NC0026441_Permit modification_20150523

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r.
May 4, 2015
NC DENR Raleigh Regional Office
Dear Mr. Thompson:
1
Pat McCrory
Governor
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 October 15, 2007 (or as subsequently amended).
200% of this arithmetic
(NH3-N) is daily.
Mr. Bryan Thompson, Town Manager
Town of Siler City
P. O. Box 769
Siler City, North Carolina 27344-0769
1617 Mail Service Center, Raleigh, North Carolina 27699-1617
Phone: [phone] \ Internet: www.ncwaterquality.org
An Equal Opportunity \ Affirmative Action Employer
Donald R. van der Vaart
Secretary
Subject: NPDES Permit Modification
Permit Number NC0026441
Siler City WWTP
Chatham County
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NCDENR
North Carolina Department of Environment and Natural Resources
Ammonia Nitrogen (NHj-N) did not meet the guidance standard that no more than 15 daily sampling
results over the 3-year (36 months) review period (March 2012 to February 2015) can be over 200% of
the monthly average limit for NHj-N. For parameters with summer and winter limits, an annual
arithmetic mean of the seasonal limits was used in the calculation which was 1.42 mg/L [seven (7)
months with 1.0 mg/L and five (5) months with 2.0 mg/L]. Sixteen (16) daily samples were greater than
----------—„ mean which is 2.83 mg/L. Monitoring frequency for Ammonia Nitrogen
Division personnel have reviewed and approved your application for minor modification of the subject
permit. Accordingly we are forwarding the attached modified permit page. Please remove the existing
“Effluent Limitations and Monitoring Requirements” page and replace it with the one attached to this
letter.
This modification reduces the effluent monitoring frequencies for Biochemical Oxygen Demand
(BOD5), Total Suspended Solids (TSS) and Fecal Coliform from daily to 2/week monitoring. The
modification was based upon an evaluation of three years of facility effluent monitoring data. The
facility’s performance satisfies the criteria established in the “DWQ Guidance Regarding the Reduction
of Monitoring Frequencies in NPDES Permits for Exceptionally Performing Facilities” as approved by
the Director of the Division of Water Resources on October 22, 2012, and justifies reduced monitoring
for these parameters. The modified monitoring frequencies will become effective on June 1, 2015.
11
Si:
attachment
Mr. Thompson
NC0026441 Monitoring Frequency Reduction 2015
Page 2 of 2
Jay Zimmerman, Director
Division of Water Resources, NCDENR
cc: Central Files
DWR/Raleigh Regional Office - Danny Smith
NPDES Permit File
ec: EP A Region 4 [[e-mail]]
If you have any questions concerning this permit, please contact Derek Denard at telephone number
[phone] or via e-mail at [e-mail].
Please note that this permit is not transferable except after notice to the Division. The Division may
require modification or revocation and reissuance of the permit. This permit does not affect the legal
requirements to obtain other permits which may be required by the Division of Water Resources or any
other Federal, State, or Local governmental permits that may be required.
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Permit NC0026441
Part I
A. (1) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
PARAMETERS
Flow 4.0 MGD Continuous Recording
5.0 mg/L 7.5 mg/L Composite
10.0 mg/L 15.0 mg/L Composite
30.0 mg/L 45.0 mg/L Composite
1.0 mg/L 3.0 mg/L Daily Composite Effluent
2.0 mg/L 6.0 mg/L Daily Composite Effluent
200/ 100 ml 400/ 100ml Grab Effluent
17pg/L
Weekly Calculated Effluent
0.5 mg/L (quarterly average)Weekly Composite Effluent
2.0 mg/L (quarterly average)Weekly Composite Effluent
2.1 pg/L 15.5 pg/ L
Monitor and Report Effluent
1.
4.
Page 3 of 10
Weekly
Weekly
Daily
Daily
Daily
Daily
Composite
Composite
Grab
Grab
Grab
Grab
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Daily average > 6.0 mg/L
> 6.0 and < 9.0 standard units
5.
6.
2.
3.
Monthly
Average
EFFLUENT LIMITS
Weekly
Average
Daily
Maximum
Measurement
Frequency
Composite
Composite
Composite
Composite
Composite
Footnote 9
Sample
Location2
Influent or
Effluent
Influent and
Effluent
Influent and
Effluent
Influent and
Effluent
Effluent
Effluent
Effluent
Effluent
Effluent
Monthly
Quarterly7
Quarterly7
Quarterly7
Quarterly
Footnote 9
2/Week10
a. During the period beginning with the effective date and lasting until expiration, the Permittee is authorized to discharge
treated wastewater through Outfall 001. Such discharges shall be limited and monitored1 by the Permittee as specified below:
MONITORING REQUIREMENTS
Sample
Type
BOD, 5 day, 20°C3
(April 1 thru October 31)_____
BOD, 5 day, 20°C 3
(November 1 thru March 31)
Total Suspended Solids3
NH3 as N
(April 1 thru October 31)_____
NH3 as N
(November 1 thru March 31)
Fecal Coliform
(geometric mean)___________
Total Residual Chlorine (TRC)4
Temperature (°C)
Dissolved Oxygen
PH
Total Nitrogen
(NO2 + NO3 + TKN)
NO3-N + NO2-N (mg/L)
TKN (mg/L)_______________
Total Phosphorus3
(April 1 thru September 30)
Total Phosphorus3
(October 1 through March 31)
Total Cadmium 6
Total Copper
Total Zinc
Chloride
Chronic Toxicity8
Effluent Pollutant Scan
Footnotes:
No later than March 1, 2015, begin submitting discharge monitoring reports electronically using NC DWR’s eDMR
application system. See Condition A. (7).
Instream monitoring shall be performed in accordance with Condition A. (2).
The monthly average effluent BOD5 and Total Suspended Solids concentrations shall not exceed 15 % of the respective
influent value (i.e., 85% removal is required).
3 RC limits and monitoring requirements apply only if chlorine or chlorine derivatives are used for disinfection. The
Permittee shall report all effluent TRC values reported by a NC-certified laboratory [including field-certified]. Effluent
values below 50 pg/L will be treated as zero for compliance purposes.
Compliance with the Total Phosphorus limits shall be based on a calendar-quarter average of weekly samples.
Total Cadmium limits become effective December 1, 2015. Monitoring shall begin on the effective date. See
Condition A. (6).
2/Week10
2/Week10
2/Week10
I
Permit NC0026441
b. Effluent shall contain no floating solids or foam visible in other than trace amounts.
A. (2)INSTREAM MONITORING REQUIREMENTS
Location 1ParameterSample Type
Dissolved Oxygen Grab LCD, LCD, RRU, RRD
Grab LCU, LCD, RRU, RRD
1.
2.
A. (3)NUTRIENT REOPENER
industrial process wastewater with high
Page 4 of 10
Grab
Grab
Grab
LCU, LCD, RRU, RRD
LCU, LCD, RRU, RRD
LCU, LCD, RRU, RRD
Temperature
Total Phosphorus
TKN__________
no3-n + no2-n
Based on information provided by the Town regarding a potential new industrial process wastewater with high
nutrient concentration, and pursuant to N.C. General Statute Section 143-215.1 and the implementing rules found in
Title 15A of the North Carolina Administrative Code, Subchapter 2H, specifically, 15A NCAC 2H.0112(b) (1) and
2H.0114(a), and Part II, Sections B-12 and B-13 of this pennit, the Director of DWR may then reopen this permit
to require supplemental nutrient limits for Total Nitrogen and/ or Total Phosphorus in accordance with the current
Basin Plan for the Cape Fear River Basin.
In the event that Permittee proposes to accept future industrial process wastewater that is expected to contain
concentrations of Total Nitrogen (TN) and/ or Total Phosphorus (TP) greater than typical domestic wastewater
concentration (i.e. greater than 40.0 mg/ L TN or greater than 5.0 mg/ L TP), the Permittee shall notify the NPDES
Complex Permitting Unit of the Division at 1617 Mail Service Center, Raleigh, NC 27699 and the Raleigh
Regional Office at 3800 Barrett Drive, Raleigh, NC 27609 within 30 days of knowledge that the town is
considering accepting new industrial process wastewater containing excess nutrients. The notification shall contain
information regarding the proposed discharge flow, composition and treatability in the Siler City WWTP. Changes
in effluent characteristics may require a pennit modification, so notification should be at least 180 days prior to the
start of the proposed discharge.
Footnotes:
LCU - Loves Creek, upstream of the discharge; LCD - Loves Creek, downstream of the discharge and above the
confluence with the Rocky River; RRU - Rocky River, upstream of the confluence with Loves Creek; RRD - Rocky
River, downstream of the confluence with Loves Creek.
All monitoring is required to be performed at the above-mentioned monitoring locations. Instream Monitoring
may be performed by the Upper Cape Fear River Basin Association as outlined in the Memorandum of Agreement
(MOA) between the association and the permittee. If so, the data is to be collected and submitted to DWR in
accordance to the terms of the MOA. Should membership in this association terminate for any reason, the permittee
shall immediately notify the Division’s NPDES Unit in writing and resume responsibility to monitor and report the
above parameters as specified in this permit.
Footnotes A.(l) Continued:
7. Sample Quarterly in conjunction with Chronic Toxicity Test.
8. Chronic Toxicity {Ceriodaphnia) at 90 %; quarterly during March, June, September, December [see Condition A. (8)].
9. The permittee shall perform three Effluent Pollutant Scans during the term of this permit [see Condition A. (9)].
10. Sampling must occur on any two non-consecutive days during the calendar week (Sunday through Saturday).
Measurement Frequency 2
3/Week (June - September),
1/Week (October-May)
3/Week (June - September),
1/Week (October-May)
Monthly
Monthly
Monthly