National Pollutant Discharge

Elimination System /State Disposal

System (NPDES/SDS) Permit Program

Fact Sheet

Permittee: Alexandria Lake Area Sanitary District

2201 Nevada Street Southwest

Alexandria, MN 56308

Facility Name: Alexandria Lake Area Sanitary District Wastewater Treatment Facility

2201 Nevada Street Southwest

Alexandria, MN 56308

Permit Number: MN0040738

Original Fact Sheet Development: 2012/2013

Fact Sheet Modified: January 2017

Current Permit Expiration: June 30, 2018

Public Comment Period Begins: January 27, 2017

Period Ends: February 27, 2017

Receiving Water: Lake Winona, Class 2B, 3C, 4A, 4B, 5, 6 Water

Proposed Action: Permit Modification

Permitting Contact

Holly Kvittem

Minnesota Pollution Control Agency

714 Lake Avenue, Suite 220

Detroit Lakes, MN 56501

Phone: 218‐846‐8111

Fax: 218‐846‐0719

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Table of Contents

Purpose and Participation.................................................................................................................. 3‐4 Applicable Statutes Purpose Public Participation

Facility Description............................................................................................................................. 4‐8 Background Information....................................................................................................... 4‐5

Facility Location Outfall Location Map of Permitted Facility

Components and Treatment Technology ............................................................................. 5‐8 Current Information Facility Layout and Flow Schematic Proposed Changes to the Compliance Schedule Significant Industrial Users Recent Compliance History Table 1. Recent Monitoring History

Receiving Water ................................................................................................................................. 8‐10 Use Classification Impairments Table 2. Downstream Impaired Waters

Existing Permit Effluent Limits ........................................................................................................... 10‐13 Technology Based Effluent Limits State Discharge Restrictions Water Quality Based Effluent Limits Table 3. Existing Permit Effluent Limits

Proposed Permit Effluent Limits ........................................................................................................ 13‐20 Technology Based Effluent Limits State Discharge Restrictions Water Quality Based Effluent Limits Table 4. Preliminary Water Quality Based Effluent Limitations Table 5. Mercury Monitoring Table 6. Proposed Permit Effluent Limits

Additional Requirements ................................................................................................................... 20‐‐21 Biosolids Mercury Minimization Plan Salty Discharge Requirements Additional Nitrogen Species Monitoring Requirements Conditional Exclusion for No Exposure – Industrial Stormwater Variances

Total Facility Requirements ............................................................................................................... 21‐22 Nondegradation and Anti‐backsliding ............................................................................................... 22

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Purpose and Participation

Applicable Statutes This fact sheet has been prepared according to the Title 40 Federal Code of Regulations (CFR) 124.8 and 124.56 and Minn. R. 7001.0100, Subp. 3 in regards to a draft NPDES/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. 7000.0650 and Minn. R. 7001.0110, your petition requesting a public informational meeting must identify the matter of concern and must include the following: items 1 through 3 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. 7000.1900, 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 1 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 and will be included in the record for this matter. 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. During the public comment period, however, you

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may request that the draft permit be presented to the MPCA’s Citizens’ Board (Board) for final decision. You may participate in the activities of the Board as provided in Minn. R. 7000.0650.

Comments, petitions, and/or requests must be submitted by the last day of the public comment period to:

Holly Kvittem Minnesota Pollution Control Agency

714 Lake Avenue, Suite 220 Detroit Lakes, MN 56501

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

Background Information Facility Location The Alexandria Lake Area Sanitary District Wastewater Treatment Facility (Facility) is located in the SW 1/4 and NW 1/4 of Section 25, Township 128 North, Range 38 West, La Grand Township, Douglas County, Minnesota. The Facility is located on the western edge of Alexandria, MN.

Outfall Location The outfall (Station SD001) for the Facility is also located in the NW 1/4 of Section 25, Township 128 North, Range 38 West, La Grand Township, Douglas County, Minnesota. The outfall pipe is on the northern edge of the Facility property and at the southern edge of Lake Winona.

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Map of Permitted Facility

Components and Treatment Technology Current Information The existing Facility consists of a main lift station, force main, influent screening, screenings washing and compaction, vortex grit removal and grit washing, two primary settling tanks, three fine pore ceramic diffuser aeration tanks, three secondary clarifiers, cloth media tertiary filtration, chlorination tanks, dissolved air floatation thickening of waste activated sludge, three aerobic digesters, centrifuge dewatering, and outfall pipeline. There are no known bypass points for the wastewater collection/treatment system. This is a Class A Facility.

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The Facility has a continuous discharge (Station SD001) to Lake Winona (Class 2B, 3C, 4A, 4B, 5, 6 water), and has an average wet weather design flow of 4,700,000 gallons per day (gpd), with a 5‐day carbonaceous biochemical oxygen demand (CBOD5) strength of 7,100 pounds per day (lbs/d). The Facility is also designed to treat up to 6,000 lbs/d of total suspended solids (TSS), 210 lbs/d of total phosphorus, and 470 lbs/d of ammonia nitrogen.

Facility Layout

STORS

MAIN PUMPSTATION

HEADWORKS AND THICKENINGBUILDING

AERATION TANKS

PRIMARY CLARIFIERSSECONDARY CLARIFIERS

SECONDARY CLARIFIER

FILTRATION AND ADMINISTRATION

MAINTENANCEBUILDING

ALASD revised plant layout

SOLIDS HANDLINGBUILDING

AEROBIC DIGE

SOLIDS HANDLING BUILDING

AEROBIC DIGESTORS

MAIN PUMP STATION

HEADWORKS AND THICKENING BUILDING

AERATION TANKS

PRIMARY CLARIFIERS SECONDARY CLARIFIERS

SECONDARY CLARIFIER

FILTRATION AND ADMINISTRATION

MAINTENANCE BUILDING

ALASD revised plant layout

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Flow Schematic

AALLAASSDD rreevviisedsed plaplanntt flofloww sscchehemamatictic FFIILLTTEERR BACBACKKWWASASHH

DIDISSCCHHAARGRGEE TTOO LALAKKEE WWIINNOONNAA

ININFFLLUUEENNTT DISINFECTION

FILTRATE

THICKENEDWASTE SLUDGE

DISSOLVED AIRFLOATATIONTHICKENING

PRIMARYSLUDGE

WASTESLUDGE

RETURN SLUDGE

LANDAPPLICATION/

STORAGECENTRIFUGE

AEROBIC DIGESTERS (3)

M

FERRIC SULFATE

FILTERSSECONDARYCLARIFIERS (3)

AERATIONTANKS (3)PRIMARY

CLARIFIERS (2)

VORTEX GRITREMOVAL

BARSCREEN (2) DISINFECTION

FILTRATE

THICKENED WASTE SLUDGE

DISSOLVED AIR FLOATATION THICKENING

PRIMARY SLUDGE

WASTE SLUDGE

RETURN SLUDGE

LAND APPLICATION/

STORAGE CENTRIFUGE

AEROBIC DIGESTERS (3)

M

FERRIC SULFATE

FILTERSSECONDARY CLARIFIERS (3)

AERATION TANKS (3)PRIMARY

CLARIFIERS (2)

VORTEX GRIT REMOVAL

BAR SCREEN (2)

CECENNTTRRAATTEE

Proposed Changes to the Compliance Schedule: The application for a permit modification includes the following changes to be made to the currently permitted compliance schedule tasks and corresponding deadlines:

1. Submittal Action: Alternative Treatment Technologies; a. The Permittee is to submit to the MPCA a progress report on the development of the Facility Plan

by March 1, 2017. b. The Permittee is to complete and submit a Facility Plan for MPCA review and approval, that

identifies alternative treatment technologies and/or other discharge locations/methods that the Permittee has identified as technically feasible to further reduce total phosphorus (TP) and total chloride in its effluent, with the final result of attaining the final effluent limits for TP and total chloride. Original Permitted Due Date: March 1, 2017. Proposed Deadline in Permit Application: September 30, 2017.

2. Plans and Specifications (P&S). The Permittee is to submit P&S for the chosen alternative from the Facility Plan, for MPCA review and approval. Original Permitted Due Date: March 1, 2018. Proposed Deadline in Permit Application: September 1, 2018.

3. Construction. The Permittee is to begin construction of the chosen alternative. Original Due Date: March 1, 2019. Proposed Deadline in Permit Application: September 1, 2019.

4. Progress Report. The Permittee is to submit a construction progress report to the MPCA. Original Due Date: March 1, 2020. Proposed Deadline in Permit Application: September 1, 2020.

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5. Complete Construction: The Permittee is to complete construction of the chosen alternative and initiate operation of the chosen alternative. Original Due Date: December 31, 2020. Proposed Deadline in Permit Application: February 28, 2021.

The Permittee is still to attain compliance with the final effluent limits for TP and total chloride by March 30, 2021. No other changes will be made, nor will there be any change to the design flow of the system.

Significant Industrial Users The Permittee has six Significant Industrial Users (SIUs) that contribute wastewater to the Facility. They are as follows:

Douglas Metal Finishing – metal cleaning and plating solutions TWF Industries – powder coating and metal plating Alexandria Extrusion Company – extruded aluminum SunOpta Ingredients – soybean and milk products SunOpta Aseptic ‐ soybean and milk products 3‐M (Minnesota Mining & Manufacturing) – adhesives, silica

Zinc and copper monitoring has been included again in this permit cycle due to the types of wastewater contributions from these industries.

Recent Compliance History The most recent inspection for this Facility occurred on January 26, 2011. The inspection consisted of a visual inspection of the Facility, a discussion with the Plant Superintendent, and a review of the monthly Discharge Monitoring Reports (DMRs) for the time period of December 1, 2009 through November 30, 2010. The biosolids compliance portion of the inspection consisted of further discussions with the Plant Superintendent and a review of all records associated with the preparation and land application of biosolids generated at the Facility. Based on the results of the inspection, there were no violations of the terms and conditions set forth in the National Pollutant Discharge Elimination (NPDES)/State Disposal System (SDS) Permit No. MN0040738.

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Table 1. Recent Monitoring History

Receiving Water

Use Classification The receiving water (Lake Winona) is a class 2B, 3B, 4A, 4B, 5, and 6 Water. There are no endangered or threatened species living in the receiving water.

7050.0200 Water Use Classifications For Waters Of The State

Subp. 3. Class 2 waters, aquatic life and recreation. Aquatic life and recreation includes all waters of the state which do or may support fish, other aquatic life, bathing boating or other recreational purposes, and where quality control is or may be necessary to protect aquatic or terrestrial life or their habitats, or the public health, safety, or welfare.

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Subp. 4. Class 3 waters, industrial consumption. Industrial consumption includes all waters of the state which 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.

Subp. 5. Class 4 waters, agriculture and wildlife. Agriculture and wildlife includes all waters of the state which 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.

Subp. 6. Class 5 waters, aesthetic enjoyment and navigation. Aesthetic enjoyment and navigation includes all waters of the state which 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.

Subp. 7. Class 6 waters, other uses. Other uses includes all waters of the state which are or may serve the above listed uses or any other beneficial uses not listed herein, 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 above declared purposes, or to conform with the requirements of the legally constituted state or national agencies having jurisdiction over such waters, or any other considerations the agency may deem proper.

Impairments Lake Winona Total Maximum Daily Load (TMDL) Study and Recommended Total Phosphorus Limit. Lake Winona was placed on the 2002 MPCA CWA Section 303(d) list of impaired waters due to excess nutrients which impede designated uses such as recreation on the lake. Lake Winona is exceeding standards when compared to numeric eutrophication standards for shallow lakes in the North Central Hardwood Forest Ecoregion. Therefore a Total Maximum Daily Load (TMDL) Study was initiated for Lake Winona in 2006.

The MPCA developed and submitted a draft TMDL for nutrient impairment to the Environmental Protection Agency (EPA) for preliminary comments in October of 2010. The draft TMDL was based on achieving compliance with the Chl‐a “response variable” found in MPCA rule. After the initial review of the draft TMDL, the EPA advised MPCA that to prepare a TMDL based primarily on the Chl‐a response variable, the MPCA should pursue adoption of a site specific standard (SSS) for phosphorus pursuant to Minn. R. 7050.0220, subp. 7, before submitting the Lake Winona TMDL for final approval. In May 2011, MPCA promulgated an SSS for Lake Winona based on modeling results developed for the TMDL. In July 2011, the Permittee requested a contested case hearing to challenge the basis for the SSS. This matter remains unresolved and a final TMDL has not been published for comment or submitted to the U.S. EPA. Draft TMDL allocations will be finalized when a SSS is approved by the EPA. The MPCA will then publish the TMDL for comment and submit a final TMDL to the EPA for final review and approval. This permit includes a limit that the Permittee will be required to meet by March 2022 based on the existing standard applicable to Lake Winona under Minn. R. 7050.0222, subp. 3 (Shallow Lakes in North Central Hardwood Forest Ecoregion). However, should the proposed SSS and TMDL based on the SSS be finalized in the first term of the permit, the MPCA may modify the effluent limit that the Permittee will be required to meet by March 2022 to reflect the SSS and TMDL‐based allocation.

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Total Chloride Impairment in Lake Winona. Lake Winona was placed on the 2010 MPCA CWA Section 303(d) list of impaired waters due to excess chloride which impedes the attainment of designated uses for Aquatic Life and Industrial Consumption. Lake Winona is exceeding the 230 mg/L chronic standard intended to protect Class 2B waters for the propagation and maintenance of a healthy community of cool or warm water sport or commercial fish and associated aquatic life, and their habitats. Class 2B waters are also protected for aquatic recreation of all kinds, including bathing, for which the waters may be usable. Lake Winona is also exceeding the 250 mg/L standard intended to protect Class 3C waters for industrial cooling and material transport without a high degree of treatment being necessary to avoid severe fouling, corrosion, scaling, or other unsatisfactory conditions.

A TMDL study has not yet been initiated to address Lake Winona’s chloride impairments. The MPCA is in the process of evaluating revisions to the aquatic life and recreation and industrial consumption chloride standards.

Table 2. Downstream Impaired Waters APPROVED

AUID REACH_NAME CAT IMPAIRMENT TMDL AFFECTED_U

21‐0081‐00 Winona 5A Chloride and Nutrients AQC, AQR

21‐0053‐00 Agnes 5B Chloride Mercury AQC

21‐0051‐00 Henry 5A Chloride and Nutrients AQC, AQR

Existing Permit Effluent Limits The effluent limits and monitoring requirements in the current permit are presented in Table 3 at the end of this section. This Table lists water quality based and technology based effluent limits and state discharge restrictions.

Technology Based Effluent Limits (TBELs) The CBOD5, TSS, percent removal and pH limits that have been included in this permit are technology based limits developed for achieving secondary treatment standards. These limits are specified in 40 CFR §133.102 and Minn. R. 7050.0211 and Minn. R. 7053.0215.

State Discharge Restrictions (SDRs) The fecal coliform limit that has been included in this permit is based on State Discharge Restrictions. This limit is specified in Minn. R. 7053.0215, Subp. 1. The 0.3 mg/l phosphorus limit in this permit was based on Minn. R. 7053.0255, subp. 3.

Water Quality Based Effluent Limits (WQBELs) Water quality based effluent limits are established to meet applicable water quality standards. Under 40 CFR 122.44(d)(1)(i), all dischargers who have the reasonable potential to cause or contribute to an exceedance of a water quality standard are required to have a water quality based effluent limit (WQBEL).

The total residual chlorine limit that has been included in this permit is a water quality based effluent limit and is the final acute value for chlorine found in Minn. R. § 7050.0222. This limit was determined to be necessary to protect the use classification for the receiving water.

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The MPCA evaluated cadmium, chromium, copper, lead, nickel, zinc, and mercury under 40 CFR § 122.44(d) to determine if there was a reasonable potential to contribute to an exceedance of a water quality standard. These effluent values were used to determine the projected effluent quality (PEQ), which was then compared to both the final acute value (FAV) and the daily maximum limit (using the most restrictive standard). If the PEQ exceeds these values, then reasonable potential to exceed the standard is indicated. The MPCA determined that there was no reasonable potential to exceed state standards for these parameters.

Special conditions in the draft permit require the Permittee to conduct tests for chronic toxicity and to monitor for priority pollutants in the wastewater treatment facility effluent.

12

           

 

 

 

Table 3. Existing Permit Effluent Limits

13

  

       

                                                         

          

                                                                       

                                                                                                         

                                                                                   

                                                                 

                                                                                                                                     

                              

                                        

                                                                      

                                                                                             

Proposed Permit Effluent Limits

The effluent limits and monitoring requirements in the proposed permit are presented in Table 6 at the end of this section. Table 4 lists the WQBELs, TBELs, and SDRs.

Technology Based Effluent Limits (TBELs) The CBOD5, TSS, percent removal and pH limits in this permit are technology based limits developed for achieving secondary treatment standards. These limits are specified in 40 CFR §133.102 and Minn. R. 7050.0211 and Minn. R. 7053.0215.

State Discharge Restrictions (SDRs) The fecal coliform limit in this permit is based on State Discharge Restrictions. This limit is specified in Minn. R. 7053.0215, Subp. 1. This permit maintains the existing 0.3 mg/L limit on phosphorus in discharges but has added an intervention limit of 0.25 mg/L based on current facility performance data. If the Facility exceeds the intervention limit, the Permittee will be required to evaluate the factors that triggered the exceedance and identify changes to the Facility that may need to be made to maintain the current performance levels, which exceed the established limit.

Water Quality Based Effluent Limits (WQBELs) Total Residual Chlorine The total residual chlorine effluent limit in this permit is based on the final acute value for chlorine found in Minn. R. § 7050.0222.

Other WQBELs This permit proposes new WQBELs for chloride and total phosphorus that the Facility must meet by March 2022. The effluent limits stated in the permit are based on current standards applicable under Minn. R. 7050.0222. However, in both cases of chloride and total phosphorus, the permit notes that the standards upon which the limits were based may change during the term of the permit. In that event, the MPCA may modify the permit to conform the WQBEL to the changed applicable standard.

Total Phosphorus Water Quality Based Effluent Limit Federal regulation 40 CFR 122.44(d)(1)(i) states that all dischargers who have the reasonable potential to cause or contribute to an exceedance of a water quality standard are required to have a water quality based effluent limit (WQBEL). Given the small size of the contributing watershed and the fact that the Permittee’s discharge is one of the major sources of total phosphorus to Lake Winona, the Permittee’s Facility has the reasonable potential to cause or contribute to the excess nutrient impairment in the lake. The Permittee’s discharge is not the only major source of total phosphorus to Lake Winona,

14

                                                                                                                                                                                        

                                     

                                                                  

                                                                

                                                                                                                                                                         

                                            

                                                                                                                                                                   

                                                    

                             

                                                            

                                                                                                                                                 

                                                                  

                                                               

                              

 

           

               

             

however. A detailed analysis of all sources of total phosphorus to Lake Winona is covered in the draft Lake Winona TMDL report (AECOM, 2011). The draft TMDL identifies the following as the primary sources for phosphorus in Lake Winona: 1. Internal loading (ie. phosphorus contaminated sediments stirred up by wind/wave turbation and carp action, etc.), 2. Discharges from the Alexandria Lake Area Sanitary District (ALASD) and 3. Stormwater runoff from the city of Alexandria and other surrounding areas. The TMDL states that “[s]ignificant reductions from all three of these sources, on the order of up to 85 percent, are needed in order to correct the nutrient impairment in Lake Winona.” (AECOM 2011, at iv).

Since a site specific standard has not been completed at this date and a WQBEL is required by federal regulations, the MPCA has used the existing state eutrophication standards for shallow lakes in the North Central Hardwood Forest Ecoregion to set effluent limit for phosphorus that the Permittee will be required to meet by March 2022. The Permittee will be required to achieve an effluent concentration of 0.081 mg/L by March 2022. This limit was calculated based on the assumption that internal loading and other sources of total phosphorus will be reduced to levels outlined in the TMDL. If these assumptions are not met in the first term of this permit, the MPCA will need to reevaluate whether compliance with this effluent limit will result in compliance with water quality standards. Whether the limit will need to be revised may turn on whether the Facility Plan submitted will be designed to produce better quality effluent which is typically done to ensure consistency in achieving permit effluent limits. If this is the case, no revision may be necessary.1

Total Phosphorus Compliance Schedule Based on its evaluation of the technology in use at the Facility, the MPCA has concluded that the existing Facility is not capable of meeting the proposed March 2022 WQBEL for total phosphorus (either current standard or projected SSS) upon permit issuance. To achieve the applicable limit as soon as possible, a compliance schedule has been included in the permit. In this permit, the MPCA has established an integrated approach towards making reasonable further progress towards compliance. The first five year permit cycle will focus on work towards phosphorus and chloride reductions in influent and internal loading, gathering information on lake response, completing regulatory processes currently underway that have the potential to change applicable standards and hence facility requirements, and design and

1 Based on historical performance data, a typical wastewater treatment facility tends to produce effluent qualities that are better than permitted effluent limits. Facilities do this by designing treatment facilities that can produce better quality effluents to ensure consistency in achieving permit effluent limits. Currently, ALASD has an effluent phosphorus limit of 0.3 mg/L. In 2010 and 2011, the annual average for effluent phosphorus was 0.190 mg/L and 0.198 mg/L, respectively. It stands to reason that at the proposed effluent limit of 0.081 mg/L, the Facility will be designed to perform better than the permitted effluent limit by a margin that would produce effluent quality that is of significantly better quality than the limit. It is estimated that the Facility will have to operate and discharge near or at the water quality standard for Lake Winona, which is 60 ug/l (0.06 mg/L).

Data from other states suggest that the same principles are applicable in those operating environments.

Facility Limit (mg/L) Performance Limit Type

Syracuse, NY 0.12 <0.10 12 Month Rolling Average

Stamford, NY 0.13 <0.02 Calendar Month Average

15

                                                

                                                                                                        

                                                                                                                                                         

                                                                    

                                                                  

                              

                                                                          

                                                                    

                                   

                                                              

    

                                                              

                                                                                                                                                                                                              

                                                                                           

                                                                    

   

                                                                                                

Facility Plan development by ALASD. The second five year permit cycle will focus on construction and sampling by ALASD to meet the revised effluent limits.

The WQBEL proposed in this permit for total phosphorus (TP) in the year 2022 assumes that internal TP loading will be reduced in Lake Winona on the order of 85 percent by that date (2022). The MPCA recognizes that the Permittee does not control sources of internal loading in Lake Winona. However, in order to achieve water quality standards, it is reasonable to require the Permittee to work with other affected parties to achieve the assumed reduction in internal TP loading. The compliance schedule requires the Permittee to submit a plan describing how the Permittee will participate in actions to reduce internal loading. After the plan is approved by the MPCA, the Permittee will be required to undertake the actions that it has identified. The compliance schedule also requires the Permittee to report to the MPCA regarding the actions that have been taken by any party during the term of this permit to reduce internal loading in Lake Winona and any data associated with that action. This information will enable the MPCA to determine whether any adjustment needs to be made to the 2022 TP WQBEL. The MPCA reserves the right to revise the proposed WQBEL for TP as reasonable and necessary to meet water quality standards based on the results of the internal loading actions.

At least 180 days prior to the end of the term of the permit, ALASD is required to submit a Facility Plan, in accordance with Minn. R. 7077.0272. The purpose of a Facility Plan, which includes a complete discussion of the process, is to study the alternatives that are available (i.e. micro filters, spray irrigation, moving the discharge location, etc.) to meet the future limit, including a financial analysis of each. A final determination for which alternative will be pursued is made at the time the Facility Plan is submitted.

From the time of permit issuance until the final phosphorus effluent limit goes into effect, ALASD will be required to meet an intervention limit of 0.25 mg/L as a calendar month average.

Total Chloride As noted above, in 2010, the MPCA listed Lake Winona as “impaired” on the basis of total chloride concentrations. No TMDL related to the chloride impairment has been drafted at this time.

Total Chloride Compliance Schedule The MPCA has evaluated the existing Facility technology and concluded that the existing Facility is not capable of meeting the WQBEL for total chloride proposed for March 2022 upon permit issuance. As a result, the MPCA has established a compliance schedule in this permit. The goal of the activities required under the schedule is to determine what reduction in chloride inputs can be achieved so that, by the end of the term of the permit, the Permittee can determine what technology, if any, will result in an effluent reduction that results in compliance with the applicable water quality standard (which may be the current standard or a revised standard emerging out of the Triennial standards review rulemaking). The Permittee is required to submit a Facility Plan addressing chloride discharges at the same time as the Facility Plan addressing phosphorus discharges. It is reasonable to require the Facility Plan, that addresses both chloride and phosphorus, to be submitted and implemented at the same time due to the fact that it is likely that the technologies employed to meet the standards will have to be designed together.

Reasonable Potential for Chemical Specific Pollutants (40 CFR § 122.44(d)(1)) Federal regulations at 40 CFR 122.44(d)(1) require that pollutants be evaluated for the potential to exceed water quality standards (“Reasonable Potential”) using acceptable technical procedures accounting for variability in the effluent (coefficient of variation, or CV). The MPCA derives Projected

16

                                                                                                              

                    

                                                                      

                                              

                                                                                                                                   

                                                                    

                                                           

                   

Effluent Quality (PEQ) from effluent monitoring data and compares that data to Preliminary Effluent Limits (PELs) determined from mass balance inputs. Both determinations account for effluent variability. Where PEQ exceeds the PEL, Reasonable Potential to cause or contribute to a water quality standards excursion is indicated. When Reasonable Potential is indicated for a particular pollutant, the permit must contain a water quality‐based effluent limit for that pollutant.

Given that the discharge from the Facility is to a lake (Lake Winona), no 7Q10 low flow of the receiving water can be determined, and thus no dilution is allowed. Each individual water quality standard (WQS) is applied at the point of discharge as a WLA, and in the case of this Facility, permit limitations are calculated from the WLAs.

The discharger has submitted six chronic Whole Effluent Technology (WET) tests batteries, one of which was a repeat test, since 2006. The Facility will continue to operate with an average wet weather (AWW) design flow of 4.7 million gallons per day (MGD) and an average dry weather (ADW) design flow of 3.0 MGD. Given that the design flows will remain unchanged, nondegradation review of the reissued permit is not triggered under Minnesota Rules, Chapter 7050.

A discussion of reasonable potential based on five priority pollutant scans as well as metals data from DMRs and the six WET test batteries is summarized below.

Table 4 contains PELs and PEQs used to make Reasonable Potential determinations for copper, nickel, zinc, and mercury (cadmium, chromium, and lead could not be evaluated because each of these pollutants were present at concentrations below their respective detection level).

17

               

 

     

 

 

 

 

 

  

 

 

 

                   

                 

                 

                   

       

 

         

                                                     

                 

                    

                                                

                   

                                  

     

 

         

     

  

               

 

 

 

 

 

 

 

 

 

   

 

         

                                

                                                                                               

                                                                                                     

                                                           

                            

                                                                

  

                                                             

Table 4. Preliminary Water Quality Based Effluent Limitations

PARAMETER (UG/L) CU‐WER

(UG/L)

NI

(UG/L)

ZN

(UG/L)

HG

(NG/L)

CL

(MG/L)

Plant ADW design flow (mgd) 3.0 3.0 3.0 3.0 3.0

Continuous standard (cs) 111 509 343 6.9 ng/l 230

Maximum standard (ms) 314 4,582 379 2400 ng/l 860

Final acute value (FAV) 629 9,164 758 4900 ng/l 1,720

Waste Load Allocation:

WLAcs

111 509 343 6.9 230

WLAms 314 4,582 379 2400 860

Coefficient Of Variation (CV) 0.496 0.6 0.525 1.00 0.080

Long Term Average: LTA cs 65 269 194 4.6 210

LTAms 118 1,471 136 488 716

WQBEL: Daily Maximum 173 837 379 22.6 252

Monthly Average 107 483 230 10.7 230

Maximum measured effluent

value

34 12 90 8.3 863

Projected effluent quality

(PEQ)

@ n data points

44.2

(25)

31.2

(5)

103.5

(25)

13.3

(20)

949

Reasonable Potential

(PEQ>Dmax/FAV)

No No No No Yes

As shown in the table above no Reasonable Potential was indicated for the metals, but Reasonable Potential was indicated for chloride. The copper WQS includes a water effect ratio (WER=4.8) adjustment factor in the analysis. A WER is a site specific determination of toxicity to live organisms of a substance in site water versus standard laboratory water to determine a ratio applicable to the numeric WQS. The WER was approved in 1993. The chloride limit is based on the daily maximum limit (using the most restrictive standard). Reasonable potential was tripped by the daily maximum limit, but not by the FAV. The daily maximum limit was determined based on the chronic standard of 230 parts per million.

Based on this analysis, the MPCA has determined that it would be appropriate to reduce monitoring for metals, other than mercury, to the frequency specified for the priority pollutant scans.

Monitoring for organic priority pollutants indicated low level detections of di‐ethyl hexyl phthalate on two of three occasions. These detections are believed to be the result of contamination of the samples during the analytical analyses at the lab. No Reasonable Potential for any organic substance could be determined.

Mercury Monitoring: The Reasonable Potential determination concluded above shows no Reasonable Potential to exceed state water quality standards and no need for an effluent limit for mercury for this Facility. The median

18

                                                            

                                                                                     

                                              

        

 

        

  

  

   

      

  

    

                                  

          

                                                                                                                                                                                      

                                             

                    

concentration of mercury in the Facility’s effluent is 1.4 ng/l. Based on this data, the MPCA has determined that twice yearly monitoring of the effluent for mercury be completed using analytical method 1631 and clean‐sampling method 1669 (grab) or their revisions should continue in the reissued permit for the following reasons: 1) widespread fish consumption advisories in Minnesota, including lakes immediately down‐gradient of Lake Winona; 2) the Facility is a major discharger; and 3) monitoring of effluent will be needed to verify point source loadings under the draft mercury Total Maximum Daily Load Study that MPCA published in 2007.

Table 5. Mercury Monitoring

Parameter Limit Unit Limit Type

Effective period

Sample Type

Frequency Notes

Mercury, Monitor ng/l Single May, Sept Grab 2X/Yr EPA method 1631, with Total as Hg only value clean techniques method

1669, and any revisions to those methods.

Chronic Whole Effluent Toxicity (WET) Six chronic WET test batteries have been submitted since 2006, which includes one repeat test. In October 2007, this Facility failed a chronic Ceriodaphnia dubia reproduction test and failed the following repeat chronic Ceriodaphnia dubia reproduction test in December 2007. After the December 2007 repeat test, this Permittee upgraded the treatment system by installing a third aeration tank and three new tertiary filters. Since that time, the WET test batteries (three) have shown no toxicity. Because the last three chronic test batteries have shown no toxicity to any species tested, there is no Reasonable Potential to warrant a WET limit.

In addition to Chronic WET testing, there are special conditions in the draft permit that require the Permittee to monitor for priority pollutants in the Facility’s effluent.

19

           

 

 

Table 6. Proposed Permit Effluent Limits

20

 

   

    

                            

                                                                           

      

                                                        

                          

                                           

                                                  

                                              

Additional Requirements

Biosolids This permit requires biosolids to be treated to meet specific standards and specifies monitoring, recordkeeping, reporting and general requirements for biosolids which 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. § 7041.0800.

Mercury Minimization Plan This permit contains requirements for mercury monitoring and for submittal of a Mercury Minimization Plan (MMP) or updated MMP. These requirements were added in response to the U.S. Environmental Protection Agency’s approval of the Minnesota state‐wide Mercury Total Maximum Daily Load (TMDL) study.

Salty Discharge Requirements Because this Facility has a receiving water stream flow to effluent dilution ration of less than 5:1, or has a salty waste stream from concentrating treatment technologies (e.g. reverse osmosis, ion exchange, membrane filtration, etc.) or food processing industries using density based (saline) sorting processes, the MPCA is requiring that the Facility monitor for salty discharge parameters. Monitoring of Bicarbonates, Calcium, Chloride, Hardness, Magnesium, Potassium, Sodium, Dissolved Solids, Specific

21

                                                            

                                                                                                             

                                                            

          

                                                            

                                                                

                                                                

                                

            

                                                                           

                                            

                                                                                      

                                                            

                                                              

    

                                

                                                                 

 

                                     

                                                              

Conductance, and Sulfate will be sampled once per month from the effluent waste stream (Station SD001). Monitoring data will be recorded on a custom supplemental form provided by the MPCA and the form will be submitted with the DMR.

With the exception of Total Chloride, the Permittee may request a reduction in monitoring if, after two years of data, the monitoring does not indicate a Reasonable Potential to exceed a water quality standard. If monitoring results indicate a Reasonable Potential for any of the parameters, the Permittee will be required to submit an application for permit modification and, if necessary, a compliance schedule will be added to the Permit to ensure progress towards meeting the water quality standards.

Additional Nitrogen Species Monitoring Requirements The draft permit requires additional monitoring for Nitrite plus Nitrate‐Nitrogen and Total Kjeldahl Nitrogen, at a frequency of two times per year for the five‐year term of the permit. Total Dissolved Solids (TDS) is part of this monitoring; however, the Permittee is required to monitor for this analyte as part of the salty discharge monitoring requirements, sampling once per month. The data will be recorded on a custom supplemental form provided by the MPCA and must be submitted with the DMR for the month when the sample is collected. These additional parameters are being added to every permitted municipal facility with an average wet weather design flow of 100,000 gallons per day or greater.

Conditional Exclusion for No Exposure ‐ Industrial Stormwater On April 5, 2010, the Industrial Stormwater General Permit (MNR050000) was issued. 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 addressed stormwater discharges associated with industrial activities at facilities that provide on‐site infiltration of industrial stormwater discharges associated with the facility.

For both industrial and municipal wastewater facilities, in lieu of obtaining coverage under both the General Permit and the individual NPDES permit, the MPCA has added the necessary industrial stormwater requirements language to this permit so that coverage under this NPDES permit alone will cover both permits. Because the Permittee applied for and received “No Exposure” certification, the “No Exposure” language has been added to this permit in Chapter 1, under Special Requirements. There will be no sampling and monitoring required at this time for industrial stormwater. The Permittee is required to submit a request for permit termination if it is currently covered under a general industrial stormwater permit.

Variances The proposed permit does not include any variances to water quality standards. At this time, the Permittee has not requested a variance, but has reserved the right to request a variance as provided under Minn. R. 7050.0190 and other applicable state and federal law upon expiration of the proposed permit.

Total Facility Requirements

All NPDES permits issued in 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 outlined in 40 CFR 122.41. These conditions are listed in the Total Facility Requirements chapter of an

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NPDES permit. These requirements cover a wide range of areas including recordkeeping, sampling, equipment calibration, equipment maintenance, reporting, facility upsets, bypass, solids handling, changes in operation, facility inspections, and permit reissuance.

Nondegradation and Anti‐Backsliding

In accordance with Minnesota Pollution Control Agency rules regarding nondegradation for all waters that are not Outstanding Resource Value Waters (ORVW), nondegradation review is required for any new or expanded significant discharge (Minn. R. 7050.0185). A significant discharge is 1) a new discharge (not in existence before January 1, 1988) that is greater than 200,000 gallons per day to any water other than a Class 7 water or 2) an expanded discharge that expands by greater than 200,000 gallons per day that discharges to any water other than a Class 7 water or 3) a new or expanded discharge containing any toxic pollutant at a mass loading rate likely to increase the concentration of the toxicant in the receiving water by greater than one percent over the baseline quality. The flow rate used to determine significance is the design average wet weather flow. The January 1, 1988 design average wet weather flow for this Facility is 2,987,000 gpd. The proposed permit does not change the design average wet weather flow, and therefore the MPCA has concluded that a nondegradation review is not required.

In accordance with MPCA rules regarding “antibacksliding,” “[a]ny point source discharger of sewage, industrial, or other wastes for which a National Pollutant Discharge Elimination System permit has been issued by the agency that contains effluent limits more stringent than those that would be established by parts 7053.0215 to 7053.0265 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.” Minn. R. 7053.0275. The proposed permit does not change any effluent limits established by the existing permit. Future changes to effluent limits as a result of variance applications or changes in water quality standards will be evaluated under Minn. R. 7053.0275 and applicable federal law.

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