National Pollutant Discharge Elimination System (NPDES)/ State Disposal System (SDS) Permit Program Fact Sheet Permit Reissuance MN

Transcription

1 National Pollutant Discharge Elimination System (NPDES)/ State Disposal System (SDS) Permit Program Fact Sheet Permit Reissuance Permittee: Facility name: City of Austin 1205 South Main Street Austin, MN Austin Wastewater Treatment Facility 1205 S Main St Austin, MN Current permit expiration date: June 30, 2015 Public comment period begins: December 6, 2018 Public comment period ends: February 4, 2019 Receiving water: Permitting contact: Cedar River - Class 2Bg, 3C, 4A, 4B, 5, 6 water Amanda Wilkens 7678 College Road, Suite 105 Baxter, MN amanda.wilkens@state.mn.us

2 Table of Contents Page Purpose and participation... 4 Applicable statutes... 4 Purpose... 4 Public participation... 4 Facility description... 5 Facility location... 5 Outfall location... 5 Map of permitted facility... 5 Components and treatment technology... 5 Current information... 6 Facility flow schematic... 7 Biosolids flow schematic... 8 Changes to facility or operation... 8 Significant industrial users (SIUs)... 8 Recent compliance history... 9 Recent monitoring history Receiving water(s) Use classification Impairments Total Maximum Daily Load (TMDL) Existing permit effluent limits Technology based effluent limits (TBELs) Water quality based effluent limits (WQBELs) Proposed permit effluent limits Technology based effluent limits (TBELs) Water quality based limits (WQBELs) Reasonable potential analysis Reasonable Potential for Chemical Specific Pollutants (40 CFR (d)(1)) Priority Pollutants Total Mercury Whole Effluent Toxicity (WET) Additional requirements Phosphorus minimization plans (PMP) Mercury minimization plan (MMP)... 20

3 Nitrogen monitoring requirements Salty parameter monitoring Industrial stormwater Biosolids Surface Water Monitoring Karst Variances Total facility requirements (TFR) Antidegradation and anti-backsliding... 21

4 Permit Reissuance Page 4 of 21 Purpose and participation Applicable statutes This fact sheet has been prepared according to the 40 CFR and and Minn. R , subp. 3, in regards to a draft National Pollutant Discharge Elimination System (NPDES)/State Disposal System (SDS) permit to construct and/or operate wastewater treatment facilities and to discharge into waters of the state of Minnesota. Purpose This fact sheet outlines the principal issues related to the preparation of this draft permit and documents the decisions that were made in the determination of the effluent limitations and conditions of this permit. Public participation You may submit written comments on the terms of the draft permit or on the Commissioner s preliminary determination. Your written comments must include the following: 1. A statement of your interest in the permit application or the draft permit. 2. A statement of the action you wish the Minnesota Pollution Control Agency (MPCA) to take, including specific references to sections of the draft permit that you believe should be changed. 3. The reasons supporting your position, stated with sufficient specificity as to allow the Commissioner to investigate the merits of your position. You may also request that the MPCA Commissioner hold a public informational meeting. A public informational meeting is an informal meeting which the MPCA may hold to help clarify and resolve issues. In accordance with Minn. R and Minn. R , your petition requesting a public informational meeting must identify the matter of concern and must include the following: items one through three identified above; a statement of the reasons the MPCA should hold the meeting; and the issues you would like the MPCA to address at the meeting. In addition, you may submit a petition for a contested case hearing. A contested case hearing is a formal hearing before an administrative law judge. Your petition requesting a contested case hearing must include a statement of reasons or proposed findings supporting the MPCA decision to hold a contested case hearing pursuant to the criteria identified in Minn. R , subp. 1, and a statement of the issues proposed to be addressed by a contested case hearing and the specific relief requested. To the extent known, your petition should include a proposed list of witnesses to be presented at the hearing, a proposed list of publications, references or studies to be introduced at the hearing, and an estimate of time required for you to present the matter at hearing. You must submit all comments, requests, and petitions during the public comment period identified on page one of this notice. All written comments, requests, and petitions received during the public comment period will be considered in the final decisions regarding the permit. If the MPCA does not receive any written comments, requests, or petitions during the public comment period, the Commissioner or other MPCA staff as authorized by the Commissioner will make the final decision concerning the draft permit. Comments, petitions, and/or requests must be submitted by the last of the public comment period to: Amanda Wilkens Minnesota Pollution Control Agency 7678 College Road, Suite 105 Baxter, MN 56425

5 Permit Reissuance Page 5 of 21 The permit will be reissued if the MPCA determines that the proposed Permittee or Permittees will, with respect to the facility or activity to be permitted, comply or undertake a schedule to achieve compliance with all applicable state and federal pollution control statutes and rules administered by the MPCA and the conditions of the permit and that all applicable requirements of Minn. Stat. ch. 116D and the rules promulgated thereunder have been fulfilled. More detail on all requirements placed on the facility may be found in the permit document. Facility description Facility location The Austin Wastewater Treatment Facility (Facility) is located at the SE ¼ of the NE ¼, Section 10, Township 102 North, Range 18 West, Austin, Mower County, Minnesota (latitude: , longitude: ). The address for the Facility is 1205 South Main Street, Austin, Minnesota Outfall location The Facility outfall (SD 002) is located next to the Facility as described above. The outfall is the combined industrial and domestic discharge of the Facility and is a continuous discharge to the Cedar River. Latitude and longitude of the outfall SD 002 is and , respectively. Map of permitted facility

6 Permit Reissuance Page 6 of 21 Components and treatment technology Current information The existing Facility has a continuous discharge from SD 002 to the Cedar River. This is a Class A Facility. The Facility is designed to treat: An wet weather (AWW) flow of million gallons per (MGD) An annual daily (AAD) flow of 6.35 MGD o Industrial: 2.1 MGD o Municipal: 4.25 MGD 5- carbonaceous biochemical oxygen demand (CBOD 5) of: o Industrial: 1300 (mg/l) o Municipal: 230 mg/l The Facility consists of two parallel facilities, both owned by the City. The industrial treatment train treats wastewater received from Hormel Foods Corporation pretreatment facility. The municipal treatment train treats wastewater received from all other contributors including residential and industrial/commercial. The two treatment facilities combine for ammonia removal, final clarification, disinfection, and discharge. Solids are treated separately then combined for storage and land application. The municipal treatment Facility is a trickling filter treatment system. It consists of a main lift station, three flow equalization tanks, grit removal, bar screens, three primary clarifiers, four trickling filters, two intermediate clarifiers, and is then pumped to the portion of the Facility shared with the industrial train to a nitrification trickling filter then to four final clarifiers prior to chlorination/dechlorination. Solids are collected from the three primary clarifiers to two primary anaerobic digesters that overflow to one secondary digester. The secondary digester overflows to a pump station then to the solids storage tanks shared with the industrial Facility. The biosolids are then thickened in the sludge storage tank and land applied. The municipal Facility has a standby generator to operate the main lift station, primary clarifiers, trickling filters, intermediate clarifiers, and chlorination/dechlorination. The main lift station bypass structure is capable of discharging untreated wastewater to the Cedar River. This bypass is locked and manually controlled. The Facility is further described in the plans and specifications on file with the MPCA.

7 Permit Reissuance Page 7 of 21 Facility flow schematic

8 Permit Reissuance Page 8 of 21 Biosolids flow schematic Changes to facility or operation There have been no changes to the Facility or its operation from the previous permit. Significant industrial users (SIUs) The Permittee has been delegated the authority to operate as the control authority under the General Pretreatment Regulations. The Permittee s delegated pretreatment program was originally approved on August 13, The Facility has six SIUs are listed in Table 1, all of which have a control mechanism associated with the Facility. Zero of the SIUs are subject to Categorical Standards. Table 1: Austin WWTF s SIUs Name Hormel Foods Corporation G&R Truck Wash Total Average Flow (mgd) Flow from process wastewater (mgd) Flow from nonprocess wastewater (MG/year) Principal Products or raw materials used 2 2 Hogs and Food materials Water and Waste from Hog Transport Considered a SIU (Y/N) Is there currently a control mechanism and/or local limits (Y/N) Y Y N Y Y N Is the IU subject to Categorical Standards? (N/Y)

9 Permit Reissuance Page 9 of 21 L.L. Parks Truck Wash International Paper SKB Austin Industrial Landfill SKB Lansing Demolition Landfill Water and Waste from Hog Transport Y Y N Paper Products Y Y N 2.0 MG/year Landfill Leachate 3.9 MG/year Landfill Leachate Industrial Waste Demolition Waste Y Y N Y Y N Recent compliance history A Compliance Evaluation Inspection (CEI) was conducted on July 18, 2018, by Cory Schultz of the MPCA. The CEI consisted of a visual inspection of the Facility and a discussion with Facility staff, Chad Heard, Ernie Hammero, Matt Olson, and Norbert Eggert. The Facility s laboratory, pretreatment, and biosolids programs were not inspected. Based on the results of the CEI, violations of terms and conditions set forth in the NPDES/SDS permit were noted but cannot be disclosed at this time, pending further action by the MPCA. For compliance and enforcement questions, please contact Cory Schultz at A Biosolids Compliance Inspection (BCI) occurred on February 10, 2015, by Jorja DuFresne of the MPCA. Operators Chad Heard and Ernest Hammero were in attendance. The BCI consisted of a review of all records associated with demonstrating compliance with the requirements of the permit, Ch. 12 and Minn. R. ch for the preparation and land application of biosolids generated at the Facility. In addition, the 2014 Biosolids Annual Report was reviewed. A preinspection review of the MPCA Biosolids File was also made to look at the recent history of biosolids management for the Facility. No field inspection of sites and the land application of biosolids because no application was occurring at this time. A Pretreatment Audit Inspection (PAI) occurred on July 13, 2016, by Jaramie Logelin of the MPCA. The PAI consisted of a review of the significant industrial user (SIU) files maintained by the Facility, an observation inspection of Hormel Foods Corporation, and discussions with the Facility staff Ernie Hammero and Chad Heard. Neither the wastewater treatment facility nor its operations were inspected. Based on the results of the PAI, the City and its staff have done a good job of implementing the requirements of the delegated pretreatment program and no violations of the terms and conditions of NPDES/SDS permit were noted.

10 Permit Reissuance Page 10 of 21 Recent monitoring history Parameter Limit Type Limit Units Jul-17 Aug-17 Sep-17 Oct-17 Nov-17 Dec-17 Jan-18 Feb-18 Mar-18 Apr-18 May-18 Jun-18 Bicarbonates CalMoMax mg/l CBOD5 CalMoAvg 15 mg/l CBOD5 CalMoAvg 20 mg/l CBOD5 CalMoAvg 25 mg/l CBOD5 CalMoAvg 481 kg/d CBOD5 CalMoAvg 641 kg/d CBOD5 CalMoAvg 801 kg/d CBOD5 MxCalWkAvg 30 mg/l CBOD5 MxCalWkAvg 35 mg/l CBOD5 MxCalWkAvg 40 mg/l CBOD5 MxCalWkAvg 961 kg/d CBOD5 MxCalWkAvg 1,121 kg/d CBOD5 MxCalWkAvg 1,281 kg/d CBOD5 % Removal MnCalMoAvg 85 % Calcium, Total CalMoMax mg/l Chloride, Total CalMoMax mg/l Chlorine, Total Residual DailyMax mg/l Fecal Coliform CalMoGeoMn 200 #/100ml Flow CalMoAvg mgd Flow CalMoMax mgd Flow CalMoTot Mgal Hardness, Calcium & Magnesium CalMoMax mg/l Magnesium, Total CalMoMax mg/l Mercury, Total CalQtrMax ng/l Nitrite Plus Nitrate CalMoAvg mg/l Nitrogen, Ammonia CalMoAvg 7.8 mg/l Nitrogen, Ammonia CalMoAvg 11 mg/l 2 Nitrogen, Ammonia CalMoAvg 12 mg/l 3 5

11 Permit Reissuance Page 11 of 21 Nitrogen, Ammonia CalMoAvg 22 mg/l 1.8 Nitrogen, Ammonia CalMoAvg 29 mg/l 5.4 Nitrogen, Ammonia CalMoAvg 41 mg/l Nitrogen, Ammonia CalMoAvg 250 kg/d Nitrogen, Ammonia CalMoAvg 352 kg/d 51 Nitrogen, Ammonia CalMoAvg 384 kg/d 155 Nitrogen, Ammonia CalMoAvg 705 kg/d 40 Nitrogen, Ammonia CalMoAvg 929 kg/d 138 Nitrogen, Ammonia CalMoAvg 1,313 kg/d Nitrogen, Kjeldahl CalMoAvg mg/l Oxygen, Dissolved CalMoMin 5 mg/l Oxygen, Dissolved CalMoMin 5.5 mg/l Oxygen, Dissolved CalMoMin 6 mg/l ph CalMoMax 9 SU ph CalMoMin 6 SU Phosphorus, Total CalMoAvg kg/d Phosphorus, Total CalMoAvg mg/l Potassium, Total CalMoMax mg/l Sodium, Total CalMoMax mg/l TDS CalMoMax mg/l TSS CalMoAvg 30 mg/l TSS CalMoAvg 961 kg/d TSS MxCalWkAvg 45 mg/l TSS MxCalWkAvg 1,442 kg/d TSS % Removal MnCalMoAvg 85 % umhos/ Specific Conductance CalMoMax cm Sulfate, Total CalMoMax mg/l

12 Permit Reissuance Page 12 of 21 Receiving water(s) Use classification The receiving water, the Cedar River, is a Class 2Bg, 3C, 4A, 4B, 5, 6 water Minn. R , Water Use Classifications for Waters of the State Class 2 waters, aquatic life and recreation. Aquatic life and recreation includes all waters of the state that support or may support fish, other aquatic life, bathing, boating, or other recreational purposes and for which quality control is or may be necessary to protect aquatic or terrestrial life or their habitats or the public health, safety, or welfare. Class 3 water, industrial consumption. Industrial consumption includes all waters of the state that are or may be used as a source of supply for industrial process or cooling water, or any other industrial or commercial purposes, and for which quality control is or may be necessary to protect the public health, safety, or welfare. Class 4 waters, agriculture and wildlife. Agriculture and wildlife includes all waters of the state that are or may be used for any agriculture purposes, including stock watering and irrigation, or by waterfowl or other wildlife and for which quality control is or may be necessary to protect terrestrial life and its habitat or the public health, safety, or welfare. Class 5 waters, aesthetic enjoyment and navigation. Aesthetic enjoyment and navigation includes all waters of the state that are or may be used for any form of water transportation or navigation or fire prevention and for which quality control is or may be necessary to protect the public health, safety, or welfare. Class 6 waters, other uses and protection of border waters. Other uses includes all waters of the state that serve, or may serve, the uses in subparts 2 to 6, or any other beneficial uses not listed in this part, including, without limitation, any such uses in this or any other state, province, or nation of any waters flowing through or originating in this state, and for which quality control is, or may be, necessary for the declared purposes in this part, to conform with the requirements of the legally constituted state of national agencies having jurisdiction over such waters, or for any other considerations the agency may deem proper. Impairments Table 2: Current Impairments to receiving water AUID or Lake ID# Reach Reach Description Use Class Impairment Cedar River Dobbins Cr to Turtle Cr 2B, 3C Mercury Cedar River Turtle Cr to Rose Cr 2B, 3C Mercury Cedar River Rose Cr to Woodbury Cr 2B, 3C Mercury, Fecal Coliform Cedar River Woodbury Cr to MN/IA border 2B, 3C Mercury Total Maximum Daily Load (TMDL) The following Total Maximum Daily Load (TMDL) studies were used: Lower Mississippi River Basin TMDL approved by the Environmental Protection Agency (EPA) on April 5, 2006 Minnesota Statewide Mercury TMDL approved by the EPA on March 27, 2007

13 Permit Reissuance Page 13 of 21 Existing permit effluent limits The limits and monitoring requirements for Station SD 002 of the current permit are presented in Table 3 at the end of this section. Applicable water quality based effluent limits, technology based effluent limits, and state discharge restriction limits are explained below. Technology based effluent limits (TBELs) The total suspended solids (TSS), potential for hydrogen (ph), and percent removal limits are technology based limits developed for achieving secondary treatment standards. These limits are specified in 40 CFR and Minn. R Water quality based effluent limits (WQBELs) The residual chlorine, dissolved oxygen (DO), CBOD 5, and Ammonia-Nitrogen limits are WQBELs. These effluent limits are based on the designated use classification of the receiving water. The residual chlorine limit is the final acute value for chlorine found in Minn. R The Ammonia-Nitrogen limit is based on a mass balance calculation, which was completed to determine the effluent limits required to meet the 0.04 mg/l in-stream water quality standard for unionized Ammonia-Nitrogen (Minn. R ) in the Cedar River. The un-ionized Ammonia effluent limit is based on the designated use classification of the receiving water. The seasonal Ammonia limit was calculated using the 30Q 10 as the stream flow. These limits were determined to be necessary to protect the use classification of the receiving water. State discharge restrictions (SDRs) The 200 #100mL geometric mean limit for Fecal Coliform is SDR limit based on Minn. R SDRs are not considered WQBELs; however, these restrictions were designed to protect water quality and maintain in-stream water quality standards. Therefore, the restrictions are strict enough to protect water quality standards. Table 3: Surface Discharge Station SD 002 Existing Limit and Monitoring Requirements Parameter Limit Unit Limit Type Effective Period Frequency Bicarbonates (HCO3) Monitor Only mg/l Cal Mth Avg 1 x CBOD kg/ Cal Mth Avg Dec-Mar 3 x CBOD 5 20 mg/l Cal Mth Avg Dec-Mar 3 x CBOD kg/ Max Cal Wk Avg Dec-Mar 3 x CBOD 5 35 mg/l Max Cal Wk Avg Dec-Mar 3 x CBOD kg/ Cal Mth Avg Apr-May, Oct-Nov 3 x CBOD 5 25 mg/l Cal Mth Avg Apr-May, Oct-Nov 3 x CBOD kg/ Max Cal Wk Avg Apr-May, Oct-Nov 3 x CBOD 5 40 mg/l Max Cal Wk Avg Apr-May, Oct-Nov 3 x CBOD kg/ Cal Mth Avg Jun-Sep 3 x CBOD 5 15 mg/l Cal Mth Avg Jun-Sep 3 x CBOD kg/ Max Cal Wk Avg Jun-Sep 3 x CBOD 5 30 mg/l Max Cal Wk Avg Jun-Sep 3 x CBOD 5 % Removal 85 % Min Cal Mth Avg 3 x Calcium, Total (as Ca) Monitor Only mg/l Cal Mth Max 1 x Chloride, Total Monitor Only mg/l Cal Mth Max 1 x Chlorine, Total Residual mg/l Daily Max 1 x Fecal Coliform 200 #100ml Cal Mth Geo Mean Apr-Oct 3 x Flow Monitor Only mgd Cal Mth Avg 1 x Flow Monitor Only mgd Cal Mth Max 1 x Flow Monitor Only MG Cal Mth Tot 1 x Hardness, Calcium & Magnesium, Monitor Only mg/l Cal Mth Max 1 x Calculated (as CaCO3) Magnesium, Total (as Mg) Monitor Only mg/l Cal Mth Max 1 x Mercury, Total (as Hg) Monitor Only ng/l Cal Qtr Max 1 x quarter Nitrite Plus Nitrate, Total (as N) Monitor Only mg/l Cal Mth Avg Apr, Sep 1 x

14 Permit Reissuance Page 14 of 21 Nitrogen Ammonia, Total (as N) 1313 kg/ Cal Mth Avg Dec-Mar 3 x Nitrogen Ammonia, Total (as N) 41 mg/l Cal Mth Avg Dec-Mar 3 x Nitrogen Ammonia, Total (as N) 929 kg/ Cal Mth Avg Apr 3 x Nitrogen Ammonia, Total (as N) 29 mg/l Cal Mth Avg Apr 3 x Nitrogen Ammonia, Total (as N) 384 kg/ Cal Mth Avg May 3 x Nitrogen Ammonia, Total (as N) 12 mg/l Cal Mth Avg May 3 x Nitrogen Ammonia, Total (as N) 250 kg/ Cal Mth Avg Jun-Sep 3 x Nitrogen Ammonia, Total (as N) 7.8 mg/l Cal Mth Avg Jun-Sep 3 x Nitrogen Ammonia, Total (as N) 352 kg/ Cal Mth Avg Oct 3 x Nitrogen Ammonia, Total (as N) 11 mg/l Cal Mth Avg Oct 3 x Nitrogen Ammonia, Total (as N) 705 kg/ Cal Mth Avg Nov 3 x Nitrogen Ammonia, Total (as N) 22 mg/l Cal Mth Avg Nov 3 x Nitrogen, Kjeldahl, Total Monitor Only mg/l Cal Mth Avg Apr, Sep 1 x Oxygen, Dissolved 5.5 mg/l Cal Mth Min Dec-Mar 1 x Oxygen, Dissolved 5.0 mg/l Cal Mth Min Apr-May, Oct-Nov 1 x Oxygen, Dissolved 6.0 mg/l Cal Mth Min Jun-Sep 1 x ph 9.0 SU Cal Mth Max 1 x ph 6.0 SU Cal Mth Min 1 x Phosphorus, Total (as P) Monitor Only kg/ Cal Mth Avg Jun-Sep 1 x Phosphorus, Total (as P) Monitor Only mg/l Cal Mth Avg 1 x Potassium, Total (as K) Monitor Only mg/l Cal Mth Max 1 x Sodium, Total (as Na) Monitor Only mg/l Cal Mth Max Jun-Sep 1 x Solids Total Dissolved (TDS) Monitor Only mg/l Cal Mth Max 1 x Solids Total Suspended (TSS) 961 mg/l Cal Mth Avg 3 x Solids Total Suspended (TSS) 30 mg/l Cal Mth Avg Jun-Sep 3 x Solids Total Suspended (TSS) 1442 Max Cal Wk Avg 3 x Solids Total Suspended (TSS) 45 mg/l Max Cal Wk Avg 3 x Solids Total Suspended (TSS) 85 % Min Cal Mth Avg Jun-Sep 3 x % Removal Specific Conductance Monitor Only umh/cm Cal Mth Max 1 x Sulfate, Total (as SO4)Sulfate, Total (as SO4) Monitor Only mg/l Cal Mth Max 1 x Proposed permit effluent limits The limits and monitoring requirements for Station SD 002 of the draft permit are presented in Table 4 at the end of this section. Applicable WQBEL, technology based effluent limits, and state discharge restriction limits are explained below. Technology based effluent limits (TBELs) The TSS, ph, and percent removal limits are technology based effluent limits developed for achieving secondary treatment standards. These limits are specified in 40 CFR and Minn. R Water quality based limits (WQBELs) The residual chlorine, DO, CBOD 5, and Ammonia-Nitrogen limits are WQBELs. These effluent limits are based on the designated use classification of the receiving water and determined to be necessary to protect the use classification of the receiving water. State discharge restrictions (SDRs) The 200 #100mL geometric mean limit for Fecal Coliform is a SDR limit based on Minn. R

15 Permit Reissuance Page 15 of 21 Table 4: Surface Discharge Station SD 002 Proposed Limit and Monitoring Requirements Parameter Bicarbonates (HCO3) BOD, Carbonaceous 05 Day (20 Deg C) BOD, Carbonaceous 05 Day (20 Deg C) BOD, Carbonaceous 05 Day (20 Deg C) BOD, Carbonaceous 05 Day (20 Deg C) Percent Removal Calcium, Total (as Ca) Chloride, Total Chlorine, Total Residual Fecal Coliform, MPN or Membrane Filter 44.5C Flow Hardness, Calcium & Magnesium, Calculated (as CaCO3) Magnesium, Total (as Mg) Discharge limitations Quantity /Loading avg. 481 calendar 801 calendar 641 calendar Quantity /Loading max. 961 calendar 1281 calendar 1121 calendar total Quantity /Loading units million gallons Quality /Conc. min. 85 minimum Quality /Conc. avg. 15 calendar 25 calendar 20 calendar 200 calendar geometric mean Quality /Conc. max. 30 calendar 40 calendar 35 calendar daily Monitoring requirements Quality/ Conc. units Frequency Sample type percent organisms per 100 milli million gallons per Calculation Grab Grab Measurement, Continuous Effective period Jun-Sep Apr-May, Oct-Nov Dec-Mar Apr-Oct

16 Permit Reissuance Page 16 of 21 Parameter Mercury, Dissolved (as Hg) Mercury, Total (as Hg) Nitrite Plus Nitrate, Total (as N) Discharge limitations Quantity /Loading avg. Nitrogen, Ammonia, Total 250 calendar (as N) Nitrogen, Ammonia, Total 705 calendar (as N) Nitrogen, Ammonia, Total 384 calendar (as N) Nitrogen, Ammonia, Total 929 calendar (as N) Nitrogen, Ammonia, Total 1313 calendar (as N) Nitrogen, Ammonia, Total 352 calendar (as N) Nitrogen, Kjeldahl, Total Nitrogen, Total (as N) Oxygen, Dissolved Oxygen, Dissolved Oxygen, Dissolved ph Phosphorus, Total (as P) Quantity /Loading max. Quantity /Loading units Quality /Conc. min. 5.5 calendar minimum 5.0 calendar minimum 6.0 calendar minimum 6.0 calendar minimum Quality /Conc. avg. 7.8 calendar 22 calendar 12 calendar 29 calendar 41 calendar 11 calendar Quality /Conc. max. 9.0 calendar Monitoring requirements Quality/ Conc. units Frequency Sample type nanograms per Grab nanograms per standard units Grab Grab Grab Grab Grab Effective period May, Sep May, Sep Jun-Sep Nov May Apr Dec-Mar Oct Dec-Mar Apr-May, Oct-Nov Jun-Sep

17 Permit Reissuance Page 17 of 21 Parameter Potassium, Total (as K) Sodium, Total (as Na) Solids, Total Dissolved (TDS) Solids, Total Suspended (TSS) Solids, Total Suspended (TSS) Percent Removal Solids, Total Suspended (TSS), grab (Mercury) Specific Conductance Sulfate, Total (as SO4) Discharge limitations Quantity /Loading avg. 961 calendar Quantity /Loading max calendar Quantity /Loading units Quality /Conc. min. 85 minimum Quality /Conc. avg. 30 calendar Quality /Conc. max. 45 calendar Monitoring requirements Quality/ Conc. units Frequency Sample type percent micromhos per cm Calculation Grab Measurement Effective period May, Sep

18 Permit Reissuance Page 18 of 21 Reasonable potential analysis Reasonable Potential for Chemical Specific Pollutants (40 CFR (d)(1)) Federal regulations require the MPCA to evaluate the discharge to determine whether the discharge has the reasonable potential to cause or contribute to a violation of water quality standards. The Agency must use acceptable technical procedures, accounting for variability (coefficient of variation, or CV), when determining whether the effluent causes, has the reasonable potential to cause, or contributes to an excursion of an applicable water quality standard. Projected effluent quality (PEQ) concentrations derived from effluent monitoring data are compared to Preliminary Effluent Limits (PEL) determined from mass balance inputs and to the Final Acute Values (FAV s). Determinations of the PEQ and PEL account for effluent variability. If the PEQ exceeds the PEL or FAV, reasonable potential to cause or contribute to a water quality standards excursion is indicated. When reasonable potential is indicated for a pollutant the permit must contain a WQBEL for that pollutant. Priority Pollutants The priority pollutant scan data and effluent monitoring data that were obtained during the life of the current permit were evaluated using reasonable potential procedures. All of the organic pollutants were below detection levels except for chloroform in 2010 which was 1.1 microgram/ (ug/l), a concentration well below state standards. All of the metal priority pollutants, except copper and zinc, were below their respective level of detection or at levels that would not violate a water quality standard. Results of the analyses do not indicate reasonable potential for the detected pollutants to cause or contribute to a water quality standards excursion. Total Mercury This reach of the receiving water is listed as impaired for mercury according to the Minnesota Statewide Mercury TMDL. Monitoring results of the effluent include 28 data points at a default CV of 0.6 and a PEQ factor of 1.0. The PEQ for mercury is derived as an upper bound value from the highest measured value [9.7 nanogram/ (ng/l)], the CV, and number of data points. The PEL calculation is based on a background mercury concentration of 6.9 ng/l. The mass balance equation used to calculate the PEL is based on the background concentration in the receiving water at the point of discharge. This calculation assures that the discharge does not cause or contribute to a water quality standards excursion for mercury impaired waters. If the PEQ exceeds the PEL (acute water quality standard only) or the FAV, there is reasonable potential to cause or contribute to a water quality standards excursion. Since PEQ does not exceed either value in this case, reasonable potential for mercury to cause or contribute to an excursion above water quality standards is not indicated. A WQBEL for mercury, therefore, is not needed. Table 5 contains inputs to and results of the reasonable potential analysis for salty parameters and mercury. Table 5: Reasonable Potential Analyses for Salty Parameters and Mercury Parameter Class 2 Cl (mg/l) Class 3 Cl (mg/l) Bicarb as HCO3 (mg/l) Hardness (mg/l) TDS (mg/l) Specific Conductance (umhos/cm) (ADW) (MGD) River 7Q10 (CFS) Background Conc Continuous Std (cs) Maximum Std (ms) 860 NA NA NA NA NA 2400 Final Acute Value 1720 NA NA NA NA NA 4900 Waste Ld Allocation: Coeff of Variation (CV) Variance Std. Dev Duration (n s) Hg (ng/l)

19 Permit Reissuance Page 19 of 21 Long Term Ave.-LTA Use LTAcs < LTAms: TRUE TRUE WQBEL: Daily Max Mo.Av. (2x) Max Meas Effl Value # data points PEQ factor Proj Effl Qual.(PEQ) PEQ > Daily Max FALSE FALSE FALSE FALSE FALSE FALSE FALSE PEQ> Monthly Ave FALSE FALSE FALSE FALSE FALSE FALSE FALSE PEQ > FAV FALSE NA NA NA NA NA NA Reasonable Potential No No No No No No No Whole Effluent Toxicity (WET) Minn. R , subp. 1, Minimum secondary treatment for municipal point source and other point source dischargers of sewage, specifies that the discharge shall not be acutely toxic or exceed the final acute value, unless the effluent satisfies acute whole effluent toxicity test conditions (i.e. - less than 50% mortality for a sensitive organism). A discharge that exceeds mortality requirements of the rule requires a permit limit for WET. Five chronic WET tests have been submitted since The Receiving Water Concentration (RWC) is 25%, or 3.6 Toxic Unit chronic (TUc), based on the plant design flow and the stream lowest 7- flow that occurs once every 10 years (7Q 10) of CFS. No chronic toxicity for fathead minnows was noted in any of sample WET tests. Four of the five WET tests had measurable chronic toxicity for Ceriodaphnia Dubia but none of the tests exceeded the 3.6 TUc limit. No reasonable potential analysis was performed because none of the tests exceeded the 3.6 TUc limit. A WQBEL for WET is not needed. Additional requirements Phosphorus minimization plans (PMP) Phosphorus is a common constituent in many wastewater discharges and a pollutant that has the potential to negatively impact the quality of Minnesota s lakes, wetlands, rivers, and streams. Phosphorus promotes algae and aquatic plant growth often resulting in decreased water clarity and oxygen levels. In addition to creating general aesthetic problems, these conditions can also impact a water body s ability to support healthy fish and other aquatic species. Therefore, phosphorus discharges are being carefully evaluated throughout the state. The Permittee is required to prepare a Streamlined Phosphorus Management Plan (PMP) and submit it to the MPCA within 180 s of permit issuance. While the PMP does not require specific reductions at this time, the MPCA strongly encourages the Permittee to identify and eliminate/reduce sources of phosphorus to and improve phosphorus management within the wastewater treatment facility. However, the Permittee should be aware that new or expanding discharges may be required to actively manage and reduce phosphorus, including complying with new or more restrictive phosphorus effluent limits. Guidance for considering phosphorus in a wastewater treatment system and preparing a PMP can be found on the web at: or For additional information about completing the PMP, please contact the MPCA at or

20 Permit Reissuance Page 20 of 21 Mercury minimization plan (MMP) The draft permit contains requirements for mercury monitoring and for submittal of a MMP or an updated MMP. These requirements were added in response to the EPA s approval of the Minnesota state-wide Mercury TMDL plan. Specific mercury monitoring requirements are found in the Surface Discharge Stations Chapter of the draft permit. Those requirements include sampling for total suspended solids via a grab sample taken at the same time as the mercury grab samples are taken. The Permittee is required to submit a Mercury Minimization Plan (MMP) within 180 s of permit issuance. The MMP requirements include educating users with regard to proper mercury disposal in order to prevent its introduction into the waste stream. Nitrogen monitoring requirements Nitrogen is a pollutant that can negatively impact the quality of Minnesota s water resources, including water used for drinking. Studies have shown that nitrogen in lakes and streams have a toxic effect on aquatic life such as fish. Like phosphorus, nitrogen is a nutrient that promotes algae and aquatic plant growth often resulting in decreased water clarity and oxygen levels. In September 2014, the MPCA completed the final draft of the Statewide Nutrient Reduction Strategy ( which identifies goals and milestones for nitrogen reductions for both point and nonpoint nitrogen sources within Minnesota. To gain a better understanding of the current nitrogen concentrations and loadings received by and discharged from the Facility, additional effluent nitrogen monitoring has been added to the permit. This monitoring has been added in accordance with Minn. Stat Refer to the Limits and Monitoring section of the draft permit for the specific influent and effluent monitoring and frequency. Salty parameter monitoring In recent years, the MPCA staff became aware of issues associated with salty discharges from industrial and municipal discharges. As a result, the MPCA staff began to request additional monitoring for these facilities and also began assigning effluent limits to facilities that have data showing a reasonable potential to exceed a water quality standard. All industrial and municipal facilities with continuous, periodic/seasonal, or intermittent waste flows, where the receiving water stream flow to effluent design flow dilution ratio under low flow conditions is less than 5:1, will be required to monitor effluent for the following parameters: bicarbonates, calcium, calcium and magnesium hardness as CaCO 3, chloride, magnesium, potassium, specific conductance, sodium, sulfates as SO 4, and total dissolved solids. These parameters shall be sampled once a. For additional information on Austin s salty parameter reasonable potential analyses, refer to Table 5 on page 18 of this document. Since there is no reasonable potential for any salty parameter, no limits were assigned. Industrial stormwater On April 5, 2015, the Industrial Stormwater General Permit (MNR050000) was reissued. This permit addresses stormwater discharges associated with industrial activity for facilities that discharge stormwater to waters of the state, including Municipal Separate Storm Sewer Systems. The General Permit also addresses stormwater discharges associated with industrial activities at facilities that provide onsite infiltration of industrial stormwater discharges associated with the facility. For both industrial and municipal wastewater treatment facilities, in lieu of obtaining coverage under both the General Permit and the individual NPDES permit, the MPCA has created the necessary industrial stormwater boilerplate language and limits and monitoring so that coverage under the NPDES permit alone will cover both permits. Austin WWTF has elected to combine their Industrial Stormwater (ISW) permit coverage with their NPDES/SDS wastewater permit coverage at this reissuance.

21 Permit Reissuance Page 21 of 21 An additional discharge station (SD 003) has been created in this permit with specific limits and monitoring requirements for stormwater monitoring purposes. Sampling and monitoring at this stormwater SD station is required on a quarterly basis through the life of the permit with the results d year on the December Discharge Monitoring Report (DMR). The draft permit also contains an Industrial Stormwater Sector T: Treatment Works chapter. References are made to an Inspection Report and Annual Report that can be found on the MPCA s website. Finally, there is a Benchmark Monitoring Factsheet on the website that must be used to ensure compliance with the limits and monitoring requirements for the facility. The documents can be found at: Biosolids This draft permit authorizes the Permittee to store and land applies domestic wastewater treatment biosolids in accordance with the provisions in this draft permit and Minn. R. ch The draft permit requires biosolids to be treated to meet specific standards, and specifies monitoring, recordkeeping, reporting, and general requirements for biosolids that are applied to the land. Unless they are exceptional quality biosolids, sites to which biosolids are applied are approved by the MPCA by the procedures found in Minn. R Surface Water Monitoring The existing permit allowed the City to request the discontinuation of monitoring of unionized ammonia if all monitoring conditions were met during a three year period. No exceedances of any water quality standard were noted in the dataset. Upon request, surface water monitoring has been removed from the draft permit. Karst The City has completed the closure and decommissioning of the two remaining sludge lagoons as required in existing permit. All karst requirements have been removed from the draft permit. Variances There are no variances in the draft permit. Total facility requirements (TFR) All NPDES/SDS Permits issued by the state of Minnesota contain certain conditions that remain the same, regardless of the size, location, or type of discharge. The standard conditions satisfy the requirements are outlined in 40 CFR , Minn. R , and These conditions are listed in the Total Facility Requirements chapter of the NPDES/SDS Permit. These requirements cover a wide range of areas, including recordkeeping, sampling, equipment calibration, equipment maintenance, reporting, facility upsets, bypasses, solids handling, changes in operation, facility inspections, and permit modification and reissuance. Antidegradation and anti-backsliding Changes to the Facility may result in an increase in pollutant loading to surface waters or other causes of degradation to surface waters. If a change to the Facility will result in a net increase in pollutant loading or other causes of degradation that exceed the loading authorized through conditions specified in the existing permit, the changes to the facility are subject to antidegradation requirements found in Minn. R to This permit also complies with Minn. R regarding anti-backsliding. Any point source discharger of sewage, industrial, or other wastes for which a NPDES permit has been issued by the agency that contains effluent limits more stringent than those that would be established by Minn. R to shall continue to meet the effluent limits established by the permit, unless the Permittee establishes that less stringent effluent limits are allowable pursuant to federal law, under section 402(o) of the Clean Water Act, United States Code, title 33, section 1342.