NC0004961_Issuance of Permit_19960729

k6 State of North Carolina
Department of Environment,
Health and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor
Jonathan B. Howes, Secretary
A. Preston Howard, Jr., P.E., Director
July 29, 1996
Mr. John S. Carter
Duke Power Company
13339 Hagers Ferry Road
Huntersville, North Carolina 28078-7929
Subject: NPDES Permit Issuance
Permit No. NC0004961
Riverbend Steam Station
Gaston County
Dear Mr. Carter:
In accordance with the application for a discharge permit received on February 19, 1996 the Division
is forwarding herewith the subject NPDES permit. This permit is issued pursuant to the requirements of
North Carolina General Statute 143-215.1 and the Memorandum of Agreement between North Carolina and
the U.S. Environmental Protection Agency dated December 6, 1983.
Responses to your concerns and comments in letter dated June 25, 1996, are summarized below:
- The Division of Environmental Management became the Division of Water Quality effective July 1, 1996.
As of this date, all references to "permitting authority" or any other title referring to the Division refer to the
Division of Water Quality. The Division is in the process of changing letterhead, documents, and all items
that require this name change. This process will take several months to complete.
- The Division of Water Quality has an email address and is capable of communicating electronically.
However, presently, the Division does not have the resources to facilitate regular electronic communication
between the State and Permittees.
- The pages in permit no. NC0004961 have been renumbered as requested.
- Supplement to Permit Cover Sheet: suggested changes have been incorporated into the final permit.
- Effluent Limitations and Monitoring Requirements page for outfall 001: suggested changes have been
incorporated into the final permit.
- The Division concurs with relocating the downstream temperature monitoring station for Riverbend Steam
Station from the forebay to the tailrace of Mt. Island Lake Dam. In addition, Duke Power Company will be
required to have secured the new relocated downstream monitoring station within four months of the
effective date of the permit.
-Effluent Limitations and -Monitoring Requirements page for outfall 002: minor suggested changes have
been incorporated into, the final permit. Suggested changes to monitoring frequencies for selected
parameters are addressed in the following paragraphs.
- Flow monitoring has been changed from daily to weekly. The daily monitoring frequency was
incorrectly specified in the draft permit and this error has been corrected.
- Oil and grease monitoring has been changed from 2/month to monthly. Review of the Discharge
Monitoring Report (DMR) data indicated effluent concentrations well below the permit limits.
P O Box 29535, Raleigh, North Carolina 27626-0535 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer 50% recycled/ 10% post -consumer paper

Mr Carter
July 29, 1996
Page 2
- Total copper and total iron will continue to be monitored 2/month. Although effluent concentrations
have been consistently below the limits specified in the permit, copper and iron are parameters of
concern at this facility and therefore, the monitonng frequency for these two parameters will not change.
- Total arsenic and total selenium will continue to be monitored monthly. These two compounds are
parameters of concern at this facility and therefore, the monitoring frequency for these two compounds
will not change.
- Total nitrogen and total phosphorus monitoring has been changed from monthly to quarterly. Review
of the DMR data indicated effluent concentrations consistently less than 1.0 mg/1 for the past two years
The Catawba River Basinwide Water Quality Management Plan does not specify a nutrient strategy for
the Mountain Island Lake section of the Catawba River because nutrients have not been demonstrated to
be a problem in this portion of the basin. However, the facility discharges into a lake which does not
assimilate wastewater as well as a moving waterbody Therefore, monitonng for these two parameters
will be reduced from monthly to quarterly, but not to serm-annually as requested by the Permittee.
- Part III, Special Conditions:
New paragraph X has been added to the draft permit (as Special Condition P), but the language will read
as follows. "If the Permittee, after collecting twelve data points or monitonng for a year (whichever of
the two is longer) determines tha_ he is consistently meeting the effluent limits contained herein, the
Permittee may request of the Director that the monitoring requirements be reduced to a lesser frequency."
New paragraph XX has been added to the draft permit (as Special Condition Q).
New paragraph XXX has not been added to the draft permit because the exact same paragraph is
contained in Part II, Section C, Item no. 5
All other suggested changes have been incorporated into the final permit except for the change to Chronic
Toxicity language. The statement -eferencing two consecutive toxicity tests has been eliminated from all
Chronic Toxicity tests and thus has not been reincorporated into the final penrut.
If any parts, measurement frequencies or sampling requirements contained in this permit are
unacceptable to you, you have the right to an adjudicatory hearing upon wntten request within thirty (30)
days following receipt of this letter. This request must be in the form of a wntten petition, conforming to
Chapter 150B of the North Carolina General Statutes, and filed with the Office of Administrative Heanngs,
Post Office Drawer 27447, Raleigh, North Carolina 27611-7447. Unless such demand is made, this
decision shall be final and binding.
Please take note that this permit is not transferable. Part II, E.4. addresses the requirements to be
followed in case of change in ownership or control of this discharge.
This permit does not affect the legal requirements to obtain other permits which may be required by
the Division of Water Quality or pernuts required by the Division of Land Resources or any other Federal or
Local governmental permit that may be required.

Permit No. NC0004961
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT, HEALTH, AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
PERMIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
In compliance with the provision of North Carolina General Statute 143-215.1, other lawful standards
and regulations promulgated and adopted by the North Carolina Environmental Management
Commission, and the Federal Water Pollution Control Act, as amended,
Duke Power Company
is hereby authorized to discharge wastewater from a facility located at
Riverbend Steam Station
Mount Holly
Gaston County
to receiving waters designated as Catawba River in the Catawba River Basin
in accordance with effluent limitations, monitoring requirements, and other conditions set forth in Parts I,
II, III, and IV hereof.
The permit shall become effective Sepember 1, 1996
This permit and the authorization to discharge shall expire at midnight on July 31, 2001
Signed this day July 29, 1996
Original Signed By
Coleen H. Sullins
A. Preston Howard, Jr., P.E., Director
Division of Water Quality
By Authority of the Environmental Management Commission
Page 1 of 5

Mr. Carter
July 29, 1996
Page 3
If you have any questions concerning this permit, please contact Paul B. Clark at telephone number
[phone], extension 580.
Sincerely,
Original Signet By
Cohen die Sultans
A Preston Howard, Jr , P.E.
Enclosures
cc: Central Files
Mooresville Regional Office, Water Quality Section
Mr. Roosevelt Childress, EPA
(Permits and Engineering Unit
Facility Assessment Umt
Aquatic Survey and Toxicology Unit

SUPPLEMENT TO PERMIT COVER SHEET
Duke Power Company
is hereby authorized to:
Permit No. NC0004961
1. Continue to discharge once through cooling water (outfall 001) consisting of intake screen
backwash, and water from plant chiller system, turbine lube oil coolers, condensate coolers,
main turbine steam condensers, and the intake tunnel unwatering sump, and ash basin
discharge (outfall 002) consisting of induced draft fan and preheater bearing cooling water,
stormwater from roof drains and paving, treated groundwater, track hopper sump
(groundwater), coal pile runoff, laboratory drain and chemical makeup tanks and drums
rinsate wastes, ash transport water, general plant/trailer sanitary wastewater, metal cleaning
waste, chemical metal cleaning waste, combustion turbine cooling water discharges, turbine
and boiler rooms sumps and stormwater from pond areas and upgradient watershed from a
facility located at Riverbend Steam Station, Mount Holly, Gaston County (See Part III of this
permit), and
2. Discharge wastewater from said treatment works at the location specified on the attached
map into the Catawba River which is classified WS -IV and B waters in the Catawba River
Basin.
Page 2 of 5

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ROAD CLASSIFICATION
SCALE 1:24 000
PRIMARY HIGHWAY LIGHT-DUTY ROAD, HARD OR
HARD SURFACE IMPROVED SURFACE
0 1 MILE
SECONDARY HIGHWAY
HARD SURFACE C=3010= UNIMPROVED ROAD
0 7000 FEET
1 0 1 KILOMETER
Latitude 35°21'28" Longitude 80158'12"
CONTOUR INTERVAL 10 FEET
Latitude 35°22'06" Longitude 80057'31"
Map # F15SW Sub -basin 030833
QUAD LOCATION
Duke Power/Riverbend Steam
Stream Class WS -IV and B
NC0004961
Discharge Class
Gaston County
Receiving Stream Catawba River
Design 0 varies Permit expires 7/31/01

A. (1). EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
Permit No. NC0004961
During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from
outfall(s) serial number 001. Such discharges shall be limited and monitored by the Permittee as specified below:
Effluent Characteristics Discharge Limitations Monitoring Requirements
Measurement Sample Sample
Monthly Avg. Weekly Avg. Daily Avg. Frequency- Tyne Location 1
Flow
Temperature' C (° F) 35 (95)
Temperature ° C (° F) 2
Temperature 3
Footnotes:
Daily Pump Logs 1 or E
Daily Grab E
32 (89.6) Daily Grab D
Daily Grab 1, E
I Sample locations: E - Effluent, I - Intake, D- Downstream at Mountain Island Lake Dam.
2 The ambient temperature shall not exceed 32.0° C (89.6° F), and is defined as the daily average downstream water temperature. When the Riverbend
Station effluent temperature is recorded below 32.0° C (89.6° F), as a daily average, then monitoring and reporting of the downstream water
temperature is not required. In cases where the Permittee experiences equipment problems and is unable to obtain daily temperatures from the existing
temperature monitoring system, the temperature monitori msut reestablished within five working days.
This temperature requirement in effect when only units with a shared control system are operating.
1. If the daily average intake temperature is below 2.5° C (36.5° F), the daily average effluent temperature shall not exceed 10° C (50° F), and
2. If the daily average intake temperature ranges from 2.5° C (36.5° F) to 12.8° C (55° F), the daily average effluent temperature shall not exceed two
times the intake temperature (° F) minus 23.
Chlorination of the once through cooling water shall not be allowed at this facility. Should Duke Power wish to chlorinate its once through cooling water,
a permit modification must be requested prior to commencing chlorination.
The Regional Administrator has determined pursuant to Section 316 (a) of the Act that the thermal component of the discharge assures the protection and
propagation of a balanced, indigenous population of shellfish, fish, and wildlife in the receiving body of water. -
There shall be no discharge of floating solids or visible foam in other than trace amounts.
Page 4 of 5

A. (2). EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
Permit No. NC0004961
During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from
outfall(s) serial number 002. Such discharges shall be limited and monitored by the Permittee as specified below:
Effluent Characteristics
Flow
Total Suspended Solids 2
Oil and Grease
Total Copper
Total Iron
Total Arsenic
Total Selenium
Total Nitrogen (NO2+NO3+TKN)
Total Phosphorus
Chronic Toxicity 3
Footnotes:
Discharge Limitations
Monthly Avg. Weekly Avg. Daily Max.
I Sample locations: E - Effluent, I - Intake.
23.0 mg/l
11.0 mg/1
1.0 mg/l
1.0 mg/1
75.0 mg/1
15.0 mg/1
1.0 mg/1
1.0 mg/1
Monitoring Reauirements
Measurement
Sample
Sample
Frequency
Tyne
Location 1
Daily
PumpLogs/Est I or E
2/month
Grab
E
Monthly
Grab
E
2/month
Grab
E
2/month
Grab
E
Monthly
Grab
E
Monthly
Grab
E
Quarterly
Grab
E
Quarterly
Grab
E
Quarterly
Grab
E
2 Monthly average of 43 mg/1 is permitted provided that the Permittee can satisfactorily demonstrate that the difference between 23 mg/1 and 43 mg/1 is a
result of the concentration of total suspended solids in the intake water.
3 Chronic Toxicity (Ceriodaphnia) P/F at 10%; January, April, July, October; See Part III, Condition J.
The metal cleaning waste, coal pile runoff, ash transport water, domestic wastewater, and low volume waste shall be discharged into the ash settling
pond.
The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units and shall monitored 2/month at the effluent by grab sample.
There shall be no discharge of floating solids or visible foam in other than trace amounts.
Page 5 of 5

Part III Permit No. NC0004961
E. There shall be no discharge of polychlorinated byphenyl compounds such as those commonly
used for transformer fluid.
F. BIOCIDE CONDITION
For outfalls that do not have toxicity monitoring, the permittee shall not use any biocides except
those approved in conjunction with the permit application. The permittee shall notify the Director
in writing no later than ninety (90) days prior to instituting use of any additional biocide used in
cooling systems which may be toxic to aquatic life other than those previously reported to the
Division of Water Quality. Such notification shall include completion of Biocide Worksheet Form
101 and a map locating the discharge point and receiving stream.
G. The term "low volume waste sources" means, taken collectively as if from one source,
wastewater from all sources except those for which specific limitations are otherwise established in
this part. Low volume wastewater sources include, but are not limited to: Wastewater from wet
scrubber air pollution control systems, ion exchange water treatment system, water treatment
evaporator blowdown, laboratory and sampling streams, boiler blowdown, floor drains, cooling
tower basin cleaning wastes, and recirculating house service water systems. Sanitary and air
conditioning wastes are not included.
H. The term "metal cleaning waste" means any wastewater resulting from cleaning (with or
without chemical cleaning compounds any metal process equipment including, but not limited to
boiler tube cleaning, boiler fireside cleaning, and air preheater cleaning. Chemical metal cleaning
will be conducted according to Duke Power approved equivalency demonstration.
I. It has been determined from information submitted that the plans and procedures in place at
Riverbend Steam Station are equivalent to that of a BMP.
J. CHRONIC TOXICITY PASS/FAIL PERMIT LIMIT (QUARTERLY)
The effluent discharge shall at no time exhibit chronic toxicity using test procedures
outlined in: The North Carolina Ceriodaphnia chronic effluent bioassay procedure (North
Carolina Chronic Bioassay Procedure - Revised *September 1989) or subsequent versions.
The effluent concentration at which there may be no observable inhibition of reproduction
or significant mortality is 10 % (defined as treatment two in the North Carolina procedure
document). The permit holder shall perform quarterly monitoring using this procedure to
establish compliance with the permit condition. The first test will be performed after thirty
days from the effective date of this permit during the months of January, April,
July, and October. Effluent sampling for this testing shall be performed at the NPDES
permitted final effluent discharge below all treatment processes.
All toxicity testing results required as part of this permit condition will be entered on the
Effluent Discharge Monitoring Form (MR -1) for the month in which it was performed,
using the parameter code TGP3B. Additionally, DWQ Form AT -1 (original) is to be sent
to the following address:
Attention: Environmental Sciences Branch
North Carolina Division of Water Quality
4401 Reedy Creek Road
Raleigh, N.C. 27607
Page 2 of 4

Test data shall be complete and accurate and include all supporting chemical/physical
measurements performed in association with the toxicity tests, as well as all dose/response
data. Total residual chlorine of the effluent toxicity sample must be measured and reported
if chlorine is employed for disinfection of the waste stream.
Should any single quarterly monitoring indicate a failure to meet specified limits, then
monthly monitoring will begin immediately until such time that a single test is passed.
Upon passing, this monthly test requirement will revert to quarterly in the months specified
above.
Should any test data from this monitoring requirement or tests performed by the North
Carolina Division of Water Quality indicate potential impacts to the receiving stream, this
permit may be re -opened and modified to include alternate monitoring requirements or
limits.
NOTE: Failure to achieve test conditions as specified in the cited document, such as
minimum control organism survival and appropriate environmental controls, shall
constitute an invalid test and will require immediate retesting(within 30 days of initial --
monitoring event). Failure to submit suitable test results will constitute noncompliance
with monitoring requirements.
K. Discharge of any product registered under the Federal Insecticide, Fungicide, and
Rodenticide Act to any waste stream which may ultimately be released to lakes, rivers,
streams or other waters of the United States is prohibited unless specifically authorized
elsewhere in this permit. Discharge of chlorine from the use of chlorine gas, sodium
hypochlorite, or other similar chlorination compounds for disinfection in plant potable and
service water systems and in sewage treatment is authorized. Use of restricted use
pesticides for lake management purposes by applicators licensed by the N.C. Pesticide
Board is allowed.
L. Beginning on the effective date of this permit and lasting until expiration, there shall be
no discharge of plants wastewater to the ash pond unless the permittee provides and
maintains at all times a minimum free water volume (between the top of the sediment level
and the minimum discharge elevation) equivalent to the sum of the maximum 24-hour plant
discharges plus all direct rainfall and all runoff flows to the pond resulting from a 10 -year,
24-hour rainfall event, when using a runoff coefficient of 1.0. During the term of the
permit, the permittee shall remove settled material from the ponds or otherwise enlarge the
available storage capacities in order to maintain the required minimum volumes at all times.
No later than December 31, 1989, and annually thereafter, the permittee shall determine and
report to the permit issuing authority: (1) the actual free water volume of the ash pond, (2)
physical measurements of the dimensions of the free water volume in sufficient detail to
allow validation of the calculated volume, and (3) a certification that the required volume is
available with adequate safety factor to include all solids expected to be deposited in the
pond for the following year. Present information indicates a needed volume of 95.36 A -ft
in addition to solids which will be deposited in the ash pond. Any change to plant
operations affecting such certification shall be reported to the Director within five days.
NOTE: In the event that adequate volume has been certified to exist for the term of the
permit, periodic certification is not needed.
M. It has been demonstrated that under certain conditions it is possible to reduce the
concentration of metals in boiler cleaning wastes in the range of 92 to99+ percent by
treatment in ash ponds. Because of dilution problems, and the existence of boundary
Page 3 of 4

interface layers atthe extremities of the plume, it is difficult to prove beyond doubt that the
quantity of iron and copper discharge will always be less than one milligram per liter times
the flow of metal cleaning when treated in this manner.
The application of physical/chemical methods of treating wastewater has also been
demonstrated to be effective in the treatment of metal cleaning wastes. However, the
effectiveness of ash pond treatment should be considered in relation to the small differences
in effluent quality realized between the two methods.
It has been demonstrated the presence of ions of copper, iron, nickel, and zinc, in the ash
pond waters was not measurably increased during the ash pond equivalency demonstration
at the Duke Power Company's Riverbend Steam Station. Therefore, when the following
conditions are implemented during metal cleaning procedures, effective treatment for metals
can be obtained at this facility:
1. Large ash basin providing potential reaction volumes in the ratio of 100 to 1.
2. Well-defined shallow ash delta near the ash basin influent.
3. Ash pond pH of no less than 6.5 prior to metal cleaning waste addition.
4. Four days retention time in ash pond with effluent stopped.
5. Boiler volume less than 86,000 gallons.
6. Chemicals for cleaning to include only one or more of the following:
a. Copper removal step- sodium bromate, NaBrO2; ammonium carbonate,
(NH4)2CO3-H2O; and ammonium hydroxide, NH4OH.
b. Iron removal step -hydrochloric acid, HCl; and ammonium bifluoride, (NH4)HF2
and proprietary inhibitors.
7. Maximum dilution of wastewater before entering ash pond 6 to 1.
8. After treatment of metal cleaning wastes, if monitoring of basin effluents as required by
the permit reveals discharges outside the limits of the permit, Permittee will re -close the
basin discharge, conduct such in -basin sampling as necessary to determine the cause of
nonconformance, will take appropriate corrective actions, and will file a report with EPA
including all pertinent data.
N. The Permittee shall report all visible discharges of floating materials, such as, an oil
sheen to the Director while submitting DMRs
O. The permittee shall check the diked areas for leaks by a visible inspection and shall
report any leakage detected.
P. If the Permittee, after collecting twelve data points or monitoring for a year (whichever of
the two is longer) determines that he is consistently meeting the effluent limits contained
herein, the permittee may request of the Director that the monitoring requirements be reduced
to a lesser frequency.
Q. Nothing contained in this permit shall be construed as a waiver by Permittee or any right
to a hearing it may have pursuant to State or Federal laws or regulations.
Page 4 of 4