NC0025071_Permit Modification_20100420

NCDENR
North Carolina Department of Environment and
Division of Water Quality
Beverly Eaves Perdue Coleen H. Sullins
Governor Director
April 20, 2010
Ms. Melinda S. Ward, Wastewater Superintendent
City of Eden
P. O. Box 70
Eden, NC 27289-0070
Subject: NPDES Permit Modification
Permit Number NCO025071
City of Eden — Mebane Bridge W WTP
Rockingham County
Dear Ms. Ward:
Natural Resources
Dee Freeman
Secretary
Division personnel have reviewed and approved your application for minor modification of the subject permit.
Accordingly we are forwarding the attached modified permit limits and monitoring pages. These pages should be
inserted into your permit and the old ones discarded. As a result of this modification, condition A. (4.) of the
permit (Conditional Monitoring for Mercury) is no longer applicable, and that page of the permit may also be
discarded.
This modification removes monitoring requirements and effluent limitations for mercury as terms of the NPDES
permit. As you noted in your request, mercury concentrations in the effluent shall continue to be monitored as
part of the facility's pretreatment requirements. Should elevated mercury concentrations be observed through that
monitoring, the permit requirements may be reinstituted.
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).
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 Quality or permits required by the Division
of Land Resources, the 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 Bob Sledge at telephone
number [phone].
Sincerely,
C leen H. Sullins
cc: Central Files
Winston-Salem Regional Office/Surface Water Protection Section
NPDES Unit
1617 Mail Service Center, Ralsgh, North Carolina 27699-1617 7�inlle 1.. t Location: 512 N. Salisbury St. Ralegh, North Carolina 27604 i� Ort11CaCO11R�1
Phone: [phone] \ FAX: [phone] \ Customer Service: 1.817.623.6748 ��tlrrll111/
Internet: www.ncwaterquality.org
a cm.y , e,.n,,,,

Permit NCO025071
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
During the period beginning on the effective date of this permit and lasting until permit 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
Average
Weekly
y
Average
Dail Y
Maximum
Measurement
� Frequency
Sam le
p
Type
Sample Location '
Flow
13.5 MGD
Continuous
Recording
Influent or Effluent
BOD, 5-day 20°C 2
30.0 mg/L
45.0 mg/L
Daily
Composite
Effluent, Influent
Total Suspended Solids (TSS) 2
30.0 mg/L
45.0 mg/L
Daily
Composite
Effluent, Influent
NH3 as N (April 1-October 31
14.8 mg/L
35.0 mg/L
Daily
Com osite
Effluent
NH3 as N November 1-March 31
3Meek
Composite
Effluent
H s
Daily
Grab
Effluent
pH
Footnote 1
Grab
Upstream',Downstream'
Fecal Coliform
(geometric mean
200 ! 100 ml
400 / 100 ml
Daily
Grab
Effluent
Total Residual Chlorine (TRC) 4
28 µg/L
Daily
Grab
Effluent
Temperature, °C
Daily
Grab
Effluent
Temperature, °C
Footnote 1
Grab
Upstream',
Downstream'
Conductivity, Nohm/cm
Footnote 1
Grab
Upstream,
Downstream
Dissolved Oxygen DO , m /L
Daily
Grab
Effluent
Dissolved Oxygen (DO), mg/L
Footnote 1
Grab
Upstream',
Downstream'
Total Cap er, ju /L 5 1k
2/Month
Composite
Effluent
Total Nitrogen (TN)
TN = NO2 + NO3 + TKN, mg/L
•
Monthly
Composite
Effluent
Total Phosphorus P , mg/L
Monthly
Composite
Effluent
Chronic Toxicity 6
Quarterly
Composite
Effluent
Total Zinc, u /L s
Quarterly
Composite
Effluent
Color 7
300 ADMI
3/Quarter
Grab
Effluent
Color
Footnote 1
Grab
Upstream'
Downstream,'
Effluent Pollutant Scan 8
Annual
Composite/
Grab
Effluent

Permit NCO025071
(continued from A.(1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS) %
Notes:
I. Sample locations: Upstream - Upstream at NCSR 1964: Downstream - Downstream at NCSR 700.
Upstream and downstream samples shall be grab samples. Stream samples shall be collected
three times per week during June. July, August and September and once per week during the
remaining months of the year.
2. The monthly average BODs and TSS concentrations shall not exceed 156/o of the respective influent
value (85% removal).
3. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
4. Total Residual Chlorine compliance is required for chlorine or chlorine derivative used for disinfection.
The Division shall consider all effluent TRC values reported below 50 ug/l to be in compliance with the
permit. However, the Permittee shall continue to record and submit all values reported by a North
Carolina certified laboratory (including field certified), even if these values fall below 50 ug/l.
5. Sampling for zinc, copper, and silver should coincide with sampling for chronic toxicity test.
6. Chronic Toxicity (Ceriodaphnia) P/F at 5.4%. Toxicity testing shall be performed in the months of
March, June, September and December (see Part A.(2.).
7. Limit is an instantaneous maximum (i.e. not to be exceeded at any time) not a daily maximum.
8. See Special Condition A.(3.) for list of pollutants.
There shall be no discharge of floating solids or visible foam in other than trace amounts.

REASONABLE POTENTIAL ANALYSIS
Eden - Mebane Bridge WWTP
NCO025071
Time Period February 2009 -January 2010
Ow (MGD) 13.5
WWTP Class IV
7010S (Cfs) 370
IWC (%) ® 7010S 5.3527
7010W (Cfs) 600
@ 701OW 3.37
3002 (Cfs) 740
@ 3002 2.7499
Avg. Stream Flow, OA (cfs) 2018
® OA 1.0263
Reeving Stream Dan River
Stream Class WS-IV
Outfall 001
Qw=13.5MGD
STANDARDS &
PARAMETER
TYPE
CRITERIA 2
POL
Units
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
(1)
NC Was/ KFAY/
n #VOL WxPmdCw AGaw"Cw
Chronk Acab
Acute: WA
Mercury
NC
12
2
nWL
27 0
100.0
_ _ _ _ _
_ _ _ _ _ — — -----
Chronic: 0
Remove ti m►t & monitoring trom permit
Acute: NIA
0 0
NIA
____ _
Chronic: _nor 0 Type
--------------------------------
Acute: WA
0 0
NIA
_
Chronic: Error ®Type -- ------------- -----------
Acute: WA
0 0
WA
_
-t
Chronic: Error ® Type
--.—.—.-- ---------- --- ----- —
Acute: WA
0 0
N/A
............
Chronic: Error ®Type
------.—_—---------—.---.----
Acute: WA
0 0
WA
Chronic: Error ®Type
--------------------- --- - - -
Acute: WA
0 0
WA
__o__ _
Chrnic: Error 1F Type
-------------------------
Acute: WA
0 0
WA
Chronic: Error Type--
— ------------------------
Acute: WA
0 0
WA
Chronic: Error @Type
-------------------_-------_- -
Acute: WA
0 0
WA
_
Chronic: Error 0 Type -----------------------------
Acute: WA
0 0
WA
Chronic: Error ®Type
.—.- — ------------ --- -.—_—
Acute: WA
0 0
WA
Chron_ic: _ Error _ @ Typo
-------------------------- --- —
Acute: WA
0 0
WA
Chronic: Error ®Type
—.—
Acute: WA
0 0
WA
__
ChroNc: Error O T_ype
------------------------_—.—.—_—
Acute: WA
0 0
WA
_
Chronic: Error ®Type ------------------------.—.—_---
' Legend: " Freshwater Discharge
C = Carcinogenic
NC = Non -carcinogenic
A = Aesthetic
NOD025071 rpa 03312010. rpa
3/31/2010

eitv of
Depagment of &utk pmenta Sewkea
March 1, 2010
2Uadkwate)t .J aeahnent Awd MAR 032010
�
Coleen H. Sullins
Division of Water Quality
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
Dear Ms. Sullins,
This letter is in regards to the provisional section of our NPDES permit, NC0025071, regarding
Mercury. "Section A. (4.) Conditional Monitoring for Mercury: Provisional Limit with weekly
monitoring for Mercury take effect August 1, 2010. If the fast 12 months of monitoring data
from the effective date shows no reasonable potential to exceed water quality standards, the
Permittee can petition the Division to remove this requirement, which can be done by letter from
the Division without having to reopen the permit. This does not effect the pretreatment
monitoring requirements."
Our permit became effective February 1, 2009, so we began monitoring for Mercury at this time.
So far, we have collected 13 months of data to share with your office and are continuing to
monitor twice a month until this is removed or goes into effect in August. We feel that this is
sufficient enough data to prove that our plant shows no reasonable potential for exceeding water
quality standards at this time. Therefore, I am petitioning your office to remove this requirement
for Mercury monitoring during this permit cycle. I understand that we must continue monitoring
quarterly in accordance with our Pretreatment requirements, and that if any data shows results
higher than the current limit, we may be required to resume monitoring.
If more information is needed, please feel free to contact me anytime at extension 130.
Sincerely,
�Va� lia,d
Melinda S. Ward
Wastewater Superintendent
Attachment
Cc: Winston Salem Regional Office
Brad Corcoran, City Manager
Dennis Asbury, Director of Environmental Services
P. O. Boa 70 • Eden, NC 27289-0070 • [phone] • Fax [phone]

Mebane Bridge WWTP Mercury Results
Date Result ng/L
2/2/2009
<200
2/9/2009
<200
2/16/2009
<200
3/2009
<210
/2009
<200
/2009
F
<200
/2009
<200
3/9/2009
<200
3/10/2009
<200
3/16/2009
<200
4/6/2009
<200
4/13/2009
<200
5/4/2009
<200
5/11/2009
<200
6/2/2009
<200
6/8/2009
<200
7/6/2009
<200
7/13/2009
<200
8/3/2009
<200
8/10/2009
<200
9/9/2009
<200
9/15/2009
<200
10/7/2009
<200
10/12/2009
<200
11/2/2009
<200
11/9/2009
<200
11/30/2009
<200 °
12/8/2009
<200
1/5/2009
<200
1/12/2009
<200
2/1/2009=<200
2/8/2009
* Sample analyzed twice and this is the average.
k The first sample for December was mistakenly taken
in November and not caught until January.