NC0047597_Permit modification_19961024

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
October 24, 1996
Mr. A.T. Rolan, Director
City of Durham
101 City Hall Plaza
Durham, North Carolina 27701
Subject: Permit Modification
NPDES Permit NC0047597
South Durham WRF
Durham County
Dear Mr. Rolan:
On September 13, 1996, the Division of Water Quality issued the subject permit to the City of
Durham. Based on discussions between City representatives and Division staff on October 15, 1996,
two issues regarding mercury have been resolved. The Division has agreed to remove the mercury
limit scheduled to take effect on February 1, 1997 provided that mercury is not detected in the
facility's effluent through the end of this year. A modified effluent sheet will be sent at that time with
the mercury limit removed. Mercury monitoring would continue on a twice per month basis. Also, a
footnote has been added stating that 0.2 µg/l is the current detection limit for mercury and that non -
detected levels should be reported as zero for compliance purposes, and the weekly average limitation
has been removed at the City's request.
Additionally, several corrections have been made to the previously issued permit. The facility name
has been corrected to South Durham Water Reclamation Facility and the Division acknowledges that
the statement made in the September 13, 1996 cover letter that this facility receives wastewater from
RTP was incorrect. Also, Part III, Condition I mistakenly required instream monitoring from
October through May for total phosphorus, NO2+NO3, TKN and PO4. Those requirements have
been deleted from the permit. The enclosed pages should be added to the permit and the existing
pages discarded. This permit modification becomes effective immediately.
All other terms and conditions in the original permit remain unchanged and in full effect. This
modification 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.
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

If you have any questions concerning this modification, please contact Mr. Greg Nizich at telephone
number 919/733-5083, ext. 541.
Sincerely,
Original Signed By
David A. Goodrich
A. Preston Howard, Jr., P.E.
enclosure
cc: Central Files
Mr. Roosevelt Childress, EPA
Raleigh Regional Office, Water Quality Section
Facility Assessment Unit
Aquatic Survey & Toxicology Unit
Technical Assistance & Certification Group
Permits and Engineering Unit

Permit No. NC0047597
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,
City of Durham
is hereby authorized to discharge wastewater from a facility located at
South Durham Water*Reclatmation-Facility
6605 Farrington Road
Durham....
Durham County
to receiving waters designated as New Hope Creek in the Cape Fear River Basin
in accordance with effluent limitations, monitoring requirements, and other conditions set forth in
Parts I, II, III, and IV hereof.
This permit shall become effective October 24, 1996.
This permit and authorization to discharge shall expire at midnight on February 28, 2001
Signed this day October 24, 1996.
�l �i��f/KJ
-tee Preston Howard, Jr., P.., Director
Division of Water Quality
By Authority of the Environmental Management Commission

Permit No. NC0047597
SUPPLEMENT TO PERMIT COVER SHEET
City of Durham
is hereby authorized to:
1. Continue to operate the existing 20.0 MGD wastewater treatment facility consisting of screening
and grit removal, primary clarification, aeration, secondary clarification, flocculation basins,
tertiary filters, ultraviolet disinfection, residuals anaerobic digesters, aerobic digesters, gravity
belt thickeners, sand drying beds, and belt filter press, located at South Durham Water
Reclamation Facility, 6605 Farrington Road, Durham, Durham County (See Part III of this
Permit), and
2. Discharge from said treatment works at the location specified on the attached map into New
Hope Creek which is classified Class WS-IV NSW waters in the Cape Fear River Basin.

A. (1). EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS SUMMER (April 1 - October 31) Permit No. NC0047597'
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 Max. Frequency Type_ Location1
Flow 20.0 MCA Continuous Recording I or E
BOD, 5-Day, 20°C2 5.0 mg/I 7.5 mg/I Daily Composite I,E
Total Suspended Residue2 30.0 mg/1 45.0 mg/I Daily Composite I,E
NH3 as N 1.0 mg/1 Daily Composite E
Dissolved Oxygen 3 Daily Grab E1
Fecal Coliform (geometric mean) 200 /100 ml 400 /100 ml Daily Grab E1
Total Residual Chlorine4 17.0 µg/1 Daily Grab E
-. Total Phosphorus5 0.5 mg/I Weekly Composite E1
Total Nitrogen (NO2 + NO3 + TKN) Monthly Composite E
Chronic Toxicity6 Quarterly Composite E
Conductivity 1 Grab 1
1 Sample locations: E - Effluent, I - Influent. See Part III, Condition I for instream monitoring requirements.
2 The monthly average effluent BOD5 and Total Suspended Residue concentrations shall not exceed 15% of the respective influent value (85 %
removal).
3 The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/1.
4 Limit and monitoring apply if chlorine disinfection is employed.
5 Compliance shall be based upon a Quarterly average of weekly samples.
6 Chronic Toxicity (Ceriodaphnia) P/F at 90%; January, April, July and October; See Part III, Condition G.
The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units and shall be monitored daily at the effluent and as specified in Part
III, Condition I.
There shall be no discharge of floating solids or visible foam in other than trace amounts.

A. (1). EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS SUMMER (April 1 - October 31)
Permit No. NC0047597
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. (Continued)
Effluent Characteristics
Mercury
Mercury (effective 2/1/97)7
Copper
Zinc
Silver
PO4
TKN
Total Phosphorus
NO2+NO3
Temperature
Discharge Limitations Monitoring
Measurement
Monthly. Avg. Weekly Avg. Daily Max. Frequency
2/Month
0.012 14/18 Weekly
Monthly
Monthly
Monthly
Weekly
Weekly
Weekly
Weekly
Daily
7 This limit will be deleted if mercury is not detected in the effluent through 12-31-96.
Requirements
Sample Sample.
Type Location1
Composite E
Composite E
Composite E
Composite E
Composite E
Grab 1
Grab 1
Grab 1
Grab 1
Grab El
8 If the measurement for this parameter is below detection limits, the quantity for purposes of compliance evaluation is considered to be zero. The current
detection limit for mercury shall be considered 0.2 µg/1. Mercury detected at levels less than detection should be reported on the DMR to be <0.2 14/1.

A. (2). EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS WINTER (November 1 - March 31) Permit No. NC0047597 •
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
Monthly. Avg.
Flow 20.0 MC-D
BOD, 5-Day, 20°C2 7.0 mg/1
Total Suspended Residue2 30.0 m g / I
NH3 as N 2.0 mg/I
Dissolved Oxygen 3
Fecal Coliform (geometric mean) 200 /100 ml
Total Residual Chlorine4
Total Phosphorus5 2.0 mg/I
Total Nitrogen (NO2 + NO3 + TKN)
Chronic Toxicity6
Conductivity
Limitations Monitoring
Measurement
Weekly Avg. ' Daily Max. Frequency
Continuous
10.5 mg/I Daily
45.0 mg/I Daily
Daily
Daily
400 /100 mi Daily
17.0 µg/I Daily
Weekly
Monthly
Quarterly
1
Requirements
Sample Sample
Type Locations
Recording
Composite
Composite
Composite
Grab
Grab
Grab
Composite
Composite
Composite
Grab
I or E
I,E
I,E
E
E1
E1
E
E1
E
E
1
1 Sample locations: E - Effluent, I - Influent. See Part III, Condition I for instream monitoring requirements.
2 The monthly average effluent BOD5 and Total Suspended Residue concentrations shall not exceed 15% of the respective influent value (85 %
removal).
3 The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/l.
4 Limit and monitoring apply if chlorine disinfection is employed.
5 Compliance shall be based upon a Quarterly average of weekly samples.
6 Chronic Toxicity (Ceriodaphnia) P/F at 90%; January, April, July and October; See Part III, Condition G.
The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units and shall be monitored daily at the effluent and as specified in Part
III, Condition I.
There shall be no discharge of floating solids or visible foam in other than trace amounts.

A. (2). EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS WINTER (November 1 - March 31) Permit No. NC0047597
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. (Continued)
Effluent Characteristics
Discharge Limitations
Monitoring Requirements
Measurement Sample Sample
Monthly. Avg. Weekly Avg. Daily Max. Frequency Type Location1
Mercury 2/Month Composite E
Mercury (effective 2/1/97)7 0.012 µg/I8 Weekly Composite E
Copper Monthly Composite E
Zinc Monthly Composite E
Silver Monthly Composite E
PO4 Weekly Grab 1
TKN Weekly Grab 1
Total Phosphorus Weekly Grab 1
NO2+NO3 Weekly Grab 1
Temperature Daily Grab E1
7 This limit will be deleted if mercury is not detected in the effluent through 12-31-96.
8 If the measurement for this parameter is below detection limits, the quantity for purposes of compliance evaluation is considered to be zero. The current
detection limit for mercury shall be considered 0.2 14/1. Mercury detected at levels less than detection should be reported on the DMR to be <0.2 14/1.

I. INSTREAM MONITORING REQUIREMENTS:
Upstream and Downstream
Permit No. NC0047597
Parameter
Frequency
Sample Type
DO
3/week, Jun - Sep; 1/week, Oct - May
Grab
Fecal Coliform
3/week, Jun - Sep; 1/week, Oct - May
Grab
Temperature
3/week, Jun - Sep; 1/week, Oct - May
Grab
Conductivity
3/week, Jun - Sep; 1/week, Oct - May
Grab
pH
3/week, Jun - Sep; 1/week, Oct - May
Grab
Total Phosphorus
1/week, June - Sep;
Grab
NO2 + NO3
1/week, June - Sep;
Grab
TKN
1/week, June - Sep;
Grab
PO4
1/week, June - Sep;
Grab
Monitoring Locations:
Upstream - New Hope Creek at 1-40
Downstream - At NCSR 1107