National Pollutant Discharge Elimination System · NPDES permit for the discharge of pollutants...

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Permittee: Duke Energy Indiana, LLC 1000 East Main Street Plainfield, Indiana 46168

Existing Permit Information:

Permit Number: IN0002763

Expiration Date: February 28, 2018

Facility Contact: Mr. Tom Knapke, Environmental Coordinator

765-492-7727

Facility Location: Cayuga Generating Station 3300 State Road 63 Cayuga, Indiana 47982 Vermillion County

Receiving Stream: Wabash River

GLI/Non-GLI: Non-GLI

Proposed Permit Action: Permit Renewal

Date Application Received: August 25, 2017

Source Category NPDES Major – Industrial

Permit Writer: Brad Gavin, Environmental Engineer I

317-234-4155 or [email protected]

National Pollutant Discharge Elimination System

Fact Sheet for

DUKE ENERGY INDIANA, LLC CAYUGA GENERATING STATION

Draft May 2018

Indiana Department of Environmental Management

100 North Senate Avenue Indianapolis, Indiana 46204

(317) 232-8603 Toll Free (800) 451-6027

www.idem.IN.gov

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Table of Contents

1.0 Introduction ......................................................................................................................... 3 2.0 Facility Description ............................................................................................................. 3

2.1 General ............................................................................................................................3 2.2 Outfall Locations ..............................................................................................................4 2.3 Outfall Description and Wastewater Treatment ...............................................................6 2.4 Changes in Operation .................................................................................................... 12 2.5 Facility Storm Water ...................................................................................................... 12 2.6 Effluent Characterization ............................................................................................... 13

3.0 Permit History .................................................................................................................... 18 3.1 Compliance History ....................................................................................................... 18

4.0 Receiving Water and Use Designations .......................................................................... 18 4.1 Receiving Stream Water Quality .................................................................................... 19

5.0 Permit Limitations ............................................................................................................. 19 5.1 Technology-Based Effluent Limits (TBELs) ................................................................... 19 5.2 Water Quality-Based Effluent Limits (WQBELs) ............................................................ 20 5.3 Effluent Limitations and Monitoring Requirements ........................................................ 20 5.4 Whole Effluent Toxicity (WET) Testing .......................................................................... 45 5.5 Antibacksliding ............................................................................................................... 46 5.6 Antidegradation ............................................................................................................. 46 5.7 Storm Water .................................................................................................................. 47 5.8 Water Treatment Additives ............................................................................................ 49

6.0 Permit Draft Discussion .................................................................................................... 51 6.1 Effluent Limitations, Monitoring Conditions and Rationale ............................................. 51 6.2 Schedule of Compliance ................................................................................................ 58 6.3 Special Conditions and Other Permit Requirements ..................................................... 59 6.4 Spill Response and Reporting Requirement .................................................................. 69 6.5 Permit Processing/Public Comment .............................................................................. 69

Appendix A-Wasteload Allocation Report WLA002329 ............................................................. 70

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1.0 Introduction

The Indiana Department of Environmental Management (IDEM) received a National Pollutant Discharge Elimination System (NPDES) Permit application from Duke Energy Indiana, LLC on August 25, 2017. The current five year permit was issued with an effective date of March 1, 2013 and an expiration date of February 28, 2018. The permit was subsequently modified on October 11, 2013. Since the facility filed a timely renewal application, the permit is considered to be administratively extended in accordance with 327 IAC 5-2-6(b). A five year permit is proposed in accordance with 327 IAC 5-2-6(a). The Federal Water Pollution Control Act (more commonly known as the Clean Water Act), as amended, (Title 33 of the United States Code (U.S.C.) Section 1251 et seq.), requires an NPDES permit for the discharge of pollutants into surface waters. Furthermore, Indiana laws requires a permit to control or limit the discharge of any contaminants into state waters or into a publicly owned treatment works. This proposed permit action by IDEM complies with and implements these federal and state requirements. In accordance with Indiana Administrative Code (IAC) 327 Article 5-3-8, as well as Title 40 of the Code of Federal Regulations (CFR) Sections 124.8 and 124.56, development of a Fact Sheet is required for certain NPDES permits. This permit does require a Fact Sheet. This document fulfills the requirements established in those regulations. This Fact Sheet was prepared to explain the derivation of the terms and conditions in the permit and the reasons for them.

2.0 Facility Description

2.1 General The current NPDES permit was issued to Duke Energy Indiana, Inc.; however, effective January 1, 2016, Duke Energy converted its corporation, Duke Energy Indiana, Inc., to a limited liability company, Duke Energy Indiana, LLC. This renewed permit will be issued to Duke Energy Indiana, LLC. Duke Energy Indiana, LLC, Cayuga Generating Station consists of two coal-fired units (Units 1 and 2) that generate 1,075 MW of electricity. In addition to providing electricity, the plant provides steam to the neighboring International Paper Company plant. The primary Standard Industrial Classification (SIC) code applicable to the Cayuga Generating Station is 4911, Electric Services. The majority of the water used at the facility is taken directly from the Wabash River. The facility does use a small amount of potable water obtained from the Town of Cayuga. A map showing the location of the facility has been included as Figure 1.

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Figure 1: Facility Location

The facility location is: Cayuga Generating Station

3300 State Road 63 Cayuga, Indiana 47982 Vermillion County

2.2 Outfall Locations The location of the Outfalls at the facility are listed in the below table. The coordinates for Outfalls 001, 003, and 004 in the below table are different than the coordinates listed in the current permit. These outfall points have not been moved, instead the revised coordinates more accurately represent the actual location of those outfalls.

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A map showing the location of these outfalls (and seeps which have been identified by the permittee) is included below as Figure 2.

Outfall Latitude Longitude Decimal Degrees Receiving Water 001 39° 55' 06" -87° 24' 50" 39.9182, -87.4140 Wabash River 002 39° 54' 50" -87° 24' 42" 39.9139, -87.4117 Wabash River 003 39° 55' 33" -87° 25' 28" 39.9258, -87.4244 Wabash River

004 39° 55' 34" -87° 25' 46" 39.9261, -87.4294 Unnamed tributary of the Wabash River

101 39° 55' 18" -87° 25' 42" 39.9217, -87.4283 Outfall 001 Discharge Canal 102 39° 55' 20" -87° 25' 37" 39.9222, -87.4269 Outfall 002 Discharge Canal

Figure 2. Map showing location of Outfalls

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2.3 Outfall Description and Wastewater Treatment The facility has been making changes to its treatment system and to reflect these changes submitted two flow diagrams with its NPDES renewal application. The first of these reflected the processes as of the date that the application was submitted in August 2017, and the second represents the processes that will exist in 2018. Most of the changes have already been implemented. These two flow diagrams and a description of each outfall is included below.

Outfall 001 The discharge from Outfall 001 includes condenser cooling water; cooling water from turbine oil coolers, bearing cooling, heat exchangers and hydrogen coolers; intermittent discharges of cooling water from auxiliary once through cooling towers; and treated flue gas desulfurization (FGD) wastewater from Outfall 101 (see below). The long term average flow is 558 MGD (from the permittee’s renewal application Form 2-C), and the highest monthly average flow over the past two years is 807.5 MGD (from DMR data). Formerly, storm water from the on-site substation was discharged through this outfall after treatment in an oil water separator. However, the overflow from this separator has been routed to a newly installed sump and pumping system and then to the main oil water separator on the site, which then flows to the central lift station and to the new retention basins that discharge through Outfall 002.

Internal Outfall 101 - Treated Flue Gas Desulfurization (FGD) Wastewater Sulfur dioxide is removed from the combustion exhaust gas (flue gas) using wet scrubbing with a limestone slurry. This flue gas desulfurization (FGD) wastewater is sometimes used in the dry ash fixation process and mixed with gypsum, fly ash, and quick lime with the resulting material being sent to the on-site FGD gypsum landfill. The flue gas desulfurization (FGD) wastewater not used in the dry ash fixation process is treated using chemical precipitation prior to discharge through Outfall 001 via Outfall 101. The sludge from this treatment process is either beneficially reused for on-site structural fill as part of the Ash Pond closure or sent to the on-site gypsum landfill. The long term average flow is 0.126 MGD (from the permittee’s renewal application Form 2-C), and the highest monthly average flow over the past two years is 0.177 MGD (from DMR data). The permittee is evaluating alternate treatment options for this wastestream to comply with the new requirements established in the November 2015 U.S. EPA Effluent Guidelines and Standards for the Steam Electric Power Generating Point Source category. Figure 3 and 4. Water Balance Diagrams

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Outfall 002 The permittee recently completed construction of a new wastewater treatment system for the wastewaters contributing to Outfall 002. The treatment system consists of a lined primary retention pond, a lined holding retention pond, a secondary retention basin (also called the process lined water treatment pond), and a finishing pond (also referred to as the new lined outfall basin). In general, the primary retention basin will receive flow from all process and storm water from the facility. The holding retention basin receives coal yard diversion water (storm water from around the coal pile). Each of these basins flow into the secondary retention basin, which then flows into the south lined ditch to the finishing pond/new lined outfall basin. The finishing pond discharges to the Wabash River through Outfall 002. See Figure 5 for a diagram of the new lined primary retention pond, lined holding retention pond, and secondary retention basin (also called the process lined water treatment pond). More specifically, wastewater from demineralizer water treatment, coal yard sumps, station drains, plant site storm water (with the ability to add polymer to these wastestreams), and treated sanitary wastewater (Outfall 102) are discharged to the new lined primary retention basin. Bottom ash sluice water (also known as bottom ash transport water) is also currently discharged to this basin (the permittee is changing its processes to eliminate this wastewater to comply with new requirements established in the November 2015 U.S. EPA Effluent Guidelines and Standards for the Steam Electric Power Generating Point Source category. Although complete elimination of wastewater from this process is not required until December 31, 2021, the conversion of bottom ash handling to a closed loop system should be complete and the system operational in March or April 2018). Coal yard diversion water (storm water from around the coal pile) and non-chemical boiler and air heater wash (intermittent) is discharged to the holding retention basin. The permittee has the capability to add caustic to this holding retention basin and there is the capability to add polymer to the discharge from the basin. Both the new lined primary retention basin and the holding retention basin discharge to the new lined secondary retention basin. Leachate from the FGD Gypsum Landfill also discharges to the new lined secondary retention basin. The secondary retention basin discharges to the south lined ditch. Storm water from the capped ash pond area will also discharge to this south lined ditch. Acid can be added to the wastewater in this ditch to adjust the pH. The south lined ditch discharges to the new lined outfall basin. Storm water from the FGD Gypsum Landfill, the FGD site and the closed and capped ash pond area will also discharge into this basin. Some of the ash pond area has been capped, some is in the process of being capped, and capping for some of the areas has not yet started. In the past, metal cleaning wastes were sent to this outfall; however, this was discontinued. Currently, metal cleaning wastes will either go into the dry ash fixation product or be hauled off-site for disposal. Also, fly ash transport water used to contribute to this Outfall. The permittee has converted to a dry system for its fly ash; although, under the applicable federal regulations and this permit, the permittee is not required to achieve zero discharge from this process until November 1, 2018. Further, the intermittent wastestream, wet vacuum truck coal combustion residuals, which formerly discharged to this outfall will now be transported to the fixation pad, mixed with material, and then hauled to the approved landfill. This change was made to comply with the federal CCR regulations.

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Formerly, all of these wastestreams were sent to the ash pond system for treatment prior to discharge through Outfall 002; however, these ash ponds are being closed pursuant to the new requirements established in the April 2015 U.S. EPA Hazardous and Solid Waste Management System; Disposal of Coal Combustion Residuals from Electric Utilities (the “CCR Rule”). The IDEM Office of Land Quality is responsible for implementing these federal coal combustion residuals (CCR) regulations. As of February 23, 2018, the transfer of the wastestreams from the ash pond system to the new wastewater treatment system had not yet occurred. As of this date, the transfer of the wastewater to the new wastewater treatment system is tentatively scheduled for late March 2018. (Under the CCR Rule, the permittee is required to stop sending wastewater to their existing ash ponds by April 17, 2018.) The long term average flow is 4.6 MGD (from the permittee’s renewal application Form 2-C), and the highest monthly average flow over the past two years is 7.17 MGD (from DMR data). Also, on March 8, 2018, the permittee informed IDEM that flow from a groundwater seep was impacting the liner of the new finishing pond. The permittee is redirecting this seep so that it will be discharged into the finishing pond. It would be contributing a flow of approximately 7,500 gpd into the finishing pond and the permittee anticipated that this flow would be reduced or perhaps eliminated when dewatering of the adjacent ash pond was completed (completion of dewatering is tentatively scheduled for May or June 2018).

Internal Outfall 102-Treated Sanitary Wastewater This internal outfall consists of treated sanitary wastewater and discharges to the new lined primary retention basin, which ultimately discharges to the Wabash River through Outfall 002. The sanitary wastewater enters the wastewater treatment package plant by passing through a comminutor and/or bar screen for gross solids removal. This step provides for the mechanical reduction of solids prior to aeration. Once the wastewater has entered the aeration chamber, the untreated flow is mixed with an active biomass in a rolling action that takes place the length and width of the chamber in a slow forward progression. This rolling mixing action is the result of air originating from air diffusers located along one side of the bottom of the tank. This insures that adequate mixing is maintained in the tank. The chambers are filleted on each side along the bottom to assure and enhance the rolling motion of the water and to eliminate any “dead zones” in the tank. After aeration, the wastewater flows to the clarifier that typically has a hopper bottom configuration. The wastewater clarifiers are sized to provide the required retention time based on an average twenty-four hour design flow. During the settling period, solids settle on the bottom of the clarifier. Airlift pumps with adjustable pumping capabilities are used to return these solids, as activated sludge, to the aeration chamber to maintain the maximum efficiency of the biological process. A skimmer airlift pump is used to return floatable solids and scum to the aeration chamber for further processing. The treated water flows from the clarifier to a disinfection chamber for treatment using chlorine prior to discharge the new lined primary retention basin. The long term average flow is 0.0027 MGD (from DMR data), and the highest monthly average flow over the past two years is 0.004 MGD (from DMR data).

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Figure 5 New Treatment Ponds-Outfall 002

Outfall 003 Outfall 003 is screen backwash from the intake. No treatment is provided prior to discharge into the Wabash River. No monitoring is required for this wastestream in the current permit. No analytical data was provided for this outfall in the renewal application. On the flow diagram submitted with the application, the flow at this outfall was specified as 5,200 gpm (7.5 mgd).

Outfall 004 This outfall consists entirely of storm water. The total surface area drained is 18.5 acres, with 1 acre of impervious surface. The drainage area includes a vehicle fueling area, a general materials and storage area and a temporary sand and gravel storage area. Based on DMR data, the flow at this outfall ranges from 0.3 MGD to 2.2 MGD. This outfall discharges to an unnamed tributary of the Wabash River.

Seeps 1 through 19 and Finishing Pond Seep The permittee identified 22 seeps in its renewal application [in the current permit, the permittee had identified 19 seeps; however, in the current application, the permittee informed IDEM that

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three of these seeps had been split for identification purposes into two seeps each (Seep 3 became Seep 3 and 3A, Seep 5 became Seep 5A and 5B, and Seep 10 became Seep 10A and 10B) resulting in a total of 22 seeps]. In the current permit, these seeps were not treated as outfalls, but monitoring for a number of parameters was required at three of these seeps. The permittee submitted some sampling data for each of the seeps in its renewal application. Also, on March 8, 2018, the permittee informed IDEM that flow from a groundwater seep was impacting the liner of the new finishing pond. The permittee is redirecting this seep so that it will be discharged into the finishing pond. It would contribute approximately 7,500 gpd to the finishing pond and the permittee anticipated that this flow would be reduced or perhaps eliminated when dewatering of the adjacent ash pond was completed (completion of dewatering is tentatively scheduled in May or June 2018). Seeps 1-7 discharge to the Outfall 001 drainage canal downstream of the Outfall 001 sampling point; Seeps 8-12 discharge directly to the Wabash River between Outfall 001 and 002; and Seeps 13-19 discharge to the Outfall 002 drainage canal downstream of the Outfall 002 sampling point. The flow at these seeps is highly variable, and limited flow data exists; however, based on the information that is available, the approximate combined flow for Seeps 1-7 is 1.2 MGD; for Seeps 8-is 0.85 MGD and for Seeps 13-19 is 0.60 MGD. Sampling data for these seeps indicate the presence of some coal combustion residuals-related constituents above naturally occurring levels. These seeps are being removed from the NPDES permit and will instead be addressed by an Agreed Order. The two options that IDEM considered for addressing these seeps was to either include them as permitted outfalls in the NPDES permit, with both technology-based and water quality-based permit limits, or remove the seeps from the permit entirely so they could be addressed through an enforcement action. During this deliberation, IDEM became aware of a letter that EPA Region 4 sent to the North Carolina Department of Environmental Quality that directly addressed this issue (Letter dated June 16, 2016 from James D. Giattina, Director, Water Protection Division, EPA Region 4, to S. Jay Zimmerman, Director, Division of Water Resources, North Carolina Department of Environmental Quality). In this letter, EPA Region 4 included the following comment regarding a North Carolina draft NPDES permit which proposed to include seeps:

“the draft permit authorizes discharges from unengineered seeps that are not discharged through an engineered outfall or collected and rerouted to an engineered outfall. This creates challenges in permit development and compliance monitoring as it is unclear how such discharges can be accurately monitored for flow and discharge characterization. Although [the North Carolina Division of Water Resources] includes a Seep Pollutant Analysis with options for addressing water quality exceedances in the NPDES permit, we note that an enforcement mechanism providing for elimination or rerouting these seeps is an alternative and potentially preferable approach for addressing seeps of this nature. It has been [North Carolina’s] election to develop permits for these discharges rather than addressing them through an enforcement action, notwithstanding the difficulty of developing appropriate permit conditions and monitoring requirements.”

Following the receipt of this letter from EPA, North Carolina reconsidered its approach to seeps and has decided to address this type of seep through an enforcement action instead of including them in an NPDES permit.

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Based on the above and discussions with the permittee, IDEM has decided that using an enforcement action (an Agreed Order) to address these seeps is the preferable approach. As such, the proposed NPDES permit does not include or authorize discharge from these seeps. IDEM and the permittee intend to enter into this Agreed Order contemporaneously with the issuance of this permit renewal.

Wastewater Treatment System Classification In the Fact Sheet for the current permit, it states that the permittee has a Class D industrial wastewater treatment plant. At the time, this classification was based on the FGD wastewater treatment system (Outfall 101), which had a stated flow of 576,000 gallons per day. Under 327 IAC 5-22-5(a)(5), a chemical treatment plant with a flow of more than 200,000 GPD is a Class D facility. Based on current data, the flow of the FGD wastewater treatment system has been reduced substantially and now averages 126,000 GPD. However, the permittee has just installed a new treatment system to replace its ash pond system. The new treatment system treats storm water and various process wastewaters and uses polymer addition for two of the wastestreams sent to this new treatment system and one of these component wastestreams totals approximately 2 MGD based on the submitted flow diagram. Therefore, the permittee still has a Class D wastewater treatment plant under 327 IAC 5-22-5(a)(5). The permittee must have the wastewater treatment facilities under the responsible charge of an operator certified by the Commissioner in a classification corresponding to the classification of the wastewater treatment plant as required by IC 13-18-11-11 and 327 IAC 5-22-5. In order to operate a wastewater treatment plant the operator shall have qualifications as established in 327 IAC 5-22-7.

2.4 Changes in Operation The permittee has made significant changes in its wastewater treatment system and processes and is continuing to make changes. Changes in wastewater treatment systems are noted above. As noted above, metal cleaning wastes were formerly sent to Outfall 002; however, this was discontinued. Currently, metal cleaning wastes will go into the dry ash fixation product or will be hauled off-site for disposal. Further, as noted above, the intermittent wastestream, wet vacuum truck coal combustion residuals, which formerly discharged to this outfall will now be transported to the fixation pad, mixed with material, and then hauled to the approved landfill. This change was made to comply with the federal CCR regulations. Also, with respect to Outfall 002, the permittee has converted to a dry ash handling system for its fly ash and the conversion to a closed loop system for bottom ash should be operational in March or April 2018.

2.5 Facility Storm Water As noted above, the wastestreams contributing to Outfall 002 include storm water and Outfall 004 solely consists entirely of storm water.

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2.6 Effluent Characterization The following is a summary of effluent data obtained from the permittee’s NPDES renewal application and DMR data (No data is available for Outfall 003):

Parameter

Outfall 001 (units in mg/l unless noted)


# Samples Average Maximum # Samples Average Maximum Flow (MGD) 1,096 558 817 1,096 4.6 11.7 pH (s.u.) 1,067 7.4 (min) 8.6 163 7.5 (min) 9.2 Temperature (winter) °F 544 63 91

3 7 8 Temperature (summer) °F 552 86 102 Aluminum 72 1.3 10.4 72 0.26 1.4 Aluminum, Dissolved (µg/l) 72 <71 423 72 <94 1,180 Ammonia (as N) 72 <0.18 3.04 72 <0.17 3.09 Arsenic (µg/l) 1 NA <4.1 72 7 <30 Barium (µg/l) 1 NA <85 1 NA <39 Beryllium (µg/l) 72 <3.2 48 1 NA <5 Boron (µg/l) 1 NA 400 1 NA 1,300 Bromide 1 NA <0.5 1 NA <0.089 Cadmium (µg/l) 1 NA <2 72 <2 <100 Chloride 72 32 58 72 38 209 Chromium (µg/l) 1 NA 6.6 1 NA <5 Copper (µg/l) 1 NA <6.8 72 <4.1 <30 E. coli (units/100 ml) 1 NA 488 1 NA <1 Fluoride 1 NA 0.19 1 NA 0.44 Hardness (as CaCO3) 1 NA 490 1 NA 420 Hexavalent Chromium (µg/l) 1 NA <0.3 1 NA 0.34 Iron (µg/l) 72 1,600 8,500 72 918 1,330 Lead (µg/l) 1 NA <3.2 1 NA <5 Manganese (µg/l) 1 NA 150 1 NA 46 Mercury (ng/l) 33 4.7 20.8 33 <1.3 3.4 Molybdenum (µg/l) 1 NA <3.7 1 NA 68 Nickel (µg/l) 1 NA <6.4 1 NA <3.5 Nitrate 1 NA 6.4 1 NA 5.3 Nitrate/Nitrite 1 NA 4.9 1 NA 5.1 Nitrite 1 NA <0.1 1 NA <0.049 Oil and grease 72 <2.3 <5 55 <2.5 <5 Selenium (µg/l) 1 NA <15 71 <11.7 58 Silver (µg/l) 1 NA <5 1 NA <5 Sulfate 1 NA 50 72 198 331 Titanium (µg/l) 1 NA 79 1 NA <2.4 Total Dissolved Solids 1 NA 390 1 NA 550 Total Kjeldahl Nitrogen 1 NA <5 1 NA 5.6

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Parameter



# Samples Average Maximum # Samples Average Maximum Total Organic Nitrogen (as N) 1 NA <3 1 NA 5.6

Total Residual Chlorine 1047 0.04 0.14 125 0.03 0.10 Total Suspended Solids 73 56 175 141 12.3 41.9 Zinc (µg/l) 1 NA <16 72 <33 <200

Parameter

Outfall 101 (FGD Wastewater) (units in mg/l unless noted)

# Samples Average Maximum Flow (MGD) 999 0.13 0.44 pH (s.u.) 68 7.8 (min) 8.6 Ammonia (as N) 67 5 13 Arsenic (µg/l) 67 15 82 BOD, 5-Day 66 7 22 Boron 67 893 5,140 Cadmium (µg/l) 67 3 13 Chloride 67 4,056 7,640 Chromium (µg/l) 67 13 100 Copper (µg/l) 67 11 36 Lead (µg/l) 67 3 10 Manganese (µg/l) 67 34,200 116,000 Mercury (ng/l) 24 47 188 Nitrate/Nitrite 67 143 570 Oil and grease 65 2.6 7.2 Selenium (µg/l) 67 299 806 Total Dissolved Solids 66 19,400 35,200 Total Suspended Solids 68 15 46 Zinc (µg/l) 67 41 <500

Outfall 102 (Sanitary Wastewater) (units in mg/l unless noted)

Parameter # Samples Average Maximum Flow (MGD) 1770 0.003 0.04 CBOD, 5-day 118 6.6 183 E. Coli (CFU/100ml) 88 1.5 (geo mean) 2,419

Outfall 004 Data (units in mg/l unless noted) Parameter # Samples Average Maximum Flow (MGD) 10 1.4 2.2 Benzene, Ethylbenzene, Toluene, Xylene combined 9 <22 <25

CBOD, 5-day 10 <3 4

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Outfall 004 Data (units in mg/l unless noted) Parameter # Samples Average Maximum Total Dissolved Solids 1 NA 72 Total Suspended Solids 10 245 798 Ammonia (as N) 1 NA 0.11 Hardness (as CaCO3) 1 NA 183 pH (s.u.) 10 7.1 (min) 8.59 Chloride 1 NA 1.6 Total Residual Chlorine 1 NA <0.02 Nitrate/Nitrite 1 NA 0.84 Total Nitrogen (as N) 1 NA 0.84 Oil and grease 10 <7 12 Sulfate 1 NA 22.3 Aluminum 1 NA 3.4 Dissolved Aluminum (µg/l) 1 NA <0.2 Boron (µg/l) 1 NA <100 Iron (µg/l) 1 NA 3.7 Manganese (µg/l) 1 NA 117 Total Kjeldahl Nitrogen 1 NA 0.67 Arsenic (µg/l) 1 NA 3.8 Beryllium (µg/l) 1 NA 0.3 Cadmium (µg/l) 1 NA 0.24 Chromium (µg/l) 1 NA 7.9 Copper (µg/l) 1 NA 7.5 Lead (µg/l) 1 NA 7 Mercury (ng/l) 1 NA 12.2 Selenium (µg/l) 1 NA 1.2 Zinc (µg/l) 1 NA 617

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Parameter

Seeps 1-7 (units in mg/l unless noted)



# Samples Average Maximum #

Samples Average Maximum #

Samples Average Maximum Flow (MGD) 92 0.004 1.1 49 0.005 0.66 69 0.0023 0.55 Aluminum 20 <0.24 0.69 18 0.51 3.9 18 0.35 0.68 Ammonia (as N) 20 0.11 0.41 18 <0.12 0.24 18 <0.1 <0.2 Antimony 20 10 16 18 12 21 18 <3 <10 Arsenic (µg/l) 20 <4 10 18 <4 <10 18 <3 <10 Barium (µg/l) 20 50 99 18 61 78 18 59 66 Beryllium (µg/l) 20 <2.4 <5 18 <2 <5 18 <2 <5 Boron (µg/l) 20 5,490 8,100 18 3,600 6,000 18 2,200 3,400 Cadmium (µg/l) 20 <1 <2 18 <0.8 <2 18 <0.7 <2 Chloride 20 39 98 18 38 46 18 34 40 Chromium (µg/l) 20 <2.5 <5 18 <2 <5 18 <2 <4 Cobalt (µg/l) 20 <2.9 <7 18 <3 <7 18 <3 <7 Copper (µg/l) 20 <11 <25 18 <10 <25 18 <10 <25 Dissolved Aluminum 20 <0.18 <0.20 18 <0.18 <0.2 18 <0.17 <0.2 Fluoride 20 0.24 0.33 18 0.28 0.35 18 0.25 0.43 Iron (µg/l) 20 411 3,700 18 570 4,700 18 362 670 Lead (µg/l) 20 <2.5 7 18 <2 <5 18 <2 <5 Magnesium (µg/l) 20 27,940 60,000 18 25,400 34,000 18 24,200 26,000 Manganese (µg/l) 20 124 1,600 18 26 150 18 40 77 Mercury (ng/l) 28 0.86 3.8 26 1 6 26 4 39 Molybdenum (µg/l) 20 126 220 18 263 390 18 167 210 Nickel (µg/l) 20 7.3 <40 18 <4 <40 18 2.4 4.5 Oil and grease 8 <4.8 <4.9 6 <4.8 <4.9 6 <4.8 <5

pH (s.u.) 20 7.5 (min) 9.9 18 7.53 (min) 10.1 18 7.73

(min) 8.7

Selenium (µg/l) 20 88 180 18 14 45 18 10 19 Silver (µg/l) 20 <2.3 <5 18 <2 <5 18 2 5 Sulfate 19 308 680 18 229 280 18 189 217 Thallium (µg/l) 20 <4 <10 18 <3 <10 18 <4 <10 Tin (µg/l) 20 <46 <100 18 <40 <100 18 <34 <100

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Parameter




# Samples Average Maximum #

Samples Average Maximum #

Samples Average Maximum Titanium (µg/l) 20 <12 <50 18 <12 <60 18 <8.5 <10 Total Dissolved Solids 20 703 1,600 18 582 700 18 509 560 Total Residual Chlorine 10 0.03 0.12 5 0.03 0.06 6 0.03 0.05 Total Suspended Solids 20 <8 26 18 14 52 18 22 142 Vanadium (µg/l) 20 <5 <10 18 <5 <10 18 <4 <10 Zinc (µg/l) 20 <24 <50 18 <22 <50 18 <21 <50

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3.0 Permit History

3.1 Compliance History A review of this facility’s effluent monitoring data using DMR data downloaded from EPA’s Enforcement and Compliance History Online (ECHO) for the period from March 2013 through December 2017 showed the following effluent limitation violations:

Month Outfall Parameter Violation(s) March 2013 Outfall 101 Manganese Violation of daily max limitation April 2013 Outfall 101 Manganese Violation of daily max limitation April 2013 Outfall 102 E. coli Two violations of daily max limitation May 2013 Outfall 101 Manganese Violation of daily max limitation Aug 2013 Outfall 101 TSS Violation of monthly average limitation Aug 2013 Outfall 101 Manganese Violation of daily max limitation Oct 2013 Outfall 101 Manganese Two violations of daily max limitation Nov 2013 Outfall 101 Arsenic Two violations of daily maximum limitation Dec 2013 Outfall 101 Arsenic Violation of daily max limitation June 2014 Outfall 001 Mercury Violation of monthly average limitation Oct 2014 Outfall 102 E. coli Violation of daily max and monthly average limitations Feb 2015 Outfall 102 BOD Violation of monthly average and daily max limitations July 2015 Outfall 002 pH Violation of daily max limitations Aug 2015 Outfall 002 pH Five violations of daily max limitation

Aug 2015 Outfall 101 Lead Violation of daily max and monthly average limitations (due to higher detection levels)

There are no pending or current enforcement actions regarding this NPDES permit. (As noted under Section 2.3; Seeps, IDEM and the permittee will enter into an Agreed Order to address the seeps at the facility).

4.0 Receiving Water and Use Designations

The receiving stream for Outfalls 001, 002, 003 is the Wabash River. Outfall 004 discharges to an unnamed tributary of the Wabash River. The permittee has a water intake on the Wabash River downstream of Outfall 004, but upstream of Outfall 001, which reduces the available flow of the Wabash River for Outfall 001. The Q7,10 low flow value of the Wabash River for all of the Outfalls except Outfall 001 is 1,310 cfs. Due to the permittee’s water intake upstream of Outfall 001, the Q7,10 low flow value of the Wabash River for Outfall 001 is 24 cfs. The Q7,10 low flow value of the unnamed tributary which receives the flow from Outfall 004 is 0 cfs. Pursuant to 327 IAC 2-1-3, the applicable use designations of these receiving waters are: full-body contact recreation and capable of supporting a well-balanced, warm water aquatic community. In addition, the Wabash River is used as an industrial water supply by the permittee. The 12-digit hydrologic unit code (HUC) for the receiving waters for these outfalls is 051201081602.

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4.1 Receiving Stream Water Quality Section 303(d) of the Clean Water Act requires states to identify waters, through their Section 305(b) water quality assessments, that do not or are not expected to meet applicable water quality standards with federal technology based standards alone. States are also required to develop a priority ranking for these waters taking into account the severity of the pollution and the designated uses of the waters. Once this listing and ranking of impaired waters is completed, the states are required to develop Total Maximum Daily Loads (TMDLs) for these waters in order to achieve compliance with the water quality standards. Indiana's 2016 303(d) List of Impaired Waters was developed in accordance with Indiana's Water Quality Assessment and 303(d) Listing Methodology for Waterbody Impairments and Total Maximum Daily Load Development for the 2016 Cycle. See http://www.in.gov/idem/nps/2647.htm for the 2016 303(d) list and associated information. This segment of the Wabash River was listed on the 2016 Indiana Consolidated List as Category 4A for E. coli and nutrients (Assessment unit- INB08E1_M1050). Category 4A means that a TMDL has already been completed and approved by EPA for the pollutants. The TMDL for the E. coli and nutrient impairments was approved by EPA in September 2006 and is available from the following page: https://in.gov/idem/nps/2841.htm. The 2006 TMDL established a WLA for E. coli for this facility. Limits on E. coli are placed on the internal treated sanitary wastestream to implement this TMDL. In addition, this segment of the Wabash River is listed on the 2016 Indiana Consolidated List as Category 4B for temperature. Category 4B means that Indiana expects that other pollution control requirements are reasonably expected to result in attainment of water quality standards in a reasonable period of time. For temperature, Category 4B means that it is anticipated that the impairment will be addressed through the imposition of controls in applicable NPDES permit in a reasonable period of time.

5.0 Permit Limitations

Two categories of effluent limitations exist for NPDES permits: Technology-based effluent limits (TBELs) and water quality-based effluent limits (WQBELs).

5.1 Technology-Based Effluent Limits (TBELs) Technology-based effluent limits (TBELs) require every individual member of a discharge class or category to operate their water pollution control technologies according to industry-wide standards and accepted engineering practices. TBELs are developed by applying the federal effluent limitation guidelines (ELGs) established by U.S. EPA for specific industrial categories. Technology-based treatment requirements under Sections 301(b) and 306 of the CWA represent the minimum level of control that must be imposed in an NPDES permit (see 327 IAC 5-5-2(a)). EPA has established effluent limitation guidelines (ELGs) that are applicable to this facility; these are at 40 CFR 423, Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Source Category. These effluent limitation guidelines regulate a number of different wastestreams and parameters. Implementation of these effluent limitation guidelines for this facility is discussed below. In the absence of effluent limitation guidelines, technology-based effluent limits can also be determined on a case-by-case basis using best professional judgment (BPJ) pursuant to 327 IAC 5-2-10 and 5-5 (which implement 40 CFR 122.44, 125.3, and Section 402(a)(1) of

http://www.in.gov/idem/programs/water/tmdl/

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http://www.in.gov/idem/nps/2647.htm

https://in.gov/idem/nps/2841.htm

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the Clean Water Act (CWA)). IDEM has developed case-by-case basis, technology-based effluent limits using best professional judgment for this facility, which are discussed in more detail below.

5.2 Water Quality-Based Effluent Limits (WQBELs) Water quality-based effluent limits (WQBELs) are designed to be protective of the beneficial uses of the receiving water and are independent of the available treatment technology. The WQBELs for this facility are based on water quality criteria under 327 IAC 2-1-6 or developed under the procedures described in 327 IAC 2-1-8.2 through 327 IAC 2-1-8.7 and implementation procedures in 327 IAC 5. Limitations are required for any parameter which has the reasonable potential to cause or contribute to an exceedance of a water quality criterion as determined using the procedures under 327 IAC 5-2-11.1(h). As part of this permit renewal, a wasteload allocation (WLA) was conducted for a number of parameters and outfalls. This WLA, WLA002329, 2/1/2018 is attached as Appendix A of this Fact Sheet. The implementation of this wasteload allocation for this facility is discussed below.

5.3 Effluent Limitations and Monitoring Requirements Under 327 IAC 5-2-10 (see also 40 CFR 122.44), NPDES permit limits are based on either technology-based effluent limits (TBELs), including TBELs developed on a case-by-case basis using BPJ, where applicable, or water quality-based effluent limits (WQBELs), whichever is most stringent. The decision to limit or monitor the parameters contained in this permit is based on information contained in the permittee’s NPDES application and other available information relating to the facility and the receiving waterbody as well as the applicable federal effluent limitations guidelines. In addition, when renewing a permit, the existing permit limits, the antibacksliding requirements under 327 IAC 5-2-10(a)(11), and the antidegradation requirements under 327 IAC 2-1.3 must be considered.

5.3.1 All External Outfalls A. Narrative Water Quality Based Limits The narrative water quality criteria contained under 327 IAC 2-1-6(a)(1) and (2) have been included in this permit as narrative limits at all of the Outfalls to ensure that these narrative water quality criteria are met.

5.3.2 Outfall 001 A. Flow The effluent flow is to be monitored as required by 327 IAC 5-2-13(a)(2). As is the case in the current permit, the flow at this outfall may be estimated based on engineering calculations.

B. pH The effluent pH is limited to between 6.0 and 9.0 s.u. to ensure compliance with 327 IAC 2-1-6(b)(2).

C. Temperature/Thermal Requirements See Section 6.3.1 of this Fact Sheet for a detailed discussion of the thermal requirements applicable to this Outfall.

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D. Aluminum Monitoring for both total recoverable and dissolved aluminum is required in the current permit. Continued monitoring for both forms of aluminum is proposed in this permit. For information only, IDEM has proposed the adoption of aquatic life criteria for aluminum under 327 IAC 2-1-6 (see second notice LSA document #14-58, Nov. 15, 2017); and in addition, EPA proposed updated aquatic life criteria for aluminum in July 2017 (see https://www.epa.gov/wqc/aquatic-life-criteria-aluminum). The water quality-based effluent limitations for aluminum at Outfall 001 based on these proposed criteria would be (if such permit limits were determined to be necessary):

Basis

mg/l

Data Used Monthly Average

Daily Maximum

IDEM Proposed Criteria 3.3 6.7 Hardness of 299 (50th percentile)

EPA Proposed Criteria 1.4 2.8 Hardness of 299, pH of 8.2 (average) and dissolved organic carbon of 2.97 (10th percentile, Wabash River Vigo County)

E. Ammonia (as N) Monitoring for ammonia (as N) is required in the current permit. Water quality-based effluent limitations are required for ammonia (as (N) based on an analysis of reasonable potential. See WLA 002329. These limits are set forth in the below table. Weekly sampling is proposed for this parameter.

Parameter

Quality or Concentration Quantity or Loading Monthly Average

Daily Maximum

Units

Monthly Average

Daily Maximum Units

Total Ammonia (as N) Summer 0.77 1.9 mg/l 5,200 13,000 lbs/day Winter 1.4 3.5 mg/l 9,400 24,000 lbs/day

F. Beryllium Monitoring for beryllium is required in the current permit. Water quality-based effluent limitations are required for beryllium based on an analysis of reasonable potential. See WLA 002329. These limits are set forth in the below table. Weekly sampling is proposed for this parameter.

Parameter


Daily Maximum

Units

Monthly Average

Daily Maximum Units

Beryllium 2.1 5.2 µg/l 14 35 lbs/day

IDEM has proposed to eliminate the water quality criterion upon which the above water quality-based effluent limitations for beryllium are based (see second notice LSA document #14-58, Nov. 15, 2017).

G. Bromide Bromide monitoring is proposed in this permit. Bromide is naturally present in some types of coal. In addition, the permit allows the permittee to use bromine as an antifouling agent in its cooling water. IDEM has started including bromide monitoring in

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NPDES permits for coal-fired power plants to gather information on the levels of bromide being discharged at these types of facilities in Indiana. Based on recent studies, the presence of bromide in surface waters has created an issue for some surface water-based public water supplies. The presence of bromide, combined with the use of chlorine in the treatment process, results in the formation of brominated and mixed chlorinated-brominated disinfection byproducts. In general, brominated disinfection byproducts have higher health risks than chlorinated disinfection by-products. See Section 14.4 Site Specific Water Quality-Based Effluent Limitations, U.S. EPA Technical Development Document for the Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category, September 2015 for a comprehensive discussion. There are no surface water-based public water supplies on the Wabash River downstream of this facility, therefore, the presence of bromide in the effluent should not impact any public water supplies. However, as indicated above, IDEM is gathering information on the level of bromide present in the discharges from this type of facility.

H. Chloride The current permit included water quality-based effluent limitations for chloride of 481 mg/l monthly average and 966 mg/l daily maximum. These limits were calculated using the Q7,10 of the Wabash River without taking into account the amount of water withdrawn from the Wabash River by the permittee upstream of this Outfall. Water quality-based limits for chloride using the actual Q7,10 flow at this Outfall would be 410 mg/l monthly average and 710 mg/l daily maximum. See WLA 002329. Since the existing permit does contain water quality-based effluent limitations for chloride, water quality-based effluent limitations for chloride will be included in this permit; however, the limits will be based on the correct Q7,10 flow for this Outfall. These limits are as follows:

Parameter


Daily Maximum

Units

Monthly Average

Daily Maximum Units

Chloride 410 710 mg/l 2,800,000 4,800,000 lbs/day

I. Total Residual Chlorine The permittee currently uses total residual chlorine as a biocide to control biofouling on the condenser tubes. Under the federal effluent guidelines applicable to this facility (existing plants with a total electric generating capacity of 25 or more megawatts), under 40 CFR 423.13, BAT requirements of a maximum total residual chlorine limitation of 0.2 mg/l has been established. In addition, under this regulation, total residual chlorine may not be discharged from any single generating unit for more than two hours per day unless the discharger demonstrates to the permitting authority that discharge for more than two hours is required for macroinvertebrate control. Simultaneous multi-unit chlorination is permitted. Further, Indiana has established a water quality criterion for intermittent total residual chlorine of 0.2 mg/l as a 4-day average aquatic life criterion under 327 IAC 2-1-6(a)(3) Table 6-1. To be considered an intermittent discharge for the criterion, total residual chlorine shall not be detected in the discharge for a period of more than 40 minutes in duration and such periods shall be separated by at least 5 hours.

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If the discharge of chlorine does meet the definition of “intermittent” established under 327 IAC 2-1-6(a)(3) Table 6-1; then, to ensure compliance with both the technology-based and the water quality-based requirements, the permit will establish a maximum limit of 0.2 mg/l which will be applicable during intermittent usage of total residual chlorine. If the chlorine discharge does not meet the definition of “intermittent” established under 327 IAC 2-1-6(a)(3) Table 6-1, then water quality-based effluent limits for total residual chlorine of 0.01 mg/l monthly average and 0.02 mg/l daily maximum would be applicable. See WLA 002329. These limits are more stringent than the limits of 0.02 mg/l monthly average and 0.04 mg/l daily maximum that are in the current permit. An incorrect dilution flow was used to calculate these limits in the current permit; rather than subtracting the amount of water withdrawn through the permittee’s intake upstream of Outfall 001, the entire flow of the Wabash River was used. In either case, the federal BAT requirement for total residual chlorine will also be applicable. Thus, total residual chlorine may not be discharged from any single generating unit for more than two hours per day unless the discharger demonstrates to the permitting authority that discharge for more than two hours is required for macroinvertebrate control. Simultaneous multi-unit chlorination is permitted. The water quality-based effluent limits of 0.01 mg/l monthly average and 0.02 mg/l daily maximum are less than the limit of quantitation (LOQ) of 0.06 mg/l for this parameter. Pursuant to 327 IAC 5-2-11.1(f)(1), the permittee will be required to use an approved analytical methodology for total residual chlorine and the permit is required to contain certain conditions specified under this subsection of the rule. By policy, IDEM is not including mass limits in a permit if the concentration limitations are less than the limit of quantitation; therefore, mass limits are not being included in the permit for total residual chlorine.

J. Total Residual Oxidants (Bromine) The permittee has requested that the permit also authorize the use of bromine in case the permittee wanted to switch from the use of chlorine to bromine as a biocide. The water quality-based effluent limits for total residual oxidants (bromine) are 0.00011 mg/l (0.11 µg/l) monthly average, 0.00028 mg/l (0.28 µg/l) daily maximum. See WLA 002329. These limits are more stringent than the limit of 0.06 mg/l daily maximum that was in the previous permit. The prior permit used the limit of quantitation (LOQ) as the daily maximum limit instead of using monthly average and daily maximum water quality-based effluent limits. The EPA approved methods for total residual chlorine are the same methods that would be used to analyze for total residual bromine in the effluent—these methods do not distinguish between chlorine and bromine. As was the case for the total residual chlorine limit, above, these limits for bromine are less than the limit of quantitation (LOQ) of 0.06 mg/l for this parameter. Pursuant to 327 IAC 5-2-11.1(f)(1), the permittee will be required to use an approved analytical methodology for bromine and the permit is required to contain certain conditions specified under this subsection of the rule.

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The federal BAT requirements applicable to total residual chlorine (0.2 mg/l maximum and usage of no more than 2 hours per day per unit) are not applicable to the use of bromine. However, IDEM proposes to require the facility to report bromination frequency, dose duration, and duration/day as is done for total residual chlorine. By policy, IDEM is not including mass limits in a permit if the concentration limitations are less than the limit of quantitation; therefore, mass limits are not being included in the permit for total residual oxidants (bromine).

K. Iron Monitoring for iron is required in the current permit. This monitoring is proposed to be continued in this permit.

L. Mercury Mercury is limited in the current permit. Water quality-based effluent limitations are still required for mercury based on an analysis of reasonable potential. See WLA 002329. These limits are set forth in the below table. Every other month (6 X yearly) sampling is proposed for this parameter, which is the current monitoring frequency.

Parameter

Quality or Concentration Monthly Average

Daily Maximum

Units

Mercury 12 20 ng/l

M. Oil and Grease and Total Suspended Solids The effluent guidelines-based effluent limitations for oil and grease and total suspended solids applicable to this discharge have been applied at internal Outfall 101 (the treated flue gas desulfurization [FGD] wastewater). Continued monitoring for total suspended solids and oil and grease will be required at this Outfall.

N. Selenium Selenium monitoring has been added as a new parameter to this permit to characterize the levels of selenium present at this outfall. The permittee only included 1 result for selenium at this outfall in the submitted 2-C application and it was reported present at <15 µg/l. The current chronic water quality criterion for selenium is 35 µg/l. Although 15 µg/l is less than this chronic criterion; with only one sample, it is possible that additional sampling may reveal that selenium is present at levels closer to this chronic criterion. Also, EPA recently released a final updated recommended national chronic aquatic life criteria for selenium that IDEM is proposing to adopt (see second notice LSA document #14-58, Nov. 15, 2017). This final EPA criteria document and proposed IDEM criteria established a chronic water column criterion for selenium of 3.1 µg/l.

5.3.3 Outfall 101 [treated flue gas desulfurization (FGD) wastewater] The requirements established at this outfall are based on federal effluent limitations guidelines established under 40 CFR 423, Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Source Category, as well as technology-based effluent limits determined on a case-by-case basis using best professional judgment (BPJ) pursuant to 327 IAC 5-2-10 and 5-5 (which implement 40 CFR 122.44, 125.3, and Section 402(a)(1) of the Clean Water Act (CWA)).

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On November 3, 2015, EPA promulgated revisions to 40 CFR 423, which were further revised on September 18, 2017 to change some of the compliance deadlines established in the November 3, 2015 regulations. Under these regulations, flue gas desulfurization (FGD) wastewater was defined to mean:

any wastewater generated specifically from the wet flue gas desulfurization scrubber system that comes into contact with the flue gas or the FGD solids, including but not limited to, the blowdown from the FGD scrubber system, overflow or underflow from the solids separation process, FGD solids wash water, and the filtrate from the solids dewatering process. Wastewater generated from cleaning the FGD scrubber, cleaning FGD solids separation equipment, cleaning FGD solids dewatering equipment, or that is collected in floor drains in the FGD process area is not considered FGD wastewater.

Relative to this wastestream, the November 3, 2015 regulations established best practicable control technology currently available (BPT) limitations for total suspended solids (TSS) and oil and grease under 40 CFR 423.12(b)(11); formerly, FGD wastewater was included in the definition of low volume waste sources and was subject to the same BPT limits applicable to these low volume waste sources. These BPT limits applicable to FGD wastewater are the same as the BPT limits that were applicable when the wastewater was considered a low volume waste source. The BPT regulations also contain pH limitations under 40 CFR 423.12(b)(1), which are unchanged. In addition, these new regulations established best available technology economically achievable (BAT) limits for this FGD wastewater under 40 CFR 423.13(g). There were two sets of BAT limits established, limitations on TSS that were the same as the BPT limitations for TSS, and limitations on mercury, arsenic, selenium, and nitrate/nitrite as N (for facilities that opt into the voluntary incentive program, the second set of BAT limits are on mercury, arsenic, selenium, and total dissolved solids [TDS].) These BAT limitations must be met “by a date determined by the permitting authority that is as soon as possible beginning November 1, 2020, but no later than December 31, 2023,” or for facilities that opt into the voluntary incentive program, the limitations must be met by December 31, 2023. Under 40 CFR 423.11(t) “as soon as possible” is defined as November 1, 2020 for the FGD wastestream (a date of November 1, 2018 applies to other wastestreams) unless the permitting authority establishes a later date, after receiving information from the discharger, which reflects a consideration of the following factors:

(1) Time to expeditiously plan (including to raise capital), design, procure, and install equipment to comply with the requirements of this part. (2) Changes being made or planned at the plant in response to:

(i) New source performance standards for greenhouse gases from new fossil fuel-fired electric generating units, under sections 111, 301, 302, and 307(d)(1)(C) of the Clean Air Act, as amended, 42 U.S.C. 7411, 7601, 7602, 7607(d)(1)(C); (ii) Emission guidelines for greenhouse gases from existing fossil fuel-fired electric generating units, under sections 111, 301, 302, and 307(d) of the Clean Air Act, as amended, 42 U.S.C. 7411, 7601, 7602, 7607(d); or (iii) Regulations that address the disposal of coal combustion residuals as solid waste, under sections 1006(b), 1008(a), 2002(a), 3001, 4004, and 4005(a) of the Solid Waste Disposal Act of 1970, as amended by the Resource Conservation and

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Recovery Act of 1976, as amended by the Hazardous and Solid Waste Amendments of 1984, 42 U.S.C. 6906(b), 6907(a), 6912(a), 6944, and 6945(a).

(3) For FGD wastewater requirements only, an initial commissioning period for the treatment system to optimize the installed equipment. (4) Other factors as appropriate.

The permittee did submit information to IDEM, in letters dated January 16, 2017 and January 10, 2018, requesting alternate compliance dates for the FGD wastestream: In the permittee’s initial January 16, 2017 letter, the permittee proposed a date of November 1, 2018 to determine whether they would be able to fixate all of the FGD wastewater and thus achieve zero discharge (“determination date”). If they determined that this zero-discharge option was viable, the permittee would opt in to the voluntary incentive program and meet the applicable limits established under 40 CFR 423.13(g)(3). Under this voluntary incentive option, EPA’s regulations establish a compliance date of December 31, 2023. If the permittee did not chose this voluntary incentive option; the permittee stated that an additional 41 months would be needed to design, procure, construct, and start-up and optimize the necessary wastewater treatment system. Based on the November 1, 2018 determination date proposed in this initial letter, March 31, 2022, was the end of this 41 month period. In their updated letter, dated January 10, 2018, the permittee requested a delay in the determination date from November 1, 2018 to December 31, 2019. Again, if they chose the voluntary incentive program, the regulatory deadline for compliance would be December 31, 2023. If the permittee does not choose this voluntary incentive option, they would still need the 41 months to design, procure, construct, and start-up and optimize the necessary wastewater treatment system set forth in the original letter. With the new December 31, 2019 determination date, May 31, 2023 is the end of this 41 month period. In the permittee’s initial letter, they requested 24 months, from December 2016 through November 1, 2018, to complete the refinement and optimization of the fixation system and study the ability of the fixation process to fixate all the FGD blowdown and achieve zero discharge. In their January 2018 letter, the permittee explained that, in addition to evaluating the effectiveness of its fixation process over the past year, the permittee was also in the process of completely changing its wastewater treatment system (primarily to comply with EPA’s CCR regulations). This effort devoted to the new wastewater treatment system prevented the permittee from completing a more formal engineering evaluation of the fixation system and test pilot systems, so that it could appropriately evaluate alternatives that could achieve the new effluent guidelines limitations. In their January 2018 letter, the permittee included a schedule detailing the steps that they would be taking in 2018 and 2019 to complete their evaluation of alternatives to comply with these new limitations. Once this initial determination was complete, if the permittee determined that the fixation process would not be able to fixate all of the FGD wastewater, the permittee’s initial January 2017 letter provided information describing the steps they would take to install a new wastewater treatment system for their FGD wastewater. They described the technology evaluation, engineering, procurement, and construction and installation steps that would be needed to complete this new wastewater treatment plant in 41 months. Based on the information provided by the permittee in these letters, IDEM is proposing the following compliance dates for attainment of the BAT requirements for the FGD wastewater:

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Action Proposed Compliance Dates Permittee will determine if zero discharge option is viable: Dec. 31, 2019

• If viable, FGD BAT compliance date: Dec. 31, 2023 • If not viable, FGD BAT compliance date: May 31, 2023

A reopening clause has been included in the permit allowing the permit to the modified, or alternatively, revoked and reissued, after public notice and opportunity for hearing if EPA promulgates revised effluent guidelines which contain different conditions for FGD wastewater, including different compliance deadlines or effluent limits.

A. Flow The effluent flow is to be monitored as required by 327 IAC 5-2-13(a)(2).

B. pH The effluent pH is limited to between 6.0 and 9.0 s.u. pursuant to the BPT requirements established under 40 CFR 423.12(b)(1).

C. Total Suspended Solids (TSS) The total suspended solids limits of 30 mg/l monthly average and 100 mg/l daily maximum are BPT limitations established pursuant to 40 CFR 423.12(b)(11). These are the same limitations established in the current permit. Once the compliance date for the applicability of the BAT limitations has passed, the legal authority for the TSS limitations will be the BAT requirements established under 40 CFR 423.13(g); however, since the BPT and BAT limitations are the same, the limits in the permit will not change.

D. Oil and Grease The oil and grease limits of 15 mg/l monthly average and 20 mg/l daily maximum are BPT limitations established pursuant to 40 CFR 423.12(b)(11). These are the same limitations established in the current permit.

E. Arsenic The arsenic limit of 85 µg/l daily maximum will be retained from the current permit until such time that the BAT limitations for arsenic are applicable. The current limitation was determined on a case-by-case basis using best professional judgment (BPJ) based on the following rationale (from the 2013 Fact Sheet):

DEI Cayuga provided design removal rates associated with its FGD wastewater physical/chemical treatment system. Therefore, IDEM is basing the Draft Permit Arsenic limit on the design removal rate of 47%. A Daily Maximum effluent limit of 85 ug/l is proposed.

As stated above, by December 31, 2019, the permittee will determine whether they will choose to comply with the voluntary limits under 423.13(g)(3) or take the steps necessary to comply with the limitations under 40 CFR 423.13(g)(1). Based on that determination, the following BAT arsenic limits and compliance dates will be applicable:

Parameter

40 CFR 423.13(g)(1) Effective May 31, 2023

Voluntary Limits (40 CFR 423.13(g)(3))

Effective December 31, 2023 Average Maximum Average Maximum

Arsenic, total (ug/L) 8 11 NA 4

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F. Cadmium The cadmium limit of 59 µg/l daily maximum will be retained from the existing permit. The current limitation was determined on a case-by-case basis using best professional judgment (BPJ) based on the following rationale (from the 2013 Fact Sheet):

DEI Cayuga provided design removal rates associated with its FGD wastewater physical/chemical treatment system. Therefore, IDEM is basing the Draft Permit Cadmium limit on the design removal rate of 63%. A Daily Maximum effluent limit of 59 ug/l is proposed.

G. Chromium The chromium limit of 361 µg/l daily maximum will be retained from the existing permit. The current limitation was determined on a case-by-case basis using best professional judgment (BPJ) based on the following rationale (from the 2013 Fact Sheet):

DEI Cayuga provided design removal rates associated with its FGD wastewater physical/chemical treatment system. IDEM evaluated Chromium data provided by the permittee and compared it to the projected design removal rates. Based on the data, the design removal rate is not consistent, possibly due in part to continuous changes being made at the facility related to air pollution control equipment. Therefore, IDEM used a statistical procedure, generally used by EPA, to determine a Daily Maximum effluent limitation for Chromium. EPA’s procedure, and that used by IDEM, involves fitting effluent data to distributions and using estimated upper percentiles of the distributions. EPA defines the maximum daily limitation as an estimate of the 99th percentile of the distribution of the daily measurements. EPA bases its limitations on percentiles chosen with the intention that they be high enough above the long-term average to accommodate reasonably anticipated variability within control of the facility.

Using the statistical procedure detailed above, a Daily Maximum effluent limit of 361 ug/l is proposed.

H. Copper The copper limit of 50 µg/l daily maximum will be retained from the existing permit. The current limitation was determined on a case-by-case basis using best professional judgment (BPJ) based on the following rationale (from the 2013 Fact Sheet):

DEI Cayuga provided design removal rates associated with its FGD wastewater physical/chemical treatment system. Therefore, IDEM is basing the Draft Permit Copper limit on the design removal rate of 88%. A Daily Maximum effluent limit of 50 ug/l is proposed.

I. Lead The lead limit of 11 µg/l daily maximum will be retained from the existing permit. The current limitation was determined on a case-by-case basis using best professional judgment (BPJ) based on the following rationale (from the 2013 Fact Sheet):

DEI Cayuga provided design removal rates associated with its FGD wastewater physical/chemical treatment system. Therefore, IDEM is basing the Draft Permit Lead limit on the design removal rate of 93%. A Daily Maximum effluent limit of 11 ug/l is proposed.

J. Mercury The mercury limit of 50 µg/l daily maximum will be retained from the current permit until such time that the BAT limitations for mercury are applicable. The current limitation was

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determined on a case-by-case basis using best professional judgment (BPJ) based on the following rationale (from the 2013 Fact Sheet):

DEI Cayuga provided design removal rates associated with its FGD wastewater physical/chemical treatment system. Therefore, IDEM is basing the Draft Permit Mercury limit on the design removal rate of 50%. A Daily Maximum effluent limit of 50 ug/l is proposed.

As stated above, by December 31, 2019, the permittee will determine whether they will choose to comply with the voluntary limits under 423.13(g)(3) or take the steps necessary to comply with the limitations under 40 CFR 423.13(g)(1). Based on that determination, the following BAT mercury limits and compliance dates will be applicable:

Parameter




Mercury, Total (ug/L) 0.356 0.788 0.024 0.039

K. Nitrate/Nitrite (as N) The current permit requires monitoring for nitrate/nitrite (as N). Monitoring, without limits, will be retained until such time that the BAT limitations apply, if applicable. As stated above, by December 31, 2019, the permittee will determine whether they will choose to comply with the voluntary limits under 423.13(g)(3) or take the steps necessary to comply with the limitations under 40 CFR 423.13(g)(1). Based on that determination, the following BAT nitrate/nitrite (as N) limits and compliance dates will be applicable:

Parameter




Nitrate/nitrite as N (mg/L) 4.4 17.0 Monitor only Monitor only

L. Selenium The current permit requires monitoring for selenium. Monitoring, without limits, will be retained until such time that the BAT limitations apply. As stated above, by December 31, 2019, the permittee will determine whether they will choose to comply with the voluntary limits under 423.13(g)(3) or take the steps necessary to comply with the limitations under 40 CFR 423.13(g)(1). Based on that determination, the following BAT selenium limits and compliance dates will be applicable:

Parameter



Effective December 31, 2023

Average Maximum Average Maximum Selenium, total (ug/L) 12 23 Monitor only 5

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M. Total Dissolved Solids (TDS) The current permit requires monitoring for total dissolved solids (TDS). Monitoring, without limits, will be retained until such time that the BAT limitations apply, if applicable. As stated above, by December 31, 2019, the permittee will determine whether they will choose to comply with the voluntary limits under 423.13(g)(3) or take the steps necessary to comply with the limitations under 40 CFR 423.13(g)(1). Based on that determination, the following BAT total dissolved solids (TDS) limits and compliance dates will be applicable:

Parameter



Effective December 31, 2023

Average Maximum Average Maximum Total dissolved solids (TDS) (mg/l)

Monitor only Monitor only 24 50

N. Ammonia (as N) The current permit requires monitoring for ammonia (as N). Even though ammonia is not a pollutant regulated by the applicable effluent limitations guidelines, this permit proposes to continue this monitoring requirement at the same monitoring frequency. At Outfall 001, water quality-based effluent limitations were required for ammonia (as N) based on an analysis of reasonable potential. The majority of the wastewaters contributing to Outfall are noncontact cooling water. Outfall 101 should be the only significant contributor of ammonia to Outfall 001. Therefore, continued monitoring for ammonia is proposed at this outfall.

O. BOD5 The current permit requires monitoring for BOD5. The BOD levels in the effluent at this outfall have been relatively low, averaging 7 mg/l with a maximum of 22 mg/l. Since this wastestream mixes with Outfall 001 prior to discharge, the level of BOD in this wastestream should not have any impact on the receiving waterbody. In addition, this pollutant is not regulated by the technology-based requirements under the applicable federal effluent limitations guidelines. Therefore, this permit proposes to eliminate this monitoring requirement.

P. Boron The current permit requires monitoring for boron. Although the levels of boron at his outfall have been relatively high (averaging 893 mg/l with a maximum of 5,140 mg/l), due to the dilution provided by Outfall 001, the contribution of boron from this outfall should not have an adverse impact on the receiving waterbody. In addition, this pollutant is not regulated by the technology-based requirements under the applicable federal effluent limitations guidelines. Therefore, this permit proposes to eliminate this monitoring requirement.

Q. Chloride The current permit requires monitoring for chloride. Although the levels of chloride at his outfall have been high (averaging 4,056 mg/l with a maximum of 7,640 mg/l), due to the dilution provided by Outfall 001, the contribution of chloride from this outfall should not

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have an adverse impact on the receiving waterbody. In addition, this pollutant is not regulated by the technology-based requirements under the applicable federal effluent limitations guidelines. Therefore, this permit proposes to eliminate this monitoring requirement.

R. Manganese The current permit requires monitoring for manganese. Although the levels of manganese at his outfall have been high (averaging 34 mg/l with a maximum of 116 mg/l), due to the dilution provided by Outfall 001, the contribution of manganese from this outfall should not have an adverse impact on the receiving waterbody. In addition, this pollutant is not regulated by the technology-based requirements under the applicable federal effluent limitations guidelines. Therefore, this permit proposes to eliminate this monitoring requirement.

S. Zinc The current permit requires monitoring for zinc. The levels of zinc at his outfall have been relatively low (averaging 41 ug/l with a maximum of <500 µg/l). In addition, with the dilution provided by Outfall 001, the contribution of zinc from this outfall should not have an adverse impact on the receiving waterbody. In addition, this pollutant is not regulated by the technology-based requirements under the applicable federal effluent limitations guidelines. Therefore, this permit proposes to eliminate this monitoring requirement.

T. Beryllium Monitoring for beryllium is being added to the permit at this Outfall due to the high concentrations that have been identified at Outfall 001, even though beryllium is not a pollutant regulated by the applicable effluent limitations guidelines. At Outfall 001, water quality-based effluent limitations were required for beryllium based on an analysis of reasonable potential. The majority of the wastewaters contributing to Outfall are noncontact cooling water. Outfall 101 should be the only significant contributor of beryllium to Outfall 001. Therefore, this permit proposes to include monitoring for beryllium at this outfall.

5.3.4 Outfall 002 Some of the wastestreams contributing to this Outfall are governed by federal effluent guidelines under 40 CFR 423 Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Source Category. These regulated wastestreams are categorized as low volume waste sources, fly ash transport water, bottom ash transport water, coal pile runoff, and combustion residual leachate. Other wastewaters contributing to this outfall are not governed by these federal regulations, including stormwater (other than the coal pile runoff), and treated sanitary wastewater (Outfall 102). On November 3, 2015, EPA promulgated revisions to 40 CFR 423, which were further revised on September 18, 2017 to change some of the compliance deadlines established in the November 3, 2015 regulations. The federal regulations established the following best practicable control technology currently available (BPT) limitations for pH, total suspended solids (TSS) and oil and grease under 40 CFR 423.12.

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BPT Limits Citation Total Suspended Solids Oil and Grease Low volume waste sources 40 CFR 423.12(b)(3) 30 mg/l monthly average,

100 mg/l daily maximum 15 mg/l monthly average; 20 mg/l daily maximum

Fly and Bottom ash transport water 40 CFR 423.12(b)(4) 30 mg/l monthly average,


Coal Pile Runoff 40 CFR 423.12(b)(9) 50 mg/l instantaneous maximum NA

Combustion Residual Leachate 40 CFR 423.12(b)(11) 30 mg/l monthly average,


For all of the above wastestreams, a BPT limit for pH of between 6.0 and 9.0 s.u. was established by 40 CFR 423.12(b)(1).

Further, these regulations established the following best available technology economically achievable (BAT) requirements for:

BAT Limits Citation Requirement/Limit

Before Compliance Date After Compliance Date Fly ash transport water 40 CFR 423.13(h)(1) BPT TSS Limits No discharge of

pollutants Bottom ash transport water 40 CFR 423.13(k)(1) BPT TSS Limits No discharge of

pollutants Combustion Residual Leachate 40 CFR 423.12(b)(11) BPT TSS Limits No change

The no discharge of pollutants BAT limitation for fly ash transport water must be met “by a date determined by the permitting authority that is as soon as possible beginning November 1, 2018, but no later than December 31, 2023.” The permittee submitted a letter dated January 16, 2017 requesting the “as soon as possible” date of November 1, 2018 as the compliance date for the fly ash transport water. The no discharge of pollutants BAT limitation for bottom ash transport water must be met “by a date determined by the permitting authority that is as soon as possible beginning November 1, 2020, but no later than December 31, 2023.” Under 40 CFR 423.11(t) “as soon as possible” is defined as November 1, 2020 for this wastestream unless the permitting authority establishes a later date. Under this definition, the permitting authority may establish a later compliance date for these wastestreams after receiving information from the discharger, which reflects a consideration of the following factors:

(1) Time to expeditiously plan (including to raise capital), design, procure, and install equipment to comply with the requirements of this part. (2) Changes being made or planned at the plant in response to:

(i) New source performance standards for greenhouse gases from new fossil fuel-fired electric generating units, under sections 111, 301, 302, and 307(d)(1)(C) of the Clean Air Act, as amended, 42 U.S.C. 7411, 7601, 7602, 7607(d)(1)(C); (ii) Emission guidelines for greenhouse gases from existing fossil fuel-fired electric generating units, under sections 111, 301, 302, and 307(d) of the Clean Air Act, as amended, 42 U.S.C. 7411, 7601, 7602, 7607(d); or (iii) Regulations that address the disposal of coal combustion residuals as solid waste, under sections 1006(b), 1008(a), 2002(a), 3001, 4004, and 4005(a) of the Solid Waste Disposal Act of 1970, as amended by the Resource Conservation and Recovery Act of 1976, as amended by the Hazardous and Solid Waste Amendments of 1984, 42 U.S.C. 6906(b), 6907(a), 6912(a), 6944, and 6945(a).

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(3) For FGD wastewater requirements only, an initial commissioning period for the treatment system to optimize the installed equipment. (4) Other factors as appropriate.

The permittee did submit information to IDEM, in letters dated January 16, 2017 and January 10, 2018, requesting alternate compliance dates for the bottom ash transport water wastestream. In the permittee’s initial January 16, 2017 letter, the permittee proposed a date of September 30, 2019 to meet the applicable BAT limits established under 40 CFR 423.13(k)(1). In their updated letter, dated January 10, 2018, the permittee requested a delay in the compliance date from September 30, 2019 to December 31, 2021. In the permittee’s initial letter, they stated that they anticipated that equipment installation to convert the wet bottom ash transport system to a closed loop system would be complete by March 2018; however, the permittee stated that after this new dry system was operational, they would need 18 months to optimize the system to operate as a zero discharge system. The reason they are installing this closed loop system for the bottom ash is to meet the requirements of EPA’s CCR regulations to eliminate the discharge of this bottom ash to their current ash pond system by April 2018. The permittee explained that significant portions of the bottom ash system would need to be replaced to comply. The permittee is installing a remote mechanical drag chain system to achieve a closed loop system for the bottom ash. In their January 2018 letter, the permittee explained that an issue of uncertainly that they had only recently identified was whether additional treatment or water holding systems would be necessary in the event of leaks, system outages, or maintenance issues. The permittee stated that they expect that there will be instances in which wastewater from the system is generated but there is currently no plan in place to address those events in the long run. Because the system is not fully operational and since the permittee did not have experience with similar systems, the specific additional treatment or holding system requirements are unknown. The permittee included a modified schedule in their January 2018 letter detailing the steps they would be taking to comply with the new requirements. Based on the information provided by the permittee in these letters, IDEM is proposing the following compliance date for attainment of the BAT requirements for the bottom ash transport wastewater:

Action Proposed Compliance Date Bottom Ash Zero Discharge: December 31, 2021

A reopening clause has been included in the permit allowing the permit to the modified, or alternatively, revoked and reissued, after public notice and opportunity for hearing if EPA promulgates revised effluent guidelines which contain different conditions for bottom ash transport water, including different compliance deadlines or effluent limits. As indicated above, this outfall includes wastestreams that are regulated by the effluent limitations guidelines established under 40 CFR 423 as well as wastestreams that are not regulated by these federal guidelines. As stated in Section 14.1.5 of the Technical Development Document for the Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category, EPA-821-R-15-007, September 2015 (“Technical Development Document”), “[i]n such cases, to derive effluent limitations or standards at the point of discharge, the permitting authority typically combines the allowable pollutant concentrations loadings for each set of requirements to arrive at a specific

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limitation or standard, per pollutant, for the combined wastestream, using the building block approach or combined waste stream formula (CWF).” As further stated in this Technical Development Document, “[i]n some cases, a wastestream … containing a regulated pollutant … combines with other wastestreams that contain the same pollutant, but that are not regulated for that pollutant …. In these cases, based on the information in its record, EPA strongly recommends that in applying the building block approach or CWF to the regulated pollutant …, permitting authorities either treat the wastestream that does not have a limitation or standard for the pollutant … as a dilution flow or determine a concentration for that pollutant based on representative samples of that wastestream.” IDEM intends on following the recommendations set forth in the Technical Development Document.


B. pH The effluent pH is limited to between 6.0 and 9.0 s.u. pursuant to the BPT requirements established under 40 CFR 423.12(b)(1) and to ensure compliance with 327 IAC 2-1-6(b)(2)..

C. Total Suspended Solids (TSS) The current permit contains TSS limitations of 30 mg/l monthly average and 70 mg/l daily maximum at Outfall 002. These limits have remained the same since at least the 1985 NPDES permit. The fact sheets of the current and former permits were reviewed to determine the basis for these limitations in these permits. The rationale from each one is set forth below:

1985: “TSS is limited to 30 mg/l average, 70 mg/l maximum. The maximum TSS limitations is set at 70 mg/l to consider coal pile runoff and comply with 423.12(b)(12).”

1990: “This limitation is unchanged from the previous permit. The maximum TSS limitation is set at 70 MG/L to consider the presence of coal pile runoff and comply with 423.12(b)(12).”

2007: “TSS limits for Daily Maximum, in the permit are more stringent than the effluent limit guidelines in 40 CFR 423.12. Therefore, in accordance with anti-backsliding requirements set forth in 327 IAC 5-2-10(11), the existing limits shall remain in the permit.”

2013: To summarize, in this fact sheet, a version of the combined wastestream formula was used to calculate TSS limits. The calculation was based on three wastestreams, coal pile runoff, low volume wastewaters, and fly ash transport wastewater. For the coal pile runoff, a daily maximum of 50 mg/l and a flow of 90 gpm was used. For the low volume wastewaters and fly ash transport wastewaters, an average of 30 mg/l (from the effluent limitations guidelines) and a maximum of 70 mg/l (“as set by the previous and current draft NPDES permit for Outfall 002”) was used. The combined flow used for the low volume and fly ash wastewaters was 6,210 gpm. The calculation resulted in an average limit of 30.28 mg/l which was rounded to 30 and a maximum limit of 69.71 mg/l which was rounded to 70.

At IDEM’s request, the permittee provided estimated TSS limits for future site conditions in its application using the combined wastestream formula. A number of the anticipated future site changes incorporated into these calculations have already been implemented in whole or part. Also, this portion of the application provided data for the various wastestreams which contribute to this outfall which had not been provided in previous

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applications. The resulting TSS limits from the permittee’s calculations included in the application were 31 mg/l monthly average and 97 mg/l daily maximum. In its calculations, for the low volume waste sources and the combustion residual leachate, the permittee proposed using the effluent limitation guidelines limitations of 30 mg/l monthly average and 100 mg/l daily maximum. These are the BPT limits applicable to these wastestreams. For the coal pile runoff, the permittee proposed using 50 mg/l as both the daily maximum and monthly average [the BPT effluent limitations guidelines establish 50 mg/l as an instantaneous or absolute maximum limitation, not a daily maximum. The guidelines do not establish an average limit for this wastestream]. In an August 22, 1985 EPA memo providing Guidance for NPDES Permits Issued to Steam Electric Power Plants from Rebecca W. Hanmer to Regional Water Management Division Directors and State NPDES Directors; EPA provided a number of examples demonstrating the application of these BPT TSS limits. In one of the examples “Case II”, there were a number of wastestreams contributing to the discharge, including coal pile runoff. In this example, both the daily average and daily maximum TSS limit for coal pile runoff was set as 30 mg/l in the calculation stating that as BPJ, “that 30 mg/l as both daily average and daily maximum is equivalent to the guideline limit of 50 mg/l as an instantaneous maximum.” Therefore, 30 mg/l will be used in the calculations in this permit as the monthly average and daily maximum contribution from coal pile runoff. [Statistically, a daily maximum, which is the average of all samples taken in a day, is significantly different than an absolute or instantaneous maximum—which is the maximum value of all samples taken in a day. A monthly average, the average of all samples taken in a month, is different than a daily maximum. A common ratio used in NPDES for the difference between a daily maximum and a monthly average is 2:1, which means that a daily maximum limit will typically be twice a monthly average limit. Application of the statistical procedures in the EPA Technical Support Document for Water Quality-based Toxics Control, March 1991, commonly result in a ratio between the daily maximum and monthly average WQBEL of approximately of 2:1. These statistical procedures are also the procedures that EPA uses when developing technology-based limits. Similar statistical procedures could be applied to the 50 mg/l instantaneous maximum TSS limit applicable to coal pile runoff to derive daily maximum and monthly average values which are equivalent to this instantaneous maximum limit for use in the calculation of the TSS limits for this outfall. However, as indicated above, IDEM has chosen to use the recommendations set forth in EPA’s memo instead of applying these statistical procedures.] The permittee proposed including the sanitary wastewater (Outfall 102) as dilution flow (which means that a concentration of 0 mg/l of TSS would be allocated to this wastestream). Since this permit is including TSS limits at Outfall 102 of 30 mg/l monthly average and 60 mg/l daily maximum, the below calculations include an allocation for TSS for this wastestream. The allocation will be 3 mg/l monthly average and 6 mg/l daily maximum, based on an assumption that the new treatment system will have a removal rate for TSS of 90%. Also, the permittee proposed considering general plant stormwater which discharges through this outfall as an “unregulated flow;” which, with a strict application of the combined wastestream formula, indirectly resulted in this stormwater receiving an allocation of 31.1 mg/l as a monthly average and 97 mg/l as a daily maximum. In the permittee’s request, with respect to TSS, it stated “[n]on-regulated plant stormwater

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flows are designated as unregulated flows for TSS because the pollutant is expected to be present, considering that construction related to the on-going ELG facility changes that will continue into 2023.” As recommended by the Technical Development Document for the Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category, IDEM is going to take the approach that wastestreams which do not have a regulatory limitation or standard for a pollutant will either be treated as a dilution flow or a concentration for that pollutant will be determined based on representative samples or other data/information. In discussions with the permittee, the permittee agreed that gathering additional data is necessary to determine the appropriate allocation for total suspended solids for this wastestream. The data needed for this determination would be the total suspended solids concentrations of the stormwater flows discharging to this treatment system and the removal rate for total suspended solids of the new treatment system.

Wastestream Category Flow (gpm)

TSS Limit/Allocation (mg/l)

Flow times Concentration

Monthly Average

Daily Maximum Avg Max

Landfill Leachate Combustion Residual Leachate 13 30 100 390 1,300

General Plant Stormwater Not regulated 735 ? ? X Y

Coal Yard Diversion Sump Stormwater

Coal Yard Runoff 92 30 30 2,760 2,760

Permutit Sump (Demineralizer)

Low Volume Waste Source 460 30 100 13,800 46,000

Car Dumper Sump

Low Volume Waste Source 0.2 30 100 6 20

Reclaim Hopper Sump


Plant Drains Low Volume Waste Source 177 30 100 5,310 17,700

Main Sanitary Sump Not regulated 3 3 6 9 18

SFC Loadout Sump

Low Volume Waste Source 1 30 100 30 100

Boiler Area Sump Low Volume Waste Source 864 30 100 25,920 86,400

TOTAL: 2,345.4 TOTAL: 48,231 + X

154,318 + Y

The above table includes the wastestreams that the permittee identified in its combined wastestream formula calculations. Wastewater from fly ash transport water and bottom ash transport water were not included in the permittee’s calculation or in the above table. The permittee has converted or is in the process of converting these two wastestreams to zero discharge systems. However, they are still authorized to discharge these two wastestreams through this outfall until the respective compliance deadlines.

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On May 4, 2018, the permittee provided updated information on the anticipated flows of bottom ash transport water which would discharge through Outfall 002 with the dry bottom ash handing system installed (although the dry bottom ash handling system has been installed and is operational, the permittee is not yet able to meet zero discharge from this system. The permittee is required to comply with the zero discharge requirement for this wastestream by December 31, 2021). Therefore, with the dry bottom ash handling system installed, the permittee anticipates that overflows and leakages from the system will be 22,560 gpd [16 gpm]. The permittee also explained that there are a number of anticipated intermittent leaks and events, such as ash line leaks, ash hopper leaks, pyrite jet pump failures, and DBA blowdown events, that are expected to occur and that the permittee will be learning to control over the next three years. Those intermittent events could result in additional discharges as high as approximately 60,000 gpd (for a total discharge of 82,560 gpd [57 gpm] including more common overflows and leakage). If the bottom ash overflow system failed, the permittee would anticipate a discharge as high as 174,720 gpd [121 gpm], assuming the failure could be repaired very quickly (less than 8 hours). The bottom ash transport water is subject to the 30 mg/l monthly average and 100 mg/l daily maximum BPT limitations for TSS. The facility has and is undergoing considerable changes which impact this outfall. Their flow at this outfall has decreased/is decreasing significantly primarily due to the installation of a dry system for fly ash and a closed loop system for their bottom ash (these changes are not yet fully implemented). Further, they have just constructed a new treatment system to replace their existing ash ponds. They will start using this new treatment system in March or April 2018. In addition, there will be significant construction activity at the site while they close their ash ponds, which could impact the levels of total suspended solids in the storm water contributing to this outfall. However, the permittee does not currently have data to demonstrate that these changes justify higher permit limits for total suspended solids at this outfall. If a monthly average and daily maximum allocation of 0 mg/l was used for the general plant storm water wastestream, the resulting total suspended solids permit limits would be 21 mg/l monthly average and 66 mg/l daily maximum [the addition of the bottom ash transport water to these calculations, would at most change these to 21 mg/l monthly average and 67 mg/l daily maximum]; while if a monthly average of 31.1 mg/l and a daily maximum of 97 mg/l was used as indirectly proposed by the permittee in its application, the resulting total suspended solids limits would be 30 mg/l and 96 mg/l as the monthly average and daily maximum, respectively [the addition of the bottom ash transport water to these calculations would not change these values]. [For this type of wastestream, storm water, an allocation of 0 mg/l would not be a reasonable assumption] As indicated above, the permittee is going to collect data to determine the appropriate allowance for total suspended solids for the general plant stormwater contributing to this outfall. A reopening clause will be included in the permit to allow the permit to be modified or revoked and reissued to revise these total suspended solids limits based on the data that is collected and any other data provided by the permittee. If the permit is reopened and the TSS limits revised prior to the date that the permittee is required to meet the zero discharge requirement for the bottom ash transport water, then the average flow and limits applicable to the discharge of bottom ash transport water would need to be included in these calculations.

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The permittee’s current TSS limits are 30 mg/l monthly average and 70 mg/l daily maximum. Based on effluent data for TSS for this outfall for the period from March 31, 2013 through January 31, 2018, the highest monthly average and the highest daily maximum TSS concentrations reported in the discharge are 23.7 mg/l and 41.9 mg/l, respectively. While the permittee is collecting this data, it is proposed to retain the limits from the permittee’s current permit of 30 mg/l monthly average and 70 mg/l daily maximum.

D. Oil and Grease The current permit contains oil and grease limitations of 15 mg/l monthly average and 20 mg/l daily maximum at Outfall 002. These limits have remained the same since at least the 1985 NPDES permit. As with the TSS limits above, since this Outfall includes both wastestreams subject to federal effluent guidelines limitations as well as wastestreams which are not subject to such limitations, the effluent limitations at Outfall 002 have to be calculated using the applicable BPT limitations for those wastestreams subject to those limits and determining an appropriate allocation for oil and grease for those wastestreams not subject to the effluent limitations guidelines. At IDEM’s request, the permittee provided estimated oil and grease limits for future site conditions in its application using the combined wastestream formula. A number of the anticipated future site changes incorporated into these calculations have already been implemented in whole or part. Also, this portion of the application provided data for the various wastestreams which contribute to this outfall which had not been provided in previous permit applications. The resulting oil and grease limitations from the permittee’s calculations included in its application were 10.3 mg/l monthly average and 13.7 mg/l daily maximum. For the low volume waste sources and the combustion residual leachate, the permittee proposed using the effluent limitation guidelines limitations of 15 mg/l monthly average and 20 mg/l daily maximum, which are the BPT limits applicable to these wastestreams. For the coal pile runoff, the permittee used 0 mg/l as both the daily maximum and monthly average. The permittee proposed including the sanitary wastewater as dilution flow (which means that a concentration of 0 mg/l of oil and grease would be allocated to this wastestream). For the majority of the plant stormwater contributing to this outfall, the permittee appropriately considered it a dilution flow (which means that a concentration of 0 mg/l of oil and grease would be allocated to this wastestream). For the portion of stormwater flow from drainage areas with oil or petroleum sources, the permittee proposed that it be treated as “unregulated flow;” which, with a strict application of the combined wastestream formula, indirectly resulted in this stormwater receiving an allocation of 10.3 mg/l monthly average and 13.7 mg/l daily maximum in the permittee’s calculations. Since this wastestream has a low flow in relation to the other flows contributing to this outfall, the oil and grease concentrations assigned to this wastestream do not significantly change the resulting permit limitations. The resulting permit limits for oil and grease would be 10 mg/l monthly average, 13 mg/l daily maximum if a value of 0 mg/l is used for this wastestream or if values of 10.3 mg/l

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monthly average and 13.7 mg/l daily maximum are used, the resulting limits would be 10.1 mg/l monthly average and 13.5 mg/l daily maximum. For the purpose of this calculation, a value of 0 mg/l of oil and grease will be allocated to this wastestream. As is the case with total suspended solids, the permittee has agreed to gather additional data to determine the appropriate allocation for oil and grease for this wastestream. The data needed for this determination would be the oil and grease concentrations in the effluent from the oil water separators used to treat this storm water before it is discharged to the treatment system and the removal rate for oil and grease of the new treatment system.

Wastestream Category Flow (gpm)

Oil and Grease Limit/Allocation (mg/l)

Flow times Concentration

Monthly Average

Daily Maximum Avg Max

Landfill Leachate Combustion Residual Leachate 13 15 20 195 260

General Plant Stormwater

Not Regulated/Dilution 642 0 0 0 0

Stormwater from Drainage Areas with Oil/Petroleum Sources

Not Regulated 93 0 0 0 0

Coal Yard Diversion Sump Stormwater

Coal Yard Runoff 92 0 0 0 0

Permutit Sump (Demineralizer)

Low Volume Waste Source 460 15 20 6,900 9,200

Car Dumper Sump Low Volume Waste Source 0.2 15 20 3 4

Reclaim Hopper Sump


Plant Drains Low Volume Waste Source 177 15 20 2,655 3,540

Main Sanitary Sump

Not Regulated/Dilution 3 0 0 0 0

SFC Loadout Sump Low Volume Waste Source 1 15 20 15 20

Boiler Area Sump Low Volume Waste Source 864 15 20 12,960 17,280

TOTAL: 2,345.4 TOTAL: 22,731 30,308

The above table includes the wastestreams that the permittee identified in its combined wastestream formula calculations. Wastewater from fly ash transport water and bottom ash transport water were not included. The permittee has converted or is in the process of converting these two wastestreams to zero discharge systems. However, they are still authorized to discharge these two wastestreams through this outfall until the respective compliance deadlines. On May 4, 2018, the permittee provided updated information on the anticipated flows of bottom ash transport water which would discharge through Outfall 002 with the dry bottom ash handing system installed (although the dry bottom ash handling system has been installed and is operational, the permittee is not yet able to meet zero discharge

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from this system. The permittee is required to comply with the zero discharge requirement for this wastestream by December 31, 2021). Therefore, with the dry bottom ash handling system installed, the permittee anticipates that overflows and leakages from the system will be 22,560 gpd [16 gpm]. The permittee also explained that there are a number of anticipated intermittent leaks and events, such as ash line leaks, ash hopper leaks, pyrite jet pump failures, and DBA blowdown events, that are expected to occur and that the permittee will be learning to control over the next three years. Those intermittent events could result in additional discharges as high as approximately 60,000 gpd (for a total discharge of 82,560 gpd [57 gpm] including more common overflows and leakage). If the bottom ash overflow system failed, the permittee would anticipate a discharge as high as 174,720 gpd [121 gpm], assuming the failure could be repaired very quickly (less than 8 hours). The bottom ash transport water is subject to the 15 mg/l monthly average and 20 mg/l daily maximum BPT limitations for oil and grease. The bottom ash transport water wastestream was not included in the above table; however, the oil and grease limits discussed in this section and proposed in the permit would not change even if this wastestream was included in these calculations. The facility has and is undergoing considerable changes which impact this outfall. Their flow at this outfall has decreased/is decreasing significantly primarily due to the installation of a dry system for fly ash and a closed loop system for their bottom ash (these changes are not yet fully implemented). Further, they have just constructed a new treatment system to replace their existing ash ponds. They will start using this new treatment system in March or April 2018. As indicated above, the permittee may collect data to determine the appropriate allowance for oil and grease for the stormwater from drainage areas with oil/petroleum sources contributing to this outfall. A reopening clause will be included in the permit to allow the permit to be modified or revoked and reissued to revise these oil and grease limits based on the data that is collected and any other data provided by the permittee. If the permit is reopened and the oil and grease limits revised prior to the date that the permittee is required to meet the zero discharge requirement for the bottom ash transport water, then the average flow and limits applicable to the discharge of bottom ash transport water would need to be included in these calculations. Using the above data, the proposed limits for oil and grease in this permit will be 10 mg/l monthly average and 13 mg/l daily maximum. The permittee’s current oil and grease limits are 15 mg/l monthly average and 20 mg/l daily maximum. Based on effluent data for oil and grease for this outfall, the oil and grease levels have been less than 5 mg/l.

E. Aluminum Monitoring for both dissolved and total recoverable aluminum is required in the current permit. Continued monitoring for both dissolved and total recoverable aluminum is proposed. IDEM has proposed the adoption of aquatic life criteria for aluminum under 327 IAC 2-1-6 (see second notice LSA document #14-58, Nov. 15, 2017); and in addition, EPA proposed updated aquatic life criteria for aluminum in July 2017 (see https://www.epa.gov/wqc/aquatic-life-criteria-aluminum). The water quality-based effluent limitations for aluminum at Outfall 002 based on these proposed criteria would be (if such permit limits were determined to be necessary):

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Basis

mg/l

Data Used Monthly Average

Daily Maximum

IDEM Proposed Criteria 10 20 Hardness of 299 (50th percentile)

EPA Proposed Criteria 3.2 6.4 Hardness of 299, pH of 8.2 (average) and dissolved organic carbon of 2.97 (10th percentile, Wabash River Vigo County)

F. Ammonia (as N) Ammonia monitoring is required by the current permit. Based on the effluent data, ammonia does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, limits will not be included in this permit. Monitoring requirements will be retained.

G. Arsenic Arsenic monitoring is required by the current permit. Based on the effluent data, arsenic does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, limits will not be included in this permit. Monitoring requirements will be retained.

H. Bromide Bromide monitoring is proposed in this permit. Bromide is naturally present in some types of coal. IDEM has started including bromide monitoring in NPDES permits for coal-fired power plants to gather information on the levels of bromide being discharged at these types of facilities in Indiana. Based on recent studies, the presence of bromide in surface waters has created an issue for some surface water-based public water supplies. The presence of bromide, combined with the use of chlorine in the treatment process, results in the formation of brominated and mixed chlorinated-brominated disinfection byproducts. In general, brominated disinfection byproducts have higher health risks than chlorinated disinfection by-products. See Section 14.4 Site Specific Water Quality-Based Effluent Limitations, U.S. EPA Technical Development Document for the Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category, September 2015 for a comprehensive discussion. There are no surface water-based public water supplies on the Wabash River downstream of this facility, therefore, the presence of bromide in the effluent should not impact any public water supplies. However, as indicated above, IDEM is gathering information on the level of bromide present in the discharges from this type of facility.

I. Cadmium Monitoring for cadmium is required in the current permit. Continued monitoring for cadmium is proposed. IDEM has proposed to revise the aquatic life criteria for cadmium under 327 IAC 2-1-6 (see second notice LSA document #14-58, Nov. 15, 2017). The water quality-based effluent limitations for cadmium at Outfall 002 based on these proposed criteria would be (if such permit limits were determined to be necessary):

Parameter Monthly Average (µg/l) Daily Maximum (µg/l) Cadmium 2 3

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J. Chloride Chloride monitoring is required by the current permit. Based on the effluent data, chloride does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, limits will not be included in this permit. Monitoring requirements will be retained.

K. Total Residual Chlorine Total residual chlorine monitoring is required by the current permit. Based on the effluent data, total residual chlorine does demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, the following limits are proposed to be included in this permit.

Parameter Monthly Average (µg/l) Daily Maximum (µg/l) Total Residual Chlorine 20 40

These water quality-based effluent are less than the limit of quantitation (LOQ) of 0.06 mg/l for this parameter. Pursuant to 327 IAC 5-2-11.1(f)(1), the permittee will be required to use an approved analytical methodology for total residual chlorine and the permit is required to contain certain conditions specified under this subsection of the rule. In addition, the permit shall contain provisions allowing the permit to be reopened to include additional requirements or limitations if the information gathered indicates that such additional requirements or limitations are necessary.

L. Copper The current permit includes water quality-based effluent limitations for copper of 0.04 mg/l monthly average and 0.10 mg/l daily maximum that are applicable only when metal cleaning wastes are discharged from the ash pond. Federal effluent guidelines, under 423.12(b)(5) (BPT) and 40 CFR 423.13(e) (BAT) established 1.0 mg/l as both a monthly average and a daily maximum which are applicable when metal cleaning wastes are discharged. Since copper is very toxic to aquatic life, water quality-based limits for copper were established in lieu of the BPT and BAT limitations to ensure that copper would not be discharged in toxic amounts. Since the permittee has discontinued the discharge of any metal cleaning wastes, BPT and BAT limitations for copper are no longer required. Based on the effluent data, copper does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits for copper. Since the copper limits in the current permit were only applicable when metal cleaning wastes were being discharged and since metal cleaning wastes will no longer be discharged through this outfall, these limits are being removed from the permit. However, the monitoring requirement for copper will be retained.

M. Iron The current permit includes a limitation for iron of 1.0 mg/l as both a monthly average and a daily maximum which are applicable when metal cleaning wastes are discharged from the ash pond. These limits were established to comply with BPT limitations for iron for metal cleaning wastes established under 40 CFR 423.12(b)(5) and BAT limitations for iron for metal cleaning wastes established under 40 CFR 423.13(e). Since the permittee

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has stopped discharging any metal cleaning wastes at the facility, these limitations are proposed to be removed from the permit. In addition, the current permit requires monitoring for iron during periods when metal cleaning wastes are not being discharged. Based on the effluent data, iron does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, limits will not be included in this permit. The permit also proposes to eliminate the monitoring requirement for iron at this outfall.

N. Mercury Mercury monitoring is required by the current permit. Based on the effluent data, mercury does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, limits will not be included in this permit. Monitoring requirements will be retained.

O. Selenium Selenium monitoring is required by the current permit. Based on the effluent data, selenium does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, limits will not be included in this permit. Monitoring requirements will be retained. Also, EPA recently released a final updated recommended national chronic aquatic life criteria for selenium that IDEM is proposing to adopt (see second notice LSA document #14-58, Nov. 15, 2017). This final EPA criteria document and proposed IDEM criteria establishes a chronic water column criterion for selenium of 3.1 µg/l.

P. Sulfate Sulfate monitoring is required by the current permit. Based on the effluent data, sulfate does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, limits will not be included in this permit. Monitoring requirements will be retained.

Q. Zinc Zinc monitoring is required by the current permit. Based on the effluent data, zinc does not currently demonstrate a reasonable potential to exceed water quality-based effluent limits; therefore, limits will not be included in this permit. Monitoring requirements will be retained.

R. Storm Water Requirements Since storm water is a significant component of this Outfall, as is the case with the current permit, storm water specific monitoring and non-numeric effluent limits and a storm water pollution prevention plan are applicable to this Outfall. See Section 5.7 of this Fact Sheet for additional information.

5.3.5 Outfall 102 Treated Sanitary Wastewater This internal outfall consists of treated sanitary wastewater and discharges to the new lined retention basin system prior to its eventual discharge through Outfall 002. Outfall 002 consists of a variety of different wastestreams; however, the majority of the flow at Outfall 002 consists of storm water and the discharge from the boiler systems demineralizer water treatment system.

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Based on the water balance information submitted with the permit application, the treated sanitary wastewater discharge is 3 gpm (about 0.004 MGD) while the flow of Outfall 002 is 2,335 gpm (about 3.4 MGD), a dilution ratio of about 780:1. Based on DMR data (September 2012 through July 2017), the average flow at Outfall 102 is 0.0027 MGD while the average flow at Outfall 002 is 5.9 MGD; which results in a dilution ratio of 2,160:1. This internal outfall is governed by the small sanitary discharge requirements under 327 IAC 5-10-5 and the disinfection requirements under 327 IAC 5-10-6. Under 327 IAC 5-10-5, IDEM rules establish requirements for discharges from continuous discharge sanitary wastewater treatment facilities with a design flow of 0.05 MGD or less. Under 327 IAC 5-10-5(c), “industrial plants with small sanitary discharges mixing with nontoxic, nonorganic, nonnutrient containing wastewaters, such as cooling water, ash sluicing, etc. prior to discharge may use the other wastewaters as dilution” in applying the small sanitary discharge limitations. With a dilution ration of about 780:1 (or 2,160:1) provided by the other wastestreams contributing to Outfall 002, the applicable monthly average and daily maximum limitations for Outfall 102 determined pursuant to 327 IAC 5-10-5(a) are as follows:

Parameter Monthly Average

Daily Maximum Units

CBOD5 25 40 mg/l Total Suspended Solids (TSS) 30 60 mg/l

The provisions of 327 IAC 5-10-6(a)(5)(B) contains a procedure for calculating weekly average limits by multiplying the monthly average limit from subsection (a) of the rule by a factor of 1.5. However, in industrial permits, limits are typically expressed in terms of a daily maximum limit rather than a weekly average limit, and are typically obtained by multiplying the monthly average limit by a factor of 2. The daily maximum TSS limit in the above table was obtained by multiplying the monthly average limit of 30 mg/l by 2 to obtain a daily maximum limit of 60 mg/l. For CBOD5, the daily maximum limit in the permit at this Outfall has been 40 mg/l in the current permit and, with the exception of a violation of the daily maximum and monthly average limit for BOD in February 2015, the permittee has been in compliance with this limitation, therefore, this daily maximum limitation will be retained in this permit. Disinfection requirements applicable to sanitary dischargers are found under 327 IAC 5-10-6. This rule requires that sanitary wastewater discharges be disinfected from April 1 through October 31. This disinfection rule does require dechlorination when chlorine is used as the disinfectant (chlorine is used at the disinfectant at this outfall). However, the reason that this rule requires dechlorination is to ensure that toxic levels of chlorine are not discharged to Indiana waters. Since the discharge volume of this sanitary wastestream is very small in relation to the other wastestreams contributing to Outfall 002, requiring dechlorination at this outfall to meet WQBELs for total residual chlorine is not needed. However, total residual chlorine monitoring has been added to this outfall to determine the levels of total residual chlorine in the effluent from this internal outfall. The applicable limits for E. coli are established at 327 IAC 5-10-6(e). The concentration of E. coli in the undiluted discharge shall not exceed one hundred twenty-five (125) cfu or MPN per one hundred (100) milliliters as a geometric mean of the effluent samples taken in a

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calendar month. When not less than ten (10) samples are taken and analyzed for E. coli in a calendar month, not more than ten percent (10%) of the samples shall exceed two hundred thirty-five (235) cfu or MPN per one hundred (100) milliliters as a daily maximum. Under this provision, the calculation of ten percent (10%) of the samples taken shall be limited to the lowest whole number result. If less than 10 samples are taken and analyzed for E. coli in a month, all samples shall be less than or equal to 235 cfu or MPN in that month. In addition, the limits for E. coli at this outfall are needed to implement the E. coli wasteload allocation for this facility from the September 2006, EPA-approved TMDL for the Wabash River.

5.3.6 Outfall 003 Intake Screen Backwash This Outfall, which is limited to backwash from the intake screen, does not have any monitoring requirements in the current permit and the only limits are the narrative water quality standards. The same requirements are proposed in this permit for this Outfall.

5.3.7 Outfall 004 Storm Water This Outfall, which is limited to storm water runoff, currently includes monitoring for a number of parameters and also requires compliance with non-numeric effluent limits and pollution prevention requirements.


B. Oil and Grease, CBOD5, Total Suspended Solids, pH, Total BTEX (Benzene, Toluene, ethylbenzene, and Xylene).

The current permit requires monitoring for Oil and Grease, CBOD5, Total Suspended Solids, pH, Total BTEX (benzene, toluene, ethylbenzene, and xylene). This permit will continue this monitoring.

C. Zinc In the monitoring results provided with the permittee’s renewal application, one sample result for zinc was included at 617 µg/l. Additional monitoring will be required in this permit for zinc to characterize the level of zinc present in the effluent. At a hardness of 250 mg/l, the current chronic and acute water quality criteria for zinc are 230 µg/l and 250 µg/l, respectively.

D. Storm Water Requirements Since this outfall consists of storm water, as is the case with the current permit, storm water specific monitoring and non-numeric effluent limits and a storm water pollution prevention plan are applicable to this Outfall. See Section 5.7 of this Fact Sheet for additional information regarding these requirements.

5.4 Whole Effluent Toxicity (WET) Testing The permit does not contain a requirement to conduct Whole Effluent Toxicity (WET) Testing.

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5.5 Antibacksliding In certain cases, 327 IAC 5-2-10(a)(11) [“Antibacksliding Rule”] prohibits a permit from being renewed which contains effluent limitations that are less stringent than limitations in the previous permit. This permit does not propose to increase any effluent limits; therefore, the antibacksliding prohibitions under 327 IAC 5-2-10(a)(11) are not applicable.

5.6 Antidegradation The purpose of Indiana’s antidegradation standard and implementation procedures, established under 327 IAC 2-1.3, is, in general, to protect and maintain the existing quality of Indiana’s surface waters. “Tier I” of Indiana’s antidegradation standard, 327 IAC 2-1.3-3(a), provides the floor of water quality in all surface waters of Indiana. This provision applies a minimum level of protection to all waters and requires the existing uses and level of water quality necessary to protect those existing uses to be maintained and protected for all surface waters of Indiana. IDEM implements the Tier 1 antidegradation standard by including within NPDES permits water quality-based effluent limits and implementation of best management practices (BMPs) for regulated pollutants that ensure the narrative and numeric water quality criteria applicable to each of the designated uses are achieved in the water and any designated uses of the downstream water are maintained and protected. “Tier 2” of Indiana’s antidegradation standard, 327 IAC 2-1.3-3(b), applies to those surface waters where the existing water quality for a parameter is better than the water quality criterion for that parameter established in 327 IAC 2-1-6 or 327 IAC 2-1.5. These surface waters are considered high quality for that parameter and this high quality is required to be maintained and protected unless IDEM finds that allowing a significant lowering of water quality is necessary and accommodates important social or economic development in the area in which the waters are located. In addition to the NPDES permit requirements for Tier I waters, IDEM implements the Tier 2 antidegradation standard for regulated pollutants through application of the antidegradation implementation procedures in 327 IAC 2-1.3-5 and 2-1.3-6 if there will be a proposed new or increased loading of a regulated pollutant to surface waters of the State from a deliberate activity subject to the Clean Water Act, including a change in process or operation that will result in a significant lowering of water quality. This NPDES permit does propose to add new water quality-based effluent limitations for ammonia and beryllium at Outfall 001 and total residual chlorine at Outfall 002. However, IDEM does not believe that the presence of these pollutants in these outfalls is due to any deliberate activity (such as a change in process or operation) on the part of the permittee. The current permit had required monitoring for these parameters. Based on the monitoring results that the permittee submitted as a result of this requirement, IDEM has determined that the pollutants are present in the effluent at levels that require the imposition of water quality-based effluent limitations. Since the presence of these pollutants in the effluent is not due to any deliberate activity on the part of the permittee, the Antidegradation Implementation Procedures in 327 IAC 2-1.3-5 and 2-1.3-6 do not apply to the permitted discharge. In addition, the permittee is prohibited from undertaking any deliberate action that would result in a new or increased loading of a bioaccumulative chemical of concern (BCC) or a new or increased loading for a regulated pollutant that is not a BCC unless information is

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submitted to the commissioner demonstrating that the proposed new or increased discharge will not cause a significant lowering of water quality, or an antidegradation demonstration submitted and approved in accordance 327 IAC 2-1.3-4.

5.7 Storm Water Under 327 IAC 5-4-6, if an individual permit is required under 327 IAC 5-4-6(a) for discharges consisting entirely of storm water, or if an individual permit is required under 327 IAC 5-2-2 that includes discharge of commingled storm water associated with industrial activity, IDEM may consider the following in determining the requirements to be contained in the permit:

(1) The provisions in the following: (A) 327 IAC 15-5, 327 IAC 15-6, and 327 IAC 15-13, as appropriate to the type of storm water discharge, (B) NPDES Pesticide General Permit for Point Source Discharges to Waters of the State from the Application of Pesticides, Permit Number ING870000, effective October 31, 2016, available at: http://www.in.gov/idem/cleanwater/2480.htm#pesticide or from the IDEM Office of Water Quality, Permits Branch, 100 North Senate Avenue, Indianapolis, IN 46204-2251, and (C) 327 IAC 5-2, 327 IAC 5-5, and 327 IAC 5-9 for establishing NPDES permit effluent limitations and conditions. (2) "Interim Permitting Approach for Water Quality-Based Effluent Limitations in Storm Water Permits", EPA 833-D-96-001, September 1, 1996, available from U.S. EPA/NSCEP, P.O. Box 42419, Cincinnati, Ohio 45242-0419 or from the department. (3) The nature of the discharges and activities occurring at the site or facility. (4) Other information relevant to the potential impact on water quality.

Under 327 IAC 15-2-2(a), the commissioner may regulate storm water discharges associated with industrial activity, as defined in 40 CFR 122.26(b)(14) consistent with the EPA 2008 NPDES Multi-Sector General Permit for Stormwater Discharges Associated with Industrial Activity, as modified, effective May 27, 2009, under an NPDES general permit. Using best professional judgment as authorized under 327 IAC 5-2-10 and 5-5 (which implement 40 CFR 122.44, 125.3, and Section 402(a)(1) of the Clean Water Act (CWA)), IDEM has developed storm water requirements for individual permits that are consistent with the EPA 2008 NPDES Multi-Sector General Permit for Stormwater Discharges Associated with Industrial Activity, as allowed in 327 IAC 15-2-2(a). According to 40 CFR 122.26(b)(14) and 327 IAC 15-6-2 facilities classified under Industrial Classification (SIC) Code 4911 are considered to be engaging in “industrial activity” for purposes of 40 CFR 122.26(b). Therefore, the permittee is required to have all storm water discharges associated with industrial activity permitted. Treatment for storm water discharges associated with industrial activities is required to meet, at a minimum, best available technology economically achievable/best conventional pollutant control technology (BAT/BCT) requirements. EPA has determined that non-numeric technology-based effluent limits have been determined to be equal to the best practicable technology (BPT) or BAT/BCT for storm water associated with industrial activity. Storm water associated with industrial activity must be assessed to determine compliance with all water quality standards. The non-numeric storm water conditions and effluent limits contain the technology-based effluent limitations. Effluent limitations, as defined in the CWA, are restrictions on quantities, rates, and concentrations of constituents which are discharged. Effective implementation of these requirements should meet the applicable

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water quality based effluent limitations. Violation of any of these effluent limitations constitutes a violation of the permit. Additionally, IDEM has determined that with the appropriate implementation of the required control measures and Best Management Practices (BMPs) found in Part I.D. of the permit, the discharge of storm water associated with industrial activity from this facility will meet applicable water quality standards and will not cause a significant lowering of water quality. Therefore, the storm water discharge is in compliance with Antidegradation Standards and Implementation Procedures found in 327 IAC 2-1.3 and an Antidegradation Demonstration is not required. The technology-based effluent limitations require the permittee to minimize exposure of raw, final, or waste materials to rain, snow, snowmelt, and runoff. In doing so, the permittee is required, to the extent technologically available and economically achievable, to either locate industrial materials and activities inside or to protect them with storm resistant coverings. In addition, the permittee is required to: (1) use good housekeeping practices to keep exposed areas clean, (2) regularly inspect, test, maintain and repair all industrial equipment and systems to avoid situations that may result in leaks, spills, and other releases of pollutants in storm water discharges, (3) minimize the potential for leaks, spills and other releases that may be exposed to storm water and develop plans for effective response to such spills if or when they occur, (4) stabilize exposed area and contain runoff using structural and/or non-structural control measures to minimize onsite erosion and sedimentation, and the resulting discharge of pollutants, (5) divert, infiltrate, reuse, contain or otherwise reduce storm water runoff, to minimize pollutants in the permitted facility discharges, (6) enclose or cover storage piles of salt or piles containing salt used for deicing or other commercial or industrial purposes, including maintenance of paved surfaces, (7) train all employees who work in areas where industrial materials or activities are exposed to storm water, or who are responsible for implementing activities necessary to meet the conditions of this permit (e.g., inspectors, maintenance personnel), including all members of your Pollution Prevention Team, (8) ensure that waste, garbage and floatable debris are not discharged to receiving waters by keeping exposed areas free of such materials or by intercepting them before they are discharged, and (9) minimize generation of dust and off-site tracking of raw, final or waste materials. To meet the non-numeric effluent limitations in Part I.D.4, the permit requires the facility to select control measures (including BMPs) to address the selection and design considerations in Part I.D.3. The permittee must control its discharge as necessary to meet applicable water quality standards. It is expected that compliance with the non-numeric effluent limitations and other terms and conditions in this permit will meet this effluent limitation. However, if at any time the permittee, or IDEM, determines that the discharge causes or contributes to an exceedance of applicable water quality standards, the permittee must take corrective actions, and conduct follow-up monitoring.

“Terms and Conditions” to Provide Information in a Storm Water Pollution Prevention Plan (SWPPP) Distinct from the effluent limitation provisions in the permit, the permit requires the discharger to prepare a Storm Water Pollution Prevention Plan (SWPPP) for the permitted facility. The SWPPP is intended to document the selection, design, installation, and implementation (including inspection, maintenance, monitoring, and corrective action) of

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control measures being used to comply with the effluent limits set forth in Part I.D. of the permit. In general, the SWPPP must be kept up-to-date, and modified when necessary, to reflect any changes in control measures that were found to be necessary to meet the effluent limitations in the permit. The requirement to prepare a SWPPP is not an effluent limitation, rather it documents what practices the discharger is implementing to meet the effluent limitations in Part I.D. of the permit. The SWPPP is not an effluent limitation because it does not restrict quantities, rates, and concentrations of constituents which are discharged. Instead, the requirement to develop a SWPPP is a permit “term or condition” authorized under sections 402(a)(2) and 308 of the Act. Section 402(a)(2) states, “[t]he Administrator shall prescribe conditions for [NPDES] permits to assure compliance with the requirements of paragraph (1) of this subsection, including conditions on data and information collection, reporting, and such other requirements as he deems appropriate.” The SWPPP requirements set forth in this permit are terms or conditions under the CWA because the discharger is documenting information on how it intends to comply with the effluent limitations (and inspection and evaluation requirements) contained elsewhere in the permit. Thus, the requirement to develop a SWPPP and keep it up-to-date is no different than other information collection conditions, as authorized by Section 402(a)(2) of the Clean Water Act. It should be noted that EPA has developed a guidance document, “Developing your Storm Water Pollution Prevention Plan – A guide for Industrial Operators (EPA 833-B09-002), February 2009, to assist facilities in developing a SWPPP. The guidance contains worksheets, checklists, and model forms that should assist a facility in developing a SWPPP.

Public availability of documents Part I.E.2.d(2) of the permit requires that the permittee retain a copy of the current SWPPP at the facility and it must be immediately available, at the time of an onsite inspection or upon request, to IDEM. Additionally, interested persons can request a copy of the SWPPP through IDEM. By requiring members of the public to request a copy of the SWPPP through IDEM, the Agency is able to provide the permittees with assurance that any Confidential Business Information contained within the permitted facility’s SWPPP is not released to the public.

5.8 Water Treatment Additives In the event that changes are to be made in the use of water treatment additives that could significantly change the nature of, or increase the discharge concentration of any of the additives contributing to Outfalls 001 or 002 the permittee must apply for and obtain approval from IDEM prior to such discharge. Discharges of any such additives must meet Indiana water quality standards. The permittee must apply for permission to use water treatment additives by completing and submitting State Form 50000 (Application for Approval to Use Water Treatment Additives) available at: http://www.in.gov/idem/5157.htm. In the review and approval process, IDEM determines, based on the information submitted with the application, whether the use of any new or changed water treatment additives/chemicals or dosage rates could potentially cause the discharge from any permitted outfall to cause chronic or acute toxicity in the receiving water. The authority for this requirement can be found under one or more of the following: 327 IAC 5-2-8(11)(B), which generally requires advance notice of any planned changes in the

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permitted facility, any activity, or other circumstances that the permittee has reason to believe may result in noncompliance with permit requirements; 327 IAC 5-2-8(11)(F)(ii), which generally requires notice as soon as possible of any planned physical alterations or additions to the permitted facility if the alteration or addition could significantly change the nature of, or increase the quantity of, pollutants discharged; and 327 IAC 5-2-9(2) which generally requires notice as soon as the discharger knows or has reason to know that the discharger has begun or expects to begin to use or manufacture, as an intermediate or final product or byproduct, any toxic pollutant that was not reported in the permit application. The following is a list of water treatment additives currently approved for use at the facility:

IDEM-APPROVED WATER TREATMENT ADDITIVES Supplier Name Outfall Purpose Date Approved

NALCO FERRALYTE 8130 Outfall 001 Coagulant-FGD Wastewater Treatment Feb. 1, 2010

NALCO NALMET 1689 Outfall 001 Water Clarification Aid; FGD Wastewater Treatment

Feb. 1, 2010 Nov. 18, 2010

NALCO NALCLEAR 7766 Plus Outfall 001 Anionic acrylamide copolymer (FGD

wastewater) Dec. 18, 2012

Hydrated Lime Outfall 001 pH Control Dec. 18, 2012

NALCO THRUGUARD THR404 Outfall 001

Prevent formation of calcium carbonate crystals and scale on the metallic surfaces of

heat exchangers

March 1, 2013 (approved in 2013 NPDES

permit)

NALCO NALCLEAR 7768 Outfall 002 Flocculate suspended solids in the bottom ash pond Nov. 23, 2015

NALCO Ultrion 8186 Outfall 002 Flocculate suspended solids in the bottom ash pond Nov. 23, 2015

Gaseous Carbon Dioxide Outfall 002 pH Control March 30, 2017

BioSafe Systems LLC* GreenClean Liquid 5.0 Outfall 002 Algaecide July 27, 2017

Brenntag Sodium Hydroxide 25% Outfall 002 pH control August 17, 2017

NALCO* Core Shell 71301 Outfall 002 Sludge Dewatering August 17, 2017

NALCO EN/ACT 7894 Outfall 002 Spot treatment of high total

suspended solids in the pond treatment system

March 22, 2018

NALCO OPTIMER 9901 Outfall 002 Spot treatment of high total

suspended solids in the pond treatment system

March 22, 2018

Sodium Bisulfite Solution Outfall 001 Shock the condensers to

treat chlorine March 22, 2018

Brenntag Sulfuric Acid 66 BE Outfall 002 pH Control March 28, 2018 *IDEM is currently reviewing these two water treatment additives (BioSafe Systems GreenClean Liquid 5.0 and NALCO Core Shell 71301) to determine whether or not approval is still warranted.

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6.0 Permit Draft Discussion

6.1 Effluent Limitations, Monitoring Conditions and Rationale 6.1.1 NPDES Renewal Application (Form 2C and Form 2E) For renewal of this permit, submittal of the IDEM 2C application form was applicable to Outfalls 001, 002, and 101. This application form requires submittal of certain analytical data under Item V. A, B, C. Part V.A must be completed by all applicants for all outfalls. The results of the analysis is required to include at least one sample for every pollutant in the table. Part V.B must be completed by all applicants for all outfalls. In this Part, for every pollutant for which the permittee has marked the parameter as “Believed Present”, the permittee is required to provide a minimum of 12 samples (3 samples per month for a period of 4 months). For every outfall which contains process wastewater (Outfall 001, 002 and 101), Part V.C must be completed by primary industries for all of the metals, cyanides, and total phenols as well as the organic fractions listed in Table 2C-2 of the application (facilities which are steam electric power plants are required to test for the volatile, acid, and base/neutral organic fractions). For every pollutant for which testing is either required or for which the permittee has marked a pollutant as “Believed Present”, the permittee is required to provide a minimum of 12 samples (3 samples per month for a period of 4 months). The permittee’s Form 2-C application did not include 12 sample results (3 samples per month for a period of 4 months) for the majority of the parameters at any of the outfalls. Further, for the Outfall 101, treated FGD wastewater, the permittee’s Form 2-C application did not include any sampling for many required parameters. Outfall 102, treated sanitary wastewater, required the submittal of Form 2E which is applicable to non-process wastewater discharges. Part IV of the form required the submittal of results for a number of listed parameters. The permittee’s Form 2E for this outfall did not include results for most of the listed parameters. For Outfall 101, if the permittee does not select the no discharge option for the treated flue gas desulfurization wastewater, the permit will require the permittee to submit a complete Form 2-C within 6 months of that decision. For Outfall 102, the permittee will be required to submit a complete Form 2E within 6 months of the effective date of the permit. 6.1.2 Effluent Limitations and Monitoring: Section 5.3 above, explains the rationale for the effluent limitations and monitoring at Outfall 001 and 002. 6.1.3 Analytical and Sampling Methods: Analytical and sampling methods used must comply with the version of 40 CFR 136 referenced in 327 IAC 5-2-13(d)(1) and incorporated by reference in 327 IAC 5-2-1.5. (Currently, IDEM rules incorporate by reference the July 1, 2011 version of this federal regulation. IDEM is in the process of updating this rule to incorporate by reference the July 1, 2016 version of 40 CFR 136. It is anticipated that this rulemaking will be effective May 15, 2018.) 6.1.4 Mass limits: Mass limits are typically required under 327 IAC 5-2-11(e). However, as provided under that section, if standards are expressed in terms other than mass, for example concentration levels, mass limits are not required. Pollutants limited in terms of mass additionally may be limited in terms of other units of measurement, and the permit shall require the permittee to comply with both limitations. The current permit does not contain any mass limits. This permit proposes to include mass limits (in addition to the new

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concentration limits) for ammonia (as N) and beryllium at Outfall 001. In addition, this permit proposes to add mass limits for chloride at Outfall 001. Mass limits are being included for these water-quality-based effluent limitations in this permit to ensure protection of the receiving water when the effluent flow rate at these outfalls exceeds the flow rate used to calculate the concentration-based water quality-based effluent limits determined in the wasteload allocation. 6.1.5 Total vs Total Recoverable Metals: The technology-based effluent limitations for metals under 40 CFR 423 are expressed in terms of “total” metal. The water quality-based effluent limitations for metals established in this permit are expressed in terms of “total recoverable” metals as required by 327 IAC 5-2-11.1(d). As stated under 40 CFR 136, Table 1B, Footnote 4, total metals are equivalent to total recoverable metals [Also, in an August 19, 1998 EPA memorandum From William A. Telliard to Pat Sosinski, it stated that EPA uses the term “total metal” and “total recoverable metal” “synonymously to refer to metals solubilized by digestion with strong solutions of mineral acids.”] Therefore, the technology-based effluent limitations for metals in this permit will be expressed as total recoverable metals. 6.1.6 Monitoring Frequency: For most parameters, the monitoring frequencies proposed in this permit are the same as the monitoring frequencies in the current permit; however, the following monitoring frequencies have changed:

Outfall 001: The current permit included monitoring for ammonia and beryllium. This permit is proposing water quality-based effluent limitations for the parameters. Since WQBELs are being added for these parameters, the monitoring frequency is proposed to be increased from 2 X monthly to weekly. Also, the sampling frequency for pH was 1 X monthly at this outfall. Since the monitoring frequency for ammonia and beryllium are being increased to weekly, this permit proposes to also increase the pH monitoring to weekly. Outfall 002: The current permit included monitoring for total residual chlorine. This permit is proposing water quality-based effluent limitations for the parameter. Since WQBELs are being added for this parameter, the monitoring frequency is proposed to be increased from 2 X monthly to weekly.

6.1.7 Sample Type: Typically, to ensure a representative sample of the effluent is collected, a 24-hour composite is used in NPDES permit, unless the parameter is one that requires the use of a grab sample, such as oil & grease, total residual chlorine and pH. In the current permit, at all outfalls, an 8-hour composite was required instead of a 24-hour composite (except that TSS required the use of a grab sample). To ensure that the samples collected are representative of the discharge, the 8-hour composite sample requirement is being changed to 24-hour composite sample at all outfalls. The sample type for TSS is being changed from a grab sample to a 24-hour composite sample at all outfalls.

6.1.8 Outfall 001


Daily Maximum Units

Minimum Frequency

Sample Type

Source of requirement

Flow Report Report MGD Daily 24-Hour Total 327 IAC 5-2-13(a)(2)

Total Suspended Solids (TSS)

Report Report mg/l 2 X Monthly 24-Hr. Comp BPJ

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Daily Maximum Units

Minimum Frequency

Sample Type


Oil & Grease Report Report mg/l 2 X Monthly Grab BPJ

Upstream Flow Report Report MGD Daily Gauge WQBEL/316(a) Temperature-Upstream NA Report °F Hourly Instantaneous WQBEL/316(a)

Temperature-Effluent NA Report °F Continuous Report WQBEL/316(a)

Temperature-Downstream NA Report °F Continuous Report WQBEL/316(a)

Total Residual Chlorine-Continuous

10 20 µg/l Daily Grab WQBEL

Total Residual Chlorine-Intermittent

NA 0.2 mg/l Daily Grab WQBEL/TBEL

Total Residual Oxidants (Bromine)

0.11 0.28 µg/l Daily Grab WQBEL

Chlorination-Frequency NA 4 times/day Daily Report WQBEL

Chlorination-Dose Duration NA 40 minutes/

dose Daily Report WQBEL

Chlorination-Duration/Day NA 120 minutes/

day Daily Report TBEL

Bromination-Frequency NA Report times/day Daily Report BPJ

Bromination -Dose Duration NA Report minutes/

dose Daily Report BPJ

Bromination -Duration/Day NA Report minutes/

day Daily Report BPJ

Aluminum, Dissolved Report Report mg/l 2 X

Monthly 24-Hr. Comp BPJ

Aluminum, Total Recoverable Report Report mg/l 2 X


Ammonia (as N) Summer Winter

0.77 1.4

1.9 3.5

mg/l mg/l

Weekly 24-Hr. Comp WQBEL

Ammonia (as N) Summer Winter

5,200 9,400

13,000 24,000

lbs/day lbs/day

Weekly 24-Hr. Comp WQBEL

Beryllium, Total Recoverable 2.1 5.2 µg/l Weekly 24-Hr. Comp WQBEL

Beryllium, Total Recoverable 14 35 lbs/day Weekly 24-Hr. Comp WQBEL

Bromide Report Report µg/l 2 X Monthly 24-Hr. Comp BPJ

Chloride 410 710 mg/l 2 X Monthly 24-Hr. Comp WQBEL

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Daily Maximum Units

Minimum Frequency

Sample Type


Chloride 2,800,000 4,800,000 lbs/day 2 X Monthly 24-Hr. Comp WQBEL

Iron, Total Recoverable Report Report mg/l 2 X


Mercury, Total Recoverable 12 20 ng/l 6 X Yearly 24-Hr. Comp WQBEL

Selenium Report Report µg/l 2 X Monthly 24-Hr. Comp BPJ

Parameter Daily

Minimum Daily

Maximum Units Minimum

Frequency Sample

Type Source of

requirement pH 6.0 9.0 Std Units Weekly Grab WQBEL

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6.1.9 Outfall 101


Daily Maximum Units

Minimum Frequency

Sample Type




30 100 mg/l 2 X Monthly 24-Hr. Comp TBEL

Oil & Grease 15 20 mg/l 2 X Monthly Grab TBEL

Ammonia (as N) Report Report mg/l 2 X Monthly 24-Hr. Comp BPJ

Arsenic, Total Recoverable1,2 NA 85 µg/l 2 X

Monthly 24-Hr. Comp BPJ-TBEL

Beryllium, Total Recoverable Report Report µg/l 2 X


Boron, Total Report Report mg/l 2 X Monthly 24-Hr. Comp BPJ

Cadmium, Total Recoverable NA 59 µg/l 2 X


Chloride Report Report mg/l 2 X Monthly 24-Hr. Comp BPJ

Chromium, Total Recoverable NA 361 µg/l 2 X


Copper, Total Recoverable NA 50 µg/l 2 X


Lead, Total Recoverable NA 11 µg/l 2 X


Manganese, Total Recoverable

Report Report mg/l 2 X Monthly 24-Hr. Comp BPJ

Mercury, Total Recoverable1,2 NA 50 µg/l 6 X Yearly Grab BPJ-TBEL

Nitrate/Nitrite (as N)1 Report Report mg/l 2 X


Selenium, Total Recoverable1,2 Report Report mg/l 2 X


Total Dissolved Solids (TDS)2 Report Report mg/l 2 X


Zinc, Total Recoverable Report Report mg/l 2 X


Parameter Daily

Minimum Daily


Frequency Sample

Type Source of

requirement

pH 6.0 9.0 Std Units

2 X Monthly Grab TBEL

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1The following BAT limits will apply on May 31, 2023 if the Permittee does not opt into the Voluntary Incentive Program:


Daily Maximum Units

Minimum Frequency

Sample Type


Arsenic, Total Recoverable 8 11 µg/l 2 X

Monthly 24-Hr. Comp TBEL

Mercury, Total Recoverable 356 788 ng/l 6 X Yearly Grab TBEL

Selenium, Total Recoverable 12 23 µg/l 2 X


Nitrate/nitrite as N 4.4 17 mg/l 2 X Monthly 24-Hr. Comp TBEL

2The following BAT limits will apply on December 31, 2023 if the Permittee opts into the Voluntary Incentive Program:


Daily Maximum Units

Minimum Frequency

Sample Type


Arsenic, Total Recoverable Report 4 µg/l 2 X


Mercury, Total Recoverable 24 39 ng/l 6 X Yearly Grab TBEL

Selenium, Total Recoverable Report 5 µg/l 2 X


Total Dissolved Solids (TDS) 24 50 mg/l 2 X


6.1.10 Outfall 002


Daily Maximum Units

Minimum Frequency

Sample Type




30 70 mg/l 1 X Weekly 24-Hr. Comp TBEL

Oil & Grease 10 13 mg/l 1 X Monthly Grab TBEL

Aluminum, Total Recoverable Report Report mg/l 2 X


Aluminum, Dissolved Report Report mg/l 2 X


Ammonia (as N) Report Report mg/l 2 X Monthly 24-Hr. Comp BPJ

Arsenic, Total Recoverable Report Report µg/l 2 X


Bromide Report Report µg/l 2 X Monthly 24-Hr. Comp BPJ

Cadmium, Total Recoverable Report Report µg/l 2 X


Chloride Report Report mg/l 2 X Monthly 24-Hr. Comp BPJ

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Daily Maximum Units

Minimum Frequency

Sample Type


Total Residual Chlorine 20 40 µg/l Weekly Grab WQBEL

Copper, Total Recoverable Report Report µg/l 2 X


Mercury, Total Recoverable Report Report ng/l 6 X Yearly 24-Hr. Comp BPJ

Selenium, Total Recoverable Report Report µg/l 2 X


Sulfate Report Report mg/l 2 X Monthly 24-Hr. Comp BPJ

Zinc, Total Recoverable Report Report µg/l 2 X


Parameter Daily

Minimum Daily


Frequency Sample

Type Source of

requirement

pH 6.0 9.0 Std Units 1 X Weekly Grab WQBEL/TBEL

6.1.11 Outfall 102


Daily Maximum Units

Minimum Frequency

Sample Type



CBOD5 25 40 mg/l 2 X Monthly 24-Hr. Comp 327 IAC 5-10-

5(a) Total Suspended Solids (TSS)

30 60 mg/l 2 X Monthly 24-Hr. Comp 327 IAC 5-10-

5(a)

E. coli 125 235 Count/ 100 ml

2 X Monthly Grab 327 IAC 5-10-

6(e) Total Residual Chlorine Report Report mg/l 2 X

Monthly Grab 327 IAC 5-10-6

6.1.12 Outfall 003

No monitoring or limits are proposed at this outfall (other than the narrative water quality limits that are applicable at every external outfall).

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6.1.13 Outfall 004

Parameter Daily


Frequency Sample

Type Source of

requirement

Flow Report MGD Semi-Annual Estimate 327 IAC 5-2-

13(a)(2)

CBOD5 Report mg/l Semi-Annual Grab BPJ

Oil & Grease Report mg/l Semi-Annual Grab BPJ


Report mg/l Semi-Annual Grab BPJ

Total BTEX Report mg/l Semi-Annual Grab BPJ

Zinc, Total Recoverable Report mg/l Semi-

Annual Grab BPJ

pH Report Std Units Semi-Annual Grab BPJ

6.2 Schedule of Compliance The draft permit contains new effluent limits for beryllium and ammonia at outfall 001 and new limits for total residual chlorine at Outfall 002. The rules which authorize the inclusion of a schedule of compliance in an NPDES permit in certain circumstances can be found at 327 IAC 5-2-12 and IC 13-18-3-2.6 (see also 40 CFR 122.47(a) and 40 CFR 123.25(a)(18)). These rules allow a schedule of compliance in a NPDES permit when requested and justified by the permittee, but only when appropriate and when the schedule of compliance requires achievement of compliance “as soon as possible” and meets other specified conditions. The permittee has requested the following 18 month schedule of compliance for the new water quality-based effluent limits for total residual chlorine at Outfall 002.

Phase Description Time

Phase 1: Evaluate Compliance Requirements

a. Compile and review existing analytical data pertinent to Outfall 002 b. Determine if existing data quality is sufficient to evaluate proposed

compliance requirements i. Limits of detection and quantitation for analytical equipment and

methods used ii. Potential analytical interference from other constituents

c. Procure appropriate analytical equipment and establish related test methods, if required

d. Perform additional sampling and analysis, if required e. Validate and update water balances for related systems f. Review treatment processes and chemical usage for related systems g. Consider potential impacts from planned or future process changes

2 months

Phase 2: Evaluate Treatment Alternatives

a. Compile a list of potential treatment technologies and processes b. Perform a screening study to eliminate alternatives that are not feasible or

practicable c. Evaluate feasible alternatives

i. Identify requirements for new equipment, modifications to existing systems, chemical usage and storage, and utilities (power, water, air)

ii. Evaluate performance and reliability based on previous applications and testing

4 months

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Phase Description Time iii. Evaluate environmental, health, and safety considerations including

potential risks iv. Estimate implementation and operating costs

d. Perform a Decision Analysis to compare alternatives and select the optimal solution

Phase 3: Perform Bench and/or Pilot Testing

a. Perform bench and/or pilot testing to validate expected treatment performance

b. Evaluate test results and adjust accordingly 3-4 months

Phase 4: Implement Final Treatment System

a. Complete design engineering for new equipment and systems b. Procure equipment and materials c. Construct and install new equipment and systems d. Develop procedures and provide training to operations and maintenance

personnel e. Start up and commission new systems f. Monitor treatment performance and tune controls

4-8 months

A compliance schedule has been included in the permit to allow the permittee time to comply with this new limit. Also, in accordance with 40 CFR 423, the permittee has been given time to comply with the new requirements applicable to fly ash transport water, bottom ash transport water, and flue gas desulfurization wastewater.

6.3 Special Conditions and Other Permit Requirements

6.3.1 Clean Water Act (CWA) Section 316(a) Alternative Thermal Effluent Limitations A. Summary In its current permit, the permittee does have alternate thermal effluent limitations. This section provides a summary of the history of these existing alternate thermal limitations as well as the legal authority for and requirements pertaining to such limits. The permittee was required to submit an updated 316(a) demonstration by January 20, 2018 (see February 2013 NPDES permit and June 15, 2017 letter from IDEM to the permittee) and did submit this updated demonstration on January 18, 2018. IDEM is in the process of reviewing this updated demonstration. Until such time that this review has been completed, except as noted below, IDEM proposes to continue the thermal requirements that were in the February 2013 permit. When this review is complete, if revisions to the existing alternate thermal limitations are determined to be necessary, the permit will be modified or revoked and reissued to make these revisions.

B. History of Alternative Thermal Limitations for the Duke Cayuga Generating Station (taken verbatim from the Fact Sheet for the 2013 NPDES renewal permit, except for some grammatical changes and rewording for clarity)

The initial NPDES permit for PSI’s Cayuga Generating station was issued by the U.S. EPA in November 1974. Among other things, the permit required PSI to construct a closed cycle recirculating condenser cooling water system and allowed PSI to discharge only blowdown from the recycle system. In addition, the permit specified that the thermal discharge from the generating station was to comply with instream water quality standards for temperature.

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In December 1974, PSI requested an adjudicatory hearing for the permit contesting the closed cycle condenser cooling requirement, the application of Indiana’s water temperature standards and numerous other minor provisions of the permit. The request for hearing was granted by EPA and the Indiana Stream Pollution Control Board intervened as an affected party. In early October, 1976, a consolidated adjudicatory hearing was held regarding the thermal issues raised by PSI on the Wabash River Generating Station permit and the Cayuga Generating Station permit. In December 1976, the federal administrative law judge certified on record of the hearing proceedings to the EPA Regional Administrator (RA) for region 5. An Initial Decision on the two permits was issued by the RA on May 11, 1978, in which the RA found that PSI had made a successful demonstration under Section 316(a) of the Clean Water Act in support of the PSI’s proposed thermal discharges from the generating station, irrespective of his simultaneous finding that the thermal discharges had caused adverse harm to the affected community of aquatic organisms in the Wabash River. Most of the biological data considered at the time of the hearing stemmed from research on the biota of the Wabash River conducted by Dr. James R. Gammon from 1967 through 1975. Both the Enforcement Division of the U.S. EPA, Region 5, and the Indiana Stream Pollution Control Board appealed the RA’s Initial Decision to the EPA Administrator, contending that the Regional Administrator had misinterpreted the law in reaching his decision and had failed to consider crucial ancillary issues. After briefing of the issues by EPA, the Board, and PSI, the Administrator, Douglas M. Costle, issued a Remand to Region 5’s Regional Administrator on November 29, 1979. In his remand the Administrator concluded that Region 5’s Regional Administrator has misconstrued Section 316(a) and EPA’s regulations establishing criteria for implementing that statute. Under the remand, the Regional Administrator was to determine unequivocally whether prior appreciable harm had occurred to the river’s aquatic life due to PSI’s thermal discharges and whether such harm is probable under critical low flow (Q7,10) conditions, and possibly, whether any modifications were appropriate to PSI’s desired alternative thermal limitations. Promptly following issuance of the Administrator’s remand, PSI moved the Administrator to vacate the remand order (and implicitly the entire adjudicatory proceeding) as moot for the reason that the two NPDES permits in issue had expired. EPA, Region 5, Enforcement Staff and the State both filed counter-motions. The Administrator stayed the remand pending a decision on PSI’s motion to vacate on February 27, 1980. No further action occurred in the federal adjudicatory proceeding. (The above permit history was excerpted from the 1985 Fact Sheet for this permit.) In 1985, a renewal of this permit was drafted and public noticed which again required PSI to install closed cycle cooling towers at both plants. PSI strenuously objected to this provision. The agency responses to PSI’s objections were addressed in a 13 page attachment to the Fact Sheet, prepared by Larry J. Kane, what was at the time Chief of the Permits Section. The permit was issued September 30, 1985, and subsequently was appealed by PSI.

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In the resulting settlement conferences, PSI agreed to derate the plant, if necessary, to comply and the agency agreed to drop the requirement for a closed cycle cooling towers. The permit was modified February 24, 1987, as agreed to in the settlement negotiations, and the PSI withdrew their appeal by letter May 5, 1987. No formal adjudicatory proceeding was held. Thermal issues were not the only agency concern with regards to the Cayuga Permit. In July and August of 1977 very low dissolved oxygen (D.O.) concentrations were observed in the Wabash River between river miles 240 and 245. No cause for this event was apparent. However, in late August and September, 1983, Indiana State Board of Health (ISBH) staff observed similar low D.O. values in the same approximate location of the Wabash River during a period of lower river flow. Following this corroborative second low D.O. event, HydroQual, Inc. (HQ), which has been hired by an industrial consortium (which included PSI) to study additional assimilative capacity of the river, proceeded to study the data and subsequently propound the hypothesis that the extremely low D.O. values resulted from substantial mortality or other adverse effects to algae entrained in the condenser cooing system of the Cayuga Generating Station at times of low river flow (when the majority of the river is diverted through the condensers). PSI did not accept this hypothesis. The evidence was not conclusive to the agency that the Cayuga Station was the primary cause of the phenomenon although IDEM staff did believe that it was a contributing factor to some degree. The permit issued in September of 1985, as modified in February of 1987, contained a requirement for PSI to organize a dissolved oxygen study of the river, to be conducted during a low flow period, and submit a report to IDEM on the results of the study. Initially, the study was to be done in 1986, but timing and river flow conditions precluded this. Similar occurrences happened in 1987. As it turns out, this was fortuitous because the study was then delayed until the summer of 1988, when drought conditions provided a text book example of worst case conditions. Field staff for this study included personnel from PSI as well as DePauw University, Purdue University, the Illinois State Water Survey, and IDEM. The resulting report, dated April 1989, confirmed that the D.O. sag was reoccurring. Among the most significant of the conclusions was that the sag actually begins slightly upstream of the Cayuga GS, and continued to occur during a forced outage of the plant which occurred in order to comply with the thermal limitations in the NPDES permit. In addition to the above text taken from the Fact Sheet for the 2013 NPDES renewal permit, the 2007 NPDES permit included alternate thermal limitations applicable during the summer months (May through October). The 2013 NPDES permit included alternate thermal limitations for the winter months (November through April).

C. 316(a) Applicability, Purpose and Scope The information in this section is taken in large part from an October 28, 2008 memorandum from James A. Hanlon to Region 1-10 Water Division Directors regarding the implementation of Clean Water Act Section 316(a) Thermal Variances in NPDES Permits. Section 316(a) of the Clean Water Act (CWA) is applicable to point sources with thermal discharges. It authorizes the NPDES permitting authority to impose alternate effluent limitations for the control of the thermal component of a discharge in lieu of the effluent limitations that would otherwise be required.

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Federal regulations implementing section 316(a) are codified at 40 CFR Part 125, subpart H; while Indiana has established rules implementing section 316(a) of the CWA at 327 IAC 5-7. These rules and regulations identify the criteria and processes for determining whether an alternate effluent limitation (i.e. a thermal variance from the otherwise applicable limits) may be included in a permit, and, if so, what that limit should be. This means that before a thermal variance can be granted, 327 IAC 5-7-3 and 4 (see also 40 CFR 125.72 and 125.73) require the permittee to demonstrate that the otherwise applicable thermal discharge effluent limit is more stringent that necessary to assure the protection and propagation of the waterbody’s balanced indigenous community of shellfish, fish and wildlife. The burden of proof is on the permittee to demonstrate that it is eligible to receive an alternative effluent limit under 316(a). In support of any proposed alternative thermal limit, the discharge must demonstrate that the alternative limit will assure protection of the waterbody’s balanced indigenous population, considering the impacts of its thermal discharge considering the “cumulative impact of its thermal discharge together with all other significant impacts on the species affected.” (see 327 IAC 5-7-4(a) and 40 CFR 125.73(a)) When applying for an alternative thermal limit, an applicant must submit the supporting information and demonstrations identified and described in 327 IAC 5-7-3 and 4 (see also 40 CFR 125.72 and 73). Among other things, the applicant must identify and describe (1) the requested alternative effluent limitation, (2) methodology used to support the limitation, (3) the organisms comprising the balanced indigenous community along with supporting data and information, and (4) the types of data, studies, experiments and other information the applicant intends to use to demonstrate that the alternative thermal limit assures the protection and propagation of the balanced indigenous community. 327 IAC 5-7-3(a) and (b) (see also 40 CFR 125.72(a) and (b)) In making the demonstration the discharger shall consider IDEM’s Guidance for Conducting a Demonstration as a Requirement of a 316(a) Alternative Thermal Effluent Limitation Request, available from: https://in.gov/idem/cleanwater/2365.htm. When requesting the renewal of a permit containing a 316(a) thermal variance, the permittee must submit the information required to support the continuation of the variance.

D. Criteria and standards for the determination of ATELs Thermal discharge effluent limitations or standards established in permits may be less stringent than those required by applicable standards and limitations if the discharger demonstrates to the satisfaction of the IDEM that such effluent limitations are more stringent than necessary to assure the protection and propagation of a balanced, indigenous community of shellfish, fish and wildlife in and on the body of water into which the discharge is made. This demonstration must show that the alternative effluent limitation desired by the discharger, considering the cumulative impact of its thermal discharge together with all other significant impacts on the species affected, will ensure the protection and propagation of a balanced indigenous community of shellfish, fish and wildlife in and on the body of water into which the discharge is to be made. Existing dischargers may base their demonstration upon the absence of prior appreciable harm in lieu of predictive studies in accordance with 327 IAC 5-7-5(c)(1)

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(see also 40 CFR 125.73(c)(1)). Any such demonstrations shall show: (i) That no appreciable harm has resulted from the normal component of the discharge (taking into account the interaction of such thermal component with other pollutants and the additive effect of other thermal sources to a balanced, indigenous community of shellfish, fish and wildlife in and on the body of water into which the discharge has been made; or (ii) That despite the occurrence of such previous harm, the desired alternative effluent limitations (or appropriate modifications thereof) will nevertheless ensure the protection and propagation of a balanced, indigenous community of shellfish, fish and wildlife in and on the body of water into which the discharge is made. In determining whether or not prior appreciable harm has occurred, IDEM shall consider the length of time in which the applicant has been discharging and the nature of the discharge.

E. The 316(a) Alternate Thermal Effluent Limitations Renewal Process As stated above, the permittee submitted an updated 316(a) demonstration of January 18, 2018. IDEM is still in the process of reviewing this demonstration. If warranted, the permit will be modified upon completion of this review to incorporate revised thermal requirements. A 316(a) variance is a permit condition. It expires along with the permit. A permittee may request renewal of its 316(a) variance prior to the expiration of the permit. Therefore, when the permittee submits its NPDES permit renewal application, if the permittee still wants the 316(a) variance, it must also request renewal of its 316(a) variance. At this time, IDEM has not identified any additional information that would need to be included in the permittee’s 316(a) renewal application.

F. Proposed Thermal Limitations As noted above, IDEM is in the process of reviewing the permittee’s updated 316(a) demonstration which was submitted on January 18, 2018. Since this review has not been completed, the proposed thermal limitations in this permit are, except as noted, the same as the limitations in the current (2013) permit. These are as follows:

a. The permittee shall control the electrical power output of the Cayuga Generating Station and operate existing auxiliary cooling tower to assure that the water temperature of the discharge from Outfall 001 shall not cause the calculated river temperature at the current downstream compliance point (the Mixed River Temperature) to exceed the applicable maximum temperature in the following tables. Summer Limits (May 1st – October 31st of each year) During the annual period of May 1 through October 31, the permittee’s discharge is subject to the thermal limitations in Table 1-A below. The water temperature of the discharge from Outfall 001 shall not cause the Mixed River Temperature to exceed the instantaneous maximum temperature in Table 1-A by more than one percent (1%) of the hours (2650 minutes) in the six (6) month period. Monitoring and reporting of the discharge temperature is to occur on a continuous basis. Intake, Effluent, and Mixed River Temperature measurements shall be recorded at a minimum frequency of once per hour and the highest single recorded measurement for each day shall be reported on the state monthly monitoring report. The highest single recorded daily measurement shall be reported on the federal discharge monitoring report as the maximum daily temperature of that

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month. Additionally, the total number of hours above the corresponding maximum limits in Table 1-A for the six (6) months shall be reported. At no time shall the Mixed River Temperature exceed the maximum limits in the following table by more than three degrees Fahrenheit (3ºF) (one and seven-tenths degrees Celsius (1.7ºC)).

Table 1-A May June July August Sept. Oct. ºF 80 90 90 90 90 78 ºC 26.7 32.2 32.2 32.2 32.2 25.5

Winter Limits (November 1st - April 30th of each year) During the annual period of November 1 through April 30, the permittee’s discharge is subject to the thermal limitations in Table 1-B below. The discharge from Outfall 001 shall not cause the Mixed River Temperature to exceed the instantaneous maximum temperature in Table 1-B. Monitoring and reporting of the discharge temperature is to occur on a continuous basis. Intake, effluent, and Mixed River Temperature measurements shall be recorded at a frequency of once per hour and the highest single recorded measurement for each day shall be reported on the state monthly monitoring report. The highest single recorded daily measurement shall be reported on the federal discharge monitoring report as the maximum daily temperature of that month.

Table 1-B Jan Feb (1-14) Feb (15-end) Mar (1-15) Mar (16-31) April Nov Dec ºF 55 50 55 70 75 80 70 60 ºC 12.8 10 12.8 21.1 23.9 26.7 21.1 15.6

b. The existing auxiliary cooling tower(s) shall be operated continuously when the upstream river temperature reaches 78 ºF and the river falls below 4,000 cfs as measured at the Cayuga Generating Station gauge. During periods of unavoidable malfunction of the tower(s), this condition (requiring operation of auxiliary tower(s)) shall be temporarily waived. In such cases the permittee shall take emergency maintenance measures to assure return of the full operations as soon as possible, and shall report all such events along with the monthly DMR form. Temperature limits still apply during periods of unavoidable malfunction of the tower(s).

c. The permittee shall use a mathematical model applying the RIVCAL procedures to calculate the Mixed River Temperature to be used to determine compliance with the alternative thermal limitations set forth in the Table above. The calculation shall be calibrated and verified by river surveys.

In absence of a 316(a) thermal variance, the following temperature limitations from 327 IAC 2-1-6(b)(4) apply for a direct discharge from Outfall 001 to the Wabash River

(A) There shall be no abnormal temperature changes that may adversely affect aquatic life unless caused by natural conditions. (B) The normal daily and seasonal temperature fluctuations that existed before the addition of heat due to other than natural causes shall be maintained.

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(C) The maximum temperature rise at any time or place above natural temperatures shall not exceed:

(i) five (5) degrees Fahrenheit (two and eight-tenths (2.8) degrees Celsius) in streams; and (ii) three (3) degrees Fahrenheit (one and seven-tenths (1.7) degrees Celsius) in lakes and reservoirs.

(D) Water temperatures shall not exceed the maximum limits in the following table during more than one percent (1%) of the hours in the twelve (12) month period ending with any month. At no time shall the water temperature at such locations exceed the maximum limits in the following table by more than three (3) degrees Fahrenheit (one and seven-tenths (1.7) degrees Celsius):

Month

°F(°C)

January

50 (10.0) February

50 (10.0)

March

60 (15.6) April

70 (21.1)

May

80 (26.7) June

90 (32.2)

July

90 (32.2) August

90 (32.2)

September

90 (32.2) October

78 (25.5)

November

70 (21.1) December

57 (14.0)

G. Thermal Emergencies The current permit contains a provision under Part III.E. containing reporting and other requirements which are applicable in the event of an energy demand event. The permittee has not needed to utilize these provisions for many years. This permit proposes to delete these requirements.

6.3.2 Clean Water Act Section 316(b) Cooling Water Intake Structure(s) (CWIS)

A. Introduction Pursuant to Clean Water Act (CWA) Section 316(b) and 40 CFR 401.14, the location, design, construction and capacity of cooling water intake structures (CWIS) of any point source for which a standard is established pursuant to section 301 or 306 of the Act shall reflect the best technology available for minimizing adverse environmental impact. On August 15, 2014, the EPA promulgated regulations to implement CWA section 316(b). 79 Fed. Reg. 48300-439 (August 15, 2014). These regulations established requirements that reflect the best technology available for minimizing adverse impacts, impingement and entrainment of aquatic organisms, associated with the use of cooling water intake structures. The regulation became effective on October 14, 2014. Under these regulations, for permits expiring prior to July 2018, the permittee can (1) negotiate an alternative schedule for submitting required information with the Director (IDEM) after demonstrating need, or (2) request waiver(s) for submitting required

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information. An alternative schedule for submission of information required under the current CWA section 316(b), or waiver(s) of submittal requirements shall be reviewed by EPA Region 5 and approved by IDEM. Upon approval of such alternative schedules and/or waivers, or until the time the required information/reports are submitted and the permit is renewed or modified following public notice, the IDEM is required to make a BTA determination using Best Professional Judgment (BPJ) to comply with CWA Section 316(b) based on existing information. The BTA determination is subject to change after the required information is submitted in accordance with the federal regulations. In a letter dated July 26, 2016, the permittee requested an alternate schedule for submittal of the required 316(b) information. On August 2, 2016, IDEM approved the below alternate schedule:

Activity Timeline Cayuga CWA 316(b) Planning and Contracting November 2014-October 2015 Preliminary evaluations and CWA 316(b) study plan development March 2015-November 2015

Informal peer review of the study plan December 2015 Permit Director input on study plan January 2016 – February 2016 CWA 316(b) Field studies – Year 1 March 2016-September 2016 Laboratory analyses-Year 1 April 2016-December 2016 CWA 316(b) Field studies – Year 2 March 2017-September 2017 Laboratory analyses-Year 2 April 2017-March 2018 CWA 316(b) Report preparation January 2017-Sepember 2019 CWA 316(b) Reports Peer Review October 2019-January 2020 Address Peer Review comments February 2020-March 2020 Submit to IDEM the information required by 40 CFR 122.21(r)(2) through 13 April 30, 2020

B. Description of Existing Intake (description from 2013 permit Fact Sheet and 2017 renewal application) The Cayuga Generating Station consists of two coal fired units with a total generating capacity of 1,070 MW. The Cayuga Station withdraws circulating water from the Wabash River through a shoreline intake structure. The intake is set back from the river in an embankment, along the west bank of the river. A floating boom is deployed to deflect logs and larger debris. The intake structure is divided into two (2) identical units, each having two (2) circulating water pumps (4 pumps total) withdrawing cooling water through four (4) intake bays (8 bays total). Each intake bay has a bar rack, stop log gate, and a traveling water screen. The top deck of each unit is at elevation El. 506.0 ft. All elevations reference mean sea level. The invert of each unit is at El. 452.0 ft. Each screen bay is 11.75 ft. wide. The bar racks are located at the face of the intake structure and are used to prevent ice and large debris from entering the intake. The bar racks have 4 inch by 3/8 inch bars spaced 3 inches on-center and have an invert at El. 456.0 ft. Traveling water screens are located approximately 26 ft. downstream of the bar racks. Each traveling water screen 10 ft. screens has 3/8 inch square screen mesh openings and a basket width of 10 ft. The screens can be rotated at 2.5 ft./min or 10 ft./min depending on debris loading and can be controlled manually or automatically. A high pressure front-wash spray system is used to remove impinged fish and debris from the screens. The wash water

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flows into a single trough and transitions into a discharge pipe that discharges fish and debris back to the Wabash River approximately 275 ft. downstream of the intake structure. Cooling water for each unit is provided by two (2) cooling water pumps. The pumps are located approximately 27 ft. downstream of the traveling screens. Each pump has an approximate capacity of 172.8 MGD. Cayuga also has two (2) service water pumps per unit that withdraw water through the intake structure. Each service water pump has an approximate capacity of 43.2 MGD. The total design intake capacity is 852 MGD. Cooling water is discharged into the Wabash River via a canal that is approximately 3,200 ft. long and starts approximately 360 ft. east of the intake structure. Two helper towers, located approximately 2,500 ft. east of the intake structure are used during summer to reduce the temperature of the discharge prior to entering the Wabash River. The calculated intake velocity of the cooling water intake structure is based on full cooling and service water pumps. The design low water flow (El. 466.5 ft.) was used to determine the approach velocities. The velocity approaching the trash rack is 1.34 ft./sec. The velocity approaching the traveling water screen is 1.14 ft. /sec. The through-screen velocity is calculated to be 2.3 ft./sec assuming that the permittee withdraws the maximum flow when the water level in the Wabash River and in front of the traveling screens is at its long-term low level; and to be approximately 1.7 ft/s assuming that the permittee withdraws the maximum flow when the water level in the Wabash River (and in front of the traveling screens) is normal/average. .

C. Conclusion IDEM has determined using best professional judgment (BPJ), based on the information that is currently available, that the existing cooling water intake structure at Duke Energy-Cayuga represents Best Technology Available (BTA) to minimize adverse environmental impact in accordance with Section 316(b) of the federal Clean Water Act (33 U.S.C. section 1326) based on the following information at this time:

• The historical study (1976/1977) concluded that the Generating Station was not reducing or impairing the ecological functioning of the Wabash River and no threatened or endangered species appeared to be directly or indirectly adversely affected by operation of the intakes.

• Operation and description of the intakes and associated pumps and velocities has not changed since the historical study.

• The updated study submitted in 2007 summarized that based on the most recent data collected and historic results for the Generating Station, although the impingement and entrainment estimates generated from the 2007 study were higher than previously documented by historical impingement and entrainment studies at Cayuga, the 2007 results demonstrate that annual differences in the absolute number of impinged and entrained fish and their relative abundance can be expected at Cayuga, as has been documented at most facilities where long term data are available. Variability in year-class strength, especially for species commonly impinged or entrained, such as gizzard shad, freshwater drum, and channel catfish, could result in order of magnitude differences among years, as observed by the densities of freshwater drum type eggs in the entrainment samples and increased impingement of juvenile freshwater drum and gizzard shad. Although the magnitude of impingement and entrainment will vary considerably from year to year,

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impingement and entrainment are expected to be dominated by the same few species or taxa, especially gizzard shad and freshwater drum.

IDEM will reassess this BTA determination when the permittee submits, on or before April 30, 2020, the information required by 40 CFR 122.21(r)(2) through 13.

D. Permit Conditions In accordance with 40 CFR 122 and 40 CFR 125, the owner or operator of a facility that has cooling water intake structure with a Design Intake Flow (DIF) or Actual Intake Flow (AIF) > 125 MGD must submit the information required at 40 CFR 122.21(r)(2) through (13), including all of the associated supporting documentation and/or studies, no later than July 14, 2018, unless an alternate schedule for submission is approved or a waiver of a particular requirement is requested and granted under 40 CFR 125.95. The permittee has requested and IDEM has approved the following alternate schedule for submittal of this information:

Activity Timeline Cayuga CWA 316(b) Planning and Contracting November 2014-October 2015 Preliminary evaluations and CWA 316(b) study plan development March 2015-November 2015

Informal peer review of the study plan December 2015 Permit Director input on study plan January 2016 – February 2016 CWA 316(b) Field studies – Year 1 March 2016-September 2016 Laboratory analyses-Year 1 April 2016-December 2016 CWA 316(b) Field studies – Year 2 March 2017-September 2017 Laboratory analyses-Year 2 April 2017-March 2018 CWA 316(b) Report preparation January 2017-Sepember 2019 CWA 316(b) Reports Peer Review October 2019-January 2020 Address Peer Review comments February 2020-March 2020 Submit to IDEM the information required by 40 CFR 122.21(r)(2) through 13 April 30, 2020

In addition, the permittee shall comply with requirements below: 1. In accordance with 40 CFR 125.98(b)(1), nothing in this permit authorizes take for the

purposes of a facility’s compliance with the Endangered Species Act. 2. At all times properly operate and maintain the intake equipment. 3. Inform IDEM of any proposed changes to the cooling water intake structure or

proposed changes to operations at the facility that affect the information taken into account in the current BTA evaluation.

4. There shall be no discharge of debris from intake screen washing which will settle to form objectionable deposits which are in amounts sufficient to be unsightly or deleterious, or which will produce colors or odors constituting a nuisance.

5. All required reports shall be submitted to the IDEM, Office of Water Quality, NPDES Permits Branch.

E. Submittal of Permit Application to U.S. Fish and Wildlife Under 40 CFR 125.98(h), IDEM is required to transmit all permit applications subject to Subpart J of Part 125 (316(b) requirements applicable to existing facilities) to the

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appropriate Field Office of the U.S. Fish and Wildlife Service upon receipt for a 60 day review prior to public notice of the draft or proposed permit. Pursuant to this requirement, the NPDES application for this permit was submitted to the Bloomington, Indiana U.S. Fish and Wildlife Service office on October 23, 2017. On November 22, 2017, the Bloomington Field Office, U.S. Fish and Wildlife Service informed IDEM that they have no comments on this application.

6.3.3 Polychlorinated Biphenyl (PCB) There shall be no discharge of polychlorinated biphenyl (PCB) compounds attributable to facility operations such as those historically used in transformer fluids. In order to determine compliance with the PCB discharge prohibition, the permittee shall provide the following PCB data with the next NPDES permit renewal application for at least one sample taken from each final outfall (this includes Outfalls 001, 002 and 004. This does not include Outfall 003). The corresponding facility water intakes shall be monitored at the same time as the final outfalls.

Pollutant Test Method LOD LOQ PCBs* EPA 608 0.1 ug/L 0.3 ug/L

*PCB 1242, 1254, 1221, 1232, 1248, 1260, 1016

6.4 Spill Response and Reporting Requirement Reporting requirements associated with the Spill Reporting, Containment, and Response requirements of 327 IAC 2-6.1 are included in Part II.B.2.(d), Part II.B.3.(c), and Part II.C.3. of the NPDES permit. Spills from the permitted facility meeting the definition of a spill under 327 IAC 2-6.1-4(15), the applicability requirements of 327 IAC 2-6.1-1, and the Reportable Spills requirements of 327 IAC 2-6.1-5 (other than those meeting an exclusion under 327 IAC 2-6.1-3 or the criteria outlined below) are subject to the Reporting Responsibilities of 327 IAC 2-6.1-7. It should be noted that the reporting requirements of 327 IAC 2-6.1 do not apply to those discharges or exceedances that are under the jurisdiction of an applicable permit when the substance in question is covered by the permit and death or acute injury or illness to animals or humans does not occur. In order for a discharge or exceedance to be under the jurisdiction of this NPDES permit, the substance in question (a) must have been discharged in the normal course of operation from an outfall listed in this permit, and (b) must have been discharged from an outfall for which the permittee has authorization to discharge that substance.

6.5 Permit Processing/Public Comment Pursuant to IC 13-15-5-1, 327 IAC 5-3-9, and 327 IAC 5-3-12, IDEM is required to public notice this draft permit. IDEM will publish a general notice in the newspaper with the largest general circulation within the county that this facility is located. A 30-day comment period is available in order to solicit input from interested parties, including the general public. Comments concerning the draft permit should be submitted in accordance with the procedure outlined in the enclosed public notice form.

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