NPDES Permit No. IL0048151

Notice No. LRL:12030801.daa

Public Notice Beginning Date: May 24, 2013

Public Notice Ending Date: June 24, 2013

National Pollutant Discharge Elimination System (NPDES)

Permit Program

Draft Reissued NPDES Permit to Discharge into Waters of the State

Public Notice/Fact Sheet Issued By:

Illinois Environmental Protection Agency

Bureau of Water 

Division of Water Pollution Control

Permit Section

1021 North Grand Avenue East

Post Office Box 19276

Springfield, Illinois 62794-9276

217/782-0610

Name and Address of Discharger: Name and Address of Facility:

Exelon Generation Company, LLC Exelon Generation Company, LLC

4300 Winfield Road LaSalle County Generating Station

Warrenville, Illinois 60555 2601 N. 21st Road

Marseilles, Illinois 61341

(LaSalle County)

The Illinois Environmental Protection Agency (IEPA) has made a tentative determination to issue a NPDES permit to discharge into the 

waters of the state and has prepared a draft permit and associated fact sheet for the above named discharger. The Public Notice 

period will begin and end on the dates indicated in the heading of this Public Notice/Fact Sheet. The last day comments will be 

received will be on the Public Notice period ending date unless a commentor demonstrating the need for additional time requests an 

extension to this comment period and the request is granted by the IEPA. Interested persons are invited to submit written comments on 

the draft permit to the IEPA at the above address. Commentors shall provide his or her name and address and the nature of the issues 

proposed to be raised and the evidence proposed to be presented with regards to those issues. Commentors may include a request for 

public hearing. Persons submitting comments and/or requests for public hearing shall also send a copy of such comments or requests 

to the permit applicant. The NPDES permit and notice number(s) must appear on each comment page.

The application, engineer's review notes including load limit calculations, Public Notice/Fact Sheet, draft permit, comments received, 

and other documents are available for inspection and may be copied at the IEPA between 9:30 a.m. and 3:30 p.m. Monday through

Friday when scheduled by the interested person.

If written comments or requests indicate a significant degree of public interest in the draft permit, the permitting authority may, at its 

discretion, hold a public hearing. Public notice will be given 45 days before any public hearing. Response to comments will be 

provided when the final permit is issued. For further information, please call Leslie Lowry at 217/782-0610.

The applicant operates LaSalle County Station which is an existing nuclear-fueled steam electric generating facility. Two boiling water 

nuclear fission reactors provide steam to turbine generators with a maximum generating capacity of 2156 MW (net) electric power (SIC 

4911). Plant operation results in an average discharge of 34.98 MGD of cooling pond blowdown from outfall 001, an intermittent 

discharge of demineralizer regenerant wastes from internal outfall A01, 0.01 MGD of sewage treatment plant effluent from internal 

outfall B01, 0.021 of wastewater treatment system effluent from internal outfall C01, an intermittent discharge of cooling water intake 

screen backwash (cooling pond) from internal outfall D01, an intermittent discharge of unit 1 and 2 radwaste treatment system effluent 

from internal outfall E01, an intermittent discharge of auxiliary reactor equipment cooling and flushing water from internal outfall F01, an 

intermittent discharge of north side stormwater runoff from internal outfall G01, an intermittent discharge of south site stormwater runoff 

from internal outfall H01, 0.003 MGD of reverse osmosis system reject water and greensand filter backwash from internal outfall I01, 

and an intermittent discharge of Illinois River make-up water intake screen backwash from outfall 002. 
Public Notice/Fact Sheet -- Page 2 -- NPDES Permit No. IL0048151

The following modification is proposed:

Added the following wastestreams to internal outfall C01, standby liquid control test skid flush water and groundwater.

Application is made for existing discharges which are located in LaSalle County, Illinois. The following information identifies the 

discharge point, receiving stream and stream classifications:

Outfall Receiving Stream Latitude Longitude

Stream 

Classification

Integrity

Rating

001 Illinois River 41 18' 38" North 88 39' 58" West General Use Not Rated

002 Illinois River 41 18' 40" North 88 39' 46" West General Use Not Rated

To assist you further in identifying the location of the discharge please see the attached map. 

The stream segment D-23 receiving the discharge from outfalls 001 and 002 is on the 2010 303(d) list of impaired waters and is not a 

biologically significant stream on the 2008 Illinois Department of the Natural Resources publication Integrating Multiple Taxa in a 

Biological Stream Rating System. 

The following parameters have been identified as the pollutants causing impairment:

Designated Use Potential Cause

Fish Consumption and Primary Contact Mercury, Polychlorinated Biphenyls, Fecal Coliform

This permit recognizes and continues the year-round disinfection exemption approved by the IEPA on June 27, 1995 and included in 

past NPDES permit actions since that date.

The discharges from the facility shall be monitored and limited at all times as follows:

LOAD LIMITS lbs/day

DAF (DMF) 

CONCENTRATION

LIMITS mg/l 

PARAMETER

30 DAY

AVERAGE

DAILY

MAXIMUM REGULATION

30 DAY

AVERAGE

DAILY

MAXIMUM REGULATION

Outfall 001:

Flow (MGD)

pH 6 - 9 s.u. 35 IAC 304.125

Temperature 35 IAC 302.211

Total Residual Chlorine / 

Total Residual Oxidant 

0.05 35 IAC 302.208 

& 40 CFR 125.3

Zinc (Total) Monitor Only

Outfall A01:

Flow (MGD)

Total Suspended Solids 15 30 35 IAC 304.124
Public Notice/Fact Sheet -- Page 3 -- NPDES Permit No. IL0048151

LOAD LIMITS lbs/day

DAF (DMF) 

CONCENTRATION

LIMITS mg/l 

PARAMETER

30 DAY

AVERAGE

DAILY

MAXIMUM REGULATION

30 DAY

AVERAGE

DAILY

MAXIMUM REGULATION

Outfall B01:

Flow (MGD)

pH 6 - 9 s.u. 35 IAC 304.125

CBOD5 13 42 35 IAC 304.120 25 50 35 IAC 304.120

Total Suspended Solids 15 50 35 IAC 304.120 30 60 35 IAC 304.120

Outfall C01:

Flow (MGD)

pH 6 - 9 s.u. 35 IAC 304.125

Total Suspended Solids 5 17 40 CFR 423.12 15 30 35 IAC 304.124

Oil/Grease 2.5 3.34 40 CFR 423.12 15 20 40 CFR 423.12

Outfall D01:

This discharge is limited to cooling water intake screen backwash free from other wastewater discharges. Adequate maintenance of 

the trash basket is required to prevent the discharge of floating debris collected on intake screens back to the cooling pond.

Outfall E01:

Flow (MGD)

Total Suspended Solids 15 30 35 IAC 304.124

Oil/Grease 15 20 40 CFR 423.12

Outfall F01:

This discharge is limited to auxiliary reactor equipment cooling and flushing water free from other wastewater discharges.

Outfall G01:

SWPPP

Outfall H01:
Public Notice/Fact Sheet -- Page 4 -- NPDES Permit No. IL0048151

SWPPP

LOAD LIMITS lbs/day

DAF (DMF) 

CONCENTRATION

LIMITS mg/l 

PARAMETER

30 DAY

AVERAGE

DAILY

MAXIMUM REGULATION

30 DAY

AVERAGE

DAILY

MAXIMUM REGULATION

Outfall I01:

Flow (MGD)

Total Suspended Solids 15 30 35 IAC 304.124

Outfall 002:

SWPPP

Load Limit Calculations:

Internal Outfall B01 load limit calculations for the following pollutant parameters were based on a design average flow of 0.06 MGD and 

a maximum flow of 0.1 MGD and using the formula of maximum flow (MGD) X concentration limit (mg/l) X 8.34 = the average or 

maximum load limit (lbs/day): CBOD5, and Total Suspended Solids.

Internal Outfall C01 load limit calculations for the following pollutant parameters were based on a design average flow of 0.044 MGD 

and a maximum flow of 0.082 MGD and using the formula of maximum flow (MGD) X concentration limit (mg/l) X 8.34 = the average or 

maximum load limit (lbs/day): Total Suspended Solids and Oil/Grease.

The load limits appearing in the permit will be the more stringent of the State and Federal Guidelines.

The following explain the conditions of the proposed permit:

The Special Conditions clarify flow, pH, temperature, total residual chlorine / total residual oxidant, monitoring locations, discharge 

monitoring report submission, stormwater, and additives.

The facility has not been granted additional thermal relief and must comply with existing thermal water quality standards as found in 35 

IAC 302.211 at the edge of the mixing zone. See Special Condition 3 for the temperature special condition.

The facilities intake structure consists of three 3-stage vertical turbine pumps each with a capacity of approximately 30,000 gpm are 

used to provide cooling pond make-up. The pumps will pump up to 90,000 gpm of river water to the cooling pond through 18,000 feet 

of 60 inch diameter pipe. Normal operation of the station call for one or two pumps to be used to maintain proper pond levels. 

Due to evaporation, blowdown, and possible some seepage, it is expected that continuous pumping of cooling pond make-up water will 

be necessary to maintain the cooling pond water level. It is estimated that approximately 49,000 gpm of make-up water will 

continuously be required to replace 19,000 gpm of water lost due to evaporation and another 30,000 gpm of water lost due to pond 

blowdown. 

The intake system consists of an intake flume channeled into the bottom of the Illinois River and extending approximately 50 feet out 

from the shoreline. Recessed 24 feet from the shoreline is a 72 foot wide funnel inlet. At the mouth of the inlet, a floating boom has 

been installed to divert floating debris. The funneled inlet leads to two adjacent bar racks which precede two traveling screens, with 3/8 

inch screen openings, located in the river screen house. River water then flows to compartments in the lower bay area of the

screenhouse where the enclosed impellers of the three vertical turbine pumps are located. 

During normal make-up periods, the cooling pond make-up rate will be 30,000 gpm with one pumps operating. River intake velocities 

at the approach inlet of the canal near the shoreline have been calculated to range from 0.4 fps to 0.6 fps, depending on river pool 

elevations. The 0.4 fps velocity corresponds to the high river elevation and the 0.6 fps velocity to the low river elevation. At normal 

river pool elevation, river intake velocities of approximately 0.5 fps will occur. 

The facility utilizes a closed-cycle recirculating cooling system, a 2058 acre cooling pond, for cooling of plant condensers and is 

determined to be the equivalent of Best Technology Available (BTA) for cooling water intake structures to prevent/minimize 

impingement mortality in accordance with the Best Professional Judgment (BPJ) provisions of 40 CFR 125.3 because it allows the 
Public Notice/Fact Sheet -- Page 5 -- NPDES Permit No. IL0048151

facility to only withdraw the amount of water necessary to maintain the cooling pond level rather than the entire volume used for cooling 

of the plant condensers. Special Condition 15 requires additional information to be submitted to the Agency pursuant to 316(b), so that 

the Agency can evaluate the potential impacts of the cooling water intake structure operations pursuant to 40 CFR 125.90(b).
NPDES Permit No. IL0048151

Illinois Environmental Protection Agency

Division of Water Pollution Control

1021 North Grand Avenue East

Springfield, Illinois 62794-9276

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM

Reissued (NPDES) Permit

Expiration Date: Issue Date: 

Effective Date: 

Name and Address of Permittee: Facility Name and Address:

Exelon Generation Company, LLC Exelon Generation Company, LLC

4300 Winfield Road LaSalle County Generating Station

Warrenville, Illinois 60555 2601 N. 21st Street

Marseilles, Illinois 61341

(LaSalle County)

Discharge Number and Name: Receiving Waters: 

001 Cooling Pond Blowdown Illinois River

A01 Demineralizer Regenerant Wastes

B01 Sewage Treatment Plant Effluent

C01 Wastewater Treatment System Effluent

D01 Cooling Water Intake Screen Backwash 

E01 Unit 1 and 2 Radwaste Treatment System Effluent

F01 Auxiliary Reactor Equipment Cooling and Flushing Water

G01 North Site Stormwater Runoff

H01 South Site Stormwater Runoff

I01 Reverse Osmosis System Reject Water and

Greensand Filter Backwash

002 Illinois River Make-Up Water Intake Screen Backwash Illinois River

In compliance with the provisions of the Illinois Environmental Protection Act, Title 35 of Ill. Adm. Code, Subtitle C and/or Subtitle D, 

Chapter 1, and the Clean Water Act (CWA), the above-named permittee is hereby authorized to discharge at the above location to the 

above-named receiving stream in accordance with the standard conditions and attachments herein.

Permittee is not authorized to discharge after the above expiration date. In order to receive authorization to discharge beyond the 

expiration date, the permittee shall submit the proper application as required by the Illinois Environmental Protection Agency (IEPA) not 

later than 180 days prior to the expiration date.

Alan Keller, P.E.

Manager, Permit Section

Division of Water Pollution Control

SAK:LRL:12030801.daa
Page 2

NPDES Permit No. IL0048151

Effluent Limitations and Monitoring

1. From the effective date of this permit until the expiration date, the effluent of the following discharges shall be monitored and limited 

at all times as follows:

LOAD LIMITS lbs/day

DAF (DMF) 

CONCENTRATION

LIMITS mg/l 

PARAMETER

30 DAY

AVERAGE

DAILY

MAXIMUM

30 DAY

AVERAGE

DAILY

MAXIMUM

SAMPLE

FREQUENCY

SAMPLE

TYPE

Outfall 001 – Cooling Pond Blowdown*

(Average Flow = 34.9 MGD)

This discharge consists of:

1. Main Condenser Cooling Water

2. Clean Condensate System Flushing and Maintenance (Alternate Route)

3. House Service Water

4. Demineralizer Regenerant Wastes (Outfall A01)

5. Sewage Treatment Plant Effluent (Outfall B01)

6. Wastewater Treatment System Effluent (Outfall C01)

7. Cooling Pond Intake Screen Backwash (Outfall D01)

8. Unit 1 and 2 Radwaste Treatment System Effluent (Outfall E01)

9. Auxiliary Reactor Equipment Cooling and Flushing Water (Outfall F01)

10. North Site Stormwater Runoff (Outfall G01)**

11. South Site Stormwater Runoff (Outfall H01)**

12. Reverse Osmosis System Reject Water and Greensand Filter Backwash (Outfall I01)

13. Water Softener Regenerant Waste

14. North Inlet Canal Stormwater Runoff**

15. South Inlet Canal Stormwater Runoff**

16. IDNR Fish Hatchery Effluents

Flow (MGD) See Special Condition 1. Daily Continuous

pH See Special Condition 2. 2/Month Grab

Temperature See Special Condition 3. Daily Continuous

Total Residual Chlorine / 

Total Residual Oxidant

See Special Condition 4 and 16. 0.05 2/Month Grab

Zinc (Total) Monitor Only 1/Quarter Grab

* - See Special Condition 13.

** - See Special Condition 8.
Page 3

NPDES Permit No. IL0048151

Effluent Limitations and Monitoring

1. From the effective date of this permit until the expiration date, the effluent of the following discharges shall be monitored and limited 

at all times as follows:

LOAD LIMITS lbs/day

DAF (DMF) 

CONCENTRATION

LIMITS mg/l 

PARAMETER

30 DAY

AVERAGE

DAILY

MAXIMUM

30 DAY

AVERAGE

DAILY

MAXIMUM

SAMPLE

FREQUENCY

SAMPLE

TYPE

Outfall A01 – Demineralizer Regenerant Wastes*

(Intermittent Discharge)

This discharge consists of:

1. Make-Up Demineralizer Regenerant Wastes

2. Off-Specification Demineralized Water

3. Make-Up Demineralizer Maintenance Wastewater

4. Unit Waterbox Vacuum Pump Condensate

5. Radwaste Treatment Acid/Caustic System Drains

Flow (MGD) See Special Condition 1. 1/Week 24 Hour Total

Total Suspended Solids 15 30 1/Week Grab

* - Also discharge to the Wastewater Treatment System (Outfall C01) as an alternate route.

Outfall B01 – Sewage Treatment Plant Effluent

(DAF = 0.06 MGD)

This discharge consists of:

1. Sanitary Wastewater

2. Eyewash Station Wastewater

Flow (MGD) See Special Condition 1. Daily Continuous

pH See Special Condition 2. 2/Month Grab

CBOD5 13 42 25 50 2/Month 24 Hour 

Composite

Total Suspended Solids 15 50 30 60 2/Month 24 Hour 

Composite
Page 4

NPDES Permit No. IL0048151

Effluent Limitations and Monitoring

1. From the effective date of this permit until the expiration date, the effluent of the following discharges shall be monitored and limited 

at all times as follows:

LOAD LIMITS lbs/day

DAF (DMF) 

CONCENTRATION

LIMITS mg/l 

PARAMETER

30 DAY

AVERAGE

DAILY

MAXIMUM

30 DAY

AVERAGE

DAILY

MAXIMUM

SAMPLE

FREQUENCY

SAMPLE

TYPE

Outfall C01 – Wastewater Treatment System Effluent

(DAF = 0.044 MGD)

This discharge consists of:

1. Turbine Building Fire and Miscellaneous Non-Radioactive Wastewater Sump

2. Greensand Filter Backwash (Alternative Route)

3. Diesel Fuel Storage and Service Water Building Sump

4. Auxiliary Boiler Blowdown

5. Water Softener Regenerant Waste

6. Demineralizer Regenerant Wastes (Outfall A01 Alternate Route)

7. Heat Bay Building Roof Area

8. Fire Protection System Flushing and Maintenance*

9. Service Water System Flushing and Maintenance*

10. Domestic Water System Flushing and Maintenance*

11. Clean Condensate System Flushing and Maintenance**

12. Laboratory Liquid Wastes

13. Station Heat System Condensate

14. Diesel Generator Cooling Water

15. Standby Liquid Control Test Skid Flush Water

16. Groundwater

Flow (MGD) See Special Condition 1. Daily Continuous

pH See Special Condition 2. 1/Week Grab

Total Suspended Solids 5 17 15 30 1/Month 24 Hour 

Composite

Oil & Grease 2.5 3.34 15 20 1/Month Grab

* - Also discharges to the North Site Stormwater Runoff (Outfall G01) and/or South Site Stormwater Runoff (Outfall H01) as an 

alternate route.

** - Also discharges to the Cooling Pond Blowdown (Outfall 001) via the service water system and resulting main condenser cooling 

water as an alternate route.

Outfall D01 – Cooling Water Intake Screen Backwash*

(Intermittent Discharge)

* - This discharge is limited to cooling water intake screen backwash free from other wastewater discharges. Adequate maintenance 

of the trash basket is required to prevent the discharge of floating debris collected on intake screens back to the cooling pond.
Page 5

NPDES Permit No. IL0048151

Effluent Limitations and Monitoring

1. From the effective date of this permit until the expiration date, the effluent of the following discharges shall be monitored and limited 

at all times as follows:

LOAD LIMITS lbs/day

DAF (DMF) 

CONCENTRATION

LIMITS mg/l 

PARAMETER

30 DAY

AVERAGE

DAILY

MAXIMUM

30 DAY

AVERAGE

DAILY

MAXIMUM

SAMPLE

FREQUENCY

SAMPLE

TYPE

Outfall E01 – Unit 1 and 2 Radwaste Treatment System Effluent

(Intermittent Discharge)

This discharge consists of:

1. Equipment Drains in the Turbine, Auxiliary, and Reactor Buildings

2. Floor Drains in the Turbine, Auxiliary, and Reactor Buildings

3. Condensate Polisher Waste from the Turbine Building

4. Decontamination and Laundry Waste

Flow (MGD) See Special Condition 1. 1/Week Estimate

Total Suspended Solids 15 30 1/Week Grab

Oil & Grease 15 20 1/Week Grab

Outfall F01 – Auxiliary Reactor Equipment Cooling and Flushing Water*

(Intermittent Discharge)

* - This discharge is limited to auxiliary reactor equipment cooling and flushing water free from other wastewater discharges.

Outfall G01 – North Site Stormwater Runoff*

(Intermittent Discharge)

This discharge consists of:

1. Fire Protection System Flushing and Maintenance (Alternate Route)

2. Service Water System Flushing and Maintenance (Alternate Route)

3. Domestic Water System Flushing and Maintenance (Alternate Route)

4. Clean Condensate System Flushing and Maintenance (Alternate Route)

5. North Site Uncontaminated Stormwater Runoff

* - See Special Condition 8.
Page 6

NPDES Permit No. IL0048151

Effluent Limitations and Monitoring

1. From the effective date of this permit until the expiration date, the effluent of the following discharges shall be monitored and limited 

at all times as follows:

LOAD LIMITS lbs/day

DAF (DMF)

CONCENTRATION

LIMITS mg/l

PARAMETER

30 DAY

AVERAGE

DAILY

MAXIMUM

30 DAY

AVERAGE

DAILY

MAXIMUM

SAMPLE

FREQUENCY

SAMPLE

TYPE

Outfall H01 – South Site Stormwater Runoff*

(Intermittent Discharge)

This discharge consists of:

1. Fire Protection System Flushing and Maintenance (Alternate Route)

2. Service Water System Flushing and Maintenance (Alternate Route)

3. Domestic Water System Flushing and Maintenance (Alternate Route)

4. Clean Condensate System Flushing and Maintenance (Alternate Route)

5. South Site Uncontaminated Stormwater Runoff

* - See Special Condition 8.

Outfall I01 – Reverse Osmosis System Reject Water and Greensand Filter Backwash

(Average Flow = 0.003 MGD)

Flow (MGD) See Special Condition 1. 1/Week 24 Hour Total

Total Suspended Solids 15 30 1/Month Grab

Outfall 002 – Illinois River Makeup Water Intake Screen Backwash*

(Intermittent Discharge)

This discharge consists of:

1. River Intake Screen Backwash

2. Trench Wash Water

3. Process Sampling Discharge

4. Lake Make-Up Pump Gland Leakoff, Coolers, Reliefs, and Min Flow

5. Lake Make-Up Pump Strainer Backwash

6. Air Compressor Receiver and Prefilter Drainage

7. Dewatering Pump Discharge

8. Fire Protection Water

9. River Screen House Switchyard Stormwater Runoff**

10. River Screen House Floor Drains and Roof Drains

* - Adequate maintenance of the intake screen system is required to prevent the discharge of floating debris collected on intake 

screens back to the Illinois River.

** - See Special Condition 8.
Page 7

NPDES Permit No. IL0048151

Special Conditions

SPECIAL CONDITION 1. Flow shall be measured in units of Million Gallons per Day (MGD) and reported as a monthly average and a 

daily maximum on the Discharge Monitoring Report.

SPECIAL CONDITION 2. The pH shall be in the range 6.0 to 9.0. The monthly minimum and monthly maximum values shall be 

reported on the DMR form.

SPECIAL CONDITION 3. This facility meets the criteria for establishment of a formal mixing zone for thermal discharges pursuant to 

35 IAC 302.102. The following mixing zone defines the area and volume of the receiving water body in which mixing is allowed to 

occur. Water quality standards for temperature listed in table below must be met at every point outside of the mixing zone.

Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec.

° F 60 60 60 90 90 90 90 90 90 90 90 60

° C 16 16 16 32 32 32 32 32 32 32 32 16

A. The temperature at the edge of the mixing zone should be calculated using the mass balance equation below:

TEDGE = [0.25 x (QUS x TUS) + QE x TE] / (0.25 x QUS + QE) 

Where:

TEDGE = Temperature at the edge of the mixing zone.

QUS = Upstream Flow

TUS = Upstream Temperature

QE = Effluent Flow

TE = Temperature of the effluent.

B. There shall be no abnormal temperature changes that may adversely affect aquatic life unless caused by natural conditions. The 

normal daily and seasonal temperature fluctuations which existed before the addition of heat due to other than natural causes shall 

be maintained.

C. The maximum temperature rise above natural temperatures shall not exceed 2.8 C (5 F).

D. The water temperature at the edge of the mixing zone defined above shall not exceed the maximum limits in the following table

during more than one percent of the hours in the 12 month period ending with any month. Moreover, at no time shall the water 

temperature at the edge of the mixing zone exceed the maximum limits in the following table by more than 1.7 C (3 F).

E. The monthly maximum value shall be reported on the DMR form.

SPECIAL CONDITION 4. All samples for Total Residual Chlorine / Total Residual Oxidant shall be analyzed by an applicable method 

contained in 40 CFR 136, equivalent in accuracy to low-level amperometric titration. Any analytical variability of the method used shall 

be considered when determining the accuracy and precision of the results obtained. 

SPECIAL CONDITION 5. There shall be no discharge of complexed metal bearing wastestreams and associated rinses from chemical 

metal cleaning unless this permit has been modified to include the new discharge.

SPECIAL CONDITION 6. The Permittee shall record monitoring results on Discharge Monitoring Report (DMR) Forms using one such 

form for each outfall each month.

In the event that an outfall does not discharge during a monthly reporting period, the DMR Form shall be submitted with no discharge 

indicated.

The Permittee may choose to submit electronic DMRs (eDMRs) instead of mailing paper DMRs to the IEPA. More information, 

including registration information for the eDMR program, can be obtained on the IEPA website, 

http://www.epa.state.il.us/water/edmr/index.html.

The completed Discharge Monitoring Report forms shall be submitted to IEPA no later than the 28th day of the following month, unless 

otherwise specified by the permitting authority.
Page 8

NPDES Permit No. IL0048151

Special Conditions

Permittees not using eDMRs shall mail Discharge Monitoring Reports with an original signature to the IEPA at the following address:

Illinois Environmental Protection Agency

Division of Water Pollution Control

1021 North Grand Avenue East

Post Office Box 19276

Springfield, Illinois 62794-9276

Attention: Compliance Assurance Section, Mail Code # 19

SPECIAL CONDITION 7. The upset defense provisions as defined in 40 CFR 122.41(n) are hereby incorporated by reference.

SPECIAL CONDITION 8. 

STORM WATER POLLUTION PREVENTION PLAN (SWPPP)

A. A storm water pollution prevention plan shall be maintained by the permittee for the storm water associated with industrial activity 

at this facility. The plan shall identify potential sources of pollution which may be expected to affect the quality of storm water 

discharges associated with the industrial activity at the facility. In addition, the plan shall describe and ensure the implementation 

of practices which are to be used to reduce the pollutants in storm water discharges associated with industrial activity at the facility 

and to assure compliance with the terms and conditions of this permit. The permittee shall modify the plan if substantive changes 

are made or occur affecting compliance with this condition.

1. Waters not classified as impaired pursuant to Section 303(d) of the Clean Water Act.

Unless otherwise specified by federal regulation, the storm water pollution prevention plan shall be designed for a storm event 

equal to or greater than a 25-year 24-hour rainfall event.

2. Waters classified as impaired pursuant to Section 303(d) of the Clean Water Act.

For any site which discharges directly to an impaired water identified in the Agency's 303(d) listing, and if any parameter in the 

subject discharge has been identified as the cause of impairment, the storm water pollution prevention plan shall be designed

for a storm event equal to or greater than a 25-year 24-hour rainfall event. If required by federal regulations, the storm water 

pollution prevention plan shall adhere to a more restrictive design criteria.

B. The operator or owner of the facility shall make a copy of the plan available to the Agency at any reasonable time upon request.

Facilities which discharge to a municipal separate storm sewer system shall also make a copy available to the operator of the 

municipal system at any reasonable time upon request.

C. The permittee may be notified by the Agency at any time that the plan does not meet the requirements of this condition. After such 

notification, the permittee shall make changes to the plan and shall submit a written certification that the requested changes have 

been made. Unless otherwise provided, the permittee shall have 30 days after such notification to make the changes.

D. The discharger shall amend the plan whenever there is a change in construction, operation, or maintenance which may affect the 

discharge of significant quantities of pollutants to the waters of the State or if a facility inspection required by paragraph H of this 

condition indicates that an amendment is needed. The plan should also be amended if the discharger is in violation of any 

conditions of this permit, or has not achieved the general objective of controlling pollutants in storm water discharges. 

Amendments to the plan shall be made within 30 days of any proposed construction or operational changes at the facility, and shall 

be provided to the Agency for review upon request.

E. The plan shall provide a description of potential sources which may be expected to add significant quantities of pollutants to storm 

water discharges, or which may result in non-storm water discharges from storm water outfalls at the facility. The plan shall 

include, at a minimum, the following items:

1. A topographic map extending one-quarter mile beyond the property boundaries of the facility, showing: the facility, surface 

water bodies, wells (including injection wells), seepage pits, infiltration ponds, and the discharge points where the facility's 

storm water discharges to a municipal storm drain system or other water body. The requirements of this paragraph may be 

included on the site map if appropriate. Any map or portion of map may be withheld for security reasons.

2. A site map showing:

i. The storm water conveyance and discharge structures;
Page 9

NPDES Permit No. IL0048151

Special Conditions

ii. An outline of the storm water drainage areas for each storm water discharge point;

iii. Paved areas and buildings;

iv. Areas used for outdoor manufacturing, storage, or disposal of significant materials, including activities that generate 

significant quantities of dust or particulates.

v. Location of existing storm water structural control measures (dikes, coverings, detention facilities, etc.);

vi. Surface water locations and/or municipal storm drain locations

vii. Areas of existing and potential soil erosion;

viii. Vehicle service areas;

ix. Material loading, unloading, and access areas.

x. Areas under items iv and ix above may be withheld from the site for security reasons.

3. A narrative description of the following:

i. The nature of the industrial activities conducted at the site, including a description of significant materials that are treated, 

stored or disposed of in a manner to allow exposure to storm water;

ii. Materials, equipment, and vehicle management practices employed to minimize contact of significant materials with storm 

water discharges;

iii. Existing structural and non-structural control measures to reduce pollutants in storm water discharges;

iv. Industrial storm water discharge treatment facilities;

v. Methods of onsite storage and disposal of significant materials.

4. A list of the types of pollutants that have a reasonable potential to be present in storm water discharges in significant 

quantities. Also provide a list of any pollutant that is listed as impaired in the most recent 303(d) report.

5. An estimate of the size of the facility in acres or square feet, and the percent of the facility that has impervious areas such as 

pavement or buildings.

6. A summary of existing sampling data describing pollutants in storm water discharges.

F. The plan shall describe the storm water management controls which will be implemented by the facility. The appropriate controls 

shall reflect identified existing and potential sources of pollutants at the facility. The description of the storm water management 

controls shall include:

1. Storm Water Pollution Prevention Personnel - Identification by job titles of the individuals who are responsible for developing, 

implementing, and revising the plan.

2. Preventive Maintenance - Procedures for inspection and maintenance of storm water conveyance system devices such as 

oil/water separators, catch basins, etc., and inspection and testing of plant equipment and systems that could fail and result in 

discharges of pollutants to storm water.

3. Good Housekeeping - Good housekeeping requires the maintenance of clean, orderly facility areas that discharge storm 

water. Material handling areas shall be inspected and cleaned to reduce the potential for pollutants to enter the storm water 

conveyance system.

4. Spill Prevention and Response - Identification of areas where significant materials can spill into or otherwise enter the storm 

water conveyance systems and their accompanying drainage points. Specific material handling procedures, storage 

requirements, spill cleanup equipment and procedures should be identified, as appropriate. Internal notification procedures for 

spills of significant materials should be established.

5. Storm Water Management Practices - Storm water management practices are practices other than those which control the 

source of pollutants. They include measures such as installing oil and grit separators, diverting storm water into retention 
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NPDES Permit No. IL0048151

Special Conditions

basins, etc. Based on assessment of the potential of various sources to contribute pollutants, measures to remove pollutants

from storm water discharge shall be implemented. In developing the plan, the following management practices shall be 

considered:

i. Containment - Storage within berms or other secondary containment devices to prevent leaks and spills from entering 

storm water runoff. To the maximum extent practicable storm water discharged from any area where material handling 

equipment or activities, raw material, intermediate products, final products, waste materials, by-products, or industrial 

machinery are exposed to storm water should not enter vegetated areas or surface waters or infiltrate into the soil unless 

adequate treatment is provided.

ii. Oil & Grease Separation - Oil/water separators, booms, skimmers or other methods to minimize oil contaminated storm 

water discharges.

iii. Debris & Sediment Control - Screens, booms, sediment ponds or other methods to reduce debris and sediment in storm 

water discharges.

iv. Waste Chemical Disposal - Waste chemicals such as antifreeze, degreasers and used oils shall be recycled or disposed 

of in an approved manner and in a way which prevents them from entering storm water discharges.

v. Storm Water Diversion - Storm water diversion away from materials manufacturing, storage and other areas of potential 

storm water contamination. Minimize the quantity of storm water entering areas where material handling equipment of 

activities, raw material, intermediate products, final products, waste materials, by-products, or industrial machinery are 

exposed to storm water using green infrastructure techniques where practicable in the areas outside the exposure area, 

and otherwise divert storm water away from exposure area.

vi. Covered Storage or Manufacturing Areas - Covered fueling operations, materials manufacturing and storage areas to 

prevent contact with storm water.

vii. Storm Water Reduction - Install vegetation on roofs of buildings within adjacent to the exposure area to detain and 

evapotranspirate runoff where precipitation falling on the roof is not exposed to contaminants, to minimize storm water 

runoff; capture storm water in devices that minimize the amount of storm water runoff and use this water as appropriate 

based on quality.

6. Sediment and Erosion Prevention - The plan shall identify areas which due to topography, activities, or other factors, have a 

high potential for significant soil erosion. The plan shall describe measures to limit erosion.

7. Employee Training - Employee training programs shall inform personnel at all levels of responsibility of the components and 

goals of the storm water pollution control plan. Training should address topics such as spill response, good housekeeping and 

material management practices. The plan shall identify periodic dates for such training.

8. Inspection Procedures - Qualified plant personnel shall be identified to inspect designated equipment and plant areas. A 

tracking or follow-up procedure shall be used to ensure appropriate response has been taken in response to an inspection. 

Inspections and maintenance activities shall be documented and recorded.

G. Non-Storm Water Discharge - The plan shall include a certification that the discharge has been tested or evaluated for the 

presence of non-storm water discharge. The certification shall include a description of any test for the presence of non-storm water 

discharges, the methods used, the dates of the testing, and any onsite drainage points that were observed during the testing. Any 

facility that is unable to provide this certification must describe the procedure of any test conducted for the presence of non-storm 

water discharges, the test results, potential sources of non-storm water discharges to the storm sewer, and why adequate tests for 

such storm sewers were not feasible.

H. Quarterly Visual Observation of Discharges - The requirements and procedures for quarterly visual observations are applicable to 

all outfalls covered by this condition.

1. You must perform and document a quarterly visual observation of a storm water discharge associated with industrial activity 

from each outfall. The visual observation must be made during daylight hours. If no storm event resulted in runoff during 

daylight hours from the facility during a monitoring quarter, you are excused from the visual observations requirement for that 

quarter, provided you document in your records that no runoff occurred. You must sign and certify the document.

2. Your visual observation must be made on samples collected as soon as practical, but not to exceed 1 hour or when the runoff 

or snow melt begins discharging from your facility. All samples must be collected from a storm event discharge that is greater 

than 0.1 inch in magnitude and that occurs at least 72 hours from the previously measureable (greater than 0.1 inch rainfall) 

storm event. The observation must document: color, odor, clarity, floating solids, settled solids, suspended solids, foam, oil 
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NPDES Permit No. IL0048151

Special Conditions

sheen, and other obvious indicators of storm water pollution. If visual observations indicate any unnatural color, odor, turbidity, 

floatable material, oil sheen or other indicators of storm water pollution, the permittee shall obtain a sample and monitor for the 

parameter or the list of pollutants in Part E.4.

3. You must maintain your visual observation reports onsite with the SWPPP. The report must include the observation date and 

time, inspection personnel, nature of the discharge (i.e., runoff or snow melt), visual quality of the storm water discharge 

(including observations of color, odor, floating solids, settled solids, suspended solids, foam, oil sheen, and other obvious

indicators of storm water pollution), and probable sources of any observed storm water contamination.

4. You may exercise a waiver of the visual observation requirement at a facility that is inactive or unstaffed, as long as there are 

no industrial materials or activities exposed to storm water. If you exercise this waiver, you must maintain a certification with 

your SWPPP stating that the site is inactive and unstaffed, and that there are no industrial materials or activities exposed to 

storm water.

5. Representative Outfalls - If your facility has two or more outfalls that you believe discharge substantially identical effluents, 

based on similarities of the industrial activities, significant materials, size of drainage areas, and storm water management

practices occurring within the drainage areas of the outfalls, you may conduct visual observations of the discharge at just one 

of the outfalls and report that the results also apply to the substantially identical outfall(s).

6. The visual observation documentation shall be made available to the Agency and general public upon written request.

I. The permittee shall conduct an annual facility inspection to verify that all elements of the plan, including the site map, potential 

pollutant sources, and structural and non-structural controls to reduce pollutants in industrial storm water discharges are accurate. 

Observations that require a response and the appropriate response to the observation shall be retained as part of the plan. 

Records documenting significant observations made during the site inspection shall be submitted to the Agency in accordance with 

the reporting requirements of this permit.

J. This plan should briefly describe the appropriate elements of other program requirements, including Spill Prevention Control and 

Countermeasures (SPCC) plans required under Section 311 of the CWA and the regulations promulgated there under, and Best 

Management Programs under 40 CFR 125.100.

K. The plan is considered a report that shall be available to the public at any reasonable time upon request.

L. The plan shall include the signature and title of the person responsible for preparation of the plan and include the date of initial 

preparation and each amendment thereto.

M. Facilities which discharge storm water associated with industrial activity to municipal separate storm sewers may also be subject to 

additional requirement imposed by the operator of the municipal system

Construction Authorization

Authorization is hereby granted to construct treatment works and related equipment that may be required by the Storm Water Pollution 

Prevention Plan developed pursuant to this permit.

This Authorization is issued subject to the following condition(s).

N. If any statement or representation is found to be incorrect, this authorization may be revoked and the permittee there upon waives 

all rights there under.

O. The issuance of this authorization (a) does not release the permittee from any liability for damage to persons or property caused by 

or resulting from the installation, maintenance or operation of the proposed facilities; (b) does not take into consideration the 

structural stability of any units or part of this project; and (c) does not release the permittee from compliance with other applicable 

statutes of the State of Illinois, or other applicable local law, regulations or ordinances.

P. Plans and specifications of all treatment equipment being included as part of the stormwater management practice shall be 

included in the SWPPP.

Q. Construction activities which result from treatment equipment installation, including clearing, grading and excavation activities 

which result in the disturbance of one acre or more of land area, are not covered by this authorization. The permittee shall contact 

the IEPA regarding the required permit(s).
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NPDES Permit No. IL0048151

Special Conditions

REPORTING

R. The facility shall submit an electronic copy of the annual inspection report to the Illinois Environmental Protection Agency. The 

report shall include results of the annual facility inspection which is required by Part I of this condition. The report shall also include 

documentation of any event (spill, treatment unit malfunction, etc.) which would require an inspection, results of the inspection, and 

any subsequent corrective maintenance activity. The report shall be completed and signed by the authorized facility employee(s) 

who conducted the inspection(s). The annual inspection report is considered a public document that shall be available at any

reasonable time upon request.

S. The first report shall contain information gathered during the one year time period beginning with the effective date of coverage 

under this permit and shall be submitted no later than 60 days after this one year period has expired. Each subsequent report shall 

contain the previous year's information and shall be submitted no later than one year after the previous year's report was due.

T. If the facility performs inspections more frequently than required by this permit, the results shall be included as additional 

information in the annual report.

U. The permittee shall retain the annual inspection report on file at least 3 years. This period may be extended by request of the 

Illinois Environmental Protection Agency at any time.

Annual inspection reports shall be mailed to the following address:

Illinois Environmental Protection Agency

Bureau of Water

Compliance Assurance Section

Annual Inspection Report

1021 North Grand Avenue East

Post Office Box 19276

Springfield, Illinois 62794-9276

V. The permittee shall notify any regulated small municipal separate storm sewer owner (MS4 Community) that they maintain 

coverage under an individual NPDES permit. The permittee shall submit any SWPPP or any annual inspection to the MS4 

community upon request by the MS4 community.

SPECIAL CONDITION 9. This permit authorizes the use of water treatment additives that were requested as part of this renewal. The 

use of any new additives, or change in those previously approved by the Agency, or if the permittee increases the feed rate or quantity 

of the additives used beyond what has been approved by the Agency, the permittee shall request a modification of this permit in 

accordance with the Standard Conditions - Attachment H.

The permittee shall submit to the Agency on a yearly basis a report summarizing their efforts with water treatment suppliers to find a 

suitable alternative to phosphorus based additives. 

SPECIAL CONDITION 10. This permit may be modified to include different final effluent limitations or requirements which are 

consistent with applicable laws, regulations, or judicial orders. The Agency will public notice the permit modification.

SPECIAL CONDITION 11. The effluent, alone or in combination with other sources, shall not cause a violation of any applicable water 

quality standard outlined in 35 Ill. Adm. Code 302.

SPECIAL CONDITION 12. The use or operation of this facility shall be by or under the supervision of a Certified Class K operator.

SPECIAL CONDITION 13. There shall be no discharge of polychlorinated biphenyl compounds (PCBs).

SPECIAL CONDITION 14. Samples taken in compliance with the effluent monitoring requirements shall be taken at a point 

representative of the discharge, but prior to entry into the receiving stream.

SPECIAL CONDITION 15. The facility utilizes a closed-cycle recirculating cooling system, a 2058 acre cooling pond, for cooling of 

plant condensers and is determined to be the equivalent of Best Technology Available (BTA) for cooling water intake structures to 

prevent/minimize impingement mortality in accordance with the Best Professional Judgment (BPJ) provisions of 40 CFR 125.3 because 

it allows the facility to only withdraw the amount of water necessary to maintain the cooling pond level rather than the entire volume 

used for cooling of the plant condensers. 

In order for the Agency to evaluate the potential impacts of cooling water intake structure operations pursuant to 40 CFR 125.90(b), the 

permittee shall prepare and submit information to the Agency outlining current intake structure conditions at this facility, including a 

detailed description of the current intake structure operation and design, description of any operational or structural modifications from 
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NPDES Permit No. IL0048151

Special Conditions

original design parameters, source waterbody flow information as necessary. 

The information shall also include a summary of historical 316(b) related intake impingement and/or entrainment studies, if any, as well 

as current impingement mortality and/or entrainment characterization data; and shall be submitted to the Agency within six (6) months 

of the permit’s effective date.

Upon the receipt and review of this information, the permit may be modified to require the submittal of additional information based on a 

Best Professional Judgment review by the Agency. This permit may also be revised or modified in accordance with any laws, 

regulations, or judicial orders pursuant to Section 316(b) of the Clean Water Act.

SPECIAL CONDITION 16. For a period of 18 months following the effective date of this permit during times when the condenser 

cooling water is chlorinated intermittently, TRC may not be discharged from the station for more than 3 hours per day or from any single 

generation units main cooling condensers for more than 2 hours per day. The discharge limit during this period is 0.2 mg/l, measured 

as an instantaneous maximum.

A Total Residual Chlorine limit of 0.05 mg/l (Daily Maximum) for outfall 001 shall become effective 18 months from the effective date of 

this Permit. 

The Permittee shall construct a dechlorination system or some alternative means of compliance in accordance with the following 

schedule:

1. Status Report 4 months from the effective date

2. Commence Construction 10 months from the effective date

3. Status Report 14 months from the effective date

4. Complete Construction 16 months from the effective date

5. Obtain Operation Level 18 months from the effective date

Compliance dates set out in this Permit may be superseded or supplemented by compliance dates in judicial orders, or Pollution 

Control Board orders. This Permit may be modified, with Public Notice, to include such revised compliance dates.

The Permittee shall operate the dechlorination system or an alternative means of compliance in a manner to ensure continuous 

compliance with the Total Residual Chlorine limit, not to the extent that will result in violations of other permitted effluent characteristic, 

or water quality standards.

REPORTING

The Permittee shall submit a report no later than fourteen (14) days following the completion dates indicated above for each numbered 

item in the compliance schedule, indicating, a) the date the item was completed, or b) that the item was not completed, the reason for 

non-completion, and the anticipated completion date.
Public Notice of Draft Permit

Public Notice Number LRL:12030801.daa is hereby given by Illinois EPA, Division of Water Pollution Control, Permit Section, 1021 

North Grand Avenue East, P.O. Box 19276, Springfield, Illinois 62794-9276 (herein Agency) that a draft modified National Pollutant 

Discharge Elimination System (NPDES) Permit Number IL0048151 has been prepared under 40 CFR 124.6(d) for Exelon Generation 

Company, LLC, 4300 Winfield Road, Warrenville, Illinois, 60555 for discharge into the Illinois River from the Exelon Generation 

Company, LLC, LaSalle County Generating Station, 2601 N. 21st Road, Marseilles, Illinois, LaSalle County. The applicant operates 

LaSalle County Station which is an existing nuclear-fueled steam electric generating facility. Two boiling water nuclear fission reactors 

provide steam to turbine generators with a maximum generating capacity of 2156 MW (net) electric power (SIC 4911). Plant operation 

results in an average discharge of 34.98 MGD of cooling pond blowdown from outfall 001, 0.102 MGD of demineralizer regenerant 

wastes from internal outfall A01, 0.020 MGD of sewage treatment plant effluent from internal outfall B01, 0.021 of wastewater treatment 

system effluent from internal outfall C01, an intermittent discharge of cooling water intake screen backwash (cooling pond) from internal 

outfall D01, 0.011 MGD of unit 1 and 2 radwaste treatment system effluent from internal outfall E01, an intermittent discharge of 

auxiliary reactor equipment cooling and flushing water from internal outfall F01, an intermittent discharge of north side stormwater runoff 

from internal outfall G01, an intermittent discharge of south site stormwater runoff from internal outfall H01, 0.003 MGD of reverse 

osmosis system reject water and greensand filter backwash from internal outfall I01, and an intermittent discharge of Illinois River 

makeup water intake from outfall 002. 

The application, draft permit and other documents are available for inspection and may be copied at a cost of 25 cents per page at the 

Agency between 9:30 A.M. and 3:30 P.M. Monday through Friday. A Fact Sheet containing more detailed information is available at no 

charge. For further information, call the Public Notice Clerk at 217/782-0610.

Interested persons are invited to submit written comments on the draft permit to the Agency at the above address. The NPDES Permit 

and Joint Public Notice numbers must appear on each comment page. All comments received by the Agency not later than 30 days 

from the date of this publication shall be considered in making the final decision regarding permit issuance.

Any interested person may submit written request for a public hearing on the draft permit, stating their name and address, the nature of 

the issues proposed to be raised and the evidence proposed to be presented with regards to these issues in the hearing. Such

requests must be received by the Agency not later than 30 days from the date of this publication.

If written comments and/or requests indicate a significant degree of public interest in the draft permit, the permitting authority may, at its 

discretion, hold a public hearing. Public notice will be given 30 days before any public hearing.

SAK:LRL:12030801.daa