NC0026441_Permit (Modification)_19990215

State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor
Wayne McDevitt, Secretary
A. Preston Howard, Jr., P.E., Director
February 15, 1999
Mr. Curtis Brown
Town of Siler City
P.O. Box 769
Siler City, North Carolina 27344-0769
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NCDENR
NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
Subject: NPDES Permit Modification
NPDES Permit NCO026441
Siler City WWTP
Chatham County
Dear Mr. Brown:
The Division issued the subject permit on June 7, 1996. Personnel from the NC DENR Raleigh
Regional Office recently discussed the requirements for quarterly phosphorus monitoring with you. A
request was made by the Regional Office to correct the permit so that the quarterly period used for
compliance purposes would accurately match the sampling scheme at the facility. The request has
been granted. This permit modification changes the months where Total Phosphorus is limited and
averaged for quarterly compliance evaluations.
Please find enclosed the revised permit page. This page should be inserted into your permit. The
old page may then be discarded. All other terms and conditions contained in the original permit
remain unchanged and in full effect. This permit modification is issued under the requirements of
North Carolina General Statutes 143-215.1 and the Memorandum of Agreement between North
Carolina and the U. S. Environmental Protection Agency.
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 a written petition
conforming to Chapter 150B of the North Carolina General Statutes, filed with the Office of
Administrative Hearings, Post Office Drawer 27447, Raleigh, Forth Carolina 27611-7447. Unless suc:
demand is made, this decision `shall be final and binding.
If you have any questions concerning these permit modifications, please contact Charles Weaver
at [phone], extension 511.
Si cerely,�
41X. Preston Howard, JJ,E.
cc: Central Files V
Raleigh Regional Office / Ted Cashion
Point Source Compliance Enforcement Unit
,NPDES Unit
P.O, Box 29535, Raleigh, North Carolina 27626-0535 Telephone [phone] FAX [phone]
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t.
Permit NCO02644 I
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS - FINAL 44
During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is
authorized to discharge from outfall 001. Such discharges shall be limited and monitored by the Permittee as
specified below:
EFFLUENT CHARACTERISTICS LIMITS
MONITORING REQUIREMENTS
Monthly Weekly . Daily Measurement
.Average :; Average Maxfmurh t Frequency
Sample
Type,Locationl
Sample
Flow 4.0 MGD
Continuous
RecordingInfluent
or Effluent
BOD, 5 day (20oC)2 5.0 mg/l 7.5mg/l
Daily
Composite
Influent & Effluent
(April 1— October 31)
BOD, 5 day (200C)2 10.0 mg/I 15.0 mg/I
Daily
Composite
Influent & Effluent
(November 1— March 31)
Total Suspended Residue2 0 mg/I 45.0 mg/I
Daily
Composite
Influent & Effluent
NH3 as N mg/I
F1.0
Daily
Composite
EffluentA
ril 1— October 31NH3
as N .mg/l
j Daily
Composite
Effluent
November 1— March 31
j
Dissolved Oxygen3
Daily
Grab
Effluent, Upstream
Fecal Coliform (geometric mean) 200/100 ml 400/100 ml
Daily
Grab
& Downstream
Effluent, Upstream
Oil and Grease 30.0 m /l 60.0 m /l
3/Week
& Downstream
Effluent
Total Residual Chlorine 17.0 /I
Dail
Grab
Effluent
Temperature
Daily
Grab
Effluent, Upstream
Total Nitro en NO2+NO3+TKN
MonthlX
Composite
& Downstream --
Effluent
Total Phosphorus 0.5 mg/14
Weekly
Composite
Effluent, Upstream
LApril 1— September 30
& Downstream
Total Phosphorus
Weekly
Composite
Effluent, Upstream
October 1— March 31
& Downstream
Chronic Toxici 5
Quarterly
Composite
Effluent
Conductivity
Daily
Grab
Effluent, Upstream
Chromium 52.0 /
Weekly
Composite
& Downstream
Effluent
Copper
2/Month
Composite
Effluent
Mercu 0.012 PgA
Weekly
Composite
Effluent
MBAS 0.5 m /l
Weekly
Composite
Effluent'
Zinc /L
2/Month
Composite
Effluent
Bis 2-eth the I hthalate /I
Quarterl
Composite
Effluent
-Chloroform /I
l
Qu�ae
Com osite
Effluent
Chloride /I
Qul
Com osite
Effluent
Fluoride /l
Quarterly
Composite
Effluent
H6 6-9
Daily
Grab
Effluent
Footnotes:
1. For instream monitoring requirements and sample Iocations,
see Part III, Condition F.
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. Compliance shall be based upon a quarterly average of weekly samples.
5. Chronic Toxicity (Ceriodaphnia) P/F at 90%: March, June, September & December (see Part III, Condition G.).
6. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
There shall be no discharge of floating solids or visible foam in
other than trace amounts. `

WAYNS MCDEVITT
NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
RALEIGH REGIONAL OFFICE
DIVISION OF WATER QUALITY
November 19, 1998
MEMORANDUM
To: Dave Goodrich
NPDES Unit Supervisor
Through: Ken Schuster, P.E.
Regional Supervisor
From: Ted Cashion
Environmental Chemist
Subject: Total Phosphorus Limit
Siler City WWTP
NPDES Permit No. NCO026441
Chatham County
The Town of Siler City called to inquire about the total phosphorus months stated in
the permit. The permit states there is a quarterly average in effect from April 1 -
October 31. Curtis Brown with the Town stated that the Division told him when the
permit was issued that the quarterly average should be listed as April 1 - September
30, to coincide with the end of the calendar quarter, instead of ending October 31,
which is not the end of a calendar quarter as defined in the permit. He stated he was
told that the Division would reissue the permit showing this correction but has not
done so yet.
We agree with the Town that the month of October by itself would not be subject to a
quarterly average compliance evaluation. Please have someone respond
appropriately to the Town regarding this request.
If questions please call.
Siler.mem
3800 BARRETT DRIVE, SUITE 101, RALEIGH, NORTH CAROLINA 27609
PHONE [phone] FAX [phone]
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PartII
U Page 2 of 14
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a. The "average monthly concentration," other than for fecal coliform bacteria, is the sum of
the concentrations of all daily discharges sampled and/or measured during a calendar month
on which daily discharges are sampled and measured, divided by the number of daily
discharges sampled and/or measured during such month (arithmetic mean of the daily
concentration values). The daily concentration value is equal to the concentration of a
composite sample or in the case of grab samples is the arithmetic mean (weighted by flow
value) of all the samples collected during that calendar day. The average monthly count for
fecal coliform bacteria is the geometric mean of the counts for samples collected during a
calendar month. This limitation is identified as "Monthly Average" under "Other Limits" in
Part I of the permit.
b. The "average weekly concentration," Other than for fecal coliform bacteria, is the sum of the
concentrations of all daily discharges sampled and/or measured during a calendar week
(Sunday/Saturday) on which daily discharges are sampled and measured divided by the
number of daily discharges sampled and/or measured during such week (arithmetic mean of
the daily concentration values). The daily concentration value is equal to the concentration
of a composite sample or in the case of grab samples is the arithmetic mean (weighted by
flow value) of all the samples collected during that calendar day. The average weekly count
for fecal coliform bacteria is the geometric mean of the counts for samples collected during
a calendar week. This limitation is identified as "Weekly Average" under "Other Limits" in
Part I of the permit.
c. The "maximum daily concentration" is the concentration of a pollutant discharge during a
calendar day. If only one sample is taken during any calendar day the concentration of
pollutant calculated from it is the "Maximum Daily Concentration". It is identified as
'Daily Maximum" under "Other Limits" in Part I of the permit.
d. The "average annual concentration," other than for fecal coliform bacteria, is the sum of the
concentrations of all daily discharges sampled and/or measured during a calendar year on
which daily discharges are sampled and measured divided by the number of daily
discharges sampled and/or measured during such year (arithmetic mean of the daily
concentration values). The daily concentration value is equal to the concentration of a
composite sample or in the case of grab samples is the arithmetic mean (weighted by flow
value) of all the samples collected during that calendar day . The average yearly count for
fecal coliform bacteria is the geometric mean of the counts for samples collected during a
calendar year. This limitation is identified as "Annual Average" under "Other Limits" in
Part I of the permit.
e. The "daily average concentration" (for dissolved oxygen) is the minimum allowable amount
of dissolved oxygen required to be available in the effluent prior to discharge averaged
over a calendar day. If only one dissolved oxygen sample is taken over a calendar day, the
sample is considered to be the "daily average concentration" for the discharge. It is
identified as "daily average" in the text of Part I.
f. The "quarterly average concentration" is the average of all samples taken over a calendar
quarter. It is identified as "Quarterly Average Limitation" in the text of Part I of the permit.
g. A calendar quarter is defined as one of the following distinct periods: January through
March, April through June, July through September, and October through December.