NC0085359_Permit (Issuance)_20100902

NPDES DOCIMENT SCANNING COVER SHEET
NPDES Permit:
NC0085839
Twelve Mile Creek WWTP
Document Type: -'"Permit
Issuance``)
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
September 2, 2010
This document is printed on reuse paper - ignore any
content on the reirerse side

AVA
NCDENR
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coleen H. Sullins Dee Freeman
Governor Director Secretary
September 2, 2010
Mr. Ed Goscicki, Public Works Director
Union County Public Works
500 North Main Street, Suite 500
Monroe, NC 28112-4730
ZOR) Renew
Subject: Issuance of NPDES Permit NC0085359
Twelve Mile Creek WWTP
Union County
Dear Mr. Goscicki:
The Division of Water Quality (Division) personnel have reviewed and approved your application for
renewal of the subject permit. Accordingly, we are forwarding the attached NPDES discharge permit.
It 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.
There are no significant changes in this final permit from the draft permit sent to you on June 23, 2010.
All modifications previously made in the draft permit are retained, as follows:
• A new footnote for total chlorine residual (TRC) was added, which allows sample results up to 50
pg/L to be considered in compliance with the limit. The footnote also indicates that the permittee
shall continue to record and submit all values reported by a North Carolina certified laboratory even
if these values fall below 50 pg/l.
• The effluent limitations and monitoring tables for 2.5 MGD and 3.0 MGD were eliminated. The
Division has received an engineer's certification for the expanded capacity of 6.0 MGD, and we are
currently tracking compliance at the 6.0 MGD level.
• The facilities description on the permit supplement sheet was updated.
If any parts, measurement frequencies, or sampling requirements contained in this permit are
unacceptable, you have the right to an adjudicatory hearing upon written request within thirty (30)•days
after receiving this letter. Your request must take the form of a written petition conforming to Chapter
150B of the North Carolina General Statutes, and must be filed with the Office of Administrative
Hearings, 6714 Mail Service Center, Raleigh, North Carolina 27699-6714. Unless such demand is
made, this permit remains final and binding.
1617 Mail Service Center, Raleigh. North Carolina 27699-1617
Location: 512 N. Salisbury St. Raleigh, North Carolina 27604
Phone: [phone] ; FAX: [phone] . Customer Service: 1-877-623-6748
Internet: www.ncwaterquality.orccj
An Equal opportunity Affirmative Action Emplover
One
North Carolina
!aturaIfj,'

This permit is not transferable except after notifying the Division of Water Quality. The Division may
modify and reissue, or revoke this permit. Please notice that this permit does not affect your legal
obligation to obtain other permits required by the Division of Water Quality, the Division of Land
Resources, the Coastal Area Management Act, or other federal or local governments.
If you have questions, or if we can be of further service, please contact Mr. Gil Vinzani at
[qil.vinzani @ ncdenr.gov] or call [phone].
Enclosure: NPDES Permit FINAL NC0085359
cc:
Sinc rely,
0
een H. Sullins
Mooresville Regional Office/Surface Water Protection Section
NPDES Permit Files
Central Files
Aquatic Toxicology Unit, Susan Meadows (E-mail copy)
EPA Region 4, Marshall Hyatt (permit and fact sheet, E-mail copy)
1617 Mail Service Center. Raleigh. North Carolina 27699-1617
Location: 512 N. Salisbury St. Raleigh, North Carolina 27604
Phone: [phone] FAX: [phone] Customer Service: 1-87 7-623.6748
Internet: www.ncwaterquality.org
Ar.fqual Opportunity 1 Affirmative Actroh Employer
One
North Carolina
. atlflYlly

Permit NC0085359
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
PERMIT
•
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
In compliance with the provision of North Carolina General Statute 143-215.1, other lawful
standards and regulations promulgated and adopted by the North Carolina Environmental
Management Commission, and the Federal Water Pollution Control Act, as amended, the
Union County Public Works Department
•
is hereby authorized to discharge wastewater from a facility located at the
Twelve Mile Creek Wastewater Treatment Plant
8299 Kensington Drive
Waxhaw, NC
Union County
to receiving waters designated as Twelve Mile Creek in the Catawba River Basin in
accordance with effluent limitations, monitoring requirements, and other conditions set forth in
Parts I, I1, III, and IV hereof.
This permit shall become effective October 1, 2010.
This permit and authorization to discharge shall expire at midnight on June 30, 2015.
Signed this day September 2, 2010:
etIti leen H. Sullins, Director
Division of Water Quality
By Authority of the Environmental Management Commission

Permit NC0085359
SUPPLEMENT TO PERMIT COVER SHEET
All previous NPDES Permits issued to this facility, whether for operation or discharge are
hereby revoked, and as of this issuance, any previously issued permit bearing this number is no
longer effective. Therefore, the exclusive authority to operate and discharge from this facility
arises under the permit conditions, requirements, terms, and provisions included herein.
• •
The Union County Public Works Department is hereby authorized to:
1. Continue to operate an existing 6.0 MGD wastewater treatment facility that includes the following
components:
•
• Influent pump station with stand-by generator
• Self-cleaning influent filter screening structure and manual bar screen
• Vortex grit chamber
• Four FAO basins (anoxic and oxidation reactors)
• FAO distribution structure
• MLSS distribution structure
• Four final clarifiers
• Four tertiary sand filters
• Two ultraviolet Tight disinfection systems
• Cascade post aeration
• Sludge thickening facility with a gravity belt thickener and associated polymer storage
and feed system
• Four aerobic digesters with diffused aeration
• Sodium aluminate storage and feed facilities for phosphorus removal
• Odor control facilities
• Main stand-by power generator
This facility is located at the Twelve Mile Creek Wastewater Treatment Plant off Kensington
Drive near Waxhaw in Union County.
2. Discharge from said treatment works at the location specified on the attached map into Twelve
Mile Creek, a class C stream in the Catawba River Basin.

114.
•
• • .••• I
•
t
• • .".71.--.1."
•••••
, . .
\`‘
• •
-N.
41 !
1 I
16‘
• 1,1
I I
Th,
"c, \ •, I
-7-1= \ ••••-.-/./ `P.
'• 1 • (Y
)...-. .,...... --• -,,,-...,---••••.,:. j ''." i). ' \?c,.‘..,‘.`-:',•• / /
i
, ..,„„,-;—"""=_.• y i - c c .,-.-- -.-- .--' #
i \ , . \ \ — - . . . ' ' .. . • . . " , ' ' .
\\ , . . . , : s • . - ,
''.... ' 1
1' ' .•''S:)' . 1 1 i
1 :1,. i ,I I
Facility Information
Latitude:
Lonqitude:
Quad #:
Stream Class:
34°57'01"
80°45'44"
H15NE
Sub -Basin: 03-08-38
8-Digit HUC 03050103
ReceiVinq Stream: Twelve Mile Creek
Permitted Flow: 6.0 MGD
NOT TO SCALE
r
Twelve Mile Creek WWTP
NC0085359
Union County

Permit NC0085359
A (1) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
During the period beginning upon the effective date of this permit and lasting until expiration, the Permittee is
authorized to discharge from outf all 001. Such discharge shall be limited and monitored by the Permittee as
specified below:
EFFLUENT
CHARACTERISTICS
LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Max.
Measurement
Frequency
Sample
Type
Sample
Locationl
Flow
' 6.0 MGD
'Continuous
Recording
I or E
BOD, 5-day, 20°C
(April 1 - October 31) 2
5.0 mg/L
7.5 mg/L
Daily
Composite
I & E
BOD, 5-day, 20°C
(November 1 - March 31) 2
10.0 mg/L
15.0 mg/L
Daily
Composite
1 & E
Total Suspended Solids 2
30.0 mg/L
,
45.0 mg/L
• Daily
Composite
I & E
NH3 as N
(April 1 — October 31)
1.0 mg/L
3.0 mg/L
Daily
Composite
E •
NH3 as N
(November 1 — March 31)
2.0 mg/L
6.0 mg/L
Daily
Composite
E
Dissolved Oxygen3
Daily
Grab
E
Dissolved .Oxygen
(June through September)
3/Week
Grab
U & D
Dissolved Oxygen
(October through May)
1/Week
Grab
U & D
.
pH
> 6.0 and < 9.0 standard units
Daily
Grab
E
Total Residual Chlorine4
17.0 pg/L
Daily
Grab
E
Total Nitrogen
(NO2+NO3+TKN)
Monthly -
Composite
E
Total Phosphorus 5
- Monthly Average: 41.70 lbs/day
12 Month Avg.: 20.85 lbs/day
Monthly
Composite '
E
Temperature, °C
Daily
Grab
E '
Temperature, °C
(June through September)
3/Week
Grab
• U & D
Temperature, °C
(October through May)
• 1/Week
,
Grab
U & D
Fecal Coliform (geo. mean)
200/100 ml
400/100 ml
• Daily
Grab
E
Fecal Coliform (geo. mean)
(June through September)
3/Week
•
Grab
U & D
Fecal Coliform (geo. mean)
(October through May)
_
1/Week
Grab
- U& D
Conductivity
Daily
Grab
E
Conductivity
(June through September)
3/Week
Grab
U & D
Conductivity
(October through May)
1/Week
Grab
U& D
Total Copper
. 13.2 pg/l
18.5 pg/I
Weekly
_
Composite '
E
Total Zinc
175 pg/I
Weekly
Composite
E
Chronic Toxicity6
Quarterly
Composite
E
Annual Pollutant Scan7
•
Annually
Composite
E
Footnotes on following page

Permit NC0085359
A (1) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
[continued]
Footnotes to previous table:
1. E=Effluent; l=Influent; U=Upstream; D=Downstream. Upstream: 50 feet upstream from the outfall.
Downstream samples shall be collected at each of two locations, D1 and D2. D1: One quarter mile
downstream from the outfall, before confluence with the firgt tributary. D2: at NCSR 1301.,
Additional downstream dissolved oxygen monitoring is recommended to provide DO stream profile
of Twelve Mile Creek in North Carolina and South Carolina.
2. The monthly average effluent BOD5 and Total Suspended Solids 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. Monitoring requirement and limit applies only if chlorine is added for disinfection. The Division shall
consider all effluent TRC values reported below 50 pg/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 erg/I.
5. Special condition A (3) describes the methodology for calculation of the monthly average and 12-
month limits.
6. Chronic Toxicity (Ceriodaphnia) P/F © 90% with testing in February, May, August and November,
refer to A (2).
7. See Special Condition A (4).
There shall be no discharge of floating solids or foam.
TP 1-1,m(710
(114 = 41.70 ib/d = 1114(7/3 x $.3 y x ji_e=0.(n/i4jte T�
An�uul Av� _ 10.(65 12 x $.3Y n )y, = o. z 1 ?" /i Tr'

Permit NC0085359
SUPPLEMENT TO EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
SPECIAL CONDITIONS
A (2) CHRONIC TOXICITY PASS/FAIL PERMIT LIMIT
The effluent discharge shall at no time exhibit observable inhibition of reproduction or significant
mortality to Ceriodaphnia dubia at an effluent concentration of 90%.
The permit holder shall perform at. a minimum, quarterly monitoring using test procedures•outlined in
the "North Carolina Ceriodaphnia Chronic Effluent Bioassay Procedure," Revised February 1998, or
subsequent versions or "North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure"
(Revised -February 1998) or subsequent versions. The tests will be performed during the months of
February, May, August, and November. Effluent sampling for this testing shall be performed at the
NPDES permitted final effluent discharge below all treatment processes.
If the test procedure performed as the first test of any single quarter results in a failure or ChV below
the permit limit, then multiple -concentration testing shall be performed at a minimum, in each of the two
following months as described in "North Carolina Phase II Chronic Whole Effluent Toxicity Test
Procedure" (Revised -February 1998) or subsequent versions.
The chronic value for multiple concentration tests will be determined using the geometric mean of the
highest concentration having no detectable impairment of reproduction or survival and the lowest
concentration that does have a detectable impairment of reproduction or survival. The definition of
"detectable impairment," collection methods, exposure regimes, and further statistical methods are
specified in the "North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure" (Revised -
February 1998) or subsequent versions.
All toxicity testing results required as part of this permit condition will be entered on the Effluent
Discharge Monitoring Form (MR-1) for the months in which tests were performed, using the parameter
code TGP3B for the pass/fail results and THP3B for the Chronic Value. Additionally, DWQ Form AT-3
(original) is to be sent to the following address:
Attention: NC DENR / DWQ / Environmental Sciences Section
1621 Mail Service Center
Raleigh, North Carolina 27699-1621
Completed Aquatic Toxicity Test Forms shall be filed with the Environmental Sciences Section no later
than 30 days after the end of the reporting period for which the report is made.
Test data shall be complete, accurate, include all supporting chemical/physical measurements and all
concentration/response data, and be certified by laboratory supervisor and ORC or approved designate
signature. Total residual chlorine of the effluent toxicity sample must be measured and reported if
chlorine is employed for disinfection of the waste stream.
Should there be no discharge of flow from the facility during a month in which toxicity monitoring is
required, the permittee will complete the information located at the top of the aquatic toxicity (AT) test
form indicating the facility name, permit number, pipe number, county, and the month/year of the report
with the notation of "No Flow" in the comment area of the form. The report shall be submitted to the
Environmental. Sciences Section at the address cited above.
Should the permittee fail to monitor during a month in which toxicity monitoring is required, monitoring
will be required during the following month.
Should any test data from this monitoring requirement or tests performed by the North Carolina Division
of Water Quality indicate potential impacts to the receiving stream, this permit may be re -opened and
modified to include alternate monitoring requirements or limits.
NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum control
organism survival, minimum control organism reproduction, and appropriate environmental controls,
shall constitute an invalid test and will require immediate follow-up testing to be completed no later than
the last day of the month following the month of the initial monitoring.
•

Permit NC0085359
A (3) TOTAL PHOSPHORUS (TP) MONITORING
The Permittee shall calculate a 12-month rolling average mass loading as the sum of monthly loadings,
according to the following equations:
(1) Monthly Average (pounds/day) = TP x QW x 8.34
Where:
TP = the arithmetic average of total phosphorus concentrations (mg/L) obtained via composite
samples (either daily; weekly, or monthly average values) collected during the month
Qw = the average daily waste flow (MGD) for the month
8.34= conversion factor, from (mg/L x MGD) to pounds
The 12-month rolling average mass loading is defined as the sum of the monthly average loadings for
the previous 12 months inclusive of the reporting month:
12
(2) 12-Month Average Mass Loading (pounds/day)= ETPma =12 (inclusive of reporting month)
Where:
TPma is defined as the total phosphorus monthly average mass loading (calculated above).
The monthly average and 12-month average mass loadings shall•be reported on the attached
worksheet [see next page] and submitted with the Discharge Monitoring Report (DMR) for Twelve Mile
Creek WWTP.
The Permittee shall report the TP concentration for each sample on the appropriate DMR. Reporting of
and compliance with the TP limit shall be done on a monthly basis.

Permit NC0085359
A (4) EFFLUENT POLLLUTANT SCAN
The permittee shall perform an annual pollutant scan of its treated
Ammonia (as N) Trans-1,2-dichloroethylene
Chlorine (total residual, TRC)
Dissolved oxygen
Nitrate/Nitrite
Total Kjpldahl nitrogen
Oil and grease
Total Phosphorus
Total dissolved solids
Hardness
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
Lead
• Mercury (Method 1631 E)
Nickel
Selenium
Silver
Thallium
Zinc
Cyanide
Total phenolic compounds
Volatile organic compounds:
Acrolein
Acrylonitrile
Benzene
Bromoform
Carbon tetrachloride
Chlorobenzene
Chlorodibromomethane
Chloroethane
2-chloroethylvinyl ether
Chloroform
Dichlorobromomethane
1,1-dichloroethylene
1,2-dichloropropane
1,3-dich loropropylene
Ethylbenzene
Methyl bromide
Methyl chloride
Methylene chloride
1,1,2,2-tetrachloroethane
Tetrachloroethylene
Toluene
1,1,1-trichloroethane
1,1,2-trichloroethane
Trichloroethylene
Vinyl chloride
Acid -extractable compounds:
P-chloro-m-cresol •
2-chlorophenol
2,4-dichlorophenol
2,4-dimethylphenol
4,6-dinitro-o-cresol
2,4-dinitrophenol
2-nitrophenol
4-nitrophenol
Pentachlorophenol
Phenol
2,4,6-trichlorophenol
Base -neutral compounds:
Acenaphthene
Acenaphthylene
Anthracene
Benzidine
Benzo(a)anthracene
Benzo(a)pyrene
3,4 benzofluoranthene
Benzo(ghi)perylene
effluent for the following parameters:
Bis (2-chloroethyl) ether
Bis (2-chloroisopropyl) ether
Bis (2-ethylhexyl) phthalate
4-bromophenyl phenyl ether
Butyl benzyl phthalate
2-chloronaphthalene
4-chlorophenyl phenyl ether
Chrysene
Di-n-butyl phthalate
Di-n-octyl phthalate
Dibenzo(a,h)anthracene
1,2-dichlorobenzene
1,3-dichlorobenzene
1,4-dichlorobenzene
3,3-dichlorobenzidine
Diethyl phthalate
Dimethyl phthalate
2,4-dinitrotoluene
2,6-dinitrotoluene
1,2-diphenylhydrazine
Fluoranthene
Fiuorene
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocycio-pentadiene
Hexachloroethane
indeno(1,2,3-cd)pyrene
Isophorone
Naphthalene
Nitrobenzene
N-nitrosodi-n-propylamine
N-nitrosodimethylam ine
N-nitrosodiphenylamine
Phenanthrene
Pyrene
1,2,4-trichlorobenzene
1,1-dichioroethane Benzo(k)fluoranthene
1,2-dichioroethane Bis (2-chioroethoxy) methane
..1. The total set of samples analyzed during the current term of the permit must be representative of
seasonal variations.
2. Samples shall be collected and analyzed in accordance with analytical methods approved under 40
CFR Part 136.
3. Unless indicated otherwise, metals must be analyzed and reported as total recoverable.
4. Test results shall be reported to the Division in DWQ Form- DMR-PPA1 or in a form approved by
the Director, within 90 days of sampling. Two copies of the report shall be submitted along with the
DMRs to the following address: Division of Water Quality, Central Files, 1617. Mail Service Center,
Raleigh, North Carolina 27699-1617. •

REASONABLE POTENTIAL ANALYSIS
Twelve Mile Creek WWTP
NC0085359
Time Period 0
Ow (MGO) 6
70103 (cis) 0.1
7010W (cis) 1.5
3002 (cis) 3.2
Avg. Stream Flow, OA (cis) 72.7
Reeving Stream Twelve Mile Creek
WWTP Class IV
!WC (%) ® 7O10S 98.936
@ 7010W 86.111
30Q2 74.4
® OA 11.341
Stream Class C
Outfall 001
Qw=6MGD
PARAMETER
TYPE
(1)
STANDARDS &
CRITERIA (2)
POL
Units
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
NCWOs/ ;4 FM
Monte Acute
n 1 Oat. ldu Pratt Cw Allowable Cw
Arsenic
C
50
ug/L
4 0
Note: n<12
Limited data
2.5
set
Acute: WA
5-1
All non-dalecl; N0 RP
Beryllium
C
6 5
ug'L
4 0
Note: n<12
Limited data
0.5
set
Acute: N/A
Chronic:---57
All non -detect; No RP
------------------------------
Cadmium
NC
2 15
ug/L
4 0
Note: n<12
Limited data
0.5
set
Acute: 15
All non dolecl; NO RP
Chromium
NC
50 1,022
ug/L
20 0
6.9
Acute: 1,022
Chronic:_—_51 —___—_—_—_—_—_—_—_—_—_—_—_—_—_—_—_—
All non -detect; No RP
Copper
VC
7 AL 7.3
u5/L
141 116
13.7
Acute: 7
_
Chronic:_--' --
RP to exceed WO and site-specilic standards.
Continue with existing limits and monhoirng frequency.
---'—' — — — — — — — — — — — — — —
Cyanide
NC
5 N 22
10
ug4_
4 1
Note: n<12
data
5.0
set
Acute: 22
_ _ _
S —' —•
Chronic:Limited
No RP
_'——'—'—'-----------•—'—'—'—'—
--•
Fluoride
NC
1,800
uryL
0 0
WA
Acute: N/A
Chronic: 1,819 -
---------------------------------
Lead
NC
25 N 33.8
ug/L
4 0
Note: n<12__—_—_—_—_—_—_—_---_---_---_---
Limited data
2.5
set
Acute: 34
All non -detect; No RP
Mercury
NC
12
2.0000
ng'L
5 5
Note: n<12
Limited data
1.0000
set
Acute: N/A
N0 RP
— — ___ ____.___._.__—_—__
Molybdenum
A
3.500
ug/L
0 0
N/A
Acute: WA
Nickel
NC
88 261
ug/L
4 0
Note: n<12
Limited data
2.5
set
Acute: 261
Chronic:---89 -----------------------------------
All non-dotect No RP
Phenols
A
1 N
ug/L
4 0
Note: n<12
Limited data
NIA
set
Acute: WA
Chronic:'-- 1 •—•
All non -detect: NO RP
—'—'—'—'-----'—'—•—•-----•-----'—
Selenium
NC
5 0 56
ug4
4 0
Note: n<12
Limited data
5.0
set
Acute: 56
_ _ _
ChronIC:'—' S'—'
All non -detect; No RP
_'—'—•-----'—'—'—•—'_'—'—'-----'—
Silver
NC
00a AL 1.23
uryL
4 0
Note: n<12---------------------------------
Limited data
25
set
Acute: 1
All non•detect; No RP
Zinc
NC
50 Al. 67
uryL
161 161
135.6
Acute: 67
Chronic:---51 —.
RP to exceed WO and site -Specific standards.
Continue with existing limits and moniloirng frequency.
._
• Legend:
C = Carcinogenic
NC = Non -carcinogenic
A = Aesthesc
" Freshwater Discharge
12-mi. Creek rpa 2009031, rpa
6/17/2010

REASONABLE POTENTIAL ANALYSIS
Arsenic
Beryllium
Date Data BDL=1/2DL Results
1 Sep-2006 < 5.0 2.5 Std Dev.
2 Dec-2207 < 5.0 2.5 Mean
3 Jun-2008 < 5.0 2.5 C.V.
4 Mar-2009 < 5.0 2.5 n
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Mult Factor =
Max. Value
Max. Pred Cw
Date Data BDL=1/2DL Results
0.0000 1 Sep-2006 < 1.0 0 5 Std Dev. 0.0000
2.5000 2 Dec-2207 < 1.0 0.5 Mean 0.5000
0.0000 3 Jun-2008 < 1.0 0.5 C.V. 0.0000
4 4 Mar-2009 < 1.0 0.5 n 4
5
1.0000 6
2.5 ug/L 7
2.5 ug/L 8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Mult Factor = 1.0000
Max. Value 0.5
Max. Pred Cw 0.5
12-mi. Creek rpa 2009031, data
- 1 - 8/11/2010

REASONABLE POTENTIAL ANALYSIS
Cadmium
Chromium
Date Data BDL=1/2DL Results
1 Sep-2006 < 1.0
2 Dec-2207 < 1.0
3 Jun-2008 < 1.0
4 Mar-2009 < 1.0
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
05
0.5 Mean
0.5 C.V.
0.5 n
Std Dev.
Mult Factor =
Max. Value
Max. Pred Cw
0.0000
0.5000
0.0000
4
1.0000
0.5 ug/L
0.5 ug/L
Date Data BDL=1/2DL Results
1 < 5 5.0 Std Dev, 0.5590
2 < 5 2.5 Mean 2.6250
3 < 5 2.5 C.V 0.2130
4 < 5 2.5 n 20
5 •< 5 2.5
6 < 5 2.5 Mult Factor = 1.3700
7 < 5 2.5 Max. Value 5.0 ug/L
8 5 2.5 Max. Pred Cw 6.9 ug/L
9 5 2.5
10 5 2.5
11 5 2.5
12 5 2.5
13 5 2.5
14 < 5 2.5
15 5 2.5
16 < 5 2.5
17 Sep-2006 < 5.0 2.5
18 Dec-2207 < 5.0 2.5
19 Jun-2008 < 5.0 2.5
20 Mar-2009 < 5.0 2.5
21
22
23
24
25
26
27
28
29
30
31 ..
12-mi. Creek rpa 2009031, data
- 1 - 8/11/2010

REASONABLE POTENTIAL ANALYSIS
Copper
Cyanide
Date
Sep-2006
Dec-2207
Jun-2008
Mar-2009
Data
BDL=1/2DL Results
2.3 2.3 Std Dev. 1.2299
Mean 4.4823
2.5 2.5 C.V. 0.2744
2.1 2.1 n 141
2.8 2.8
2.5 2.5
3. 3.0
2.3 2.3
5.0 2.5
5.0 2.5
5.0 2.5
5.0 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
5. 2.5
12. 12.0
5. 2.5
5. 2.5
5. 5.0
Mult Factor =
Max. Value
Max. Pred Cw
1.1400
12.0 ug/L
13.7 ug1L
Date Data BDL=1/2DL Results
1 Sep-2006 5.0 5.0 Std Dev. 0.0000
2 Dec-2007 ?' 5.9 5.0 Mean 5.0000
3 Jun-2008 5.0 5.0 C.V. 0.0000
4 Mar-2009 5.0 5.0 n 4
5 t.
6 g Mult Factor = 1.0000
7 Max. Value 5.0
8 Max. Pred Cw 5.0
9
10
11
12
13
14
15
16 :r
17
18
19
20
21
22 r'
24
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43 .`
44
45
46
47
48.
49
50
51
52
53
54
55
56
57
58
59,
60
12-mi. Creek rpa 2009031, data
• 1 - 6/11/2010

REASONABLE POTENTIAL ANALYSIS
9
Mercury
Date Data BDL=1/2DL Results
1 Sep-2006 0.9 1.0 Std Dev.
2 Dec-2207 0.5 1.0 Mean
3 Jun-2008 0.753 1.0 C.V.
4 Jun-2008 0.209 1.0 n
5 Mar-2009 -- 0.573 1.0
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Mult Factor =
Max. Value
Max. Pred Cw
0.0000
1.0000
0.0000
5
1.00
1.0 ng/L
1.0 ng/L
12-mi. Creek rpa 2009031, data
- 1 6/11/2010

REASONABLE POTENTIAL ANALYSIS
Silver
Zinc
Date Data BDL=1/2DL Results
1 Sep-2006 < 5.0 2.5 Std Dev. 0.0000
2 Dec-2207 <. 5.0 2.5 Mean 2.5000
3 Jun-2008 < 5.0 2.5 C.V. 0.0000
4 Mar-2009 < 5.0 2.5 n 4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
yg1
Mult Factor =
Max. Value
Max. Pred Cw
1.0000
2.5 ug/L
2.5 ug/L
1
2
3
4
5
6
7 38. 38.0
8 37. 37.0
9 26 26.0
10 20. 20.0
11 28. 28.0
12 39. 39.0
13 63. 63.0
14 59. 59.0
15 85. 85.0
16 88. 88.0
17
18 100. 100.0
19 77. 77.0
20 95. 95.0
21 85. 85.0
22 66. 66.0
23 84. 84.0
24 110. 110.0
25
26 98. 98.0
27 75. 75.0
28 78. 78.0
29 79. 79.0
30 78. 78.0
31
32 85. 85.0
33 77. 77.0
34 120. 120.0
35 100. 100.0
36 83. 83.0
37 ' 91. 91.0
38 62. 62.0
39 72. 72.0
40 63. 63.0
41
42 68. 68.0
43 78. 78.0
44 58. 58.0
45 64. 64.0
46 70. 70.0
47 74. 74.0
48 76. 76.0
49 55. 55.0
50 75. 75.0
51 73. 73.0
52
53 74. 74.0
54 71. 71.0
55
56
57 59. 59.0
58 59. 59.0
59 53. 53.0
Date Data BDL=1/2DL Results
39 39.0 Std Dev. 18.2113
42. 42.0 Mean 59.7267
C.V. 0.3049
40. 40.0 n 161
35. 35.0
Mult Factor = 1.1300
Max. Value 120.0 ug/L
Max. Pred Cw 135.6 ug/L
12-mi. Creek rpa 2009031, data
- 1 - 6/11/2010

REASONABLE POTENTIAL ANALYSIS
Nickel
Phenols
Date Data BDL=1/2DL Results
1 Sep-2006 < 5.0 2.5 Std Dev. 0.0000
2 Dec-2007 < 5.0 2.5 Mean 2.5000
3 Jun-2008 < 5.0 2.5 C.V. 0.0000
4 Mar-2009 < 5.0 2.5 n 4
5
6 Mult Factor = 1.0000
7 Max. Value 2.5 ug/L
8 Max. Pred Cw 2.5 ug/L
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Date Data BDL=1/2DL Results
1 Sep-2006 < 5.6 2.8 Std Dev.
2 Dec-2007 < 5.1 2.6 Mean
3 Jun-2008 < 5.7 2.9 C.V.
4 Mar-2009 < 5.0 2.5 n
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
0.1756
2.6750
0.0656
4
Mult Factor = N/A
Max. Value 2.9 ug/L
Max. Pred Cw N/A ug/L
12-mi. Creek rpa 2009031, data
- 1 - 8/11/2010

REASONABLE POTENTIAL ANALYSIS
13
14
Selenium
Silver
Date
Data
BDL=1/2DL
Results
Date
Data
BDL=1/2DL
Results
1
Sep-2006
<
10.0
5.0
Std Dev.
0.0000
1
Sep-2006
<
5.0
2.5
Std Dev.
0.0000
2
Dec-2007
<
10.0
5.0
Mean
5.0000
2
Dec-2207
<-
5.0
2.5
Mean
2.5000
3
Jun-2008
<
10.0
5.0
C.V.
0.0000
3
Jun-2008
<"
5.0
2.5
C.V.
0.0000
4
Mar-2009
<
10.0
5 0
n
4
4
Mar-2009
<
5.0
2.5
n
4
5
5
6
Mult Factor =
1.0000
6
Mult Factor =
1.0000
7
, ;.
Max. Value
5.0 ug/L
7
Max. Value
2.5 ug/L
8
t, .
Max. Pred Cw
5.0 ug/L
8
Max. Pred Cw
2.5 ug/L
9
9
9
10
10
11
11
12
12
13
_
: 1
13
14
14
15
15
16
16
17
17
18
18
19
19
20
20
21
21
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
12-mi. Creek rpa 2009031, data
1 - 8/11/2010

Vinzani, Gil
From: [e-mail]
Sent: Monday, June 28, 2010 2:24 PM
To: Vinzani, Gil
Subject: Re: Union County 12-Mile WWTP Draft Permit
EPA has no comments on this draft permit.
1

North Carolina ) ss
Mecklenburg County)
The Charlotte Observer Publishing Co.
Charlotte, NC
Affidavit of Publication
THE CHARLOTTE OBSERVER
DINA SPRINKLE
NCDENR/DWG/POINT SOURCE BRANCH
1617 MAIL SERVICE CENTER
RALEIGH NC 27699
REFERENCE: 30063432
6479305 PSB Public Notice
Before the undersigned, a Notary Public of said
County and State, duly authorized to administer
oaths affirmations, etc., personally appeared,
being duly sworn or affirmed according to law,
doth depose and say that he/she is a
representative of The Charlotte Observer
Publishing Company, a corporation organized and
doing business under the taws of the State of
Delaware, and publishing a newspaper known as The
Charlotte Observer in the city of Charlotte,
County of Mecklenburg, and State of North Carolina
and that as such he/she is familiar with the
books, records, files, and business of said
Corporation and by reference to the files of said
publication, the attached advertisement was
inserted. The following is correctly copied from
the books and files of the aforesaid Corporation
and Publication.
PUBLISHED ON: 06/26
AD SPACE:
FILED ON:
NAM
In Test
day and
Nota
164 LINE
07/30/10
+
i
Public Notice
North Carolina Environmental Management CommissioN
NPDES Unit
1617 Mail Service Center
Notice of Intent to Issue a NPNC DES Wastewater Permit
The North Carolina Environmental Management Commission pro-
poses to issue a NPDES wastewater discharge permit to the per-
son(S) listed below.
Written comments regarding the proposed permit will be accept-
ed until 30 days after the publish date of this notice, The Director
of the NC Division of Water quality (DWG) may hold a public hear-
ingshouki there be a significant degree of public interest Please
4
comments and'or information requests to DWO at the above
address. Interested persons may visit the DWO at 512 N.
Salisbury Street. Raleigh. NC to review information on file.
Additional Information on NPDES permits and this notice may be
found on our website: www.mcwaterqualdy.org, or by calling (919)
807-6304.
Lincoln County Schools requested renewal of permit NC0041246
for West Lincoln High School WWTP in Lincoln County: this per-
mitted discharge is treated domestic wastewater to Indian Creek.
Catawba River Basin.
Union County Public Works has applied for renewal of Permit Number NC0085359 for its Twelve Mile Creek WWTP In Union
County. This facility discharges treated domestic wastewater to
'Bivalve Mile Creek in the Catawba Rver Basin.
Aqua North Carolina, Inc. requested renewal of permit
NC0086193 for Maptecrest WTP in Gaston Counry; this permitted
discharge is heated backwash wastewater to UT
Catawba
Creek, Catawba River Basin.
Aqua North Carolina, Inc., permit NC0088142, for Oakley Park
WTP in Gaston County; this permitted discharge is treated filter
backwash wastewater to McGill Branch. Catawba River Basin.
Aqua North Carolina, Inc. requested renewal of permit
NC0084468 for Keltic Meadows Well *2 In Gaston County; this
permitted discharge is treated filter backwash wastewater to a UT
to Catawba Creek, Catawba River Basin.
Aqua��1 North Carolina, Inc. requested renewal of permit
discha72061 rge Isfor Fox Run WTP in tr treated fitter backwastllon wastewattert tos o permitted UT to Crowders Creek, Catawba River Basin.
Aqua Nonh Carolina, Inc requested renewal of permit NC0069035
for Southgate WTP in Gaston County: this permitted discharge is
treated fitter backwash wastewater to a UT to Catawba Creek,
Catawba River Basin.
Carolina Water Service, Inc. ol North Carolina, P.O. Box 240908,
Charlotte, Norm Carolina 28224 has applied for renewal of
NPOES permit NC0060755 for its Saddtewocd Subdivision WWI? off NCSR 2416 (Little Mountain Road) in Gaston County. This per-
mitted facility discharges treated wastewater to an unnamed trib-
utary to Crowders Creek in the Catawbar RiverBasin. Currently,
Ccharge maD andy affectnia futurerogen are allocations In thisNpoil on of the d. This
had,
Catawba County BOE requested renewal o1 permit NC0074233
for Blackburn Elementary School WWTP In Catawba County: this
permitted discharge is treated domestic wastewater t0 Haas
Creek, Catawba River Basin.
Diocese of Charlotte requested renewal o1 permit NC0071447 for
the Catholic Conference Center WWTP in Catawba County. This
permitted tactility discharges treated wastewater to an unnamed
tributary to Camp Creek in the Catawba River Basin.
Catawba County BOB requested renewal of permit NC0029297
for Fred T. Foard High School WW1? in Catawba County this per-
mitted discharge i5 treated domestic wastewater to Pott Creek,
Catawba River Basin.
Pine Mountain Pro Owners Assn. Inc. has applied for renew-
al of NPDES parmrt N 6935 for Pine Mountain Lakes WWTP
in Burke County. This permitted facility discharges treated waste-
water to Jacob Fork in the Catawba River Basin,
LP6479305
l_��-C �r.4 '
[A (cJ TITLE:
DATE:
: (.13- , 30 -/ 0
hereunto set my hand and affixed my seal, the
My Commission Expires: _/_/_
y, / Commission Expires May 27, 2011

Fact Sheet
NC0085359
DEN R/DWQ
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
NPDES No. NC0085359
Facility Information
Applicant/Facility Name:
Union County Public Works/ Twelve Mile Creek WWTP
Applicant Address:
500 North Main Street, Suite 500 Monroe, N.C. 28112-4730
Facility Address:
8299 Kensington Drive Waxhaw, NC 28173
Permitted Flow
6.0 MGD
Type of Waste:
100% Domestic
Facility/Permit Status:
Renewal
Facility Classification
IV
County:
Union
Miscellaneous
Receiving Stream:
Twelve Mile
Creek
Regional Office:
Mooresville
Stream Classification:
C
USGS Topo Quad:
H15NE/Catawba NE
303(d) Listed?
Yes — Copper
and Turbidity
Permit Writer:
Gil Vinzani
Subbasin:
03-08-38
Date:
June 17, 2010
Drainage Area (mi2):
76.8
Location:
Summer 7Q10 (cfs)
0.1
Winter 7Q10 (cfs):
1.5
Average Flow (cfs):
72.7
IWC (%):
99%
8-digit HUC:
03050103
Summary
Union County has requested renewal of its Twelve Mile Creek WWTP NPDES permit. The
existing WWTP has a design flow of 6.0 MGD. The existing permit also has effluent limits
pages for 2.5 MGD and for 3.0 MGD. Discharge is into Twelve Mile Creek, a class C stream.
Influent is 100% domestic and serves the Towns of Waxhaw and Weddington, along with other
portions of Union County for a total of approximately 58,000 people. There are no SIUs or ClUs
discharging to the system.
During the last permit cycle, Union County modified its permit to accommodate an expansion
from 3.0 MGD to 6.0 MGD. This modification was issued on November 27, 2006.
Copper and zinc limits were added to the previous permit renewal. They were inserted as a
result of a study done by Union County in conjunction with the State of South Carolina. A site -
specific standard for copper and zinc was developed (see section on Reasonable Potential).
There are also total phosphorus mass -based limits. The mass loading was capped to ensure
no additional TP load, even with expansion to 6.0 MGD. This limit was based on a Union County
/DWQ/SCDHEC Settlement Agreement for the inclusion of phosphorus limits to dischargers to
the main stem of the Catawba (upstream of Lake Wateree). At 6.0 MGD, this TP limit is
equivalent to 0.4 mg/I.
Union County has requested speculative limits to expand this facility. An analysis of flows (see
next page) shows that they have been increasing rapidly. Union County is the fastest growing
county in North Carolina, according to data received from the State Demographics Unit.

Fact Sheet
NC0085359
Receiving Stream
Twelve Mile Creek is formed downstream of the convergence of West Fork Twelve Mile Creek
and East Fork Twelve Mile Creek. The flows at the outfall, as noted above, are near zero, but
are all positive. Prior to obtaining updated flow data from USGS in 2002, Twelve Mile Creek
was considered a zero flow stream.
Flows
Flow figures were taken from the facility's discharge monitoring reports and the facility's
application. As shown on the following table, flows have increased rapidly over time:
Time Period
Average Daily Flow, MGD
(DMR)
Average Daily Flow, MGD
(Application)
2007
2.74
2.8
2008
3.31
3.2
2009
3.35
3.4
Jan. to April 2010
4. 18
(NA)
Compliance History
During the last permit cycle, the facility was granted a schedule of compliance for Cu and Zn.
The limits were made effective 18 months after completion of site specific standards.
Additionally, instream monitoring for DO, fecal coliform, temperature, and conductivity were
implemented.
The present requirement for toxicity testing is a chronic toxicity P/F test @ 90%; to be done in
February, May, August, and November. This will continue for this permit cycle.
With the exception of one result for August 2008, the Twelve Mile Creek WWTP has
consistently passed all its WET tests since February 2002.
In January 2005, the WWTP started having problems meeting limits. Notes on DMRs submitted
by the ORC on plant noncompliance indicated problems were due to faulty electrical controls at
the plant. Monitoring violations were incurred for BOD in 2006 and for fecal coliform and TP in
2006 and 2007. Compliance over the past two years has improved, with only two fecal
exceedances noted (January 2009 and January 2010). From historical data, fecal coliform
appears to be a chronic problem at this facility.
In May 2007, Union County requested speculative limits from SC DHEC to remotely discharge
final effluent into South Carolina's portion of Twelve Mile Creek. In December 2007, DHEC
responded that they would not allow such a discharge, due to low DO levels in the creek.
Please see next section regarding instream data for more information.
Review of Instream Data
DMR files were reviewed from 2007 until the present for instream data. No changes are
recommended to upstream/downstream monitoring at this time.
Regarding fecal coliform, whenever the upstream sites exceed the standard of 200/100m1, then
the same is generally true downstream. For example, the following table shows fecal coliform
data over the past 12 months (see next page):

Fact Sheet
NC0085359
Table 1. Fecal Coliform Sampling
Monthly Average
Upstream
Downstream site #1
Downstream Site #2
April 2010
252
155
187
March 2010
179
199
137
February 2010
292
310
303
January 2010
430
360
389
December 2009
159
128
104
November 2009
132
42
39
October 2009
33
56
41
September 2009
50
98
86
August 2009
102
98
86
July 2009
298
212
316
June 2009
703
504
755
Notes: Units are # fecal coliform per 100 ml.
Downstream: site #1: 1/a mile below the outfall
Downstream site #2: bridge at SR1301
Water Quality Standard: 200 per 100 ml
As shown above, the fecal coliform standard is still being exceeded both upstream and
downstream of the WWTP. This has persisted throughout the past two permit cycles.
Downstream results vary closely with the upstream values.
Regarding dissolved oxygen, problems with upstream concentrations not attaining the standard
of 5 mg/I was shown for the months of August September and October, 2009 (3.32, 3.05, and
3.84 mg/L respectively). Although results for the corresponding months in 2008 achieved the
standard, 2007 also showed values above the standard as follows:
Month
Upstream DO
Downstream (1)
Downstream (2)
August 2007
2.86
5.04
5.09
September 2007
2.91
5.56
5.7
October 2007
2.64
5.85
6.03
November 2007
4.41
5.86
5.96
August 2009
3.32
3.49
3.56
September 2009
3.05
3.14
3.07
October 2009
3.84
3.76
3.81
Note: Units are mg/L dissolved oxygen.
As shown, poor upstream DO recovered well in 2007, but downstream numbers remained low in
2009.
Reasonable Potential Analysis
The existing permit has limits for copper and zinc, in order to protect South Carolina waters.
The Twelve Mile Creek WWTP discharges about 2.5 miles from the SC state line. EPA had
recommended that site -specific standards be developed, and since there was a reasonable
potential to exceed these standards, limits for copper and zinc were placed in the permit.
For this renewal period, a reasonable potential analysis was conducted based on DMR data
from 2006 through February 2010. Results are as follows (see attached data analysis).

Fact Sheet
NC0085359
• Both copper and zinc showed reasonable potential to exceed the both the water quality
standard and the site specific standard. This conclusion is based on the analysis of 131
copper samples and 161 zinc samples. The present limits for both parameters will be
continued for this renewal period.
• Sample results for arsenic, beryllium, cadmium, chromium, lead, nickel, phenols,
selenium, and silver were all below detection and therefore showed no reasonable
potential.
• Chromium monitoring was already deleted from this permit on December 28, 2006.
Proposed Changes
The following modifications have been made to the permit:
1. Eliminated the effluent limitations and monitoring requirements tables for 2.5 MGD and
3.0 MGD. The Division has received an engineer's certification for the expanded
capacity of 6.0 MGD, and BIMS is currently tracking compliance at the 6.0 MGD level.
2. Added to the total residual chlorine (TRC) footnote on the effluent limitations table to
reflect the Division's policy of considering all sample results below 50 pg/L to be in
compliance with the permit.
3. Updated the facilities description on the permit supplement page.
Proposed Schedule for Permit Issuance:
Draft Permit to Public Notice: 06/23/2010
Permit Scheduled to Issue: August 2010, with an effective date of September 1, 2010
State Contact:
If you have any questions on any of the above information or on the attached permit, please
contact Gil Vinzani at [phone] or [e-mail].
SIGNATURE:
4/
47'
Regional Office Comments:
See attached
DATE: 9-! — 02(3/0

UNION COUNTY PUBLIC WORKS
December 17, 2009
Ms. Dina Sprinkle
NC DENR / DWQ / Point Source Branch
1617 Mail Service Center
Raleigh, NC 27699-1617
Subject: NPDES Permit NC0085359
Twelve Mile Creek WWTP, Union County, NC
Dear Ms. Sprinkle:
The purpose of this letter is to request the renewal of the above referenced NPDES permit for the
Twelve Mile Creek Wastewater Treatment Plant (WWTP) in Union County. The following items are
included in this renewal package:
• One signed original and two copies of the cover letter.
• One signed original and two copies of the completed application form, signed by the
permittee.
• One original and two copies of the application attachments, including the following figures
and narrative descriptions:
• Figure No. 1 — Topographic map of the facility
• Figure No. 2 — Topographic site plan of the facility
• Figure No. 3 — Topographic map of the WWTP outfall
• Figure No. 4 — Hydraulic Profile
• Figure No. 5 — Liquids Process Schematic
• Figure No. 6 — Solids Process Schematic
• Treatment Process Narrative
• Facility Improvements Narrative
We also want to bring to your attention the following items in the permit application:
• The revised permitted Total Zinc limit is 172 ug/I based on 6.0 MGD.
• The annual average values in Table A.12 related to BOD5, Fecal Coliform, and TSS
include the time period during which the plant was experiencing a process upset prior to
completion of the 6.0 MGD expansion project (February 2008).
Please contact me at [phone] or Mark Tye at [phone] if you have any questions or
need additional information.
Edward Goscicki
Director
Cc: Mark Tye
500 North Main St., Suite 500 • Monroe, NC 28112-4730 • Phone: [phone] • Fax: [phone]

FACILITY NAME AND PERMIT NUMBER:
Twelve Mile Creek WVVTP, NC0085359
PERMIT ACTION REQUESTED:
Renewal
RIVER BASIN:
Catawba
SUPPLEMENTAL APPLICATION INFORMATION
PART F.INDUSTRIAL USER DISCHARGES AND RCRA/CERCLA WASTES
All treatment works receiving discharges
complete part F.
GENERAL INFORMATION:
F.1. Pretreatment program. Does the treatment
❑ Yes ❑ No
F.2. Number of Significant Industrial Users
industrial users that discharge to the
a. Number of non -categorical SIUs.
b. Number of ClUs. 1161.
SIGNIFICANT INDUSTRIAL USE'•
Supply the following information for each
provide the information requested for each
from significant industrial users or which receive RCRA,CERCLA, or other remedial wastes must
treatment
INFOR
SIU.
SIU.
(SIUs)
I
works have, or is subject ot, an approved pretreatment program?
and Categorical Industrial Users (ClUs). Provide the number
w ks.
of each of the following types of
ATION:
more than one SIU discharges
to the treatment works, copy questions F.3 through F.8 and
F.3. Significant Industrial User Information. Provide the name and address of each SIU discharging to the treatment works. Submit additional pages
as necessary.
Name:
Mailing Address:
F.4. Industrial Processes. Describe all the industrial processes that affect or contribute to the SIU's discharge.
F.5. Principal Product(s) and Raw Material(s). Describe all of the principal processes and raw materials that affect or contribute to the SIU's
discharge.
Principal product(s):
Raw material(s):
F.6. Flow Rate.
a. Process wastewater flow rate.
day (gpd) and whether the discharge
Indicate
is
gpd
Indicate
the
gpd
the
standards,
the average daily volume
continuous or intermittent.
( continuous
volume
following:
subcategory?
of process wastewater discharge into
or intermittent)
the collection system in gallons per
discharged into the collection system
b. Non -process wastewater flow rate.
in gallons per day (gpd) and whether
the average daily
discharge is continuous
( continuous
of non -process wastewater flow
or intermittent.
or intermittent)
F.7. Pretreatment Standards. Indicate whether
a. Local limits
b. Categorical pretreatment standards
If subject to categorical pretreatment
SIU is subject to the
0 Yes
0 Yes
which category and
❑ No
0 No
EPA Form 3510-2A (Rev. 1-99) Replaces EPA forms 7550-6 & 7550-22
Page 18 of 22

FACILITY NAME AND PERMIT NUMBER:
Twelve Mile Creek VWVfP, NC0085359
PERMIT ACTION REQUESTED:
Renewal
RIVER BASIN:
Catawba
F.8. Problems at the Treatment Works Attributed to Waste Discharge by the SIU. Has the SIU caused or contributed to any problems (e.g.,
upsets, interference) at the treatment works in the past three years?
❑ Yes 0 No If yes, describe each episode.
RCRA HAZARDOUS WASTE RECEIVED BY TRUCK, RAIL, OR DEDICATED PIPELINE:
F.9. RCRA Waste. Does the treatment works receive or has it in the past three years received RCRA hazardous waste by truck, rail or dedicated pipe?
❑ Yes 0 No (go to F.12)
F.10. Waste transport. Method by which RCRA waste is received (check all that apply):
0 Truck 0 Rail 0 Dedicated Pipe
F.11. Waste Description. Give EPA hazardous waste number and amount (volume or mass, specify units).
EPA Hazardous Waste Number Amount Units
CERCLA (SUPERFUND) WASTEWATER, RCRA REMEDIATION/CORRECTIVE ACTION
WASTEWATER, AND OTHER REMEDIAL ACTIVITY WASTEWATER:
F.12. Remediation Waste. Does the treatment works currently (or has it been notified that it will) receive waste from remedial activities?
❑ Yes (complete F.13 through F.15.) 0 No
F.13. Waste Origin. Describe the site and type of facility at which the CERCLA/RCRA/or other remedial waste originates (or is excepted to origniate in
the next five years).
F.14. Pollutants. List the hazardous constituents that are received (or are expected to be received). Include data on volume and concentration, if
known. (Attach additional sheets if necessary.)
F.15. Waste Treatment.
a. Is this waste treated (or will be treated) prior to entering the treatment works?
❑ Yes ❑ No
If yes, describe the treatment (provide information about the removal efficiency):
b. Is the discharge (or will the discharge be) continuous or intermittent?
❑ Continuous 0 Intermittent If intermittent, describe discharge schedule
END OF PART F.
REFER TO THE APPLICATION OVERVIEW (PAGE 1) TO DETERMINE WHICH OTHER PARTS
OF FORM 2A YOU MUST COMPLETE
EPA Form 3510-2A (Rev. 1-99). Replaces EPA forms 7550-6 & 7550-22
Page 19 of 22

Par4-13.2- i�ur�N,'b.I_
Twelve Mile Creek
Wastewater Treatment Plant
FIGURE 1
1:24,000 USGS Topographic Map
Catawba NE/Waxhaw Quadrangles
September 2008
Twelve Mile Creek Wastewater Treatment Plant
Union County Public Works Department
FIAZENAND SAWYER
Environmental Engineers & Scientists

MI‘
Mp\ •J
-‹)
J:
4'
PLANT EFFLUENT
OUTFALL
INFLUENT SCREEN
STRUCTURE44
,
INFLUENT
JUNCTION BOX
— — _ - -
5\c
1
r
'\\ INFLUENT IiU`P
STATION
„ELECTRICAL'
;BUILDING
4
sn �
11
EXISTING' _
�Jo
------------
X
k
X
X
-
SLUDGE-40ADING
\
--`u ANOXIC AND \
955
��'� -._..� l �• � � REACTOR M6 I.... � t ,I if
�ld
1�{
ND. 5
PAD__
r ppp J(
/
I,i � CLARIFIER N0, 6 CLARIFER L r
(/,/J -� I'. •i Atom AND
rl
FURORE ODOR%CON
I- FACILITIES ; (j I � � i - F+ u REACTOR #5 — - j.--j?• i
I DIGESTER I 11 DIGESTER u I _Li,:
II
NO. 4 — -- I N0. 3 / f!--}¢--^. "-�~'�~ f ELECTRICAL
LOWER - - RAS PS No.2 BUILDING.
BLDG. No. 4
\• �•'� BLOWER
BLDG.
i_ CASCADE .r
G I AERATOR
UV
-.DISINFECTION'
IN -PLANT P.S.
I /•
&yl
` 1 / /. i • I
ANOXIC AND
REACTOR #2
ANOXIC AND.
REACTOR 61
r-\
r /�.—;,..- 1Ci —
CLARIFlE' \ I'\I CLARIFIER
NO. 2 Vb' ®) I �l I NO 1(70' m)
it-Z.- ■ ■)
FUTURE. SODIUM
ALUMINATE FEED
llk, F1 lJIFS
--1f-'ice-ELECTRICAL
AIR
i� /GENERATORL-...
COMPRESSOR FUTURESODIUM
BUILDING ALUNlINATE STORAGE
FACILITY
ELECTRICAL
BUILDING.
No. 3
II --
LABORATORY/
ADMINISTRATION
BUILDING
j MAINT.
BLDG.
GRI
REMO
ass--
Ls
ENTTLANCd
UNION COUNTY
NORTH CAROLINA
TWELVE MILE CREEK WWTP
SITE PLAN
PART B.2
FIGURE No.2
20081215 &SBA a\30831\014Nka. %\PFABI\fl8-1-SI1El.B BS:IHESRM tan SBw1 09 910015 > RF.. a\3080I\4I/\ervMng Varna \y-et,a\N631\0141ProMnBABINHf\9'-1P-ALL

580
570
560
550
540
530
520
510
500
490
480
470
460
450
T.O.W.
EL 511.134
36' DIP - 38' DIP
IRIjI 482.08 IE 481.22
�nl
�Wul
z N1�/1
24' D.I.P.
I:E. 571.17
T.O.W.
EL! 578.34
572.34
;HWL 569.30
EL 558.1.4
30' DIP
ILE. 548.50
:T.O.W.
EL. 571.00
F
F
mom
ISOLATION
GATE
SUDS
FL EL 544.75
30' DIP
-4:E. 545'75-
Eaw:-
EL. 567.67 I
HWL 566.38
FL FLI . ,4
ASe
-30' DIP
I.E. 553.45
30' DIP
I.E. 552.91
T.O.WL
EL. 560.00
--- FL.
540.92EL
30' DIP
I.E. 547.50
HWL 557
83
0j
`mao
maw
24', DIP
I.E.'• 542.00
24' DIP
T.O.w.
EL { 554.07
16' DIP
i I.E. 542.40
FL EL.
535.11
78Y1, dei+ld
I:E. 529.64
W
5
L3
30' DIP
I.E. 537.02--
HWL 547.23
T.O.W.
EL54&9
FL EL.
537.08
30' DIP
I.E. 537.02
T.O.W.
tL 5484
30' DIP
=537 1
544.98
FL EL
539.58
- I
T.O.W.
EU 544.64
30' DIP 24' !DIP
1:E-537:41-I:E.-537.9T-
1
I2 F
1
WA_ ;540.31
541.24
24' DIP
ILE. 534.83
T.O.W
EL 544.64
-24' DIP
.E. 534.83
-0
:0<
H
R. EL 533.03
24=DIP
I.E. 533.03
100-YR-FA.0OD�
EL 507.34
30' OUTFALL
I.E. 488.34-.
HV
580
570
560
550
540
530
520
510
500
490
480
470
460
450
UNION COUNTY
NORTH CAROLINA
TWELVE MILE CREEK WWTP
HYDRAULIC PROFILE
PART B.3
FIGURE No.4
20091215 9:53A O \00831\014\OrosIngi PERIBArg-4-Hmol.2 o 9X MER800 last Saved By Net 9000-

8'
INFLUENT
MECHANICAL
SCREENING
48"
24°
--r-v
36 _ -
--J
INFLUENT P/S
(0-15 MGD)
30° PV
30°x24° INCR
rr 30°x18" RED
j -18' PV-
INFL. FLOW
METER
30"x16° INCR
D 16° PV
INFLUENT LOADINGS
DESCRIPTION
AVERAGE DAILY FLOW, MGD
MAX. PEAK FLOW, MGD
BOD, MG/L
BOD, LBS/DAY
TSS, MG/L
TSS, LBS/DAY
TKN, MG/L
TKN, LBS/DAY
DESIGN
6.0
15.0
200
10008
250
12510
40
2002
FUTURE
9.0
22.5
200
15012
250
18765
40
3003
30"x18" INCR
GRIT REMOVAL
STRUCTURE
30° PV
36'x30° CROSS -1:°30" PV
HAH--(4
30° PV 30" PV
INPLANT PUMPING RATE 1400 GPM
INPLANT (BW, SUPERNATE, TANK DEWATERING, ETC.) FM.
WAS PS
8° WAS TO DIGESTERS
SEE SOLIDS SCHEMATIC
18' RAS
Q/2 + RAS 1
FAO DISTRIBUTION BOX
6.75 MGD
Q/2 + RAS 2
18"x12" CROSS
18"x16" INCR
16' PV--
AN
0XIC
1A
SG-1A
6.75 MGD
MECHANICAL SCREENING
Pa.)
a
DESCRIPTION
TYPE & NUMBER
DESIGN - 18.75 MGD
1- FILTER SCREEN
1 - FIXED, MANUAL
FUTURE - 37.5 MGD.
2- FILTER SCREENS
1 - FIXED, MANUAL
z
SCREEN OPENING
a HYDRAULIC CAP
a ACCESSORY SYSTEM
0
25 MM
22.5 MGD
ODOR CONTROL
25 MM
45.0 MGD
ODOR CONTROL
s FOR ULTIMATE CAPACITY
RAW SEWAGE PUMP STATION
DESCRIPTION
DESIGN - 15 MGD
FUTURE - 22.5 MGD
J
o TYPE
i NUMBER OF PUMPS
a
SUBMERSIBLE
3 (1 STAND-BY)
PLUS 1 SMALL
SUBMERSIBLE
4 (1 STAND-BY)
a
z
F PUMP HORSEPOWER
w
0
30 280
10 100
40 385
•
•
S -1B
OXIC
F / AN / OXIC (FAO) BASINS
AT 3.0 MGD/EACH
AN
AN
DITCH 5
OXIC
3A
SG
-2A
[E.,
SG_-_Ltf
38
FF vHTi
MLSS
DISTRIBUTION
BOX
12" PV
/ 12° RAS
RAS PS
CLARIFIER
1
(70' DIA.)
SG-C1
16" RAS
36"x36°x30
TEE 1-
30°FZI�
0° PV3
30°x36°
DITCH 6 )INCREASE
OXIC
24x30°
CROSS
itt
CLARIFIER
2
(70' DIA.)J
SG-C2
30°x36"
INCREASER
30° 36°
1-124x36"
CROSS
16° 1
12°x16"
INCREASER
24°
S' • IC
Iti
2
CLARIFIER
5
(85' DIA.)
I4 RAS PS
OXIDATION DITCHES
DESCRIPTION
DESIGN 6.0 MGD
FUTURE S.g MCD
J
NUMBER OF DITCHES
4
6
2
TOTAL NUMBER OF AERATORS
4
6
V
TOTAL # OF FIRM. MIXERS
8
12
a
TOTAL * OF 1st ANOXIC MIXERS
4
6
OPERATIONAL
TOTAL OPERATING VOLUME, M.G.
FERMENTATION BASIN
0.416
0.624
FIRST ANOXIC BASIN
0.92
1.38
AERATION BASIN
3.64
5.64
ORGANIC LOADING, LBS/DAY
OXYGEN DEMAND, LBS/DAY (AOR)
1400008
1150122
DETENTION TIME, HOURS
19.9
19.9
RETURN SLUDGE FLOW, MGD
7.50
11.25
SLUDGE AGE, DAY
15
15
F/M RATIO,
.06-.07
.06-.07
SOLIDS PRODUCTION, LBS/DAY
8006
12009
WASTE SLUDGE VOLUME, 0 0.85
122,000
183,000
.1A
36°
4.
36°
36°
24°
16" elm 8° TO
DRAIN
24"
CLARIFIER
6
(85' DIA.)
,4'
SG-C6
ALLOW 100 GPM
FROM ALL
SOURCES
FILTERS
0°
SG-F2 F2
SG-F3 F3
IN -PLANT
PUMP STATION
1300 GPM
SUPERNATE FROM
DIERS
FILTER BACKWASH (MAX T400 GPM)
200 GPM/FILTER
OR 800 GPM MAX
30"
UV
DISINFECTION
SYSTEM #1
SECONDARY CLARIFIERS
DESCRIPTION
DESIGN - 6 MGD
FUTURE - 9 MGD
¢ NUMBER/SIZE OF CLARIFIERS -
20 70'
20 70'
N DIAMETER, FEET
20 85'
40 85'
= TOTAL AREA, SF
15394
23091
a TOTAL OPERATING VOLUME, M.GAL
1.612
2.418
v DETENTION TIME, HOURS
WEIR LOADING, GAL/DAY/LF
8.32
6160
8.94
5968
= OVERFLOW RATE, GPD/SF
a
315
296
EFW
PUMP STATION CASCADE
WET WELL AERATOR
24° -{ - --
FINAL
EFFLUENT
30°
UV
DISINFECTION
SYSTEM #2
TERTIARY FILTERS
U
a
DESCRIPTION
NUMBER OF FILTERS
FILTER AREA, SF
BACKWASH PUMP TYPE
NUMBER OF BACKWASH PUMPS
BACKWASH CAPACITY, GPD/PUMP
BACKWASH CONSUMPTION, TOTAL/GPD
DESIGN
4
1728
SUBMERSIBLE
4
200
45300
FUTURE
6
2592
SUBMERSIBLE
6
200
45300
J
z
0
F
AVERAGE FILTER RATE, GPM/SF
PEAK FILTER RATE, GPM/SF
BACKWASH VOLUME PER WASH, GAL
WASTE BACKWASH RECYCLE RATE, GAL
2.4
6.0
1690.9
200
2.4
6.0
1690.9
200
EFFLUENT CRITERIA
DESCRIPTION
BOD, MG/L
NH3, MG/L
TOTAL PHOSPHOROUS
AVG. TMDL, POUNDS/DAY
MAX. MONTH TMDL, 4/DAY
AVG. CONCENTRATION, MG/L
TSS, MG/L
D0, MG
FECAL COLIFORM, 4/100 ML
TKN, MG/L
ORGANICS, MG/L
pH
TURBIDITY, TURBIDITY UNITS
NO3
DESIGN
5.0.
<0.5
20.0
40.0
0.40
5.0
6.0
<10.0
3.0
52.5
7 * 0.5
<1.0 NTU
6.5
PERMIT
10.0./5.0.
4.0s/2.0s
20.85
41.7
0.41
30.0
6.0
200
6-9
s WINTER/SUMMER
UNION COUNTY
NORTH CAROLINA
TWELVE MILE CREEK WWTP
LIQUIDS TREATMENT SCHEMATIC
PART B.3
FIGURE No.5
20091215 &02A &\OOS]1\014\pv°nW\P R PfTN-z-W"m Sd,.a°9 er111EflIa 1.0.1 S.. 9s
. 4itl, )FIEF.

PUMPS
1 & 2
OR
61, 00 200GPM GP )
BLOWER BUILDING NO. 1
50 HP 50 HP 50 HP
TO NPLANT P/S
-tt1v
("1lVI
COARSE BUBB
DIFFUSERS
( SCFM)
OVER FLOW &
DECANT
DIGESTER No. 2
(50' DIA x 15.67' SWD
VOL = 0.244 MG)
TANK DRAIN
6' AIR
TANK
—IVF DRAIN
8' WAS
4' SCUM
WAS PUMPS 3 & 4 (200 GPM OR 61,000 GPD)
BLOWER BUILDING NO. 2
125 HP 125 HP 125 HP
GRAVITY BELT THICKENER (GOT)
375 GPM
FILTRATE
THICKENED WAS
6'
TANK
TRANSFER
vI-I
15 HP SLUDGE 4
v TRANSFER 1T.
PUMP 2 i
300 9PM 4
O 30 TDH 6'
—{vI I 1 Ivl
15 HP
v
p RSEBUBBLEDIFFUSERS
SCFM)
OVER FLOW &
DECANT
DIGESTER No. 1
VOL = 0.244 MG
6' WAS TO GBT
8 WAS TO DIGESTER #3 &
PROPOSED DIGESTER #4
SLUDGE G
TRANSFER
PUMP 1
300 9PM
0 30 TDH
TRANSFER
6'
TO INPLANT P/S
(400 GPM)
0.
0
6'
STATIC MIXER
POLYMER FEED
(FROM POLYMER
SYSTEM)
0—('ti--IvErivl--Ivl
4
,"
�ZH
6' FILL
14' BFV
14' DIP AIR
14' SS
AIR-4000 SCFM
1,:. F0�
O
4
ANWAY ACCESS
400 GPM WAS 0 0.8% OR 300
GPM THICKENED WAS 0 4.0%
8' DRAIN
BLOWER BUILDING NO. 3
125 HP 125 HP
TO COARSE BUBBLE DIFFUSERS
0 18.75 SCFM OR
4000 SCFM CACH
DIGESTER No. 3
(96' DIA x 18' SWD
VOL = 1.069 MG)
6' QUICK CcV}- 8' QUICK C=1VI-
CONNECT CONNECT
8'
8'x6' REDUCER
14' DIP
AIR-4000 SCFM
8' FILL
SEPTAGE
RECEIVING
/STATION
Iv
8' C.0
8' DRAIN
6' QUICK
CONNECT
CF1v
V
COARSE BUBBLE(
DIFFUSER
AIRFLOW 4000TOTAL SCFM)
DIGESTER No. 4
(96' DIA x 18' SWD
VOL = 1.069 MG)
8' SLUDGE DRAWOFF
& DRAIN
DECANT/DRAWOFF
TANK DRAIN
8' SAN SEWER
ANWAY ACCESS
C PROPOSED NH
& 8' SS
UNION COUNTY
NORTH CAROLINA
TWELVE MILE CREEK WWTP
SOLIDS TREATMENT SCHEMATIC
PART B.3
FIGURE No.6
000215 5153A M.101131\0I4'p .n9.VE001V15-3-5dk SdAA.p 5sTNE1Poa tat Saved Do thaMd, )REF

Additional information, if provided, will appear on the following pages.
Form 2A — Part B.3
Twelve Mile Creek WWTP, NC0085359
Treatment Process Narrative
The Twelve Mile Creek WWTP is located at 8299 Kensington Drive, Waxhaw, North
Carolina. The facility has a permitted rated capacity to treat up to 6.0 MGD. The facility
employs an oxidation ditch system with integral fermentation, anoxic and oxidation
(FAO) zones. The entire treatment system is comprised of the following components:
• Influent pump station with four (4) submersible pumps and stand-by generator
with utility paralleling switchgear
• Influent screening structure with self-cleaning influent screen and manual bar
screen
• Grit removal structure with vortex grit chamber
• FAO distribution structure
• Four (4) FAO basins
• MLSS distribution structure
• Four (4) final clarifiers
• Four (4) tertiary traveling hood sand filters
• Two (2) ultraviolet light disinfection systems with a total of 4 ultraviolet
disinfection channels
• NPW pump station with a total of 3 vertical turbine pumps
• In -plant pump station with a total of 2 submersible pumps
• Cascade aeration
• Two (2) Return Activated Sludge (RAS) pump stations with a total of 4
submersible pumps.
• Waste Activated Sludge (WAS) station with a total of 2 screw centrifugal pumps
• Sludge thickening facility with a 2-meter gravity belt thickener and associated
polymer storage and feed system
• Four (4) aerobic digesters with diffused aeration and a total capacity of 2.5 MG
• Chemical storage and feed facilities for sodium aluminate (chemical phosphorus
removal)
• Main Plant stand-by generator with automatic transfer switch
NPDES FORM 2A Additional Information

• Additional information, if provided, will appear on the following pages.
Form 2A — Part B.5
Twelve Mile Creek WWTP, NC0085359
Facility Improvements Narrative
There are two projects currently underway at the Twelve Mile Creek WWTP. The
projects are the Odor Control Improvements project and Plant Reliability Improvements
project. Neither project is required by the local, State, or Federal agencies that govern
the WWTP.
The Odor Control Improvements project consists of:
• New odor control facility, including scrubber fan, scrubber towers, recirculation
pumps, chemical storage tanks (sulfuric acid, sodium hypochlorite, and sodium
hydroxide), tank mixing system, chemical metering pumps, and associated
electrical equipment.
• 4 new digester covers (extruded flat panel covers on two 50-foot diameter tanks
and geodesic dome covers on two 96-foot diameter tanks).
• New odor control ductwork, including support structures for exposed ductwork.
The Plant Reliability Improvements project consists of:
• New chemical storage and feed facilities (sodium aluminate), including chemical
feed pumps, chemical storage tank, and associated electrical equipment for
chemical phosphorus removal.
• New gravity belt thickener with associated polymer feed facilities, including a 2-
meter gravity belt thickener, polymer storage tank, polymer pumps, polymer
preparation system, and associated electrical equipment.
• Site electrical work including new conduit, wiring, and ductbank to replace
existing conduit and wiring and to reconnect existing equipment with new wiring.
These projects were implemented to improve the treatment plant's process and
operational reliability and reduce odor. All required permits have been obtained for both
projects. The Authorization to Construct (ATC) for both projects were issued by
NCDWQ on November 9, 2007. Both projects are scheduled for completion in Spring of
2010.
NPDES FORM 2A Additional Information