/A % dilution at MZ % 25% 3. If answered "Yes" to Question RMZ: harmonic mean flow na #1, then fill in dilution values RMZ: 30Q5 flow na 4. Please enter statistical Confidence Level % 95% Confidence and Probablity Probability Basis % 95% Color Key: Intermediate Calc.s Calculation Results "*" = Enter data "--" = Will calculate values (note: defaults already Pollutant Parameter Evaluation Required? Carcinogen Status # of Sample Identify Pollutants of Concern Effluent Conc. Coefficent of Variation Est. Max Eff. Conc. RP at end of pipe? In-Stream Conc. Ambient Conc. Max Total RMZ WQ Crit: Water + Fish Det. Reasonable Potential (Yes/No) (Yes/No) (µg/l) Default=0.6 (µg/l) (Yes/No) (µg/l) (µg/l) (µg/l) (µg/l) Water + Fish Fish METALS, CYANIDE, AND TOTAL PHENOLS (equivalent to Table III Other Toxic Pollutants) Antimony (as total) Yes No * * Data * Arsenic (Inorganic) Yes Yes Yes * Copper (as total) Yes No No * Mercury (as total) Yes WQ Crit. * Nickel (as total) Yes No No * Selenium (as total) Yes No No * Thallium (as total) Yes No Yes * Zinc (as total) Yes No No * Cyanide (as total) Yes No No * GC/MS FRACTION VOLATILE COMPOUNDS (equivalent to Table II Volatiles) Methylene Chloride Yes Yes No * Toluene Yes No No * WQ Crit: Fish Is there Reasonable Potential to Exceed? (Yes/No) Page 26 NPDES Permit Evaluation Report City of Florence

27 Page 27 NPDES Permit Evaluation Report City of Florence

28 ph Reasonable Potential Analysis Page 28 NPDES Permit Evaluation Report City of Florence