National Pollutant Discharge Elimination System (NPDES ... Sheet - MN0020… · This Fact Sheet has been prepared according to the 40 CFR § 124.8 and 124.56 and Minn R. 7001.0100,

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

Reissuance MN0020141 Permittee: City of Luverne

PO Box 659 Luverne, Minnesota 56156-0659

Facility name: Luverne Wastewater Treatment Facility 400 Redbird Rd

Luverne, Minnesota 56156 Current permit expiration date: August 31, 2019 Public comment period begins: April 1, 2019 Public comment period ends: May 31, 2019 Receiving water: Rock River (Class 2Bg, 3C, 4A, 4B, 5, 6 Water) Permitting contact: Ashley Wahl 504 Fairgrounds Road, Suite 200 Marshall, Minnesota 56258 507-476-4264 [email protected]

mailto:[email protected]

Table of Contents

Page

Purpose and participation ................................................................................................................................................................ ................... 4

Applicable statutes .............................................................................................................................................................................................. 4

Purpose ................................................................................................................................................................................................ .................... 4

Public participation ............................................................................................................................................................................................ 4

Facility description ................................................................................................................................................................ ................................. 5

Background information .................................................................................................................................................................................. 5

Facility location................................................................................................................................................................................................ .... 5

Outfall location ..................................................................................................................................................................................................... 5

Map of permitted facility .................................................................................................................................................................................. 6

Components and treatment technology .................................................................................................................................................... 7

Current information ........................................................................................................................................................................................... 7

Flow schematics ................................................................................................................................................................................................... 8

Changes to facility or operation ................................................................................................................................................................ ... 10

Significant industrial users (SIUs) ............................................................................................................................................................... 10

Recent compliance history ............................................................................................................................................................................. 10

Recent monitoring history ............................................................................................................................................................................. 11

Receiving water(s) ................................................................................................................................................................ ................................ 13

Use classification ............................................................................................................................................................................................... 13

Impairments ................................................................................................................................................................ ........................................ 13

Existing permit effluent limits ......................................................................................................................................................................... 13

Technology based effluent limits (TBELs) ................................................................................................................................................ 13

Water quality based effluent limits (WQBELs) ....................................................................................................................................... 14

Proposed permit effluent limits ...................................................................................................................................................................... 18

Technology based effluent limits ................................................................................................................................................................. 18

Water quality based limits ............................................................................................................................................................................. 18

Reasonable Potential for Chemical Specific Pollutants (40 CFR 122.44 (d) (1)) .................................................................. 18

Priority Pollutants ........................................................................................................................................................................................ 18

Salty Discharge Requirements ................................................................................................................................................................. 18

Mercury ............................................................................................................................................................................................................ 19

Whole Effluent Toxicity .............................................................................................................................................................................. 20

Additional requirements .................................................................................................................................................................................... 20

Total Maximum Daily Load (TMDL) .......................................................................................................................................................... 20

Mercury minimization plan (MMP) ............................................................................................................................................................ 21

Nitrogen monitoring requirements ............................................................................................................................................................ 21

Industrial stormwater ..................................................................................................................................................................................... 21

Biosolids ................................................................................................................................................................................................ ................ 21

Compliance schedules ................................................................................................................................................................ ...................... 22

Special Requirements ................................................................................................................................................................ ....................... 22

Total facility requirements (TFR) ................................................................................................................................................................... 22

Antidegradation ................................................................................................................................................................ .................................. 22

Site specific standard and antibacksliding .................................................................................................................................................. 24

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 4 of 26 Purpose and participation Applicable statutes This Fact Sheet has been prepared according to the 40 CFR § 124.8 and 124.56 and Minn R. 7001.0100, subp. 3, in regards to a draft National Pollutant Discharge Elimination System (NPDES)/State Disposal System (SDS) Permit (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 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. 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 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 day of the public comment period to:

Ashley Wahl Minnesota Pollution Control Agency 504 Fairgrounds Road, Suite 200 Marshall, MN 56258

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 5 of 26 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 Luverne Wastewater Treatment Facility (Facility) is located in the SE ¼ of the NW ¼ of Section 11, Township 102 North, Range 45 West, Luverne Township, Rock County, Minnesota. Outfall location The Facility has a continuous discharge with one outfall Surface Discharge Station (SD002). The location of SD002 is shown on the map below.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 6 of 26 Map of permitted facility

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 7 of 26 Components and treatment technology Current information The existing Class A Facility has continuous discharge (SD002) to the Rock River (Class 2Bg, 3C, 4A, 4B, 5, 6 Water) and is designed to treat an average wet weather (AWW) design flow of 1.5 million gallons per day (mgd) with a five-day carbonaceous biochemical oxygen demand strength of 250 milligrams per liter (mg/L). The influent to the Facility enters the pretreatment building via a 24-inch PVC pipe, which has a maximum capacity of 4.636 mgd. Pretreatment consists of a perforated screen followed by a vortex grit chamber. Screenings are compressed and dewatered by a screw compactor, and grit is dewatered by a dewatering screw. After pretreatment, wastewater flows into the influent pumping station wet well. Flow is then pumped to a splitter box, which splits the flow to each of the two separate biological treatment trains. The oxidation ditch treatment train consists of a primary clarifier, an oxidation ditch, a final clarifier and chlorine disinfection. The trickling filter treatment train consists of a primary clarifier, a trickling filter, a final clarifier and chlorine disinfection. If the influent flow rate exceeds the capacity of the influent pumping station, it overflows to a bypass pumping station which diverts the excess flow to the influent of the oxidation ditch or trickling filter. Following chlorine disinfection, flows from the two treatment trains are combined and dechlorinated prior to being discharged to the Rock River. The flow is discharged to the Rock River by gravity except during high river levels, during which an effluent lift station pumps the flows to the river. Waste biosolids from both primary clarifiers are sent to an anaerobic digester for digestion. The biosolids from the final clarifier downstream of the trickling filter is returned intermittently to the plant influent wet well where it is pumped with the raw wastewater to the influent splitter box and settled in both primary clarifiers. The biosolids from the final clarifier downstream of the oxidation ditch are thickened via a gravity thickener and a dissolved air flotation thickener prior to being sent to the anaerobic digester for digestion with the primary waste biosolids.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 8 of 26 Flow schematics

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 9 of 26

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 10 of 26 Changes to facility or operation The application and plans indicate that the facility will undergo an expansion and improvements project, including the following:

· Construction of a new secondary treatment train including a primary clarifier, oxidation ditch capable of biological phosphorus removal, chemical addition equipment for phosphorus removal, and a final clarifier

· Demolition of the trickling filter treatment train and disinfection basin · Expansion of the current oxidation ditch train disinfection basin to accommodate flows from both

treatment trains Following the completion of the facility expansion and improvements project, the Facility will remain a Class A facility and continue to have a continuous discharge via surface discharge station SD002 to the Rock River. The Facility will be designed to treat an AWW design flow of 2.235 mgd, peak hourly flow of 2.990 mgd, and a five-day carbonaceous biochemical oxygen demand design loading of 3,095 pounds per day (lb/day). The influent to the Facility will enter the pretreatment building via a 24-inch PVC pipe, which will have a maximum capacity of 4.636 mgd. The pretreatment will consist of a perforated screen followed by a vortex grit chamber. Screenings will be compressed and dewatered by a screw compactor, and grit will be dewatered by a dewatering screw. After pretreatment, the wastewater will flow into the influent pumping station wet well. Flow will then be pumped to a splitter box, which will split the flow to each of the two separate biological treatment trains. Both treatment trains will consist of a primary clarifier, an oxidation ditch capable of biological phosphorus removal, chemical addition for phosphorus removal, and a final clarifier. Flows will be combined following secondary treatment and will be routed through a chlorine disinfection basin and dechlorinated prior to discharge to the Rock River. The flow will be discharged to the Rock River by gravity except during high river levels, during which an effluent lift station pumps the flows to the river. Waste biosolids will be collected from both sets of primary and final clarifiers. The waste biosolids from the final clarifiers will be thickened via a gravity thickener, and a dissolved air floatation thickener. The combined biosolids will be digested by an anaerobic digester and sent to a sludge storage tank. The biosolids will be land-applied. Significant industrial users (SIUs) Existing Facility: The Facility currently accepts approximately 90,000 gpd, on average, of wastewater from Gevo, Inc, an isobutanol and ethanol production facility. The average flow is anticipated to potentially increase to 115,000 gpd at some point in the future. Proposed Facility: During the life of this permit, the Facility is planning on accepting an average of 50,000 gpd of wastewater from TruShrimp, a proposed shrimp production facility. This connection is pending the construction and initiation of operation of the proposed TruShrimp facility. The Facility is also planning to accept 200,000 gpd of wastewater from Premium Iowa Pork, a pork processing facility. This connection is also pending the start-up of the Premium Iowa Pork facility that is anticipated to occur in late 2019. The proposed SIUs will be subject to local limits as defined in user agreements between the city of Luverne (City) and the respective SIU. Recent compliance history A compliance review completed as part of this permit reissuance found that the facility is in compliance with the terms and conditions of the current NPDES/SDS permit.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 11 of 26 Recent monitoring history

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 12 of 26 Recent Monitoring History, continued.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 13 of 26 Receiving water(s) Use classification The Facility has a continuous discharge via surface discharge station SD002 to the Rock River. This water is classified as a Class 2Bg, 3C, 4A, 4B, 5, 6 water. 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 that 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. The beneficial use subclass designators "e," "g," and "m" are added to the class 2 designator as specific additional designators. The additional subclass designators do not replace the class 2 designator. All requirements for class 2 stream and river habitats in Minn. R. 7050.0222 and 7052.0100 continue to apply in addition to requirements for class 2Bg stream and river habitats in Minn. R. 7050.0222. These subclass designators are applied to lotic waters only. More information on the classification of waters can be found in Minn. R. 7050.0140. Impairments Table 1. Current impairments to receiving water

Waterbody Assessment Category & Subcategory Pollutants or Impairments Rock River 5B Fecal Coliform, Turbidity and F/M Index of Biotic Integrity

Existing permit effluent limits The limits and monitoring requirements for Station SD002 of the current permit are presented in Table 2 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 TSS, pH, and percent removal limits are technology based effluent limits developed for achieving secondary treatment standards. These limits are specified in 40 CFR § 133.102 and Minn. R. 7053.0215.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 14 of 26 Water quality based effluent limits (WQBELs) The residual chlorine, dissolved oxygen (DO), CBOD5, ammonia-nitrogen, chloride, and specific conductance 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 calendar month geometric mean limit for fecal coliform is a SDR limit based on Minn. R. 7053.0215.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 15 of 26 Table 2. Existing Limits and Monitoring Requirements for SD002

Parameter

Discharge limitations Monitoring requirements Quantity /Loading avg.

Quantity /Loading max.

Quantity /Loading units Quality /Conc. min. Quality /Conc. avg. Quality /Conc. max.

Quality/ Conc. units Frequency Sample type

Effective period

Bicarbonates (HCO3) Monitor only. calendar month maximum

milligrams per liter

once per month

24-Hour Flow Composite

Jan-Dec

BOD, Carbonaceous 05 Day (20 Deg C)

85 calendar month average

170 maximum calendar week average

kilograms per day




3 times per week


Jan-Dec

BOD, Carbonaceous 05 Day (20 Deg C) Percent Removal

85 minimum calendar month average

percent 3 times per week

Calculation Jan-Dec

Calcium, Total (as Ca) Monitor only. calendar month maximum


once per month


Jan-Dec

Chloride, Total 452 calendar month average

608 daily maximum


twice per month


Jan, Mar, May, Jul, Sep, Nov

Chlorine, Total Residual 0.038 daily maximum


once per day

Grab Jan-Dec

Fecal Coliform, MPN or Membrane Filter 44.5C

200 calendar month geometric mean

organisms per 100 milliliter

3 times per week

Grab Apr-Oct

Flow Monitor only. calendar month total

million gallons

Monitor only. calendar month average

Monitor only. calendar month maximum

million gallons per day

once per day

Measurement, Continuous

Jan-Dec

Hardness, Calcium & Magnesium, Calculated (as CaCO3)



once per month


Jan-Dec

Magnesium, Total (as Mg) Monitor only. calendar month maximum


once per month


Jan-Dec

Mercury, Dissolved (as Hg)


nanograms per liter

once per month

Grab May, Sep

Mercury, Total (as Hg) Monitor only. calendar month maximum

nanograms per liter

once per month

Grab May, Sep

Nitrite Plus Nitrate, Total (as N)

Monitor only. calendar month average


once per month


Apr, Sep

Nitrogen, Ammonia, Total 28.3 calendar kilograms 5.0 calendar milligrams per 3 times per 24-Hour Flow Dec-Mar


Parameter





Effective period

(as N) month average

per day month average liter week Composite

Nitrogen, Ammonia, Total (as N)

119.0 calendar month average

kilograms per day



3 times per week


Apr-May



kilograms per day



3 times per week


Jun-Sep



kilograms per day



3 times per week


Oct-Nov

Nitrogen, Kjeldahl, Total Monitor only. calendar month average


once per month


Apr, Sep

Oxygen, Dissolved 5.0 calendar month minimum


once per day

Grab Jan-Dec

pH 6.0 calendar month minimum

9.0 calendar month maximum

standard units once per day

Grab Jan-Dec

Phosphorus, Total (as P) Monitor only. calendar month average


once per week


Jan-Dec

Potassium, Total (as K) Monitor only. calendar month maximum


once per month


Jan-Dec

Sodium, Total (as Na) Monitor only. calendar month maximum


once per month


Jan-Dec

Solids, Total Dissolved (TDS)



once per month


Jan-Dec

Solids, Total Suspended (TSS)



kilograms per day




3 times per week


Jan-Dec

Solids, Total Suspended (TSS) Percent Removal

85 minimum calendar month average

percent 3 times per week

Calculation Jan-Dec

Solids, Total Suspended (TSS), grab (Mercury)



once per month

Grab May, Sep

Specific Conductance 2194 calendar 2571 daily micromhos per twice per 24-Hour Flow Jan, Mar,


Parameter





Effective period

month average maximum cm month Composite May, Jul, Sep, Nov

Sulfate, Total (as SO4) Monitor only. calendar month maximum


once per month


Jan-Dec

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 18 of 26 Proposed permit effluent limits The proposed limits and monitoring requirements for Station SD002 can be found in the Limits and Monitoring table of the draft permit document. Applicable WQBEL, TBEL, and SDR limits are explained below. Technology based effluent limits 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 § 133.102 and Minn. R. 7053.0215. The maximum calendar week averages for CBOD5 were incorrectly listed as 30 mg/L and 170 kg/day in the previously issued permit. Per 40 CFR 122.45, 40 CRF 133.101, Minn. R. 7001.1080, and Minn R. 7053.0215 subp.1, 2, 3, calendar week averages must be calculated at 1.5 times the calendar month average. Therefore, the limits for the limits in the draft permit have been revised to 25 mg/L and 142 kg/day. Please refer to the Limits and Monitoring section of the draft permit for a complete listing of the required limits and monitoring. Water quality based limits The residual chlorine, DO, CBOD5, ammonia-nitrogen, chloride, and specific conductance 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. Reasonable Potential for Chemical Specific Pollutants (40 CFR 122.44 (d) (1)) The discharge is located on the Rock River. The discharger is proposing to expand to a 1.44 mgd average dry weather design flow and an AWW design flow of 2.24 mgd. The dry weather design flow is used to calculate water quality-based effluent limits under critical low flow stream conditions. The low flow condition is defined by the once in ten year weekly average low flow (7Q10), which is determined to be 1.0 mgd at the Facility. The analysis below is based on data submitted to date. 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 contribute to an excursion of an applicable water quality standard. Projected effluent quality (PEQ) derived from effluent monitoring data is compared to Preliminary Effluent Limits (PELs) determined from mass balance inputs. Both determinations account for effluent variability. Where PEQ exceeds the PEL, there is reasonable potential to cause or contribute to a water quality standards excursion. When Reasonable Potential is indicated the permit must contain a WQBEL for that pollutant. Priority Pollutants The priority pollutant scan information of the effluent was evaluated using reasonable potential procedures. All of the organic priority pollutants were below the level of detection. Since these pollutants were at low enough levels not to be detected, reasonable potential to cause or contribute to a water quality standards excursion is not indicated. Metals (copper, iron, zinc, arsenic and selenium) were detectable but effluent levels are just above the level of detection and well below any water quality standards. At the given flows neither pollutants would indicate reasonable potential to cause or contribute to an excursion of a water quality standard in the receiving water. Therefore, no limit is needed in either case. The draft permit requires the submittal of three priority pollutant scans in the life of the permit. Salty Discharge Requirements At full expanded design capacity, the controlling “salty” effluent limitation for the Facility will be the 3451 kg/day monthly average chloride limit. Meeting this chloride mass based limit at the expanded 2.24 mgd AWW design flow rate, represents an effective reduction in chloride concentrations of approximately 31%.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 19 of 26 The reductions in chloride concentrations by 31% will also reduce specific conductance levels by approximately the same degree (~30%) at expanded full design capacity. The future reduction in specific conductance associated with compliance with the chloride limit, obviates the need for any additional salty effluent limitations for the Facility. Mercury Monitoring results of the effluent include 10 data points at a calculated CV of .44. PEQ is derived as an upper bound value from the highest value measured (5.5 nanograms per liter (ng/l)), and the determined variability (CV = .44) and number of data points (10). The PEL calculation assumes that the background mercury concentration is at the water quality standard (6.9 ng/l) when the listed stream impairment is for fish consumption advice, and no local river water column analytical data exist. To assure that the discharge does not cause or contribute to a water quality standards excursion for mercury impaired waters, the numeric water quality standard (6.9) is applied at the point of discharge for the mass balance equation for the subsequent preliminary effluent limit calculations. Where PEQ exceeds the PEL, there is reasonable potential to cause or contribute to a water quality standards excursion. Since PEQ does not exceed the PEL in this case, reasonable potential to cause or contribute to an excursion above water quality standards is not indicated. A WQBEL is not needed. The Table 3 contains the inputs to the reasonable potential analysis for mercury. These pollutants were evaluated on the basis of analytical measurements that made evident the need for a full determination. Where PEQs exceed PELs, a WQBEL is needed. Table 3. Inputs mercury reasonable potential analysis

PARAMETER HG (ng/l)

Maximum measured effluent value 5.5 Projected effluent quality (PEQ) @ n data points

8.42 (10)

Plant design flow (mgd) 1.44 Receiving water design flow (mgd) .97 Background concentration 6.9* Continuous standard (cs) @147 Hd 6.9 Maximum standard (ms) @ 147 Hd 2400 Final acute value (FAV) @ 250 Hd 4900 Mass Balance - cs 6.9 Mass Balance - ms 4011 Coefficient Of Variation (CV) .44 Long Term Average: LTA cs 5.73 LTAms 1629 Preliminary Effluent Limit (PEL): Daily Maximum

14.1

Monthly Average 9.07 Reasonable Potential PEQ>PEL (Dmax/FAV) No

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 20 of 26 Whole Effluent Toxicity Chronic Toxicity Requirements This permit does not include a chronic whole effluent toxicity limit; however the facility has a whole effluent toxicity testing monitoring requirement and is required to conduct chronic toxicity tests for Surface Discharge Station SD002. Results of chronic toxicity tests will be evaluated against a monitoring threshold value of 1.7 chronic toxic units (TUc). The Permittee is required to submit semi-annual chronic toxicity test battery results following the initiation of operation of the expanded facility. This requirement is listed as Phase 3 in the permit. Phase 3 will become effective upon initiation of operation of the expanded facility and will continue to be in effect until the permit is reissued. Additional information on the required toxicity testing can be found in the Chronic Toxicity Requirements section of the draft permit. State discharge restrictions (SDRs) The 200 #100mL calendar month geometric mean limit for Fecal Coliform is a SDR limit based on Minn. R. 7053.0215 Subp. 1. The 1.0 mg/L phosphorus limit is an SDR based on Minn. R. 7053.0255 Subp. 3. Additional requirements Total Maximum Daily Load (TMDL) On April 23, 2008, the Fecal Coliform and Turbidity TMDL Assessment for the Rock River Watershed was approved by the U.S. Environmental Protection Agency. The TMDL includes waste load allocations (WLAs) for both fecal coliform and TSS. The fecal coliform WLA was based on the existing AWW design flow of 1.50 mgd and will need to be increased according to the proposed AWW design flow of 2.24 mgd. Because of the proposed change in discharge from this facility to the receiving water, an expansion to the TMDL’s WLA for fecal coliform is necessary. Fecal Coliform The fecal coliform WLA was calculated correctly in the TMDL; however, the City is planning on expanding the Facility’s AWW design flow from 1.5 mgd to 2.24 mgd. The WLA is calculated by multiplying the AWW design flow for continuously discharging wastewater treatment plants (WWTPs), or the maximum permitted discharge rate for controlled discharge pond facilities, by the 126 organisms per 100 ml water quality standard. The Facility’s fecal coliform effluent limit is intended to ensure complete effluent disinfections; therefore, as long as the Facility’s discharge is at or below this permit limit, the discharge will not contribute to violations of the water quality standard regardless of their fecal coliform load. An analysis of the effects of expanded WLA, prepared by Tetratech for the Zumbro River Turbidity TMDL (Cleland 2011), demonstrates that current discharges can be expanded and new NPDES discharges can be added while maintaining water quality standards; provided the permitted NPDES/SDS effluent concentrations remain at or below the in-stream concentration targets. This NPDES/SDS Permit authorizes the expansion of the WLA for the Facility. Expansion of the WLA will not contribute to the E. coli impairment in Rock River Watershed because the NPDES/SDS Permit’s fecal coliform permitted discharge limit of 200 organisms per 100 ml is consistent with the water quality standard. As mentioned above, the existing AWW design flow is 1.5 mgd which is equivalent to 2.3208 cubic feet per second (cfs). The proposed AWW design flow is 2.24 mgd, which is 3.4657 cfs. This is a flow increase of 0.74 mgd or 1.1449 cfs. This means an increase of 1.1449 cfs of flow from the Facility to the Rock River, which in turn expands the fecal coliform loading capacity by 0.168 t-org/month. The discharge will not result in a decrease in the Rock River water quality because fecal coliform bacteria loading capacity will increase as a result of the increased stream flow resulting from the discharge.


Mercury minimization plan (MMP) The draft permit contains requirements for mercury monitoring and for submittal of 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 an updated MMP within 180 days 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 (https://www.pca.state.mn.us/water/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 influent effluent nitrogen monitoring has been added to the permit. This monitoring has been added in accordance with Minn. Stat. § 115.03. Refer to the Limits and Monitoring section of the draft permit for the specific influent and effluent monitoring and frequency. 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 on-site 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 added the necessary industrial stormwater requirements language and limits and monitoring to this permit so that coverage under this NPDES permit alone will cover both permits. This Facility has applied for and obtained a Certification of No Exposures; therefore, this permit includes language regarding the No Exposure exclusion. Biosolids This draft permit authorizes the Permittee to store and land apply domestic wastewater treatment biosolids in accordance with the provisions in this draft permit and Minn. R. ch. 7041. 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. 7041.0800.

Approved Wasteload

Allocation Flow

Increase Fecal Coliform Load

Increase Modified Wasteload

Allocation Luverne WWTP WLA Expansion 0.341 t-org/mon 1.1449 cfs 0.168 t-org/mon 0.509 t-org/mon Rock River (AUID 10170207) Loading Capacity

Expansion 1.1449 cfs 0.168 t-org/mon

https://www.pca.state.mn.us/water/nutrient-reduction-strategy

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 22 of 26 The Land Application of Wastewater Annual Report is due annually, by December 31 of each year, following permit reissuance. Compliance schedules This permit contains a compliance schedule for the total phosphorus limit of 1.0 mg/L. The permittee is required to attain compliance as soon as possible but no later than 90 days after the initiation of operation of the expanded Facility. This limit is contained in the Limits and Monitoring section of the draft permit as a Phase 2 limit. Prior to this limit becoming effective (Phase 1), the permittee must monitor effluent phosphorus weekly. Special Requirements Development of a Site Specific Standard for Specific Conductance The MPCA has calculated the effluent limit for specific conductance for this Facility based on the existing state standard under Minn. R. 7050.0224, subp. 2. In order to meet this standard, the Permittee is required to meet a specific conductance effluent limitation of 2,194 micromhos per cm as a calendar month average limit and 2,571 micromhos per cm as a daily maximum limit. The MPCA believes that a site specific specific conductance water quality standard is appropriate and has initiated development of but has not yet promulgated a proposed standard. If the U.S. EPA approves a new site specific standard for specific conductance within the term of this permit and the City submits an application requesting a permit modification, MPCA shall modify the permit in a manner consistent with state and federal law to (1) establish a new effluent limit for specific conductance based on the site-specific standard or other relevant information confirming that a higher level of specific conductance will protect downstream uses; and/or (2) render a determination that there is no reasonable potential to exceed the standard and thus remove the specific conductance limit from the 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 § 122.41, Minn. R. 7001.0150, and 7001.1090. 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 Minnesota antidegradation rules (Minn. R. 7050.0250 to .0335) require permittees to complete antidegradation procedures when wastewater permits will result in net increases in loading or other causes of degradation. The City is proposing to expand their permitted wastewater treatment plant discharge volume. The City has agreed to accept mass cap limits for a series of parameters that freeze authorized loads of some pollutants. Table 4 summarizes pollutant parameters and limits, including the frozen authorized load mass caps. Mass cap limits provide both direct control of specific pollutants, and they can also function as surrogate caps for other pollutants. Because the facility has agreed to accept mass caps, this permit will not result in a net increase in loading; and therefore, antidegradation procedures are not required including an antidegradation assessment or preliminary determination.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 23 of 26 Table 4: Current limits, proposed limits and optional mass cap limits to ensure no increase in loading.

Current Limits Proposed Limits Antidegradation

status Parameter Period Units Concentration Mass Concentration Mass

kg/day kg/day Avg Wet

Weather Flow Daily, MGD 1.5 2.24 NA

Avg Dry Weather Flow Daily, MGD 0.97 1.44 NA

TSS Monthly Average mg/L 30 170 30 170 Cap

cBOD5 Monthly Average mg/L 15 85 15 85 Cap Fecal Coliform Apr-Oct orgs/100ml 200 200 NA

Ammonia Jun 1 - Sep 30, Monthly Average mg/L 2.9 16.4 2.9 16.4 Cap

Ammonia Oct 1 - Nov 30, Monthly Average mg/L 17.0 96.3 17.0 96.3 Cap



pH 6.0-9.0 6.0-9.0 NA

DO Monthly, Minimum mg/L 5.0 5.0 NA

Residual Chlorine Daily Max mg/L 0.038 0.038 NA

Total Phosphorus mg/L 1.0 Reduced

Chloride Calendar Mo. Avg. mg/L 452 452 Capd Chloride Daily Max mg/L 608 608 3451a Cap Specific

Conductance Calendar Mo. Avg. Umhos/cm 2194 2194 Surrogate Capb

Specific Conductance Daily Max Umhos/cm 2571 2571 Surrogate Capb

Mercury Surrogate Capc

a kg/day mass unit b Specific conductance and other salts are closely linked to chloride levels. Control of chloride will ensure maintenance of specific conductance and other salts.

c The discharger does not have reasonable potential for mercury; and therefore, a water quality based effluent limit is not needed at this time. Levels of mercury will be capped or reduced through implementation of the capped TSS limit and new 1.0 mg/L total phosphorus limit. d Monthly average chloride levels are capped through the 3451 kg/day daily maximum mass cap limit.

NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 24 of 26 The existing facility does not have the reasonable potential to cause or contribute to an excursion of the mercury water quality standard. Therefore, the proposed facility is not required to receive a mercury limit. In addition, there are several limits that also serve to control for mercury. The TSS mass cap functions as a surrogate mass cap that will prevent future increases in loading. Mercury binds to sediment, so control of sediment also controls metals like mercury. Similarly, the new 1.0 mg/L total phosphorus limit provides additional control of sediment and mercury. Phosphorus, like mercury, easily binds to sediments. Control of phosphorus will, in part, be achieved by better control of sediments, which in turn, will further reduce mercury. The City has agreed to accept a mass cap for chloride. Chloride is closely associated with other Class 3 and 4 parameters, including specific conductance, through its primary source, ion exchange water softening. A review of statewide data demonstrates that WWTPs with high chloride are 30 times more likely to have high TDS1, which is strongly correlated to specific conductance. Effluent chloride concentrations are often high in communities with very hard drinking water. A lot of salt (e.g. NaCl) is needed to sufficiently reduce hardness with ion exchange softeners, which are common in both homes and businesses. Recently the City connected to the Lewis and Clark Regional Water system which draws from the Missouri River. The Missouri River water is much softer than local groundwater, which is very hard; and therefore, less salt is required to remove hardness. The shift in source water has reduced a salt demand for softening and is broadly contributing to the attainment of existing chloride and specific conductance limits. Maintenance of chloride at or below 3,451 kg/day will also ensure specific conductance cannot exceed historic levels. A future adjustment to the specific conductance limitation that results from application of a site-specific standard or other relevant information is permissible and consistent with this antidegradation review so long as the chloride load cap is not amended. Site specific standard and antibacksliding During the course of the upcoming permit, the City and the MPCA will explore development of a site specific standard (SSS) for Class 3 and 4a water quality standards. If developed and approved, reasonable potential for specific conductance and other Class 3 and 4 salty parameters will be re-evaluated on the basis of the revised standard. Reasonable potential (RP) is the water quality based effluent limit evaluation process required by federal law (40 CFR 122.44(d)). This could result in a less restrictive effluent limit or even the possibility that the permit will no longer have RP to cause or contribute to the exceedance of specific conductance or other Class 3 and 4 salty water quality standards. State and federal law prohibit the establishment of less restrictive effluent limits unless specific criteria are met2. The following discussion explains how backsliding criteria in both state and federal law are satisfied if the specific conductance effluent limit becomes less restrictive or is removed based on the adoption of a SSS. Federal Law Material and substantial alteration - Title 33 USC 1342(o)(2)(A) A permit may be modified to contain a less stringent effluent limitation if:

(A) material and substantial alterations or additions to the permitted facility occurred after permit issuance which justify the application of a less stringent effluent limitation;

The proposed new WWTP and the recent shift to a new drinking water source are material and substantial alterations or additions to the permitted facility that occurred after the issuance of the permit that included the specific conductance effluent limit. The purpose for the shift in drinking water source was to ensure a more reliable supply volume and higher quality water. Prior to the connection, the City had experienced unreliable volume because of their dependence on

1 MPCA. 2017. Chloride Work Group Policy Proposal for Minnesota. https://www.pca.state.mn.us/sites/default/files/wq-wwprm2-24.pdf pages 8, 9 2 Minn. R. 7053.0275 subp. 2; 33 U.S.C. 1342(o) and 40 CFR 122.44(l)(2)(i).

https://www.pca.state.mn.us/sites/default/files/wq-wwprm2-24.pdf


NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 25 of 26 shallow wells (about 30 feet deep) which were susceptible to drought and contamination. In the previous permit, the City received a chloride and specific conductance limit. It is not feasible to treat wastewater effluent explicitly for salts3. Source reduction and alternative softening is needed to manage salts. Switching to Lewis and Clark, the Missouri River water provides a much softer water source that requires less chloride to remove hardness. Together, the reduced demand for chloride, and reduction in source water hardness should achieve sustained attainment of chloride and specific conductance limits. If a Class 3 and 4 SSS is developed, it is possible that the City will no longer have RP for specific conductance, and the limit would likely be removed. Nonetheless, sustained attainment of the chloride mass cap limit will ensure a broad range of salty parameters are managed below historic levels, and the resulting effluent quality will support designated uses for both aquatic life and irrigation. In addition to the change in drinking water source, the permittee is undertaking a substantial rebuild of the entire WWTP which will result in better quality effluent. The MPCA will consider the resulting water quality effluent in implementing a SSS. New Information - Title 33 USC 1342(o)(2)(b)(i)

(i) information is available which was not available at the time of permit issuance (other than revised regulations, guidance, or test methods) and which would have justified the application of a less stringent effluent limitation at the time of permit issuance; or

As the bold text in the following rule language states, water quality standards for Class 4A waters require: 1) the use of the listed numeric standards used as a guide, 2) together with recommendations in “Handbook 60” and any revisions, amendments, or supplements to it (such as other soil and salinity related data), 3) to protect crops usually grown in the waters or area.

Minn. R. 7050.0224. Subp. 2. Class 4A waters. The quality of class 4A waters of the state shall be such as to permit their use for irrigation without significant damage or adverse effects upon any crops or vegetation usually grown in the waters or area, including truck garden crops. The following standards shall be used as a guide in determining the suitability of the waters for such uses, together with the recommendations contained in Handbook 60 published by the Salinity Laboratory of the United States Department of Agriculture, and any revisions, amendments, or supplements to it:

Minnesota Class 4a water quality standards directs the limit reviewer to consult Handbook 60 US Department of Agriculture Salinity guidance and other related research together with the listed numeric standards. The standards also require consideration of crops usually grown in the area. Neither of these were considered. Handbook 60 was originally published in 1954. The modern revisions, amendments, and supplements to USDA’s Handbook 60 constitute an enormous body of research, data, and tools. Many of these new data sources are now geo-referenced including high resolution crop, soils and hydrology data that allow for a more meaningful analysis of irrigation water. The previous effluent limit considered only the listed numeric standard but did not consider crops usually grown or use additional research on soil, hydrology, or salinity. A SSS and subsequent RP analysis will take these factors into consideration using information that was not previously available to the MPCA, such as crops usually grown in the area and information recommended by Handbook 60 (e.g., soil, hydrology, and salinity data). Therefore, if, through consideration of new information related to these required factors, the facility no longer has reasonable potential or a less restrictive limit is justified, the new information will satisfy a federal antibacksliding exemption.

3 MPCA. 2018. Alternatives for addressing chloride in wastewater effluent. https://www.pca.state.mn.us/sites/default/files/wq-wwprm2-18.pdf


NPDES/SDS Permit Program Fact Sheet MN0020141 Reissuance Page 26 of 26 State Law Minn. R. 7053.0275 State rules prohibit the issuance of permits with less restrictive effluent limits unless the permittee establishes that less stringent effluent limits are allowable pursuant to federal law, under Clean Water Act, United States Code, title 33, section 1342. The discussion above provides information satisfying federal antibacksliding exceptions are satisfied if a SSS is adopted.

Documents

National Pollutant Discharge Elimination System (NPDES ... Sheet - MN0020… · This Fact Sheet has been prepared according to the 40 CFR § 124.8 and 124.56 and Minn R. 7001.0100,