Text

Texas Pollutant Discharge Elimination System (Tpdes) Permit 01908
	ML20071D786
Person / Time
Site:	South Texas
Issue date:	03/11/2020
From:	Sterling L; South Texas
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	NOC-AE-20003717, WQ0001908000
	Download: ML20071D786 (56)
	v • d • e

Nuclear Operating Company South Texas Pm'iect Electric Generating Station RO. Box 289 Wadsworth. Texas 77483 March 11,2020 NOC-AE-20003717 STI:34993709 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 and 2 Docket Nos. STN 50-498 and STN 50-499 Texas Pollutant Discharae Elimination System (TPDES) Permit 01908 Pursuant to the South Texas Project Operating License, Appendix B (Environmental Protection Plan), Section 3.2, South Texas Project submits the attached copy of the Texas Pollutant Discharge Elimination System (TPDES) Permit No. 01908. Appendix B requires that renewed permits be reported to the NRC within 30 days following approval.

There are no commitments in this letter.

If you should have any questions on this matter, please contact N. Boehmisch at (361) 972-8172 or me at (361) 972-7887.

icte P. Sterling Manager, Regulatory Affairs NB

Attachment:

TPDES Permit No. WQ0001908000 ec:

Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 E. Lamar Boulevard Arlington, TX 76011-4511

TPDES PERMIT NO. WQoooi9o8ooo

[For TCEQ office use only - EPA I.D. No.

TXoo64947l TEXAS COMMISSION ON ENVIRONMENTAL QUALITY This renewal replaces TPDES Permit No.

WQoooi9o8ooo, issued on August 7, 2015.

Austin, Texas 78711-3087 PERMIT TO DISCHARGE WASTES under provisions of Section 402 of the Clean Water Act, Chapter 26 of the Texas Water Code, and 40 CFR Part 423 STP Nuclear Operating Company whose mailing address is P.O. Box 289 Wadsworth, Texas 77483 is authorized to treat and discharge wastes from the South Texas Project Electric Generating Station, a nuclear powered-steam electric generation facility (SIC 4911) located at 12090 Farm-to-Market Road 521, approximately 10 miles north ofMatagorda Bay and 12 miles south-southwest of Bay City, near the City ofWadsworth, in Matagorda County, Texas 77483 via Outfall 001 directly to the Colorado River Tidal; via Outfall 002 to the Plant Area Drainage Ditch (PADD), thence to the Colorado River Tidal; via Outfall 004 to an unnamed ditch, thence to the Colorado River Tidal in Segment No. 1401 of the Colorado River Basin; via Outfall 003 to the West Branch of the Colorado River, thence to Matagorda Bay/ Powderhorn Lake; via Outfall 005 to East Fork Utde Robbins Slough, thence to Robbins Slough, thence to Robbins Lake, thence to Robbins Slough, thence to Crab Lake, thence to Crab Bayou, thence to the Gulflntracoastal Waterway (GIWW), thence to Matagorda Bay/Powderhorn Lake; and via Outfall 006 to Little Robbins Slough, thence to an unnamed pond, thence to Robbins Slough, thence to an unnamed lake, thence to Robbins Slough, thence to Robbins Lake, thence to Robbins Slough, thence to Crab Lake, thence to Crab Bayou, thence to the GIWW, thence to Matagorda Bay/Powderhorn Lake in Segment No. 2451 of the Bays and Estuaries only according to effluent limitations, monitoring requirements, and other conditions set forth in this permit, as well as the rules of the Texas Commission on Environmental Quality (TCEQ), the laws of the State of Texas, and other orders of the TCEQ. The issuance of this permit does not grant to the permittee the right to use private or public property for conveyance ofwastewater along the discharge route described in this permit. This includes, but is not limited to, property belonging to any individual, partnership, corporation, or other entity. Neither does this permit authorize any invasion of personal rights nor any violation of federal, state, or local laws or regulations. It is the responsibility of the permittee to acquire property rights as may be necessary to use the discharge route.

This permit shall expire at midnight, five years from the date of permit issuance.

ISSUED DATE: February 21, 2020 ^ /^

For the Commission

EFFLUENT LIMITATIONS AND MONITORING REOmREMENTS Outfall Number 001

1. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge1 recirculated cooling water, cooling reservoir blowdown, previously monitored efQuents (low volume waste sources; metal cleaning waste; stormwater; treated domestic wastewater; car wash water; air conditioning condensate; and heating, ventilatmg, and air conditioning [HVAC] cooling tower blowdown), stormwater, uncontaminated groundwater currently authorized under TPDES Construction General Permit No. TXRisoooo 2, and makeup water from the Colorado River subject to the following effluent limitations:

The daily average flow of effluent shall not exceed 144 million gallons per day (MGD). The daily maximum flow shall not exceed 200 MGD.

Discharge Limitations Minimum Self-Monitoring Requirements EfQuent Characteristics DaUy Average Daily ]V[aximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Flow 144 MGD 200 MGD N/A Continuous s Record Colorado River Flow1 N/A Report, MGD N/A l/day s Estimate Temperature (degrees Fahrenheit)3 95 °F 97 °F 97 °F Continuous 3 In-Situ Total Residual Chlorine 4 N/A Q.Q5 0.05 l/week s Grab6 Enterococci _35^_ 104 7 104 7 i/month s Grab See Other Requirement No. 17.

See Other Requirement No. 13.

See Other Requirements No. 2 and No. 9.

See Other Requirement No. 16.

When discharging.

Samples must be representative of periods of chlorination.

Colony-forming units (cfa) or most probable number (MPN) per 100 mL.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored l/day 5 by grab sample.

3. There shaU be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. Effluent monitoring samples shall be taken at the following location: At Outfall 001, which is at a point in the blowdown line prior to entering the Colorado River Tidal.

Page 2 ofTPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Qytfall Number 101

l. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge low volume waste sources1 and previously monitored effluent (metal cleaning waste) subject to the following effluent limitations:

Volume: Flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements EfQuent Characteristics Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Flow Report, MGD Report, MGD N/A l/day 3 Estimate Total Suspended Solids 30 100 100 i/week 3 _Grab2 Oil and Grease 15 20 20 l/week 3 _Grab2 1 See Other Requirement No. 10.

2 If more than one source is associated with this particular waste category, for analytes other than pH, grab samples from each source must be analyzed, analytical values must be combined on a flow-weighted basis, and these calculated values must be used to determine the Daily Average for the month. The highest analytical value of all grab samples for the monthly reporting period must be reported as the Daily Maximum. For pH, the minimum and maximum values recorded among all the waste sources must be reported.

3 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored i/week 3 by grab sample 2.

3. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. EfQuent monitoring samples must be taken at the following location: At Outfall 101, where low volume waste sources1 commingled with previously monitored effluent are discharged from the neutralization basins prior to mixing with any other waste stream.

Page 2a of TPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 201

l. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge low volume waste sources1 from the oily waste treatment system and stormwater subject to the following effluent limitations:

Volume: Flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements EfQuent Characteristics Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Flow Report, MGD Report, MGD N/A l/day2 Estimate Total Suspended Solids 30 100 100 i/week2 Grab Oil and Grease 15 20 20 i/week2 Grab 1 See Other Requirement No. 10.

2 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored i/week 2 by grab sample.

3. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. Effluent monitoring samples must be taken at the following location: At Outfall 201, where low volume waste sources1 are discharged from the oily waste treatment system prior to mbcing with any other waste stream.

Page 2b ofTPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 401

l. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge treated domestic wastewater, car wash water, and air conditioning condensate subject to the following effluent limitations:

Volume: Continuous and flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements Effluent Characteristics Daily Average Daily Maximum Single Grab Report Daily Average and Daily ]V[aximum mg/L mg/L mg/L IVteasurement Frequency Sample Type Flow Report, MGD Report, MGD N/A l/day1 Estimate Biochemical Oxygen Demand, 5-day 20 45 45 l/week1 Grab Total Suspended Solids 20 45 45 i/week1 Grab 1 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored i/week1 by grab sample.

3. The effluent must contain a minimum chlorine residual of l.o mg/L after a detention time of at least 20 minutes (based on peak flow) and must be monitored i/week by grab sample.

4. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

5. Effluent monitoring samples must be taken at the following location: At Outfall 401, at the point of discharge from the sewage treatment plant (West Sanitary Waste Treatment System) prior to mixing with any other waste stream.

Page 2c ofTPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number noi

1. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge metal cleaning waste1 subject to the following effluent limitations:

Volume: Intermittent and flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements Effluent Characteristics Daily Average Daily MIaximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Flow Report, MGD Report, MGD N/A i/day 2 Estimate Total Suspended Solids 30 100 100 i/week 2 Grab Oil and Grease 15 20 20 i/week 2 Grab Total Iron 1.0 1.0 1.0 l/week 2 Grab Total Copper 0.5 1.0 1.0 i/week 2 Grab 1 See Other Requirement No. 7.

2 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored l/week 2 by grab sample.

3. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. Effluent monitoring samples must be taken at the following location: At Outfall 501, where metal cleaning waste is discharged prior to mbdng with any other waste stream.

Page 2d ofTPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 601

i. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge treated domestic wastewater, air conditioning condensate, and HVAC cooling tower blowdown subject to the following effluent limitations:

Volume: Continuous and flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements Effluent Characteristics Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Flow Report, MGD Report, MGD N/A l/day1 Estimate Biochemical Oxygen Demand, 5-day 20 _45_ _45_ l/week1 Grab Total Suspended Solids 20 -45_ 45 i/week1 Grab 1 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored l/week1 by grab sample.

3. The effluent must contain a minimum chlorine residual of l.o mg/L after a detention time of at least 20 minutes (based on peak flow) and must be monitored i/week by grab sample.

4. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

5. Effluent monitoring samples must be taken at the following location: At Outfall 601, at the point of discharge from the sewage treatment plant (Training Sanitary Waste Treatment Facility) prior to mudng with any other waste stream.

Page 2e of TPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 002

i. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge effluent from the Reservoir Relief Wells (relief wells) for the Main Cooling Reservoir (1VICR) and demineralized water from Instrumentation1 subject to the following effluent limitations 2:

Volume: Continuous and flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements Effluent Characteristics Daily Average Daily Maximum Single Grab Report Daily Average and Daily IVtaximum mg/L m^/L mg/L Measurement Frequency Sample Type Dry-Weather Flow 3 Report, MGD Report, MGD N/A i/sbc months 7 Estimate Temperature (degrees Fahrenheit)4 N/A 95 °F 95 °F l/six months 7 _In-Situ Total Residual Chlorine 4, s N/A 0.05 0.05 l/stx months 7 Grab 6 1 The Instrumentation is a dissolved oxygen analyzer.

2 See Other Requirement No. 19.

3 See Other Requirement No. 14.

4 See Other Requirement No. 15.

5 See Other Requirement No. 16.

6 Samples must be representative of periods of chlorination.

7 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored l/suc months 7 by grab sample 4.

3. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. Effluent monitoring samples must be collected at the following locations: (a) for the demineralized water: from the Instrument Tube prior to commingling with other waters and Cb) for the relief well water: at the point of discharge from any flowing relief well prior to entering the PADD s, 4.

Page 2fofTPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 00^

l. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge effluent from the relief wells for the MCR subject to the following effluent limitations1:

Volume: Continuous and flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements Effluent Characteristics Daily Average DaUy Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Dry-Weather Flow 2 Report, MGD Report, MGD N/A l/sbc months 6 Estimate Temperature (degrees Fahrenheit) s N/A 95 °F 95 °F l/six months 6 In-Situ Total Residual Chlorine 3,4 N/A 0.05 0.05 l/sk months 6 Grab s 1 See Other Requirement No. 19.

2 See Other Requirement No. 14.

3 See Other Requirement No. 15.

4 See Other Requirement No. 16.

s Samples must be representative of periods of chlorination.

6 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored l/sbc months 6 by grab sample 3.

3. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. EfQuent monitoring samples must be taken at the following location: At the point of discharge from any flowing relief well prior to mixing with the West Branch of the Colorado River 2'3.

Page 2g of TPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 004

1. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge effluent from the relief wells for the MCR and effluent from the MCR spillway gates subject to the following effluent limitations1:

Volume: Continuous and flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements Effluent Characteristics Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L _Measurement Frequency Sample Type Dry-Weather Flow 2 Report, MGD Report, MGD N/A l/sk months 6 Estimate Temperature (degrees Fahrenheit) 3 N/A 95 °F 95 °F l/sbc months 6 In-Situ Total Residual Chlorine 3,4 N/A 0.05 0.05 i/sbc months 6 Grabs 1 See Other Requirement No. 19.

2 See Other Requirement No. 14.

3 See Other Requirement No. 15.

4 See Other Requirement No. 16.

5 Samples must be representative of periods ofchlorination.

6 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored i/six months 6by grab sample 3.

3. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. Effluent monitoring samples must be taken at the following locations: (a) flow for the relief well water: at the point of discharge from any flowing relief well prior to entering the drainage ditch, (b) flow from the spiUway gate leakage: at the basin prior to mbdng with other waters, and (c) pH, total residual chlorine, and temperature: at a point in the MCR SpiUway Channel after the commingling ofspillway gate leakage and relief well water and prior to mbdng with other waters.

Page 2h ofTPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 005

l. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge effluent from the relief wells for the MCR subject to the following efQuent limitations1:

Volume: Continuous and flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements Effluent Characteristics Daily Average Daily Maximum Single Grab Report Daily Average and Daily IVIaximum mg/L mg/L mg/L Measurement Frequency Sample Type Dry-Weather Flow 2 Report, MGD Report, MGD N/A l/sbc months 6 estimate Temperature (degrees Fahrenheit) 3 N/A 95 °F 95 °F l/sbc months 6 In-Sity Total Residual Chlorine 3,4 N/A 0.05 0.05 l/sbi: months 6 _Grabs 1 See Other Requirement No. 19.

2 See Other Requirement No. 14.

3 See Other Requirement No. 15.

4 See Other Requirement No. 16.

s Samples must be representative of periods of chlorination.

6 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored i/sk months 6 by grab sample 3.

3. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. EfQuent monitoring samples must be taken at the following location: At the point of discharge from any flowing relief well prior to mixing with East Fork Little Robbins Slough 2> 3.

Page 2i of TPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 006

l. During the period beginning upon the date of permit issuance and lasting through the date of permit expiration, the permittee is authorized to discharge effluent from the relief wells for the MCR subject to the following effluent limitations1:

Volume: Continuous and flow-variable.

Discharge Limitations Minimum Self-Monitoring Requirements EfQuent Characteristics Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Dry-Weather Flow 2 Report, MGD Report, MGD N/A l/sbc months 6 _Estimate Temperature (degrees Fahrenheit) 3 N/A 95 °F 95 °F i/six months 6 In-Situ Total Residual Chlorine 3,4 N/A 0.05 0.05 l/sbc months 6 Grab s 1 See Other Requirement No. 19.

2 See Other Requirement No. 14.

3 See Other Requirement No. 15.

4 See Other Requirement No. 16.

5 Samples must be representative of periods of chlorination.

6 When discharging.

2. The pH must be neither less than 6.0 standard units nor greater than 9.0 standard units and must be monitored l/six months 6 by grab sample s.

3. There must be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. Effluent monitoring samples must be taken at the following location: At the point of discharge from any flowing relief well prior to mbdng with Little Robbins Slough near Well No. 6 2> 3.

Page 2] of TPDES Permit No. WQoooi9o8ooo STP Nuclear Operating Company

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo DEFINITIONS AND STANDARD PERMIT CONDITIONS As required by Title 30 Texas Administrative Code (TAG) Chapter 305, certain regulations appear as standard conditions in waste discharge permits. 30 TAG §§305.121 - 305.129 (relating to Permit Characteristics and Conditions) as promulgated under the Texas Water Code (TWO) ?§5.l03 and 5.105, and the Texas Health and Safety Code (THSC) §§361.017 and 36l.024(a), establish the characteristics and standards for waste discharge permits, including sewage sludge, and those sections of 40 Code of Federal Regulations (CFR) Part 122 adopted by reference by-the Commission. The following text includes tlfese conditions and incorporates them into this permit. All definitions in Texas Water Code §26.001 and 30 TAG Chapter 305 shall apply to this permit and are incorporated by reference. Some specific definitions of words or phrases used in this permit are as follows:

l. Flow Measurements

a. Annual average flow - the arithmetic average of all daily flow determinations taken within the preceding 12 consecutive calendar months. The annual average flow determination shall consist of daily flow volume determinations made by a tqtalizlng meter, charted on a chart recorder, and limited to major domestic wastewater discharge facilities with a one million gallons per day or greater permitted flow.

b. Daily average flow - the arithmetic average of all determinations of the daily flow within a

)eribd of one calendar month. The daily average flow determination shall consist of leterminations made on at least four separate days. If instantaneous measurements are used to determine the daily flow, the determination shall be the arithmetic average of all instantaneous measurements taken during that month. Daily average flow determination for intermittent discharges shall consist of a minimum of three flow determinations on days of discharge.

c. Daily maximum flow - the highest total flow for any 24-hour period in a calendar month.

d. Instantaneous flow - the measured flow during the minimum time required to interpret the flow measuring device.

e. 2-hour peak flow (domestic wastewater treatment plants) - the maximum flow sustained for a two-hour period during the geriod of daily discharge. The average of multiple measurements of instantaneous maximum Sow within a two-hour period may Be used to calculate the 2-hour peak flow.

f. Maximum 2-hour peak flow (domestic wastewater treatment plants) - the highest 2-hour peak flow for any 24-hour period in a calendar month.

2. Concentration Measurements

a. Daily average concentration - the arithmetic average of all effluent samples, composite or grab as requirecTby this permit, within a period of one calendar month, consisting of at least four separate representative measurements.

i. For domestic wastewater treatment plants - When four samples are not available in a calendar month, the arithmetic average (weighted by flow) of all values in the previous four consecutive month period consisting of at least four measurements shall be utilized as the daily average concentration.

ii. For all other wastewater treatment plants - When four samples are not available in a calendar month, the arithmetic average (weighted by flow) of all values taken during the month shall be utilized as the daily average concentration.

b. 7-day average concentration - the arithmetic average of all effluent samples, composite or grab as required T)y this permit, within a period of one calendar week, Sunday through Saturday.

c. Daily maximum concentration - the maximum concentration measured on a single day, by the sample type specified in the permit, within a period of one calendar month.

d. Daily discharge - the discharge of a pollutant measured during a calendar day or any 24-hour period that reasonably represents tHe calendar day for purposes of sampling. For pollutants with limitations expressed in terms of mass, the "daily discharge" is calculated as the total Pages

STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo mass of the pollutant discharged over the sampling day. For pollutants with limitations expressed in other units of measurement, the daily discharge" is calculated as the average measurement of the pollutant over the sampling day.

The "daily discharge" determination of concentration made using a composite sample shall be the concentration of the composite sample. When grab samples are used, the^'daily discharge" determination of concentration shall be the arithmetic average (weighted by flow value) of all samples collected during that day.

e. Bacteria concentration (Fecal coliform, E. coli, or Enterococci) - the number of colonies of bacteria per loo milliliters effluent. The daily average bacteria concentration is a geometric mean of the values for the effluent samples collected in a calendar month. The geometric mean shall be determined by calculating the nth root of the product of all measurements made in a calendar month, where n equals the number of measurements made; or computed as the antilogarithm of the arithmetic mean of the logarithms of all measurements made in a calendar month. For any measurement of bacteria equaling zero, a substitute value of one shall be made for input into either computation method. IT specified, the 7-day average for bacteria is the geometric mean of the values for all effluent samples collected during a calendar week.

f. Daily average loading (Ibs/day) - the arithmetic average of all daily discharge loading calculations during a period of one calendar month. TBese calculations must be made for each day of the month that a parameter is analyzed. The daily discharge, in terms of mass (Ibs/day),

is calculated as (Flow, MGD x Concentration, mg/L x 8.34).

g. Daily maximum loading (Ibs/day) - the highest daily discharge, in terms of mass (Ibs/day),

within a period of one calendar month.

3. Sample Type

a. Composite sample - For domestic wastewater, a composite sample is a sample made up of a minimum of three effluent portions collected in a continuous 24-hpur period or during the period of daily discharge if less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , and combined in volumes proportional to flow, and collected at the intervals required by 30 TAG §3l9.9(a). For industrial wastewater, a composite sample is a sample made ug of a minimum of three effluent portions collected in a continuous 24-hour period, or during the period of daily discharge if less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , and combined in volumes proportional to flow, and collected at the intervals required by 30 TAG

§3l9.9(c).

b. Grab sample - an individual sample collected in less than 15 minutes.

4. Treatment Facility (facility) - wastewater facilities used in the conveyance, storage, treatment, recycling, reclamation or disposal of domestic sewage, industrial wastes, agricultural wastes, recreational wastes, or other'wastes including sludge handling or disposal facilities under the jurisdiction of the Commission.

5. The term "sewage sludge" is defined as solid, semi-solid, or liquid residue generated during the treatment of domestic sewage in 30 TAG Chapter 312. This includes the solids that have not been classified as hazardous waste separated from wastewater by unit processes.

6. Bypass - the intentional diversion of a waste stream from any portion of a treatment facility.

MONITOMNGAND REPORTING REQUIREMENTS

l. Self-Reporting Monitoring results shall be provided at the intervals specified in the permit. Unless otherwise specified in this permit or otherwise ordered by the Commission, the permittee shall conduct effluent sampling and reporting in accordance with 30 TAG §§319.4 - 319.12. Unless otherwise specified, effluent monitoring data shall be submitted each month, to the Enforcement Division (MC 224), by the 20th day of the following month for each discharge that is described by this permit whether or not a discharge is made for that month. Monitoring results must be submitted online using the NetDMR reporting system available through the TCEQ website unless the permittee requests and obtains an electronic reporting waiver. Monitoring results must be signed and certified as required by Monitoring and Reporting Requirements No. 10.

Page 4

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo As provided by state law, the permittee is subject to administrative, civil and criminal penalties, as applicable, for negligently or knowingly violating the Clean Water Act; TWC Chapters 26, 27, and 28} and THSC Chapter 361, including But not limited to knowingly making any false statement, representation, or certification on any report, record, or other document submitted or required to be maintained under this permit, including monitoring reports or reports of compliance or noncompliance, or falsifying, tampering with pr knowingly rendering inaccurate any monitoring device or method required by this permit or violating any other requirement imposed by state or federal regulations.

2. Test Procedures

a. Unless otherwise specified in.this permit, test procedures for the analysis of pollutants shall comply with procedures specified In 30 TAC §§319.11 - 319.12. MEeasuremenfs, tests, and calculations shall be accurately accomplished in a representative manner.

b. All laboratory tests submitted to demonstrate compliance with this permit must meet the requirements of 30 TAG Chapter 25, Environmental Testing Laboratory Accreditation and Certification.

3. Records of Results

a. Monitoring samples and measurements shall be taken at times and in a manner so as to be representative of the monitored activity.

b. Except for records of monitoring information required by this permit related to the permittee's sewage sludge use and disposal activities, which shall be "retained for a period of at least five years~(or longer as require'd bj 40 CFR Part 503), monitoring and reporting records, including strip charts and records of cafibi-ation and maintenance, copies of alT records required by this permit, records of all data used to complete the application for this permit, and the certification required by 40 CFR §264.73(b)(9) sfiall be retained at the facility site, or shall be readily available for review by a TCEQ representative for a period of three years from the date of the record or sample, measurement, report, application or certification. This period shall be extended at the request of the Executive Director.

c. Records of monitoring activities shall include the following:

i. date, time, and place of sample or measurement; ii. identity of individual who collected the sample or made the measurement; ill. date and time of analysis; iv. identity of the individualand laboratory who performed the analysis;

v. the technique or method of analysis; arid vi. the results "of the analysis or measurement and quality assurance/quality control records.

The period during which records are required to be kept shall be automatically extended to the date of the final disposition of any administrative or judicial enforcement action that may be instituted against t&e permittee.

4. Additional Monitoring by Permittee If the permittee monitors any pollutant at the location(s) designated herein more frequently than required by thisj)ermit using approved analytical methods as specified above, all results of such monitoring shalfbe included-in the calculation and reporting of the values submitted on the approved self-report form. Increased frequency of sampling "shall be indicated on the self-report form.

5. Calibration of Instruments All automatic flow measuring or recording devices and all totalizing meters for measuring flows shall be accurately calibrated, by a trained person at plant start-up and as often thereafter as necessary to ensure accuracy, 15ut not less often than annually unless authorized by the Executive Director for a longer period. Such person shall verify in writing that the device is operating properly and giving accurate results. Copies of the verification shall be retained at the facility site or shallbe readily available for review by a TCEQ representative for a period of three years.

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STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

6. Compliance Schedule Reports Reports of compliance or noncompliance with, or any progress reports on, interim and final requirements contained in any compliance schedule of the permit shall be submitted no later than 14 days following each schedule date to the regional office and the Enforcement Division (MC 224).

7. Noncompliance Notification

a. In accordance with 30 TAG §305.125(9) any npncompliance that may endanger human health or safety, or the environment shall be reported by the permittee to the TCEQ". Report of such information shall be provided orally or l>y facsimile transmission (FAX) to tfie regional office within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of becoming aware of the noncpmpliance. A written submission of such information shall also be provided by the permittee to the regional office and the Enforcement Division (MC 224) within five wprlang days of becoming aware of the noncpmpliance. For Publicly Owned Treatment Works (POTWs), effective September l, 2020, the permittee must submit the written report for unauthorized discharges aiid unanticipated bypasses that exceed any effluent limit in the permit using the online electronic reporting system available through the TCEQ website unless the permittee requests and obtains an electronic reporting waiver."

The written submission shall contain a description of the noncompliance and its cause; the potential danger to human health or safety, or the environment; the period of noncpmpliance, including exact dates and times; if the noncompliance has not been corrected, the time it is expected, to continue; and steps taken or planned to reduce, eliminate, and prevent recurrence of the noncompliance, and to mitigate its adverse effects.

b. The following violations shall be reported under Monitoring and Reporting Requirement y.a.:

i. unauthorized discharges as defined in Permit Condition 2(g).

ii. any unanticipated bypass that exceeds any effluent limitation in the permit.

iii. violation of a permitted maximum daily discharge limitation for pollutants listed specifically in the Other Requirements section oTan Industrial TPDES permit.

c. In addition to the above, any effluent violation that deviates from the permitted efQuent limitation by more than 40% shall be reported by the permittee in wrfting to the regional office and the Enforcement Division (JVIC 224) within 5 worRing days of becoming aware of the noncompliance.

d. Any noncpmpliance other than that specified in this section, or any required information not submitted or submitted incorrectly, shall be reported to the Enforcement Division (MC 224)as promptly as possible. Foraffluent limitation violations, noncompliances shall be reported on the approved self-report form.

8. In accordance with the procedures described in 30 TAG §§35.301 - 35.303 (relating to Water Quality Emergency and Temporary Orders) if the permittee laiows in advance oftHe need for a bypass, it shall submit prior notice by applying for such authorization.

9. Changes in Discharges of Toxic Substances All existing manufacturing, commercial, mining, andsilviculturalpermittees shall notify the regional office, orally or by facsimile transmission within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ", and both the regional office and the Enforcement Division (MC 224) in writing within five (5) working days, after becoming aware of or having reason to believe:

a. That any activity has occurred or will occur that would result in the discharge, on a routine or frequent basis, of any toxic pollutant listed at 40 CFR Part 122, Appendix D, Tables II and III (excluding Total Phenols) tRat is not limited in the permit, if that discharge will exceed the highest of the following "notification levels":

i. one hundred micrograms per liter (100 pg/L);

ii. two hundred micrograms per liter (200 M^/L) for acrolein and acrylonitrile; five hundred micrograms per liter (500 (^/L) for 2,4-dlmtrophenol and for 2-methyl-4,6-dinitrophenol; and one miUigram per liter Cl mg/L) for antimony; iii. five (5) times the maximum concentration value reported for that pollutant in the permit application; or iv. t&e level established by the TCEQ.

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STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

b. That any activity has occurred or will occur that would result in any discharge, on a nonroutme or infrequent basis, of a toxic pollutant that is not limited in the permit, if that discharge will exceed the highest of the following "notification levels":

i. five hundred micrograms per liter (500 p.g/L);

ii. one milligram per Ifter (l mg/L) for antimony, iii. ten (10) times the maximum concentration value reported for that pollutant in the permit application; or iv. tfie level established by the TCEQ.

io. Signatories to Reports All reports and other information requested by the Executive Director shall be signed by the person and in the manner required by 30 TAG §305.128 (relating to Signatories to Reports).

ii. All POTWs must provide adequate notice to the Executive Director of the following:

a. any new introduction of pollutants into the POTW from an indirect discharger that would be subject to CWA §301 or §306 if it were directly discharging those pollutants;

b. any substantial change in the volume or character of pollutants being introduced into that POTW by a source introducing pollutants into the POTW at the time of issuance of the permit; and

c. for the purpose of this paragraph, adequate notice shall include information on:

i. the quality and quantity of effluent introduced into the POTW; and ii. any anticipated impact of the change on the quantity or quality of effluent to be discharged from the POTW.

PERMIT CONDITIONS

l. General

a. When the permittee becomes aware that it failed to submit any relevant facts in a permit application, or submitted incorrect information in an application or in any report to the Executive Director, it shall promptly submit such facts bi- information.

b. This permit is granted on the basis of the information supplied and representations made by the permittee during action on an application, and relying upon the accuracy and completeness oft&at information and those representations. After notice and opportunity for a hearing, this

)ermit may be modified, suspended, or revoked, in whole or in part, in accordance with 30 FAC Chapter 305, Subchapter D, during its term for good cause'including, but not limited to, the following:

i. violation of any terms or conditions of this permit; ii. obtaining this permit by misrepresentationor failure to disclose fully all relevant facts; or iii. a change'in any condition that'requires either a temporary or permanent reduction or elimination of the authorized discharge.

c. The permittee shall furnish to the Executive Director, upon request and within a reasonable time, any information to determine whether cause exists for amending, revoking, suspending, or terminating the permit. The permittee shall also furnish to the Executive Director, upon request, copies of records required to be kept by the permit.

2. Compliance

a. Acceptance of the permit by the person to whom it is issued constitutes acknowledgment and agreement that such person will "comply with all the terms and conditions embodied in the permit, and the rules'and other orders of the Commission.

b. The permittee has a duty to comply with all conditions of the permit. Failure to comply with any permit condition constitutes a^yiolation of the permit and. the Texas Water Code or the Texas Health and Safety Code, and is grounds for enforcement action, for permit amendment, Page 7

STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo revocation, or suspension, or for denial of a permit renewal application or an application for a permit for another facility.

c. It shall not be a defense for a permittee in an enforcement action that it would have been necessary to halt or reduce the permitted activity in order to maintain compliance with the conditions of the permit.

d. The permittee shall take all reasonable steps to minimize or prevent any discharge or slydge use or disposal or other permit violation tHat has a reasonable likelihood of adversely affecting human health or the environment.

e. Authorization from the Commission is required before beginning any change in the permitted facility or activity that may result in noncompliance with any permit requirements.

f. A permit may be amended, suspended and reissued, pr revoked for cause in accordance with 30 TAG §§365.62 and 305.66 and TWO §7.302. The filing of a request by the permittee for a permit amendment, suspension and reissuance, or termmation, or a notification of planned changes or anticipated rioncompliance, does not stay any permit condition.

g. There shall be no unauthorized discharge of wastewater or any other waste. For the purpose of this permit, an unauthorized discharge is considered to be any discharge ofwastewatermtopr adjacent to water in the state at any location not permitted as an outfall or otherwise defined in the Other Requirements section of this permit.

h. In accordance with 30 TAG §305.535(0), the permittee may allow any bypass to occur from a TPDES permitted facility that does not cause permitted effluent limitations to be exceeded or an unauthorized discharge to occur, but only if the bypass is also for essential maintenance to assure efficient operation.

i. The permittee is subject to administrative, civil, and criminal penalties, as applicable, under Texas Water Code §§7.051 - 7.075 (relating to AdmimstratiYe Penalties)^ 7.101 - 7.111 (relating to Civil Penalties), and 7^141 - 7.202 (relating to Criminal Offenses and Penalties) for violations including, but not limited to, negligently or Knowingly violating the federal CWA §§301, 302, 306,307,308,318, or 405,or any condition or limitation implementing any sections in a permit issued under the CWA §402, or any requirement imposed in a pretreatment program approved under the CWA §§402(a)(3) or 402(b)(8).

3. Inspections and Entry

a. Inspection and entry shall be allowed as prescribed in the TWC Chapters 26, 27, and 28, and THSC Chapter 361.

b. The members of the Commission and employees and agents of the Commission are entitled to enter any public or ]->rivatej)roperty at any reasonable time for the purpose of inspecting and investigating conditions relating to the quality of water in the state or the compliance with an^

rule, re'gulafion, permit, or othe-r order of the Commission. Members, employees, or agents oi the Commission and Commission contractors are entitled to enter public^or private property at any reasonable time to investigate or monitor or, if the responsible party is not responsive or there is an immediate danger to public health or the environment, to remove or remediate a condition related to the quality of water in the state. IVIembers, employees, Commission contractors, or agents acting under this authority who enter private property shall observe the establishment's rules and regulations concerning safety, internal security, and fire protection, and if the property has management m residence, shall notify management or the person then in charge of his presence and shall exhibit proper credentials. If any member, employee, Commission contractor, or agent is refused the right to enter in or on public or private property under this authority, the Executive Director may invoke the remedies authorized in TWC §7.002. The statement'above, that Commission entry shall occur in accordance with an establishment's rules and regulations concerning safety, internal security, and fire protection, is not grounds for denial or restriction of entry to any part of the facility, but merely describes the Commission's duty to observe appropriate rules and regulations during an inspection.

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STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

4. Permit Amendment or Renewal

a. The permittee shall give notice to the Executive Director as soon as possible of any claimed physical alterations or additions to the permitted facility if such alterations or additions.would require a permit amendment or result in a violation of permit requirements. Notice shall also be required under this paragraph when:

i. the alteration or addition to a permitted facility may meet one of the criteria for determining whether a facility'is a new source in accordance with 30 TAC §305.534 (relating to New Sources and New Dischargers); or ii. the alteration or addition could significantly change the nature or increase the quantity of pollutants discharged. This notification applies to pollutants that are subject neither to effluent limitations in the permit, nor to notification requirements in Monitoring and Reporting Requirements No. 9; or iii. the alteration or addition results in a significant change in the permittee's sludge use or disposal practices, and such alteration, addition, or change may justify the application of permit conditions that are different from or absent in the existing permit, including notification of additional use or disposal sites not reported during the permit application process or not reported pursuant to an approved land application plan.

b. Prior to any facility modifications, additions, or expansions that will increase the plant capacity beyond the permitted flow, the permittee must apply for and obtain proper authorization from the Commission before commencing construction.

c. The permittee must apply for an amendment or renewal at least 180 days prior to expiration of the existing permit iifdrder to continue a permitted activity after the expiration date'ofthe permit. If an application is submitted prior to the expiration date of the permit, the existing permit shall remain in effect until the application is approved, denied, or returned. If the application is returned or denied, authorization to continue such activity shall terminate upon t&e effective date of the action. If an application is not submitted prior to the expiration date of the permit, the permit shall expire and authorization to continue such activity shall terminate.

d. Prior to accepting pr generating wastes that are not described in the permit application or that would resulrtn a'significant change in the quantity or quality of the existing discharge, the permittee must report the proposed changes to the Commission. The permittee must apjsly for a permit amendment reflecting any necessary changes in permit conditions, including efiluent limitations for pollutants not identified and TimitecTby this permit.

e. In accordance with the TWC §26.029(b), after a public hearing, notice of which shall be given to the permittee, the Commissionmay require the permittee, from time to time^ for good.

cause, in accordance with applicable laws, to conform to new or additional conditions.

f. If any toxic effluent standard or prohibition (including any schedule of compliance specified in such effluent standard or prohibition) is promulgated under CWA §307(0) for a toxic pollutant that is present in thediscfiarge and that standard or prohibition is more stringent than any limitation on the pollutant in this permit, this permit shall be modified or revoked and reissued to conform to the toxic effluent standard pr prohibition. The permittee shall comply with effluent standards or prohibitions established under CWA §307(a) for toxic pollutants within the time provided in the regulations that established those standards or prohibitions, even if the permit has not yet been modified to incorporate the requirement.

5. Permit Transfer

a. Prior to any transfer of this permit, Commission approval must be obtained. The Commission shall be notified m writing of any change in control or ownership of facilities authorized by this permit. Such notification should be sent to the Applications Review and Processing Team (1VIC 148) of the Water Quality Division.

b. A permit may be transferred only according to the provisions of 30 TAG §305.64 (relating to Transfer of Permits) and 30 TAG §50.133 (relating to Executive Director Action on Application or WQMP update).

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STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo

6. Relationship to Hazardous Waste Activities This permit does not authorize any activity of hazardous waste storage, processing, or disposal that requires a permit or other authorization pursuant to the Texas Health and Safety Code.

7. Relationship to Water Rights Disposal of treated effluent by any means other than discharge directly to water in the state must be specifically authorized in this permit and may require a permit pursuant to Texas Water Code Chapter ll.

8. Property Rights A permit does not convey any property rights of any sort, or any exclusive privilege.

9. Permit Enforceability The conditions of this permit are severable, and if any provision of this permit, or the application of any provision of this permit to any circumstances, is^held invalid, the application of such provision to other circumstances, arid the remainder of this permit, shall hot be affected thereby.

10. Relationship to Permit Application The application pursuant to which the permit has been issued is incorporated herein; provided, however, that inthe event of a conflict between the provisions of this permit and the application, the provisions of the permit shall control.

ll. Notice of Bankruptcy.

a. Each permittee shall notify the executive director, in writing, immediately following the filing of a voluntary or involuntary petition for bankruptcy under any chapter of Title ll (Bankruptcy) of the United States Code (ll USC) by or against:

i. the permittee; ii. an entity (as that term is defined in ll USC, §101(15)) controlling the permittee or listing the permit or permittee as property of the estate; or iii. an affiliate (as that term is defined in ll USC, §101(2)) of the permittee.

b. This notification must indicate:

i. thenameofthepermittee; ii. the permit num6er(s);

iii. the bankruptcy court in which the petition for bankruptcy was filed; and iv. the date of filihg of the petition.

OPERATIONAL REQUIREMENTS

l. The permittee shall at all times ensure that the facility and all of its systems of collection, treatment, and disposal are properly operated and maintained. This includes, but is not limited to, the regular, periodic examination of wastewater solids within the treatment plant by the operator in order to maintain an appropriate quantity and quality of solids inventory as described in the various operator training manuals and according to accepted industry standards for process control. Process control, maintenance, and operations records shall be retained at the facility site, or shall be readily available for review by a TCEQ representative, for a period of three years.

2. Upon request by the Executive Director, the permittee shall take appropriate samples and provide proper analysis in order to demonstrate compliance with Commission rules. Unless otherwise specified in this permit or otherwise orderecTby the Commission, the permittee shall comply with all applicable provisions of 30 TAG Chapter 312 concerning sewage sludge use and disposaland 30 TAG^§319.21 - 319.29 concerning the discharge of certain hazardous metals.

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STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

3. Domestic wastewater treatment facilities shall comply with the following provisions:

a. The permittee shall notify the Municipal Permits Team, Wastewater Permitting Section (MC 148) of the Water Quality Division, in writing, of any facility expansion at least 90 days prior to conducting such activity.

b. The permittee shall submit a closure plan for review and approval to the Municipal Permits Team, Wastewater Permitting Section (MC 148) of the Water Quality Division, for any closure activity at least 90 days prior-to conducting such activity. Closure is the act of permanently taking a waste management unit or treatment facility out of service and includes the permanent removal from service of any pit, tank, pond, lagoon, surface impoundment or other treatment unit regulated by this permit.

4. The permittee is responsible for installing prior to plant start-up, and subsequently maintaining, adequate safeguards to prevent the discharge of untreated or inadeguately treated wastes during electrical power failures~by means of alternate power sources, standby generators, or retention of inadequately treated wastewater.

5. Unless otherwise specified, the permittee shall provide a readily accessible sampling point and, where applicable, an effluent flow measuring device or other acceptable means by which effluent flow may~be determined.

6. The permittee shall remit an annual water quality fee to the Commission as required by 30 TAG Chapter 21. Failure to pay the fee may result in revocation of this permit under TWC §7.302Cb)(6).

7. Documentation For all written notifications to the Commission required of the permittee by this permit, the permittee shall keep and make available a copy of each such notification under tfie same conditions as self-monitoring data are required to be kejit and made available. Except for information required for TPDES permit applications, effluent data, including effluentdatam permits, draft permits and permit applications, and other information specified as not confidential In 30 TAG §l.5~(d), any information submitted pursuant to this permit maybe claimed as confidential by the submitter. Any such claim must be assertecTin the manner prescribed in the application form or by stamping the words "confidential business information" on each page containing such informatiori. If no claim is made at the time of submission, informationTmay be made avaQable to the public without further notice. If the Commission or Executive Director agrees with the designation of confidentiality, the TCEQ will not provide the information for public inspection unless required by the Texas Attorney General or a court pursuant to an open records request. If the Executive Director does not agree with the designation of confidentiality, the person suBmitting the information will be notified.

8. Facilities that generate domestic wastewater shall comply with the following provisions; domestic wastewater treatment facilities at permitted industrial sites are excluded.

a. Whenever flow measurements for any domestic sewage treatment facility reach 75% of the permitted daily average or annual average flow for three consecutive months, the permittee must initiate engineering and financial planning for expansion or upgrading of the domestic wastewater treatment or collection facilities. Whenever the flow reaches 90% of the permitted daily average or annual average flow for three consecutive months, the permittee shall obtain necessary authorization from the Commission to commence construction of the necessary additional treatment or collection facilities. In the case of a domestic wastewater treatment facility that reaches 75% of the permitted daily average or annual average flow for three consecutive months, and the planned population to be served or the quantity of waste produced is not expected to exceed the design limitations of the treatment facility, the permittee shall submit an engineering report supporting this claim to the Executive Director of the Commission.

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STP Nuclear Operating Company TPDES Permit No. WQoooigoSooo If in the judgment of the Executive Director the population to be served will not cause permit noncompliance, then the requirement of this section may be waived. To be effective, any waiver must be in writing and signed by the Director of the Enforcement Division (MC 149) of the Commission, and such waiver of these requirements will be reviewed upon expiration of the existing permit; however, any such waiver shall not be interpreted as condoning or excusing any violation of any permit parameter.

b. The plans and specifications for domestic sewage collection and treatment works associated with any domestic permit must be approved by the Commission, and failure to secure approval before commencing construction of such works or maldng a discharge is a violation of this permit and each day is an additional violation until approval has been secured.

c. Permits for domestic wastewater treatment plants are granted subject to the policy of the Commission to encourage the development of area-wide waste collection, treatment, and disposal systems. The Commission reserves the right to amend any domestic wastewater permit in accordance with applicable procedural requirements to require the system covered by this permit to be integrated into an area-wide system, should sucfi be developed; to require the delivery of the wastes authorized to be collected in, treated by or discharged" from said" system, to such area-wide system; or to amend this permit in any other particular to effectuate the Commission's policy. Such amendments may be made when the changes required are advisable for water quality control purposes and are feasible on the basis of waste treatment technology, engineering, financial, and. related considerations existing at the time the changes are required, exclusive of the loss of investment in or revenues from any then existing or proposed waste collection, treatment or disposal system.

9. Domestic wastewater treatment plants shall be operated and maintained by sewage plant operators holding a valid certificate of competency at the required level as defined, in 30 TAG Cliapter 30.

10. For Publicly Owned Treatment Works (POTWs), the 30-day average (or monthly average) percent removal for BOD and TSS shall not be less than 85%, unless otherwise authorized by this permit.

ll. Facilities that generate industrial solid waste as defined in 30 TAG §335.1 shall comply with these provisions:

a. Any solid waste, as defined in 30 TAG §335.1 (including but not limited to such wastes as garbage, refuse, sludge from a waste treatment, water supply treatment plant or air pollution control facility, discarded materials, discarded materials to be recycled, whether the waste is solid, liquid, or semisolid), generated by the permittee during the management and treatment qfwastewater, must be managed in accordance with all applicable provisions of 30 TAG Chapter 335, relating to Industrial Solid Waste Management.

b. Industrial wastewater that is being collected^ accumulated, stored, or processed before discharge through any final discharge outfall, specified by this permit, is considered to be industrial solid waste until the wastewater passes through the actual jioint source discharge and must be managed in accordance with all applicable provisions ofso TAG Chapter 335.

c. The permittee shall provide written notification, pursuant to the requirements of 30 TAG

§335-8(b)(l),to the Corrective Action Section (Mt; l27)oftheRemediation Division informing tKe Commission of any closure activity involving an Industrial Solid Waste Management Unit, at least 90 days prior to conducting such an activity.

d. Construction of any industrial solid waste management unit requires the prior written notification of the proposed activity to the Registration and Reporting Section (MC 129) of the Permitting and Remediation Support Division. No person shall dispose of industrial solid waste, including sludge or other solids from wastewater treatment processes, prior to fulfilling the deed recordation requirements of 30 TAG §335.5.

e. The term "industrial solid waste management unit" means a landfill, surface impoundment, waste-pile, industrial furnace, incinerator, cement kiln, injection well, container, drum, salt dome waste containment cavern, or any other structure vessel, appurtenance, or other improvement on land used to manage industrial solid waste.

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STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

f. The permittee shall keep management records for all sludge (or other waste) removed from anywastewater treatment process. These records shall fulfill all applicable requirements of 30 TAG Chapter 335 and must include the following, as it pertains to wastewater treatment and discharge:

i. volume of waste and date(s) generated from treatment process; ii. volume of waste disposed ofon-site or shipped off-site;"

iii. date(s) of disposal; iv. identity ofhauler or transporter;

v. location of disposal site; and vi. method of final disposal.

The above records shall be maintained on a monthly basis. The records shall be retained at the facility site,_or shall be readily available for review by authorized representatives of the TCEQ for at least five years.

12. For industrial facilities to which the requirements of 30 TAG Chapter 335 do not app>ly, slud^e and solid wastes, including tank cleaning and contaminated solids for disposal, shall be disposecTofin accordance with THSC Code Chapter 361.

TCEQ Revision 01/2016 Page 13

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo OTHER REOmREMENTS Wastewater discharged via Outfall 006 must be sampled and analyzed as directed below for the parameters listed in the following table for a minimum of four sampling events, with each occurring at least one week apart. Sample collection for Outfall 006 must be completed within 60 days following issuance of this permit. Results of the analytical testing for Outfall 006 must be submitted within 90 days of obtaining and compiling the required analytical data, to the TCEQ Industrial Permits Team (MC-148).

Based on a technical review of the submitted analytical results, an amendment maybe initiated by TCEQ staff to include additional effluent limitations, monitoring requirements, or both.

OutfaUNo.: DC ^ DG^ Effluent Concentration ((ig/L) MAL2 (us/L)

Pollutants Samp. Samp. Samp. Samp. Average Flow (MGD) N/A Thallium, total 0.5 Indicate Composite Sample (C) or Grab Sample (G).

2 Minimum Analytical Level.

2. The permittee submitted a thermal plume characterization study titled Thermal Plume Study Work Plan for Characterization ofOutfall 001 Discharges - South Texas Project Electric Generating Station dated January 18, 2016 to the TCEQ in accordance with the agreement reached by the TCEQ and the U.S. Environmental Protection Agency (EPA) in their letters dated April 29, 2014 and May 12, 2014 for approval and implementation, respectively. The study plan was reviewed and approved by TCEQ staff on February 8, 20l6. Upon initiation of discharge via Outfall 001, the permittee shall implement the TCEQ-approved thermal plume characterization study, submit the results to the TCEQ upon completion of the study and include the study with the next Industrial Wastewater Permit Application following completion of the study. The permittee is hereby placed on notice that the executive director of the TCEQ will be initiating changes to evaluation procedures and/or rulemaking that may affect thermal requirements for this facility.

3. COOLING WATER INTAKE STRUCTURE REQUIREMENTS A. Specialized Definitions (l) Actual Intake Flow (AIF), as defined at 40 CFR § 125.92(0), means the average volume of water withdrawn on an annual basis by the cooling water intake structures over the past three years. After October 14, 2019, AIF means the average volume of water withdrawn on an annual basis by the cooling water intake structures over the previous five years. Actual intake flow is measured at a location within the cooling water intake structure that the Director deems appropriate. The calculation of actual intake flow includes days of zero flow. AIF does not include flows associated with emergency and fire suppression capacity.

(2) Closed Cycle Recirculating System (CCRS), as defined as 40 CFR § 125.92(0), means a system designed and properly operated using minimized make-up and blowdown flows withdrawn from a water of the United States to support contact or non-contact cooling uses within a facility, or a system designed to include certain impoundments. A closed-cycle recirculating system passes cooling water through the condenser and other components of the cooling system and reuses the water for cooling multiple times.

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STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo

a. CCRS also includes a system with impoundments of waters of the United States (WOTUS) where the impoundment was constructed prior to October 14, 2014 and created for the purpose of serving as part of the cooling water system as documented in the project purpose statement for any required Clean Water Act section 404 permit obtained to construct the impoundment. In the case of an impoundment whose construction pre-dated the CWA requirement to obtain a section 404 permit, documentation of the project's purpose must be demonstrated to the satisfaction of the Director. This documentation could be some other license or permit obtained to lawfully construct the impoundment for the purposes of a cooling water system, or other such evidence as the Director finds necessary.

For impoundments constructed in uplands or not in WOTUS, no documentation of a section 404 or other permit is required. IfWOTUS are withdrawn for purposes of replenishing losses to a CCRS other than those due to blowdown, drift, and evaporation from the cooling system, the Director may determine a cooling system is a CCRS if the facility demonstrates to the satisfaction of the Director that make-up water withdrawals attributed specifically to the cooling portion of the cooling system have been minimized B. Monitorine Requirements The permittee shall adhere to the requirements of 40 CFR § 125.96 when the CWIS is in operation. Specifically, the facility shall:

(l) monitor actual intake flow, as defined at 40 CFR § 125.92(0), withdrawn by the CWIS for cooling purposes, including cooling water withdrawals and make-up water withdrawals, on a daily basis; and (2) conduct visual or remote inspections, on a weekly basis, as required by 40 CFR l25.96(e).

Alternatives to the procedures described at 40 CFR § 125.96(6) have not been approved by the TCEQ. Requests for alternative procedures must be submitted in writing to the TCEQ's Industrial Permits Team (MC-148) for review and approval.

Results of monitoring activities conducted during the term of this permit must be submitted to the TCEQ with the subsequent renewal permit application, as required by 40 CFR § 122.2l(r).

C. Record Keeping Requirements Records (e.g. elecb'onic logs, data acquisition system records, operating procedures, operator logs, etc.) documenting the operation and maintenance described above shall be kept on site until the subsequent permit is issued, per the requirements of 40 CFR § l25.97(d), and made available to TCEQ personnel upon request.

D. Changes in the Cooling Water Intake Structure The facility must notify the TCEQ Industrial Permits Team (MC 148) and TCEQ Region 12 Office in writing at least 30 days prior to any changes or modifications of the design of the CWIS.

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STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo If it is determined that the proposed CWIS configuration does not meet best technology available standards for impingement mortality and entrainment, the permit may be reopened to incorporate additional requirements.

4. MONITORING AND REPORTING A. This provision supersedes and replaces Provision l, Paragraph l of Monitoring and Reporting Requirements found on Page 4 of this permit.

Monitoring results shall be provided at the intervals specified in this permit. Unless otherwise specified in this permit or otherwise ordered by the Commission, the permittee shall conduct effluent sampling and reporting in accordance with 30 TAG §§319.4 - 319.12.

Unless otherwise specified, effluent monitoring data shall be submitted each month, to the Enforcement Division (MC 224), by the 25th day of the following month for each discharge that is described by this permit whether or not a discharge is made for that month.

Monitoring results must be submitted online using the NetDMR reporting system available through the TCEQ website unless the permittee requests and obtains an electronic reporting waiver. Monitoring results must be signed and certified as required by Monitoring and Reporting Requirements No. 10.

B. Monitoring results must be provided at the intervals specified in this permit. For pollutants which are monitored annually, effluent reports must be submitted in September of each year.

For pollutants which are monitored twice per year, the first effluent report must be submitted six months after the date of plant start-up or discharge, whichever comes first, and subsequent reports every six months thereafter. For pollutants which are monitored four times per year, the first efQuent report must be submitted three months after the date of plant start-up or discharge, whichever comes first, and subsequent reports every three months thereafter.

5. Violations of daily maximum limitations for the following pollutants shall be reported orally or by facsimile to TCEQ Region 12 within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months from the time the permittee becomes aware of the violation, followed by a written report within five working days to TCEQ Region 12 and the Enforcement Division (MC 224):

Pollutant MAL1 (mg/L)

Copper (Total) 0.002 Iron (Total) 0.007 1 Minimum Analytical Level Test methods used must be sensitive enough to demonstrate compliance with the permit effluent limitations. If an efQuent limit for a poUutant is less than the MAL, then the test method for that pollutant must be sensitive enough to demonstrate compliance at the MAL. Permit compliance /

noncompliance determinations will be based on the effluent limitations contained in this permit, with consideration given to the MAL for the pollutants specified above.

When an analysis of an effluent sample for a pollutant listed above indicates no detectable levels above the MAL and the test method detection level is as sensitive as the specified MAL, a value of zero shall be used for that measurement when maldng calculations for the self-reporting form.

This applies to determinations of daily maximum concentration, calculations of loading and daily averages, and other reportable results.

When a reported value is zero based on this MAL provision, the permittee shall submit the following statement with the self-reporting form either as a separate attachment to the form or as a statement in the comments section of the form:

Page 16

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo "The reported value(s) of zero (o) for Flist parameterfs~)1 on the self-reporting form for

[monitoring period date rangel is based on the following conditions: (l) the analytical method used had a method detection level as sensitive as the MAL specified in the permit, and (2) the analytical results contained no detectable levels above the specified MAL."

When an analysis of an effluent sample for a pollutant indicates no detectable levels and the test method detection level is not as sensitive as the MAL specified in the permit, or an MAL is not specified in the permit for that pollutant, the level of detection achieved shall be used for that measurement when making calculations for the self-reporting form. A zero may not be used.

6. Wastewater discharged via Outfall 001 must be sampled and analyzed as directed below for those parameters listed in Tables l, 2,3,4,and 5 of Attachment A of this permit. Analytical testing for Outfall 001 must be completed within 60 days of initiation of discharge. Results of the analytical testing must be submitted within 90 days of initiation of discharge to the TCEQ Industrial Wastewater Permits Team (MC-148). Based on a technical review of the submitted analytical results, an amendment may be initiated by TCEQ staff to include additional effluent limitations, monitoring requirements, or both.

Table l: Analysis is required for all pollutants. Wastewater must be sampled and analyzed for those parameters listed in Table l for a minimum of one sampling event.

Table 2: Analysis is required for those pollutants in Table 2 that are used at the facility that could in any way contribute to contamination in the Outfall 001 discharge. Sampling and analysis must be conducted for a minimum of one sampling event.

Table 3: For all pollutants listed, the permittee shall indicate whether each pollutant is believed to be present or absent in the discharge. Sampling and analysis must be conducted for each pollutant believed present for a minimum of one sampling event.

Table 4: Analysis is required for all pollutants. Wastewater must be sampled and analyzed for those parameters listed in Table 4 for a minimum of one sampling event.

Table 5: Analysis is required for all pollutants. Wastewater must be sampled and analyzed for those parameters listed in Table 5 for a minimum of one sampling event.

The permittee shall report the flow at Outfall 001 in 1VIGD in the attachment. The permittee shall indicate on each table whether the samples are composite (C) or grab (G) by checking the appropriate box.

7. The term metal cleaning waste means any wastewater resulting from cleaning [with or without chemical compounds] any metal process equipment including, but not limited to, boiler tube cleaning, boiler fireside cleaning, and air preheater cleaning.

8. The term chemical metal cleaning waste means any wastewater resulting from the cleaning of any metal process equipment with chemical compounds, including, but not limited to, boiler tube cleaning.

9. For discharges via Outfall 001, the daily average temperature is defined as the flow weighted average temperature (FWAT). The FWAT must be computed and recorded on a daily basis at equal time intervals not greater than two hours on days when Outfall 001 is discharging. The method of calculating FWAT is as follows:

Page 17

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo FWAT = y.dNSTANTANEOUSFLOWx INSTANTANEOUS TEMPERATURE)

^(INSTANTANEOUS FLOW)

Daily average temperature must be calculated as the arithmetic average of all FWATs calculated during the calendar month. Daily maximum temperature must be the highest FWAT calculated during the calendar month.

10. The term low volume waste sources means, taken collectively as if from one source, wastewater from all sources except those for which specific limitations or standards are otherwise established in 40 CFR part 423. Low volume waste sources include, but are not limited to, the following:

Wastewaters from ion exchange water treatment system, water treatment evaporator blowdown, laboratory and sampling streams, boiler blowdown, floor drains, cooling tower basin cleaning wastes, recirculating house service water systems, and wet scrubber air pollution control systems whose primary purpose is particulate removal. Sanitary wastes, air conditioning wastes, and wastewater from carbon capture or sequestration systems are not included in this definition.

ll. Mixing Zone Definitions Outfall 001: The mbdng zone is defined as a volume within a radius of 60 feet extending over the receiving waters from the point where discharge from each jet port enters the Colorado River. Chronic toxic criteria apply at the edge of the mbdng zone.

Outfall 002: There is no mbdng zone established for this discharge to an intermittent stream.

Acute toxic criteria apply at the point of discharge.

Outfall 003: The chronic aquatic life mbdng zone is defined as a volume within a radius of 30 feet from the point of discharge. Chronic toxic criteria apply at the edge of the chronic aquatic life mixing zone.

OutfaU 004: There is no mixing zone established for this discharge to an intermittent stream.

Acute toxic criteria apply at the point of discharge.

Outfall 005: There is no mbdng zone established for this discharge to an intermittent stream.

Acute toxic criteria apply at the point of discharge.

Outfall 006: There is no mixing zone established for this discharge to an intermittent stream with perennial pools. Chronic toxic criteria apply at the point of discharge.

12. This provision supersedes and replaces Definition and Standard Permit Conditions No. 2.a., Daily Average Concentration, as defined on page 3 of this permit:

Daily average concentration shall mean the arithmetic average (weighted by flow) of all efQuent samples, composition or grab as required by this permit, within a period of one calendar month, consisting of at least four separate representative measurements. When four samples are not available in a calendar month, the arithmetic average (weighted by flow) of the four most recent measurements or arithmetic average (weighted by flow) of all values taken during the month shall be utilized as the daily average concentration.

13. The discharge ofuncontaminated groundwater generated during excavations for the construction of the new electric generating Units 3 and 4 is authorized under TPDES Construction General Permit No. TXRisoooo. This groundwater may be discharged temporarily via OutfaU 001 during the construction of Units 3 and 4. This discharge must not cause nuisance conditions.

Page 18

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

14. Measurement of Flow at Outfalls 002, oo.rt, 004. ooci, and 006 From the 776 relief wells surrounding the M[ain Cooling Reservoir (MCR), the permittee has identified and documented the relief wells covered in the drainage area for each of the outfaUs. The permittee has established that there are always at least five wells that are flowing within the drainage area of each outfall during a monitoring event. Within each outfall drainage area, the permittee shall clearly identify each relief weU used for flow monitoring with a number and record the relief wells used during each monitoring event. The permittee shaU not use exactly the same five wells for flow monitoring in successive sampling events. The flow estimate (i.e., dry-weather flow) for each of the outfalls shall be determined as foUows:

Outfall 002 At the time of sample collection, the permittee shall measure the flow at five of the 168 relief wells before the discharge enters the Plant Area Drainage Ditch (PADD). The average flow from the relief wells (Fl) must be calculated as the arithmetic average of all five of the measured flows. Measured flow means the determination of volume ofeffluent discharged per unit time (e.g., gallons per minute). The demineralized water flow (F2) must be measured at the Instrument Tube prior to commingling with other waters.

The flow for Outfall 002 must be reported as [(Fixi68) + F2] in MGD.

Outfall oo.'?

At the time of sample collection, the permittee shall measure the flow at five of the 70 relief wells before the discharge enters West Branch of the Colorado River. The average flow (Fx) at Outfall 003 must be calculated as the arithmetic average of aU five of the measured flows.

The flow for Outfall 003 must be reported as (Fx x 70) in MGD.

Outfall 004 At the time of sample collection, the permittee shall measure the flow at five of the 66 relief wells before the discharge enters the unnamed ditch. The average flow from the relief wells (Fl) must be calculated as the arithmetic average of all five of the measured flows. The flow from MCR spiUway gate leakage (F2) must be estimated at the basin prior to commingling with other waters.

The flow for Outfall 004 must be reported as [(Fix66) + F2] in MGD.

Outfall OQFi At the time of sample collection, the permittee shall measure the flow at five of the 265 relief wells before the discharge enters East Fork Little Robbins Slough. The average flow (Fx) at Outfall 005 must be calculated as the arithmetic average of all five of the measured flows.

The flow for Outfall 005 must be reported as (Fx x 265) in MGD.

Outfall 006 At the time of sample collection, the permittee shall measure the flow at five of the 207 relief wells before the discharge enters Little Robbins Slough. The average flow (Fx) at Outfall 006 must be calculated as the arithmetic average of aU five of the measured flows.

The flow for Outfall 006 must be reported as (Fx x 207) in MGD.

15. Measurement ofpH, Temperature, and Total Residual Chlorine at Outfalls 002, oo.^, 004, oo.s, and op6 Within each outfall drainage area, the permittee shall clearly identify each of the five relief wells sampled with a number and record the numbers of the five relief wells used during each sampling Page 19

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo event. The relief wells sampled must be the same five relief wells used to determine the flow. The permittee shall not use exactly the same five wells in successive sampling events.

Samples for total residual chlorine analysis for discharges via Outfalls 002, 003, 004, and 005 may be collected from the relief wells located in the drainage area for Outfall 006 as authorized by Other Requirement No. 16 of this permit. For each outfall, the pH and temperature must be determined, and the total residual chlorine maybe determined as follows:

Outfall 002 Grab samples must be obtained from each of the five relief wells, and a grab sample of the demineralized water must be collected from the Instrument Tube. Analytical results for each parameter analyzed at the Instrument Tube and the relief wells must be compared, and the maximum temperature, the maximum total residual chlorme, and the maximum and minimum pH values must be used for compliance reporting purposes at Outfall 002.

Outfall 003 Grab samples must be obtained from each of the five relief wells. Analytical results for each parameter analyzed at the relief wells must be compared, and the maximum temperature, the maximum total residual chlorine, and the maximum and minimum pH values must be used for compliance reporting purposes at Outfall 003.

Outfall 004 Grab samples must be obtained at a point in the Main Cooling Reservoir (M:CR) SpiUway Channel after the commingling of spillway gate leakage and relief well water but prior to mbdng with other waters. The maximum temperature, the maximum total residual chlorine, and the maximum and minimum pH values must be used for compliance reporting purposes at OutfaU 004.

Outfall 005 Grab samples must be obtained from each of the five relief wells. Analytical results for each parameter analyzed at the relief weUs must be compared, and the maximum temperature, the maximum total residual chlorine, and the maximum and minimum pH values must be used for compliance reporting purposes at Outfall 005.

Outfall 006 Grab samples must be obtained from each of the five relief wells. Analytical results for each parameter analyzed at the relief wells must be compared, and the maximum temperature, the maximum total residual chlorine, and the maximum and minimum pH values must be used for compliance reporting purposes at Outfall 006.

16. Total Residual Chlorine A. The term total residual chlorine (or total residual oxidants for intake water with bromides) means the value obtained using any of the "chlorinetotal residual" methods in Table IB in 40 CFR Part 136.3(a), or other methods approved by the permitting authority.

B. 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.

C. Simultaneous multi-unit chlorination is permitted.

D. Samples for total residual chlorine analysis for discharges via Outfalls 002, 003, 004, and 005 may alternatively be collected from the relief weUs located in the drainage area for Outfall 006.

Page 20

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo E. Total residual chlorine sampling for reporting at Outfall 006 must be conducted as follows:

The permittee shall collect a grab sample from the same five relief wells that will be used to determine the flow. The maximum total residual chlorine concentration recorded must be reported.

17. The flow volume discharged from the Main Cooling Reservoir via Outfall 001 must not exceed 12.5%

of the flow of the Colorado River at the discharge point, and there must be no discharge from OutfaU ooi when the receiving water flow adjacent to the plant is less than 800 cubic feet per second.

l8. This permit does not authorize discharges of stormwater associated with industrial activity via Outfalls 002,003, 004, 005, or oo6. These discharges are currently authorized under the permittee's TPDES Industrial Stormwater Multi-Sector General Permit (Permit No. TXRosP472).

19. Flow measurements or sampling events conducted at Outfalls 002, 003, 004, 005, and oo6 on days when the rainfall exceeds 0.1 inches during any 24-hour period must not be used for compliance monitoring purposes. The permittee shall maintain a permanent rain gauge at the plant site and keep daily records of rainfall that can be made available to the TCEQ personnel upon request.

20. There shall be no discharge ofpolychlorinated biphenyl compounds such as those commonly used for transformer fluid.

21. The executive director reviewed this action for consistency with the goals and policies of the Texas Coastal Management Program (CMP) in accordance with the regulations of the General Land Office and determined that the action is consistent with the applicable CM? goals and policies.

Page 21

STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo Attachment A Table i Outfall No. 001 l CIC DG Effluent Concentration (mg/L)

Pollutant Samp. l Samp. 2 Samp. 3 Samp. 4 Average Flow (MGD)

BOD (s-day)

CBOD (5-day)

Chemical oxygen demand Total organic carbon Dissolved oxygen Ammonia nitrogen Total suspended solids Nitrate nitrogen

?^gy?^^;

Total organic nitrogen Total phosphorus Oil and grease 3'3W<8ff Total residual chlorine %!sy--sss.

Total dissolved solids Sulfate Chloride Fluoride Total alkalinity (mg/L as CaCOs)

Temperature (°F) pH (standard units)

MAL2 Pollutant Effluent Concentration (pg/L) 1 (US/L)

Aluminum, total 2.5 Antimony, total _5_

Arsenic,total 0.5 Barium, total _3_

Beryllium, total 0.5 Cadmium, total 1 Chromium, total _3_

Chromium, hexavalent 3 Chromium, trivalent N/A Copper, total 2 Cyanide, available 2 Lead, total 0.5 Mercury, total 0.005 Nickel, total 2 Selenium, total _5_

Silver, total 0.5 Thallium, total 0.5 Zinc,total 5.0 Indicate units if different from ^ig/L.

Minimum Analytical Level.

Page 22

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo Table 2 - Toxic Pollutants with Water Quality Criteria OutfallNo.: l DCDG Samp. i Samp. 2 Samp. 3 Samp. 4 Avg. MAL2 Pollutant (?/L)1 (ng/L)1 (ng/L)1 (Pg/L)1 (?/L)1 (Hg/L)

Acrylonitrile 50 Anthracene 10 Benzene 10 Benzidine 50 Benzo(a)anthracene

_5_

Benzo(a)pyrene 5 Bis(2-chloroethyl) ether 10 Bis(2-ethylhexyl) phthalate 10 Bromodichloromethane 10

[Dichlorobromomethane]

Bromoform 10 Carbon tetrachloride 2 Chlorobenzene 10 Chlorodibromomethane 10

[Dibromochloromethane]

Chloroform 10 Chrysene _5_

m-Cresols [3-Methylphenol] 10 o-Cresols [2-Methylphenol] 10 p-Cresols [4-Methylphenol] 10 1,2-Dibromoethane 10 m-Dichlorobenzene 10

[1,3-Dichlorobenzene]

o-Dichlorobenzene 10

[1,2-Dichlorobenzene]

p-Dichlorobenzene 10

[1,4-Dichlorobenzene]

3,3'-Dichlorobenzidine _5_

1,2-Dichloroethane 10 1,1-Dichloroethene 10

[l, l-Dichloroethylene]

Dichloromethane 20

[Methylene chloride]

1,2-Dichloropropane 10 1,3-Dichloropropene 10

[1,3-Dichloropropylene]

2,4-Dimethylphenol 10 Di-n-Butyl Phthalate 10 Ethylbenzene 10 Fluoride 500 Hexachlorobenzene _5_

Hexachlorobutadiene 10 Hexachlorocyclopentadiene 10 Hexachloroethane 20 Methyl ethyl ketone 50 Nitrobenzene 10 Page 23

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo OutfallNo.: DCDG Samp. l Samp. 2 Samp. 3 Samp. 4 Avg. MAL2 Pollutant (Hg/L)1 (Pg/L)1 (Hg/L)^ (Pg/L)* (pg/L)^ (Hg/L)

N-Nitrosodiethylamine 20 JV-Nitroso-di-n- Butylamine 20 Nonylphenol _333^

Pentachlorobenzene 20 Pentachlorophenol _5_

Phenanthrene 10 Polychlorinated Biphenyls (PCBs) 3 0.2 Pyridine 20 1,2,4,5-Tetrachlorobenzene 20 1,1,2,2-Tetrachloroethane 10 Tetrachloroethene 10

[Tetrachloroethylene]

Toluene 10 1,1,1-Trichloroethane 10 1,1,2-Trichloroethane 10 Trichloroethene 10

[Trichloroethylene]

2,4,5-Trichlorophenol 50 TTHM (Total trihalomethanes) 10 Vinyl Chloride 10 Indicate units if different from Hg/L.

2 Minimum Analytical Level.

3 Total of detects for PCB-1242, PCB-1254, PCB-1221, PCB-1232, PCB-1248, PCB-i26o, PCB-ioi6. If all values are non-detects, enter the highest non-detect preceded by a "<" symbol.

Table 3 - Believed Present ' Believed Absent Outfall No. ooi aC aG Believed Believed Effluent Concentration (mg/L) 1 No. of Present Absent Samples Pollutant Average Maximum Bromide Color (PCU)

Nitrate-Nitrite (as N)

Sulfide (as S)

Sulfite (as 803)

Surfactants Boron, total Cobalt, total Iron, total Magnesium, total Manganese, total Molybdenum, total Tin,total Titanium, total Indicate units if different from lng/L.

Page 24

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo Table 4 - Volatile Compounds Outfall No. 001 aC aG Average Maximum No. of MAL Pollutant (Pg/L)1 (?/L)1 Samples (Pg/L)

Acrolein 50 Acrylonitrile 50 Benzene 10 Bromoform 10 Carbon tetrachloride 2 Chlorobenzene 10 Chlorodibromomethane 10 Chloroethane 50 2-Chloroethylvinyl ether 10 Chloroform 10 Dichlorobromomethane [Bromodichloromethane] 10 l, i-Dichloroethane 10 1,2-Dichloroethane 10 1,1-Dichloroethylene [1,1-Dichloroethene] 10 1,2-Dichloropropane 10 1,3-Dichloropropylene [1,3-Dichloropropene] 10 Ethylbenzene 10 Methyl bromide [Bromomethane] 50 Methyl chloride [Chloromethane] 50 Methylene chloride [Dichloromethane] 20 1,1,2,2-Tetrachloroethane 10 Tetrachloroethylene [Tetrachloroethene] 10 Toluene 10 l,2-Trans-dichloroethylene[l,2-Trans-10 dichloroethene]

1,1, l-Trichloroethane 10 1,1,2-Trichloroethane 10 Trichloroethylene[Trichloroethene] 10 Vinyl chloride 10 Indicate units if different from ng/L.

Page 25

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo Table 5 - Acid Compounds Outfall No. 001 aC aG Average Maximum No. of MAL Pollutant (jig/L)^ (pg/L)^ Samples (ng/L) 2-Chlorophenol 10 2,4-Dichlorophenol 10 2,4-Dimethylphenol 10 4,6-Dinitro-o-Cresol 50 2,4-Dinitrophenol 50 2-Nitrophenol 20 4-Nitrophenol 50 p-Chloro-m-cresol 10 Pentachlorophenol 5 Phenol 10 2,4,6-Trichlorophenol 10 Indicate units if different from ug/L.

Page 26

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo BIOMONITOMNG REQUIREMENTS CHRONIC BIOMONITORING REQUIREMENTS: MARINE The provisions of this section apply to Outfall 001 for whole effluent toxicity (WET) testing.

l. Scope, Frequency and Methodology

a. The permittee shall test the effluent for toxicity in accordance with the provisions below. Such testing will determine if an appropriately dilute effluent sample adversely affects the survival or growth of the test organisms.

b. The permittee shall conduct the following toxicity tests using the test organisms, procedures, and quality assurance requirements specified below and in accordance with "Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms," third edition (EPA-821-R 014) or its most recent update:

l) Chronic static renewal 7-day survival and growth test using the mysid shrimp (Mysi'dopsis bahia) (Method 1007.0). A minimum of eight replicates with five organisms per replicate shall be used in the control and in each dilution. This test shall be conducted once per quarter.

2) Chronic static renewal 7-day larval survival and growth test using the inland silverside (Menidia beryllind) (Method 1006.0). A minimum of five replicates with eight organisms per replicate shall be used in the control and in each dilution. This test shall be conducted once per quarter.

The permittee must perform and report a valid test for each test species during the prescribed reporting period. An invalid test must be repeated during the same reporting period. An invalid test is defined as any test failing to satisfy the test acceptability criteria, procedures, and quality assurance requirements specified in the test methods and permit.

c. The permittee shall use five effluent dilution concentrations and a control in each toxicitytest. These effluent dilution concentrations are 5%, 7%, lo%, 13%, and 17%

effluent. The critical dilution, defined as 13% effluent, is the effluent concentration representative of the proportion ofeffluent in the receiving water during critical low flow or critical mixing conditions.

d. This permit may be amended to require a WET limit, a chemical-specific limit, a best management practice, or other appropriate actions to address toxicity. The permittee may be required to conduct a toxicity reduction evaluation (TRE) after multiple toxic events.

e. Testing Frequency Reduction

1) If none of the first four consecutive quarterly tests demonstrates significant toxicity, the permittee may submit this information in writing and, upon approval, reduce the testing frequency to once per sue months for the invertebrate test species and once per year for the vertebrate test species.

Page 27

STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo

2) If one or more of the first four consecutive quarterly tests demonstrates significant toxicity, the permittee shall continue quarterly testing for that species until this permit is reissued. If a testing frequency reduction had been previously granted and a subsequent test demonstrates significant toxicity, the permittee will resume a quarterly testing frequency for that species until this permit is reissued.

2. Reauired ToxicityTesting Conditions

a. Test Acceptance - The permittee shall repeat any toxicity test, including the control and all effluent dilutions, which fails to meet any of the following criteria:

l) a control mean survival of 80% or greater;

2) a control mean dry weight of surviving mysid shrimp of 0.20 mg or greater;

3) a control mean dry weight for surviving unpreserved inland silverside of 0.50 mg or greater and 0.43 mg or greater for surviving preserved inland silverside.

4) a control coefficient of variation percent (CV%) between replicates of 40 or less in the growth and survival tests;

5) a critical dilution CV% of 40 or less in the growth and survival endpoints for either growth and survival test. However, if statistically significant lethal or nonlethal effects are exhibited at the critical dilution, a CV% greater than 40 shall not invalidate the test;

6) a percent minimum significant difference of 37 or less for mysid shrimp growth; and

7) a percent minimum significant difference of 28 or less for inland silverside growth.

b. Statistical Interpretation l) For the mysid shrimp and the inland silverside larval survival and growth tests, the statistical analyses used to determine if there is a significant difference between the control and an effluent dilution shall be in accordance with the manual referenced in Part l.b.

2) The permittee is responsible for reviewing test concentration-response relationships to ensure that calculated test-results are interpreted and reported correctly. The document entitled "Method Guidance and Recommendation for Whole Effluent Toxicity (WET) Testing (40 CFR Part 136)" (EPA 821-B-oo-004) provides guidance on determining the validity of test results.

3) If significant lethality is demonstrated (that is, there is a statistically significant difference in survival at the critical dilution when compared to the survival in the control), the conditions of test acceptability are met, and the survival of the test organisms are equal to or greater than 80% in the critical dilution and all dilutions below that, then the permittee shall report a survival No Observed Effect Concentration (NOEC) of not less than the critical dilution for the reporting requirements.

Page 28

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

4) The NOEC is defined as the greatest effluent dilution at which no significant effect is demonstrated. The Lowest Observed Effect Concentration (LOEC) is defined as the lowest effluent dilution at which a significant effect is demonstrated. A significant effect is herein defined as a statistically significant difference between the survival, reproduction, or growth of the test organism in a specified effluent dilution compared to the survival, reproduction, or growth of the test organism in the control (o% effluent).

5) The use of NOECs and LOECs assumes either a monotonic (continuous) concentration-response relationship or a threshold model of the concentration-response relationship. For any test result that demonstrates a non-monotonic (non-continuous) response, the NOEC should be determined based on the guidance manual referenced in Item 2.

6) Pursuant to the responsibility assigned to the permittee in Part 2.b. 2), test results that demonstrate a non-monotonic (non-continuous) concentration-response relationship may be submitted, prior to the due date, for technical review. The guidance manual referenced in Part l.b. will be used when making a determination of test acceptability.

7) TCEQ staff will review test results for consistency with rules, procedures, and permit requirements.

c. Dilution Water l) Dilution water used in the toxicity tests must be the receiving water collected as close to the point of discharge as possible but unaffected by the discharge.

2) Where the receiving water proves unsatisfactory as a result of preexisting instream toxicity (i.e., fails to fulfill the test acceptance criteria of Part 2.a.), the permittee may substitute synthetic dilution water for the receiving water in all subsequent tests provided the unacceptable receiving water test met the foUow-ing stipulations:

a) a synthetic lab water control was performed (in addition to the receiving water control) which fulfilled the test acceptance requirements of Part 2.a; b) the test indicating receiving water toxicity was carried out to completion (i.e., 7 days); and c) the permittee submitted all test results indicating receiving water toxicity with the reports and information required in Part 3.

3) The synthetic dilution water shall consist of standard, reconstituted seawater.

Upon approval, the permittee may substitute other dilution water with chemical and physical characteristics similar to that of the receiving water.

Page 29

STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo

d. Samples and Composites l) The permittee shall collect a minimum of three composite samples from Outfall ooi. The second and third composite samples will be used for the renewal of the dilution concentrations for each toxicity test.

2) The permittee shall collect the composite samples such that the samples are representative of any periodic episode of chlorination, biocide usage, or other potentially toxic substance being discharged on an intermittent basis.

3) The permittee shall initiate the toxicity tests within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months after collection of the last portion of the first composite sample. The holding time for any subsequent composite sample shall not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . Samples shall be maintained at a temperature of 0-6 degrees Centigrade during collection, shipping, and storage.

4) If Outfall 001 ceases discharging during the collection of effluent samples, the requirements for the minimum number of effluent samples, the minimum number of effluent portions, and the sample holding time are waived during that sampling period. However, the permittee must have collected an effluent composite sample volume sufficient to complete the required toxicity tests with renewal of the effluent. When possible, the effluent samples used for the toxicity tests shall be collected on separate days if the discharge occurs over multiple days. The sample collection duration and the static renewal protocol associated with the abbreviated sample collection must be documented in the full report.

3. Reporting All reports, tables, plans, summaries, and related correspondence required in this section shall be submitted to the attention of the Standards Implementation Team (MC 150) of the Water Quality Division.

a. The permittee shall prepare a full report of the results of all tests conducted in accordance with the manual referenced in Part l.b. for every valid and invalid toxicity test initiated whether carried to completion or not.

b. The permittee shall routinely report the results of each biomonitoring test on the Table l forms provided with this permit.

l) Annual biomonitoring test results are due on or before January 20th for biomonitoring conducted during the previous 12-month period.

2) Semiannual biomonitoring test results are due on or before July 20th and January 20th for biomonitoring conducted during the previous 6-month period.

3) Quarterly biomonitoring test results are due on or before April 20th, July 20th, October 20th, and January 20th, for biomonitoring conducted during the previous calendar quarter.

4) Monthly biomonitoring test results are due on or before the 20th day of the month following sampling.

Page 30

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

c. Enter the following codes for the appropriate parameters for valid tests only:

l) For the mysid shrimp, Parameter TLPsE, enter a "l" if the NOEC for survival is less than the critical dilution; otherwise, enter a "o."

2) For the mysid shrimp, Parameter TOPsE, report the NOEC for survival.

3) For the mysid shrimp, Parameter TXPsE, report the LOEC for survival.

4) For the mysid shrimp, Parameter TWPsE, enter a "l" if the NO EC for growth is less than the critical dilution; otherwise, enter a "o."

5) For the mysid shrimp, Parameter TPPsE, report the NO EC for growth.

6) For the mysid shrimp, Parameter TYPsE, report the LOEC for growth.

7) For the inland silverside, Parameter TLP6B, enter a "l" if the NOEC for survival is less than the critical dilution; otherwise, enter a "o."

8) For the inland silverside, Parameter TOP6B, report the NOEC for survival.

9) For the inland silverside, Parameter TXP6B, report the LOEC for survival.

10) For the inland silverside, Parameter TWP6B, enter a "l" if the NOEC for growth is less than the critical dilution; otherwise, enter a "o."

ll) For the inland silverside, Parameter TPP6B, report the NOEC for growth.

\

12) For the inland silverside, Parameter TYP6B, report the LOEC for growth.

d. Enter the following codes for retests only:

l) For retest number l, Parameter 22415, enter a "l" if the NOEC for survival is less than the critical dilution; otherwise, enter a "o."

2) For retest number 2, Parameter 22416, enter a "l" if the NO EC for survival is less than the critical dilution; otherwise, enter a "o."

4. Persistent Toxicitv The requirements of this part apply only when a test demonstrates a significant effect at the critical dilution. Significant effect and significant lethality were defined in Part 2.b. Significant sublethality is defined as a statistically significant difference in growth at the critical dilution when compared to the growth of the test organism in the control.

a. The permittee shall conduct a total of 2 additional tests (retests) for any species that demonstrates a significant effect (lethal or sublethal) at the critical dilution. The two retests shall be conducted monthly during the next two consecutive months. The permittee shall not substitute either of the two retests in lieu of routine toxicity testing.

All reports shall be submitted within 20 days of test completion. Test completion is defined as the last day of the test.

Page 31

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

b. If the retests are performed due to a demonstration of significant lethality, and one or both of the two retests specified in Part 4.a. demonstrates significant lethality, the permittee shall initiate the TRE requirements as specified in Part 5. The provisions of Part 4.a. are suspended upon completion of the two retests and submittal of the TRE Action plan and schedule defined in Part 5. If neither test demonstrates significant lethality and the permittee is testing under the reduced testing frequency provision of Part l.e., the permittee shall return to a quarterly testing frequency for that species.

c. If the two retests are performed due to a demonstration of significant sublethality, and one or both of the two retests specified in Part 4.a. demonstrates significant lethality, the permittee shall again perform two retests as stipulated in Part 4.a.

d. If the two retests are performed due to a demonstration of significant sublethality, and neither test demonstrates significant lethality, the permittee shall continue testing at the quarterly frequency.

e. Regardless of whether retesting for lethal or sublethal effects or a combination of the two, no more than one retest per month is required for a species.

5. Toxicitv Reduction Evaluation

a. Within 45 days of the retest that demonstrates significant lethality, or within 45 days of being so instructed due to multiple toxic events, the permittee shall submit a general outline for initiating a TRE. The outline shall include, but not be limited to, a description of project personnel, a schedule for obtaining consultants (if needed), a discussion of influent and effluent data available for review, a sampling and analytical schedule, and a proposed TRE initiation date.

b. Within 90 days of the retest that demonstrates significant lethality, or within 90 days of being so instructed due to multiple toxic events, the permittee shall submit a TRE action plan and schedule for conducting a TRE. The plan shall specify the approach and methodology to be used in performing the TRE. A TRE is a step-wise investigation combining toxicity testing with physical and chemical analyses to determine actions necessary to eliminate or reduce effluent toxicity to a level not effecting significant lethality at the critical dilution. The TRE action plan shall describe an approach for the reduction or elimination oflethality for both test species defined in Part l.b. At a minimum, the TRE Action Plan shall include the following:

l) Specific Activities - The TRE action plan shall specify the approach the permittee intends to utilize in conducting the TRE, including toxicity characterizations, identifications, confirmations, source evaluations, treatability studies, and alternative approaches. When conducting characterization analyses, the permittee shall perform multiple characterizations and follow the procedures specified in the document entitled "Methods for Aquatic Toxicity Identification Evaluations: Phase I Toxicity Characterization Procedures" (EPA/6oo/6-9l/oo3) or alternate procedures. The permittee shall perform multiple identifications and follow the methods specified in the documents entitled, "Methods for Aquatic Toxicity Identification Evaluations: Phase II Toxicity Identification Procedures for Samples Exhibiting Acute and Chronic Toxicity" (EPA/6oo/R-92/o8o) and "Methods for Aquatic Toxicity Identification Evaluations: Phase III Toxicity Confirmation Procedures for Samples Exhibiting Acute and Chronic Toxicity" (EPA/6oo/R-92/o8l).

Page 32

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo All characterization, identification, and confirmation tests shall be conducted in an orderly and logical progression;

2) Sampling Plan - The TRE action plan should describe sampling locations, methods, holding times, chain of custody, and preservation techniques. The effluent sample volume collected for all tests shall be adequate to perform the toxicity characterization/identification/confirmation procedures and chemical-specific analyses when the toxicity tests show significant lethality. Where the permittee has identified or suspects specific pollutant and source ofeffluent toxicity, the permittee shall conduct, concurrent with toxicity testing, chemical-specific analyses for the identified and suspected pollutant and source of effluent toxicity;

3) Quality Assurance Plan - The TRE action plan should address record keeping and data evaluation, calibration and standardization, baseline tests, system blanks, controls, duplicates, spikes, toxicity persistence in the samples, randomization, reference toxicant control charts, and mechanisms to detect artifactual toxicity; and

4) Project Organization - The TRE action plan should describe the project staff, project manager, consulting engineering services (where applicable), consulting analytical and toxicological services, etc.

c. Within 30 days of submittal of the TRE action plan and schedule, the permittee shall implement the TRE.

d. The permittee shall submit quarterly TRE activities reports concerning the progress of the TRE. The quarterly reports are due on or before April 20th, July 20th, October 20th, and January 20th. The report shall detail information regarding the TRE activi-ties including:

l) results and interpretation of any chemical-specific analyses for the identified and suspected pollutant performed during the quarter;

2) results and interpretation of any characterization, identification, and confirmation tests performed during the quarter;

3) any data and substantiating documentation which identifies the pollutant and source of effluent toxicity;

4) results of any studies/evaluations concerning the treatability of the facility's effluent toxicity;

5) any data which identifies effluent toxicity control mechanisms that will reduce effluent toxicity to the level necessary to meet no significant lethality at the critical dilution; and

6) any changes to the initial TRE plan and schedule that are believed necessary as a result of the TRE findings.

Page 33

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

e. During the TRE, the permittee shall perform, at a minimum, quarterly testing using the more sensitive species. Testing for the less sensitive species shall continue at the frequency specified in Part l.b.

f. If the effluent ceases to effect significant lethality, i.e., there is a cessation oflethality, the permittee may end the TRE. A cessation oflethality is defined as no significant lethality for a period of 12 consecutive months with at least monthly testing. At the end of the 12 months, the permittee shall submit a statement of intent to cease the TRE and may then resume the testing frequency specified in Part l.b.

This provision accommodates situations where operational errors and upsets, spills, or sampling errors triggered the TRE, in contrast to a situation where a single toxicant or group oftoxicants cause lethality. This provision does not apply as a result of corrective actions taken by the permittee. Corrective actions are herein defined as proactive efforts that eliminate or reduce effluent toxicity. These include, but are not limited to, source reduction or elimination, improved housekeeping, changes in chemical usage, and modifications ofinfluent streams and effluent treatment.

The permittee may only apply this cessation oflethality provision once. If the effluent again demonstrates significant lethality to the same species, the permit will be amended to add a WET limit with a compliance period, if appropriate. However, prior to the effective date of the WET limit, the permittee may apply for a permit amendment removing and replacing the WET limit with an alternate toxicity control measure by identifying and confirming the toxicant and an appropriate control measure.

g. The permittee shall complete the TRE and submit a final report on the TRE activities no later than 28 months from the last test day of the retest that confirmed significant lethal effects at the critical dilution. The permittee may petition the Executive Director (in writing) for an extension of the 28-month limit. However, to warrant an extension the permittee must have demonstrated due diligence in its pursuit of the toxicity identification evaluation/TRE and must prove that circumstances beyond their control stalled the toxicity identification evaluation/TRE. The report shall provide information pertaining to the specific control mechanism selected that will, when implemented, result in the reduction ofeffluent toxicity to no significant lethality at the critical dilution. The report shall also provide a specific corrective action schedule for implementing the selected control mechanism.

h. Based upon the results of the TRE and proposed corrective actions, this permit may be amended to modify the biomonitoring requirements, where necessary, require a compliance schedule for implementation of corrective actions, specify a WET limit, speciiy a best management practice, and to specify a chemical-specific limit.

i. Copies of any and all required TRE plans and reports shall also be submitted to the U.S.

EPA Region 6 office, 6WQ-PO.

Page 34

STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo TABLE l (SHEET l OF 4)

MYSID SHRIMP SURVIVAL AND GROWTH Date Time Date Time Dates and Times No. l FROM: TO:

Composites Collected No. 2 FROM: TO:

No. 3 FROM: TO:

Test initiated: _am/pm .date Dilution water used: Receiving water MYSID SHRIMP SURVIVAL Percent Survival in Replicate Chambers Mean Percent Survival Percent cv%*

Effluent A B c D E F G H 24h 48h 7 day 0%

5%

7%

10%

13%

17%

Coefficient of Variation = standard deviation x loo/mean DATA TABLE FOR GROWTH OF MYSID SHRIMP Mean dry weight in milligrams in replicate chambers Replicate 0% 5% 7% 10% 13% 17%

A B

c D

E Page 35

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo TABLE l (SHEET 2 OF 4)

MYSID SHRIMP SURVWALAND GROWTH DATA TABLE FOR GROWTH OF MYSID SHRIMP (Continued)

Mean dry weight in milligrams in replicate chambers Replicate 0% I 5% I 7% I 10% I 13% 17%

F T

G H ][

Mean Dry Weight (mg) cv%*

PMSD

l. Dunnett's Procedure or Steel's Many-One Rank Test or Wilcoxon Rank Sum Test (with Bonferroni adjustment) or t-test (with Bonferroni adjustment) as appropriate:

Is the mean survival at 7 days significantly less than the control survival for the % effluent corresponding to lethality?

CRITICAL DILUTION (13%): .YES NO

2. Dunnett's Procedure or Steel's Many-One Rank Test or Wilcoxon Rank Sum Test (with Bonferroni adjustment) or t-test (with Bonferroni adjustment) as appropriate:

Is the mean dry weight (growth) at 7 days significantly less than the control's dry weight (growth) for the % effluent corresponding to non-lethal effects?

CRITICAL DILUTION (13%): _ YES .NO

3. Enter percent effluent corresponding to each NOEC\LOEC below:

a.) NOEC survival = _% effluent b.) LOEC survival = _% effluent c.) NOEC growth - _% effluent d.) LOEC growth = _% effluent Page 36

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo TABLE l (SHEET 3 OF 4)

INLAND SILVERSIDE MINNOW LARVAL SURVWALAND GROWTH TEST Date Time Date Time Dates and Times N0.1 FROM: TO:

Composites Collected N0.2 FROM: TO:

No. 3 FROM: TO:

Test initiated: _am/pm _date Dilution water used: Receiving water Synthetic Dilution water INLAND SILVERSIDE SURVWAL Percent Survival in Mean Percent Survival cw Percent Replicate Chambers Effluent A B c D E 24h 48h 7 days 0%

5%

7%

10%

13%

17%

Coefficient of Variation = standard deviation x loo/mean Page 37

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo TABLE l (SHEET 4 OF 4)

INLAND SILVERSIDE LARVAL SURVT^ALAND GROWTH TEST INLAND SILVERSIDE GROWTH Average Dry Weight in miUigrams in replicate Mean Percent chambers Dry Effluent Weight cv%*

A B c D E (mg) 0%

5%

7%

10%

13%

17%

PMSD Weights are for: _ preserved larvae, or _ unpreserved larvae

l. Dunnett's Procedure or Steel's IVIany-One Rank Test or Wilcoxon Rank Sum Test (with Bonferroni adjustment) or t-test (with Bonferroni adjustment) as appropriate:

Is the mean survival at 7 days significantly less than the control survival for the % effluent corresponding to lethality?

CRITICAL DILUTION (13%); _ YES. .NO

2. Dunnett's Procedure or Steel's Many-One Rank Test or Wilcoxon Rank Sum Test (with Bonferroni adjustment) or t-test (with Bonferroni adjustment) as appropriate:

Is the mean dry weight (growth) at 7 days significantly less than the control's dry weight (growth) for the % effluent corresponding to non-lethal effects?

CRITICAL DILUTION (13%): -YES. .NO

3. Enter percent effluent corresponding to each NOEC/LOEC below:

a.) NOEC survival = _% effluent b.) LOEC survival = _% effluent c.) NOEC growth = _% effluent d.) LOEC growth = _% effluent Page 38

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo 24-HOUR ACUTE BIOMONITORING REQUIREMENTS: MARINE The provisions of this section apply to Outfall 001 for whole effluent toxicity (WET) testing.

l. Scope, Frequency, and Methodology

a. The permittee shall test the effluent for lethality in accordance with the provisions in this Section. Such testing will determine compliance with Texas Surface Water Quality Standard 30 TAG § 307.6(e)(2)(B), which requires greater than 50% sm-vival of the appropriate test organisms in 100% efQuent for a 24-hour period.

b. The toxicity tests specified shall be conducted once per six months. The permittee shall conduct the following toxicity tests using the test organisms, procedures, and quality assurance requirements specified in this section of the permit and in accordance with "Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms," fifth edition (EPA-821-R-02-012) or its most recent update:

l) Acute 24-hour static toxicity test using the mysid shrimp (Afysi'dopsis bahid). A minimum of five replicates with eight organisms per replicate shall be used in the control and each dilution.

2) Acute 24-hour static toxicity test using the inland silverside (Menidia beryllina). A minimum of five replicates with eight organisms per replicate shall be used in the control and each dilution.

A valid test result must be submitted for each reporting period. The permittee must report, then repeat, an invalid test during the same reporting period. The repeat test shall include the control and all effluent dilutions and use the appropriate number of organisms and replicates, as specified above. An invalid test is defined as any test failing to satisfy the test acceptability criteria, procedures, and quality assurance requirements specified in the test methods and permit.

c. In addition to an appropriate control, a 100% effluent concentration shall be used in the toxicity tests. Except as discussed in Part 2.b., the control and dilution water shall consist of standard, synthetic, reconstituted seawater.

d. This permit may be amended to require a WET limit, a best management practice, a chemical-specific limit, additional toxicity testing, and other appropriate actions to address toxicity. The permittee may be required to conduct a toxicity reduction evaluation (TRE) after multiple toxic events.

2. Required Toxicitv Testing Conditions

a. Test Acceptance - The permittee shall repeat any toxicity test, including the control, if the control fails to meet a mean survival equal to or greater than 90%.

b. Dilution Water - In accordance with Part l.c., the control and dilution water shall consist of standard, synthetic, reconstituted seawater.

Page 39

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

c. Samples and Composites l) The permittee shall collect one composite sample from Outfall 001.

2) The permittee shall collect the composite sample such that the sample is representative of any periodic episode of chlorination, biocide usage, or other potentially toxic substance being discharged on an intermittent basis.

3) The permittee shall initiate the toxicity tests within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months after collection of the last portion of the composite sample. The sample shall be maintained at a temperature of 0-6 degrees Centigrade during collection, shipping, and storage.

4) If Outfall 001 ceases discharging during the collection of the effluent composite sample, the requirements for the minimum number of effluent portions are waived. However, the permittee must have collected a composite sample volume sufficient for completion of the required test. The abbreviated sample collection, duration, and methodology must be documented in the full report.

3. Reuorting All reports, tables, plans, summaries, and related correspondence required of this section shall be submitted to the attention of the Standards Implementation Team (MC 150) of the Water Quality Division.

a. The permittee shall prepare a full report of the results of all tests conducted in accordance with the manual referenced in Part l.b. for every valid and invalid toxicity test initiated.

b. The permittee shall routinely report the results of each biomonitoring test on the Table 2 forms provided with this permit.

l) Semiannual biomonitoring test results are due on or before July 20th and January 20th for biomonitoring conducted during the previous 6-month period.

2) Quarterly biomonitoring test results are due on or before April 20th, July 20th, October 20th, and January 20th for biomonitoring conducted during the previous calendar quarter.

c. Enter the following codes for the appropriate parameters for valid tests only:

l) For the mysid shrimp, Parameter TIEsE, enter a "o" if the mean survival at 24-hours is greater than 50% in the 100% effluent dilution; if the mean survival is less than or equal to 50%, enter a "l."

2) For the inland silverside, Parameter TIE6B, enter a "o" if the mean survival at 24-hours is greater than 50% in the 100% effluent dilution; if the mean survival is less than or equal to 50%, enter a "l."

d. Enter the following codes for retests only:

l) For retest number l, Parameter 22415, enter a "o" if the mean survival at 24-hours is greater than 50% in the 100% effluent dilution; if the mean survival is less than or equal to 50%, enter "l."

Page 40

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

2) For retest number 2, Parameter 22416, enter a "o" if the mean survival at 24-hours is greater than 50% in the 100% effluent dilution; if the mean survival is less than or equal to 50%, enter "l."

4. Persistent MEortality The requirements of this part apply when a toxidty test demonstrates significant lethality, here defined as a mean mortality of 50% or greater to organisms exposed to the 100% effluent concentration after 24-hours.

a. The permittee shall conduct 2 additional tests (retests) for each species that demonstrates significant lethality. The two retests shall be conducted once per week for 2 weeks. Five effluent dilution concentrations in addition to an appropriate control shall be used in the retests. These additional effluent concentrations are 6%, 13%, 25%,

50% and 100% effluent. The first retest shall be conducted within 15 days of the laboratory determination of significant lethality. All test results shall be submitted within 20 days of test completion of the second retest. Test completion is defined as the 24th hour.

b. If one or both of the two retests specified in item 4.0.. demonstrates significant lethality, the permittee shall initiate the TRE requirements as specified in Part 5 of this Section.

5. Toxicity Reduction Evaluation

a. Within 45 days of the retest that demonstrates significant lethality, the permittee shall submit a general outline for initiating a TRE. The outline shall include, but not be limited to, a description of project personnel, a schedule for obtaining consultants (if needed), a discussion ofinfluent and effluent data available for review, a sampling and analytical schedule, and a proposed TRE initiation date.

b. Within 90 days of the retest that demonstrates significant lethality, the permittee shall submit a TRE action plan and schedule for conducting a TRE. The plan shall specify the approach and methodology to be used in performing the TRE. A TRE is a step-wise investigation combining toxicity testing with physical and chemical analyses to determine actions necessary to eliminate or reduce effluent toxicity to a level not effecting significant lethality at the critical dilution. The TRE action plan shall lead to the successful elimination of significant lethality for both test species defined in Part i.b. At a minimum, the TRE action plan shall include the following:

l) Specific Activities - The TRE action plan shall specify the approach the permittee intends to utilize in conducting the TRE, including toxicity characterizations, identifications, confirmations, source evaluations, treatability studies, and alternative approaches. When conducting characterization analyses, the permittee shall perform multiple characterizations and follow the procedures specified in the document entitled "Methods for Aquatic Toxicity Identification Evaluations: Phase I Toxicity Characterization Procedures" (EPA/6oo/6-9l/oo3) or alternate procedures. The permittee shall perform multiple identifications and follow the methods specified in the documents entitled "Methods for Aquatic Toxicity Identification Evaluations: Phase II Toxicity Identification Procedures for Samples Exhibiting Acute and Chronic Toxicity" (EPA/6oo/R-92/o8o) and "Methods for Aquatic Toxicity Identification Evaluations: Phase III Toxicity Confirmation Procedures for Page 41

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo Samples Exhibiting Acute and Chronic Toxicity" (EPA/6oo/R-92/o8l). All characterization, identification, and confirmation tests shall be conducted in an orderly and logical progression;

2) Sampling Plan - The TRE action plan should describe sampling locations, methods, holding times, chain of custody, and preservation techniques. The effluent sample volume collected for all tests shall be adequate to perform the toxicity characterization/identification/confirmation procedures and chemical-specific analyses when the toxicity tests show significant lethality. Where the permittee has identified or suspects a specific pollutant and source of effluent toxicity, the permittee shall conduct, concurrent with toxicity testing, chemical-specific analyses for the identified and suspected pollutant and source of affluent toxicity;

3) Quality Assurance Plan - The TRE action plan should address record keeping and data evaluation, calibration and standardization, baseline tests, system blanks, controls, duplicates, spikes, toxicity persistence in the samples, randomization, reference toxicant control charts, and mechanisms to detect artifactual toxicity; and

4) Project Organization - The TRE action plan should describe the project staff, project manager, consulting engineering sersdces (where applicable), consulting analytical and toxicological services, etc.

c. Within 30 days of submittal of the TRE action plan and schedule, the permittee shall implement the TRE.

d. The permittee shall submit quarterly TRE activities reports concerning the progress of the TRE. The quarterly TRE activities reports are due on or before April 20th, July 20th, October 20th, and January 20th. The report shall detail information regarding the TRE activities including:

l) results and interpretation of any chemical-specific analyses for the identified and suspected pollutant performed during the quarter;

2) results and interpretation of any characterization, identification, and confirmation tests performed during the quarter;

3) any data and substantiating documentation that identifies the pollutant and source of effluent toxicity;

4) results of any studies/evaluations concerning the treatability of the facility's effluent toxicity;

5) any data that identifies efQuent toxicity control mechanisms that will reduce effluent toxicity to the level necessary to eliminate significant lethality; and

6) any changes to the initial TRE plan and schedule that are believed necessary as a result of the TRE findings.

e. During the TRE, the permittee shall perform, at a minimum, quarterly testing using the more sensitive species. Testing for the less sensitive species shall continue at the frequency specified in Part i.b.

Page 42

STP Nuclear Operating Company TPDES Permit No. WQoooi9o8ooo

f. If the effluent ceases to effect significant lethality, i.e., there is a cessation of lethality, the permittee may end the TRE. A cessation oflethality is defined as no significant lethality for a period of 12 consecutive weeks with at least weekly testing. At the end of the 12 weeks, the permittee shall submit a statement of intent to cease the TRE and may then resume the testing frequency specified in Part l.b.

This provision accommodates situations where operational errors and upsets, spills, or sampling errors triggered the TRE, in contrast to a situation where a single toxicant or group of toxicants cause lethality. This provision does not apply as a result of corrective actions taken by the permittee. Corrective actions are defined as proactive efforts that eliminate or reduce effluent toxicity. These include, but are not limited to, source reduction or elimination, improved housekeeping, changes in chemical usage, and modifications ofinfluent streams and effluent treatment.

The permittee may only apply this cessation oflethality provision once. If the effluent again demonstrates significant lethality to the same species, the permit will be amended to add a WET limit with a compliance period, if appropriate. However, prior to the effective date of the WET limit, the permittee may apply for a permit amendment removing and replacing the WET limit with an alternate toxicity control measure by identifying and confirming the toxicant and an appropriate control measure.

g. The permittee shall complete the TRE and submit a final report on the TRE activities no later than 18 months from the last test day of the retest that demonstrates significant lethality. The permittee may petition the Executive Director (in writing) for an extension of the l8-month limit. However, to warrant an extension the permittee must have demonstrated due diligence in its pursuit of the toxicity identification evaluation/TRE and must prove that circumstances beyond its control stalled the toxicity identification evaluation/TRE. The report shall specify the control mechanism that will, when implemented, reduce effluent toxicity as specified in Part 5.h. The report shall also specify a corrective action schedule for implementing the selected control mechanism.

h. Within 3 years of the last day of the test confirming toxicity, the permittee shall comply with 30 TAG § 307.6(e)(2)(B), which requires greater than 50% survival of the test organism in 100% ef&uent at the end of 24-hours. The permittee may petition the Executive Director (in writing) for an extension of the 3-year limit. However, to warrant an extension the permittee must have demonstrated due diligence in its pursuit of the toxicity identification evaluation/TRE and must prove that circumstances beyond its control stalled the toxicity identification evaluation/TRE.

The permittee may be exempted from complying with 30 TAG § 307.6(e)(2)(B) upon proving that toxicity is caused by an excess, imbalance, or deficiency of dissolved salts.

This exemption excludes instances where individually toxic components (e.g., metals) form a salt compound. Following the exemption, the permit may be amended to include an ion-adjustment protocol, alternate species testing, or single species testing.

i. Based upon the results of the TRE and proposed corrective actions, this permit may be amended to modify the biomonitoring requirements where necessary, require a compliance schedule for implementation of corrective actions, specify a WET limit, specify a best management practice, and to speciiy a chemical specific limit.

j. Copies of any and all required TRE plans and reports shall also be submitted to the U.S.

EPA Region 6 office, 6WQ-PO.

Page 43

STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo TABLE 2 (SHEET l OF 2)

MYSID SHRIMP SURVWAL GENERAL INFORMATION Time Date Composite Sample Collected Test Initiated PERCENT SURVIVAL Percent affluent Time Rep T~~

0% 6% 13% 25% 50% ll ioo%

A J[

T~

B 24h c

J[

D E

T MEAN Enter percent effluent corresponding to the LCso below:

24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months LCso = _% effluent Page 44

STP Nuclear Operating Company TPDES Permit No. WQoooiQoSooo TABLE 2 (SHEET 2 OF 2)

INLAND SILVERSIDE SURVIVAL GENERAL INFORMATION Time Date Composite Sample Collected Test Initiated PERCENT SURVIVAL Percent affluent Time Rep 0% 6% ll 13% 25% II 50% ll 100%

^^^ri^^T A

J[_

c I ]^^C 24h D

E I

MEAN I

Enter percent effluent corresponding to the LCso below:

24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months LCso = _% effluent Page 45

NOC-AE-20003717, Texas Pollutant Discharge Elimination System (Tpdes) Permit 01908

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NOC-AE-20003717, Texas Pollutant Discharge Elimination System (Tpdes) Permit 01908

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