NC0047597_Permit modification_19970226

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
Mr. A. T. Rolan, Director
City of Durham, Department of Water Resources
101 City Hall Plaza
Durham, North Carolina 27701
Dear Mr. Rolan:
CEI--1NFl
February 26, 1997
Subject: Modification Request
NPDES No. NC0047597
South Durham WRF
Durham County
The Division has reviewed your request received February 13, 1997 to eliminate the limit for mercury.
Based on the past year's worth of monitoring data which indicated no potential to violate the mercury limit, the
Division has approved that request. Enclosed please find the modified effluent limitations page. This page should be
inserted into your permit and the old effluent limitations pages be discarded. 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.
The Division commends the City of Durham on the efforts to address concerns regarding mercury in the
wastewater treatment plant effluent. The work which was submitted to us is very informative. The Division
requests the submission of further test results on an annual basis. Such results should be submitted to Mr. David
Goodrich at the address below.
If any parts, measurement frequencies or sampling requirements contained in this permit modification are
unacceptable to you, you have the right to an adjudicatory hearing upon written request within thirty (30) days
following receipt of this letter. This request must be in the form of a written petition, conforming to Chapter 150B
of the North Carolina General Statutes, and filed with the Office of Administrative Hearings, Post Office Drawer
27447, Raleigh, North Carolina 27611-7447. Unless such demand is made, this decision shall be final and binding.
Please take notice 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
requirement to obtain other permits which may be required by the Division of Water Quality or permits required by
the Division of Land Resources, Coastal Area Management Act or any other Federal or Local governmental permit
that may be required. If you have any questions concerning this permit, please contact Susan Robson at telephone
number 919/733-5083, ext. 551.
Sin rely,
, _---/, Lie,ept,(,A-
7r1ZPreston Howard, Jr., P.E/.
cc: Central Files
Mr. Roosevelt Childress, EPA
Raleigh Regional Office, Water Quality Section
Permits and Engineering Unit
Facility Assessment Unit
Aquatic Survey and Toxicology Unit
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

A. EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS FINAL
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 serial number
001. Such discharges shall be limited and monitored by the Permittee as specified below:
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apt o
Flow
2.0 MGD
Continuous
Recording
I or E
BOD, 5 day, 20°C" (April 1 - October 31)
5.0 m9/i
7.5 mq/I
Daily
Composite
E, I
BOD, 5 day, 20°C" (November 1 - March 31)
7.0 mg/I
10.5 mg/I
Daily
Composite
E, I
Total Suspended Residue**
30.0 mg/i
45.0 mq/I
Daily
Composite
E, I
NH3 as N (April 1 - October31)
• 1.0 mg/l
Daily
Composite
E
NH3 as N (November 1 - March 31)
2.0 mg/I
Daily
Composite
E
pH2
Daily
Grab
E
Fecal Coliform (geometric mean)
200 / 100 ml
400 / 100 mi
Daily
Grab
E'
Total Residual Chlorin&
17.0 µq/I
Daily
Grab
E
Temperature
Daily
Grab
E'
Conductivity
•
1
Grab
1
Dissolved Oxygen4
Daily
Grab
E'
Total Nitrogen (NO2 + NO3 + TKN)
Monthly
Composite
E
Total Phosphorus5 (April 1 - October 31)
0.5 mg/i
Weekly
Composite
El
Total Phosphorus5 (November 1 - March 31)
2.0 mq/I
Weekly
Composite
E'
Chronic Toxicity6
Quarterly
Composite
E
Mercury
2/Month r
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
Notes:
Sample locations: E - Effluent, I - Influent. See Part III, Condition I for instream monitoring requirements.
2 The pH shall not be Tess than 6.0 standard units nor greater than 9.0 standard units.
3 Limit and monitoring apply only if chlorine disinfection is employed.
4 The daily average dissolved oxygen effluent concentration shall not be less than 6.0 mg/I.
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 monthly average effluent BOD5 and TSS concentrations shall not exceed 15% of the respective influent value (85% removal).
There shall be no discharge of floating solids or visible foam in other than trace amounts.