NC0037508_NPDES Permit Mod_20060201

Michael F. Easley
Governor
William G. Ross, Jr., Secretary
North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.E., Director
Division of Water Quality
February 1, 2006
Mr. James D. Frye
Department of Public Works - Moore Co.
1094 Addor Rd.:
Aberdeen, North Carolina 28315
Subject: NPDES Permit Modification
Permit No. NC0037598
Moore County WWTP
Moore County 1
Dear Mr. Frye:
V'ES ..0 2036
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The Division . has reviewed your request to modify. the mercury requirement in your
NPDES permit. Based on the upstream data collected by Moore County the mercury limit has
been modified. The permit issued on May 13, 2005 contained a mercury limit of 12 ng/L. This
limit was based on -the' assumption that the stream had reached its' assimilative capacity. Moore
County , collected data upstream of . the discharge for 6 months showing a maximum mercury
concentration of: 3.72 ng/1. The mercury limit was recalculated using 3.72 ng/L as the
background concentration. The new mercury limit is 24.1. ng/L. A reasonable potential analysis
was completed using the effluent data provided by Moore County. The results show there is
reasonable potential to exceed the mercury limit; therefore the limit will be implemented in the
permit and the schedule of compliance remains in place. d
The effluent limitations and monitoring page with the mercury limit modification is
enclosed, please replace this page in your permit. If you have any questions concerning this
permit modification, please call Teresa Rodriguez at [phone], extension 553.
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Cc: NPDES Files
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Central Iles
North Carolina Division of Water Quality
Internet: h2o.enr.state.nc.us
Sincerely,
Gil Vinzani, P.E.
EAST NPDES Unit Supervisor
No One Carolina
`,Naturally
1617 Mail Service Center Raleigh, NC-27699-1617 I Phone [phone]. Customer Service
512 N. Salisbury St. Raleigh, NC 27604 , FAX [phone]
I
An Equal Opportunity/Affirmative Action Employer-50% Recycled/10% Post Consumer Paper
1

Permit NC0037508
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
During the period beginning on February 1, 2006 and lasting until expiration, the Permittee is authorized to
discharge through Outfall 001. Such discharges shall be limited and monitored by the Permittee as specified
below:
'PARAMETERS' , sg
EFFLgUENT LIMITS ? „' L
M"OMu) RINGsREQUIREMEN FS
�; n f
4hb yyd
,
p
Monthl ✓�
Average
Weekl -
, Average, ;
z Ddi l{
.1 "t�
Maxunum
Measurement 1
Frequency?
Sa`m le• -
p'�� '-,e
Type
x .� Sam le , -''
p,SS Nd S+!
„
Flow
6.7 MGD
Continuous
Recording
Influent or Effluent
BOD, 5 day, 20°C '
(April 1— October 31) 2
22.0 mg/L
33.0 mg/L
Daily
Composite
Influent & Effluent
BOD, 5 day, 20°C
(November 1— March 31) 2
30.0 mg/L
45.0 mg/L
Daily
Composite
Influent & Effluent
Total Suspended Solids (TSS) 2
30.0 mg/L
45.0. mg/L
Daily
Composite
Influent & Effluent
NH3 as N
(April 1— October 31)
2.1 mg/L
.
6.3 mg/L
Daily
Composite
Effluent
NH3 as N
(November 1— March 31)
6.2 mg/L
18.6 mg/L
Daily
Composite
Effluent
Fecal Coliform (geometric mean)
200 / 100 ml
400 / 100. ml
Daily
Grab
Effluent
Total Residual Chlorine (TRC) 3
28 µg/L
Daily
Grab
Effluent
Dissolved Oxygen
Dail average > 5.0 mg/L
Daily
Grab
Effluent
Temperature (°C)
Daily
I Grab
Effluent
Conductivity ..
Daily
Grab
Effluent
pH
. > 6.0 and <.9.0 standard units.
Daily
Grab
Effluent
Total Phosphorus
Monthly
Composite
Effluent
Total Nitrogen
(NO2-N + NO3-N + TKN)
Monthly
Composite
Effluent
Total Copper
2/Month
Composite
Effluent
Total Zinc
2/Month
. Composite
Effluent
Total Silver
2/Month
Composite
Effluent
Total Mercury 4
24.1 ng/L 4
Weekly
Grab
Effluent
Chronic Toxicity 5
Quarterly
Composite
Effluent
Temperature, °C
Variable6
Grab
U, D
Dissolved Oxygen
Variable6
Grab
U, D
Footnotes .
1. U: 'approximately 100 feet upstream of, the outfall. D: Downstream at NCSR 1225.
2. The monthly average effluent BODS and Total Suspended Solids concentrations shall not exceed 15 % of the
respective influent value (i.e., 85% removal is required).
3. Total Residual Chlorine (TRC) shall.be monitored only if chlorine is used to disinfect.
4. Mercury -- Compliance to the permit limit shall commence on July 1, 2007, 24 months following the effective date of
this permit [see A. (2.)]. To facilitate the Lumber River's Phase II TMDL process. for.mercury;, the Permittee shall report
mercury using clean -sample collection criteria/test methods established by EPA Method 1631. •
5. Chronic Toxicity (Ceriodaphnia)' at 41 %; quarterly during March, June, September, December; See A..(3.)
6. Variable: instream samples shall be collected upstream and downstream 3/week during the summer months of June,
July, August, and September; samples shall be collected weekly during the rest of the year.
Units:
mg/L = milligrams per liter µg/L = micrograms per liter
ng/L = nanograms per liter • lbs/Day = pounds per day
NH3 as N = ammonia as nitrogen
ml = milliliter
BOD = biochemical oxygen demand
Effluent shall contain no floating solids or foam visible in other than trace amounts.