NC0085359_Speculative Limits_20020614

NPDES DOCUWENT SCANNINO 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 Limi)
Environmental Assessment (EA)
Document Date:
June 14, 2002
Thisis clbocturrient iss printed cm X•leiume paper- — ignore Euriy
cc:mute/la mai the arew-erise *side

State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
Micheal F. Easley, Governor
William G. Ross, Jr., Secretary
Alan W. Klimek, P.E., Director
June 14, 2002
Mr. Jon C. Dyer, P.E., Director
Union County Public Works Department
400 North Church St.
Monroe, North Carolina 28112-4804
ATA
NCDENR
Subject: Union County -Twelve Mile Creek WWTP
Speculative Limits for Expansion
NPDES Permit No. NC0085359
Union County
Dear Mr. Dyer:
This letter is in response to the request for speculative effluent limits for proposed expansions of
the subject WWTP. Wastewater flows of 6.0, 9.0, and 12.0 MGD were targeted for expansion of
the Twelve Mile Creek WWTP into Twelve Mile Creek in the Catawba River Basin. After
consultation with the permittee, it has been determined that the staff of the NPDES will only
provide speculative effluent limits for 6.0 MGD at this time. These limits should be considered
very preliminary, as there are a number of pending actions and communications that may
influence your project. Twelve Mile Creek eventually flows into the Catawba River after
crossing the South Carolina state line. Any finalized permit will be subject to review and
scrutiny by that State, in addition to the U.S. Environmental Protection Agency.
It should be noted that expanding facilities, involving an expenditure of public funds or use of
public (state) lands, will be required to prepare an Environmental Assessment (EA) when
wasteflows exceed or equal 0.5 MGD. If the EA demonstrates that the project may result in a
significant adverse effect on the quality of the environment, an Environmental Impact Statement
(EIS) is required. DWQ will not accept a permit application for a project requiring an EA or EIS
until: (1) the document has been approved by the Department of Environment and Natural
Resources and, (2) a Finding of No Significant Impact (FONSI) has been sent to the State
Clearinghouse for review and comment or an EIS has been approved. The Division of Water
Quality's Planning Branch can provide further information regarding the requirements of the
N.C. Environmental Policy Act. Please contact Todd Kennedy of the DWQ Planning Branch at
[phone] ext. 555 if you have questions on this subject.
1617 Mail Service Center, Raleigh, North Carolina 27699-1617 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer Internet: http://h2o.enr.state.nc.us/

Twelve Mile Creek WWTP Speculative Limits
Page 2
Be advised that providing speculative limits do not guarantee that the Division will issue an
NPDES permit to discharge treated wastewater. Union County will also be required to complete
an Engineering Alternatives Analysis (EAA) that must be submitted with the application for a
flow expansion of the NPDES permit. The EAA should contain a defensible justification for the
proposed expansion and an analysis of potential alternatives, which should include a thorough
evaluation of non -discharge alternatives. Nondischarge alternatives, such as spray irrigation,
water conservation, or reuse, are considered to be environmentally preferable to a surface water
discharge. In accordance with the North Carolina General Statutes, the practicable waste
treatment and disposal alternative with the least adverse impact on environment is required to be
implemented.
This segment of the Twelve Mile Creek has a stream classification of C. The best usage of these
waters is aquatic life propagation and maintenance of biological integrity (including fishing, and
fish), wildlife, secondary recreation, and agriculture. Using information available at this current
time, the discharge point has an estimated drainage area of 76.8 square miles, with an average
flow of 69 cfs, a summer 7Q10 flow of 0.0 cfs, a winter 7Q10 flow of 1.5 cfs and a 30Q2 flow of
2.5 cfs. Please be advised that these flows were estimated by DWQ, however it is preferable that
the County request actual flow estimations from the United States Geological Survey to ensure
accuracy.
As discussed in the April 25, 2002 meeting, it is recommended that Union County perform an
extensive synoptic study of dissolved oxygen levels in Twelve Mile Creek. Instream water
quality data indicated that there were dissolved oxygen levels below the 5.0 mg/1 standard both
above and below the Twelve Mile Creek WWTP discharge. There were data that showed
occasionally the downstream DO standard contravention occurred immediately downstream of
the WWTP and then sometimes occurred in a segment of Twelve Mile Creek located in South
Carolina. The collection of DO data should help determine whether the low instream DO values
can be attributed to the discharge from Twelve Mile Creek WWTP or other environmental
factors. Union County should conduct sampling of temperature and dissolved oxygen upstream
of the WWTP and downstream of all highway and/or bridge crossings, including the South
Carolina portion of Twelve Mile Creek. Sampling should be three times per week during the
summer months (April through October) to provide data during the critical low flow period.
During the winter months (November through March) instream sampling could be done weekly.
The results of this study should be included as part of the SEPA documentation regarding the
impact of the Twelve Mile Creek WWTP on water quality in the receiving stream.
Based on available information, the tentative effluent limits for oxygen -consuming constituents
of the Union County — Twelve Mile WWTP discharge at the flow of 6.0 MGD are included on
the attached effluent sheet. Upon formal permit application, if there is an industrial wastewater
constituency, an evaluation of limits and monitoring requirements for metals and other toxicants
will be addressed at that time. Based on an agreement with the State of South Carolina, North
Carolina has agreed to apply a mass limit equivalent to 1.0 mg/1 of total phosphorus at the
existing permitted flow of 2.5 MGD. Compliance with the limit will be judged as a rolling
annual average. Union County should also prepare for the impending phosphorus total maximum
daily load (TMDL) from South Carolina within 3-5 years. This phosphorus TDML could result
in limits much lower than proposed here.

Twelve Mile Creek WWTP Speculative Limits
Page 3
It is recommended that the facility initiate quarterly effluent monitoring for copper and zinc.
During an investigation into a recent whole effluent toxicity test failures, DWQ was unable to
complete the evaluation because this discharge does not monitor for copper and zinc. DWQ has
found that copper and/or zinc are often significant causative factors in whole effluent toxicity
failures. The inclusion of monitoring for these parameters will provide DWQ with the data
required evaluating if copper and zinc are potential sources of toxicity.
The Division of Water Quality is requiring chlorine limits for all new or expanding dischargers
proposing the use of chlorine for disinfection. Dechlorination or an alternate form of
disinfection, such as ultraviolet radiation, should allow the facility to comply with this
requirement.
Final NPDES effluent limitations will be determined after a permit application has been
submitted to the Division. If there are any additional questions concerning this matter, please
feel free to contact Jackie Nowell of my staff at [phone] ext. 512.
Respectfully,
David A. Goodrich
NPDES Unit Supervisor
cc: Mooresville Regional Office/Rex Gleason
Bobby Blowe, Construction Grants
Central Files
NPDES Permit File
Jeff deBessonet, Bureau of Water DHEC, 2600 Bull St., Columbia SC 29201

Twelve Mile Creek WWTP Speculative Limits
Page 4
A. SPECULATIVE EFFLUENT LIMITATIONS AND MONITORING
REQUIREMENTS - UNION CO. — TWELVE MILE CREEK WWTP
EFFLUENT
CHARACTERISTICS
LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily .
Maximu
m
Measureme
nt
Frequency
Sample
Type
Sample Locationl
Flow
6.0 MGD
Continuous
Recording
Influent or Effluent
BOD, 5-day, 200C2
(April 1 — October 31)
5.0 mg&
7.5 mg/
Daily
Composite
Influent, Effluent
BOD, 5-day, 20°C2
(November 1 — March
30)
10.0 mg/L
15.0 mg/L
Daily
Composite
Influent, Effluent -
Total Suspended
Residue 2
30.0 mg/L
45.0 mg/L
Daily
Composite
Influent, Effluent
NH3 as N (April 1 —
October 31)
1.0 mg/L
Daily
Composite
Effluent
NH3 as N (November 1
— March 30)
2.0 mg/L
Daily
Composite
Effluent
Dissolved Oxygen3
Daily
Grab
Effluent ,Upstream,
Downstream
Fecal Coliform
(geometric mean)
200 / 100
ml
400 / 100
ml
Daily
Grab
Effluent, Upstream,
Downstream
pH4
Daily
Grab
Effluent
Conductivity
Daily
Grab
Effluent
Total Phosphorus
Monthly Average: 41.7 lbs/day
Monthly
Composite
Effluent
Total Nitrogen
(NO2+NO3+TKN)
Monthly
Composite
Effluent
Chronic Toxicity5
Quarterly
.
Composite
Effluent
Total Copper
Quarterly
Composite
Effluent
Total Zinc
Quarterly
Composite
Effluent
Temperature, °C
Weekly
Grab
Effluent, Upstream,
Downstream
Notes:
1. Influent, Effluent, Upstream 50 feet above the outfall; Downstream sampling points D1+D2; D1 - One
quarter mile below the outfall, before confluence with the first tributary; D2 - Downstream at NCSR
1301
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 dissolved oxygen effluent concentration shall not be less than 6.0 mg/1.
4. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
5. Chronic Toxicity (Ceriodaphnia) P/F at 90%; February, May, August, and November.

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
June 6, 2002
Mr. Jon C. Dyer, P.E., Director
Union County Public Works Department
400 North Church St.
Monroe, North Carolina 28112-4804
dill 1.1 Ali tA)
A I.
Subject: Union County -Twelve Mile Creek WWTP
Speculative Limits for Expansion
NPDES Permit No. NC0085359
Union County
Dear Mr. Dyer:
This letter is in response to the request for speculative effisent limits for proposed expansions of
the subject WWTP. Wastewater flows of 6.0, 9.0, and 12 MGD were targeted for expansion of
the Twelve Mile Creek WWTP into Twelve Mile Creek in the Catawba River Basin. After
consultation with the permittee, it has been determined that the staff of the NPDES will only
provide speculative effluent limits for 6.0 MGD at this time. These limits should be considered
preliminary, as there are a number of pending actions and communications that may
influence your project. Twelve Mile Creek eventually flows into the Catawba River after
crossinJeSt1reoIina state line. Any finalized permit will be subject to review and
scjutii by that State, in addition to the U.S. Environmental Protection Agency.
eso-rvyle.) let23:1-1-4ifo J-L-rcz:-c‘AxS 1-
It should be noted that expanding facilities, involvipg an expenditure of public funds or use of
public (state) lands, will be required to prepare an knvironmentali4ssessment (EA) when
wasteflows exceed or equal 0.5 MGD. If the EA demonstrates that the project may result in a
significant adverse effect on the quality of the environment, an Environmental Impact Statement
(EIS) is required. DWQ will not accept a permit application for a project requiring an EA or EIS
until: (1) the document has been approved by the Department of Environment and Natural
Resources and, (2) a Finding of No Significant Impact (FONSI) has been sent to theJtate
Clearinghouse for review and comment or an EIS has been approved. The Division of Water 6..2e
Quality's Planning Branch can provide further information regarding the requirements of the
N.C. Environmental Policy Act. Please contact Milt.-Rhiades of the DWQ Planning Branch at
[phone] ext.366 if you have questions on this subject. .7-odd
9z0v.v''' 5
Please g advised that response-te-this-request does not guarantee that the Division will issue an
NPDES permit to discharge treated wastewater inta.tivase-racriving watt's. The Union County
Publir---Isior4s-Ptepertment will also be required to complete an Engineering Alternatives
Analysis (EAA) that must be submitted with the application for tJNPDES permit. The EAA
should contain a cleaf-and-str-eng justification for the proposed effiility x an_d an analysis of
cde-k44 S;6/e._
EKpo C.
N. C. Division of Water Quality 1617 Mail Service Center Raleigh, NC 27699-1617 [phone] £
Customer Service
1 800 623-7748

Union County Public Works Department
June 6, 2002
Page 2
potential alternatives, which should include a thorough evaluation of non -discharge alternatives.
Nondischarge alternatives, such as spray irrigation, water conservation, or.Gannee4ieft444
regional-tvatrfent-and-dispasal-gy,sein, are considered to be environmentally preferable to a
surface water discharge. In accordance with the North Carolina General Statutes, the practicable
waste treatment and disposal alternative with the least adverse impact on environment is required
to be implemented.
t?')
This segment of the Twelve Mile cek has a stream cla ification of C. The b t usage of these
waters is aquatic life propagation nd maintenance of bijMogical integrity (incl ding fishing, and
". fish), wildlife, secondary recreat. on, and agriculture. U ing information avail ble at this current
time, the discharge point has a estimated drainage aret of 76.8 square miles with an average
flow of 69 cfs, a summer 7Q10 of 0.fs, a winter 7Q10 of 1.5 cfs and a 30Q2 of 2.5 cfs. Please
be advised that these flows were estimated by DWQ, however it is preferable that the County
request actual flow estimations from the United States Geological Survey to ensure accuracy.
As discussed in the meetingibotween-D-WQ-aid-Urien-C--etmty-en Apri125_, 2002), it is
recommended that Union County perform an extensive synoptic study of dissolved oxygen levels
in Twelve Mile Creek. Instream water quality dateollcctc
indicated that there were dissolved oxygen levels below the 5, g/1 standard both above and
below the Twelve Mile Creek WWTP discharge. There were data that showed occasionally the
downstream DO standard contravention occurred immediately downstream of the WWTP and
1.17then sometimes occurred in a segment of Twelve Mile Creek located in South Carolina. Union
9Q0 0, County should conduct sampling of temperature and dissolved oxygen upstream of the WWTP
vrt1 ac• and downstream at all highway and/or bridge crossings, including the South Carolina portion of
yr Ax\ Twelve Mile Creek. Sampling should be weekly during the summer months (April through
e\di
October) to provide data during the critical low flow period. During the winter months
(November through March) instream sampling could be done monthly. The results of this study
should be included as part of the SEPA documentation regarding the impact of the Twelve Mile
Creek WWTP on water quality in the receiving stream.
Based on available information, the tentative effluent limits for oxygen -consuming constituents
of the Union County - Twelve Mile WWTP discharge at the flow of aVIGD are included on the 0-A-6- -ivy"'
attached effluent sheet. Upon formal permit application, if there is an industrial wastewater YO'1.0.0.11
sj1
0,AV-el--
.5
c,‘
„DP
constituency, an evaluation of limits and monitoring requirements for metals and other toxicants
will be addressed at at time. Based on an agreement with the State of South Carolina, North --
Carolina has
to apply a mass limit equivalent to 1ang/1 of total phosphorus at the —
existing permitted flow of 2.5 MGD. Compliance with the limit will be judged as a
annual average. Union County should also prepare for the impending phosphorus from
South Carolina within 3-5 years. This phosphorus TDML could result in limits ag441N-as-0,-
P11,44- Iv -or -r-
ing, 41Av-,-- R-2.10 &Ott kPL(-
r•I ;LA
It is recommended that^quarterly effluent monitoring for copper and zinc.will-be-ackicei-te-the
NPDES permit. During an investigation e-a-recent whole effluent toxicity test failure', DWQ was
unable to dura completeevaluation ef-pefteatiab.sumeos bsuctipe tautai•er-4design-flovi
MGD) discham denot monitor for copper and zinc. It-hes4efi-demienistc-ated that copperei--
and/or zinc were significant causative factors in whole e fkent toxicity feres jeejaclision of
monitoring for these parameters will provide DWQ tt
eliser,har-ged.
,r
Goncentrmonc ..opper an zincarc parr...Ina/
-a-ferr-DWIttcrevaittate-the-potential- for

Union County Public Works Department
June 6, 2002
Page 3
The Division of Water Quality is requiring chlorine limits for all new or expanding dischargers
proposing the use of chlorine for disinfection. The.prasess.a-c.-111arination/bitchlorination or an
alternate form of disinfection, such as ultraviolet radiation, should allow the facility to comply
this requirement.
Final NPDES effluent limitations will be determined after a permit application has been
submitted to the Division. If there are any additional questions concerning this matter, please
feel free to contact Jackie Nowell of my staff at [phone] ext. 512.
Respectfully,
David A. Goodrich
NPDES Unit Supervisor
At-taehmeirr
cc: Mooresville Regional Office/Rex Gleason
Bobby Blowe, Construction Grants.
Central Files
NPDES Permit File
Jeff deBessonet, Bureau of Water DffEC, 2600 Bull St., Columbia SC 29201
4—Dora 7

Union County Public Works Department
June 6, 2002
Page 4
A. SPECULATIVE EFFLUENT LIMITATIONS AND MONITORING
REQUIREMENTS - UNION CO. — TWELVE MILE CREEK WWTP
puring period begi,jinng on the effectiVe e of the pe it nd lasting until expirapoN the
Permittee I authorized to ischarge frcirn outfa 001. uch di harges hall be_lirnited and
monitored b the Permittee asweci9e'd below:
EFFLUENT
CHARACTERISTICS
LIMITS
MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample Locationl
Flow
6.0 MGD
Continuous '
Recording
Influent or Effluent .
BOD, 5-day, 20°C2
(April 1 — October 31)
5.0 mg/L
7.5 mg/L
Daily
Composite
Influent, Effluent
BOD, 5-day, 20°C2
(November 1 — March 30)
10.0 mg/L
15.0 mg/L
Daily
Composite
Influent, Effluent
Total Suspended Residue 2
30.0 mg/L
45.0 mg/L
Daily
Composite
Influent, Effluent ,
NH3 as N (April 1 — October
31)
1.0 mg/L
Daily
Composite
Effluent
NH3 as N (November 1 —
March 30)
2.0 mg/L
Daily
Composite
Effluent
Dissolved 0xygen3
Daily
Grab
Effluent ,Upstream,
Downstream
Fecal Coliform
(geometric mean)
200 / 100 ml
400 / 100 ml
Daily
Grab
Effluent, Upstream,
Downstream
pH4
Daily
Grab
Effluent
Conductivity
4/
Daily
Grab
Effluent, Llpstr_aw17----
DownatrGeni--
Total Phosphorus
Monthly Average: 41.70
12 Month Average: 20.8
/day
lbs/day
Monthly
Composite
Effluent
Total Nitrogen
(NO2+NO3+TKN)
Monthly
Composite
Effluent
Chronic Toxicity5
Quarterly
Composite
Effluent
Total Copper
Quarterly
1 Composite
Effluent
Total Zinc
Quarterly
Composite
Effluent
Temperature, °C
Weekly
Grab
Effluent, Upstream,
Downstream
Notes:
1. Influent, Effluent, Upstream 50 feet above the outfall: Downstream sampling points D1+D2; DI - One
quarter mile below the outfall, before confluence with the first tributary; D2 - Downstream at NCSR
1301
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 dissolved oxygen effluent concentration shall not be less than 6.0 mg/t--
4. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
5. Chronic Toxicity (Ceriodaphnia) P/F at 900/o; February, May, August, and November.
IS
or lif.Sible oa th -ra—de

State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
Micheal F. Easley, Governor
William G. Ross, Jr., Secretary
Gregory J. Thorpe, Ph.D., Acting Director
Mr. Jon C. Dyer, P.E.,Director
Union County Public Works Department
400 North Church St.
Monroe, North Carolina 28112-4804
Dear Mr. Dyer:
May 16, 2002
AVA
NCDENR
Subject: Union County -Twelve Mile Creek WWTP
Speculative Limits for Expansion
NPDES Permit No. NC0085359
Union County
itfbi cAl° 5114j
? • letter is in response to the request for speculative effluent ){mits for proposed
expansi the subject WWTP. Wastewater flows of 6.0, 9.0, and 12 MD were targeted for
expansio of the Twelve Mile Creek WWTP into Twelve Mile Creek n the Catawba River
— Basin welve Mile Creek eventually flows into the Catawba River 4eeeteti—in. the South
.44 Carolin Any finalized permit will be subject to review and scrutiny by that State, as well as the
.S. Environmental Protection Agency. The staff of the NPDES Unit of the Point Source
Branch has reviewed this reqlest and will provide specslative effluent limits for 6.0 MGD at this
time. CIMGC.C.- /1411Y5 ifeWMI c-NsAft&et0( ielAy py.aminikAl 45 V*04C. dertt,
et ii“.01kVe reMeit", actroVLS 4ffd COMMt411/V4171vIJ ittott Aay yesvvw,
P11 44. '"!
It shoul be noted that expanding facilities, involving an expenditure of public funds or it
use of public (state) lands, will be required to prepare an environmental assessment (EA) when CaoGroj
wasteflows exceed or equal 0.5 MGD. If the EA demonstrates that the project may result in a
significant adverse effect on the quality of the environment, an Environmental Impact Statement
(EIS) is required. DWQ will not accept a permit application for a project requiring an EA or EIS
until: (1) the document has been approved by the Department of Environment and Natural
Resources and, (2) a Finding of No Significant Impact (FONSI) has been sent to the state
Clearinghouse for review and comment or an EIS has been approved. The Division of Water
Quality's Planning Branch can provide further information regarding the requirements of the
N.C. Environmental Policy Act. Please contact Milt Rhodes of the DWQ Planning Branch at
[phone] ext. 366 if you have questions on this subject.
1617 Mail Service Center, Raleigh, North Carolina 27699-1617 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer Internet: http://h20.enr.state.nc.us/

Union County -Twelve Mile WWTP Speculative Limits
Page 2
lad$6441'
T#114/1k/fr
•
It will also provide the necessary data for DWQ to evaluate the potential for exceedances of
action levels instream.
Please be advised that response to this request does not guarantee that the Division will
issue an NPDES permit to discharge treated wastewater into these receiving waters. The Union
County Public Works Department will also be required to complete an Engineering Alternatives
Analysis (EAA) that must be submitted with the application for the NPDES permit. The EAA
should contain a clear and strong justification for the proposed facility and an analysis of
potential alternatives, which should include a thorough evaluation of non -discharge alternatives.
Nondischarge alternatives, such as spray irrigation, water conservation, or connection to a
regional treatment and disposal system, are considered to be environmentally preferable to a
surface water discharge. In accordance with the North Carolina General Statutes, the practicable
waste treatment and disposal alternative with the least adverse impact on environment is required
to be implemented.
This segment of the Twelve Mile CreJ a&alt eam classification o The best usage
of these waters is as a source of water su for drinking, culinary. or foo rocessing. Using
rinformatiNvai1ab1ef4tme, the isc arge point has an estimated drainage area of
76.8 square mileOrith an average flow of 69 cfs, a summer 7Q10 of 0 cfs, a winter 7Q10 of 1.5
cfs and a 30Q2 (12.5 cfs. Please be advised that these flows were estimated by DWQ, however
it is preferable that the request actual flow estimations from the United States Geological
Survey to ensure accuracy. cool
Based on available information, the tentative effluent limits for oxygen -consuming
constituents of the Union County — Twelve Mile WWTP discharge at the flow of 6 MGD are
included on the attached effluent sheet. Upon formal permit application, if there is an industrial
wastewater constituency, an evaluation of limits and monitoring requirements for metals and
other toxicants will be addressed at that time. Based on an agreement with The State of South
Carolina, North Carolina has concurred to apply a mass limit equivalent to 1 mg/1 of total
phosphorus at the existing permitted flow of 2.5 MGD. Compliance with the limit will be judged
as a rolling annual average. A special condition for a phosphorus optimization study will be
included in the permit, to allow DWQ time to review Union County's preparation for the
impending phosphorus TMDL (from South Carolina) within 3-5 years. This phosphorus TDML
cou1d119e. a low as 0.1 mg/l.
L rxl% if rgi (irvIRS etc;
Because the Twelve Mile Creek WWTP is a major discharger of greater than 1.0 MGD to
the surface waters of North Carolina, quarterly effluent monitoring for copper and zinc will be
added to the NPDES permit. The inclusion of monitoring for these parameters will satisfy the
agreement between DWQ and EPA for controlling copper and zinc in point source dischargers.
The Division of Water Quality is requiring chlorine limits for all new or expanding
dischargers proposing the use of chlorine for disinfection. The process of
chlorination/dechlorination or an alternate form of disinfection, such as ultraviolet radiation,
should allow the facility to comply this requirement.

Union County -Twelve Mile WWTP Speculative Limits
Page 3
Final NPDES effluent limitations will be determined after a permit application has been
submitted to the Division. If there are any additional questions concerning this matter, please
feel free to contact Jackie Nowell of my staff at [phone] ext. 512.
Respectfully,
David A. Goodrich
NPDES Unit Supervisor
Attachment
cc: Mooresville Regional Office/Rex Gleason
Bobby Blowe, Construction Grants
Central Files
NPDES Permit File
Jeff deBessonet, Bureau of Water DHEC, 2600 Bull St., Columbia SC 29201

Union County -Twelve Mile WWTP Speculative Limits
Page 4
A. SPECULATIVE EFFLUENT LIMITATIONS AND MONITORING
REQUIREMENTS - UNION CO. — TWELVE MILE CREEK WWTP
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
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample
Type
Sample Location'
Flow
6.0 MGD
Continuous
Recording
Influent or Effluent
BOD, 5-day, 20°C2
(April 1 — October 31)
5.0 mg/L.
7.5 mg/L
Daily
Composite
Influent, Effluent
BOD, 5-day, 20°C2
(November 1 — March 30)
10.0 mg/L
15.0 mg/L
Daily
Composite
Influent, Effluent
Total Suspended Residue 2
30.0 mg/L
45.0 mg/L
Daily
Composite
Influent, Effluent
NH3 as N (April 1 — October
31)
1.0 mg/L
Daily
Composite
Effluent
NH3 as N (November 1 —
March 30)
1/mg/
Daily
Composite
Effluent
Dissolved 0xygen3
ie .0
Daily
Grab
Effluent ,Upstream,
Downstream
Fecal Coliform
(geometric mean)
200 / 100 ml
400 / 100 ml
Daily
Grab
Effluent, Upstream,
Downstream
pH4
Daily
Grab
Effluent
Conductivity
Daily
Grab
Effluent, Upstream,
Downstream
Total Nitrogen
(NO2+NO3+TKN)
Monthly
Composite
Effluent
,
Total Phosphorus
Monthly Average: 41.70 lbs/day
12 Month Average: 20.85 lbsklay
Monthly
Composite
Effluent
Chronic Toxicity5
Quarterly
Composite
Effluent
Total Copper
Quarterly
Composite
Effluent
Total Zinc
Quarterly
Composite
Effluent .
Temperature, °C
Weekly
Grab
Effluent, Upstream,
Downstream
Notes:
1. Influent, Effluent, Upstream 50 feet above the outfall; Downstream sampling points D1+D2; D1 - One
quarter mile below the outfall, before confluence with the first tributary; D2 - Downstream at NCSR
1301
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 dissolved oxygen effluent concentration shall not be less than 6.0 mg/1.
4. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
5. Chronic Toxicity (Ceriodaphnia) P/F at 90%; February, May, August, and November.

Union County -Twelve Mile WWTP Speculative Limits
Page 5
There shall be no discharge of floating solids or visible foam in other than trace",/,
• NUTRIENT STUDY
e South Carolina Department of Health and Environmental Control(SC DHEC) has
determined at Fishing Creek Reservoir, Cedar Creek Reservoir and Lake W eree are
impaired due t xcessive nutrient loads and algal response to discharges 45tream of these
lakes. The Cataw River Basinwide Water Quality Plan (December 199,9)' states that a TMDL
will be developed to dress the causes and sources of impairment iwthese South Carolina
lakes. SC DHEC has p osed the development of a phosphorus TIVIDL and is planning to limit
phosphorus for all South arolina NPDES dischargers with flowsireater than 50,000 gallons
per day. Significant dischar s of phosphorus have also bewlinked to the North Carolina
portion of the Fishing Creek R ervoir watershed. Estimateindicate that a significant portion
of the total phosphorus load com • from the Sugar Creck/Subbasin. To work towards
reduction of this load, CMUD shall ovide the Divisiodwith a study that fully investigates the
feasibility of reducing total phospho (TP) load at/this WWTP. The target TP load should be
equivalent to a TP concentration of 1 mg at the effluent. This condition should not be construed
as a permit limit. However, a limit may be mppted once the TMDL has been completed and an
implementation plan is developed.
The optimization study should include„;1‘follo g:
• An identification of significant soutces of pollu n in the system.
• An evaluation of ways in which/tfiese sources can se reduced or eliminated.
• The possibility of reducing irftuent flows to the WW to control mass loading to the
stream.
• An assessment of the cu ent treatment processes and s in which this may be
optimized to achieve a igher level of treatment.
• A plan to optimize t� current treatment system to achieve a i igher level of nutrient
removal.
• An evaluation of dditional treatment units required to achieve h her nutrient removal.
The optimizatio study should be completed one year from permit issu nce, and submitted
to the followi address:
North Care ma Division of Water Quality
Water Q ality Section/NPDES Unit
1617 ail Service Center
Rale, North Carolina 27699-1617
N

Union County -Twelve Mile Creek WWTP Meeting
April 25, 2002
10:30 am
Raleigh, NC
Introductions
1.
Agenda
Requirements of the County to hold public hearings
2. Timeline for the NPDES permit process
,-
.7- -L.;
• /CT-tit/Vim-P.7C +Ili a OK A /1,4a
h„v4 f 664f?
3. Since the County's NPDES Permit renewal is past due, does DENR
prefer to renew the existing permit or process a new permit with
new limits, including phosphorous, at a new flow of around 6.0
mgd? Moe /11,57e.
Wid
4. Review the procedures for re -rating the existing 12 Mile Creek
WWTP from 2.5 to approximately 3.0 mgd
Speculative effluent limits, including total "P", for a permitted flow
of 6 mg4
6. Potential effluent limits or requirements not in the current NPDES
permit e-uf 2-0 g.tofri,
Any additional information McKim 85 Creed/or Union County can
supply in support of the new permit
8. Information that will be required to support the request for an
expanded permit (engineering analysis of alternatives, etc.)
9. Specific requirements of the E/A for the WWTP
10. Miscellaneous/Closing

Union County Twelve Mile Creek 1/I/WTP Projected TP Limits
Design Flow
Total Phosphorus Limit
2.5 MGD
d .3
1 mg/I (20.85 lbs/day)
3 MGD
0.83 mg/I (20.85 lbs/day)
i'lviC -4(11!
6 MGD
0.41 mg/I (20.85 lbs/day)
9 MGD
0.28 mg/I (20.85 lbs/day)
12 MGD
0.21 mg/I (20.85 lbs/day)
fv160 (tirb*ingeri-&)
0,16 111.

0 .06 4,iti
-
(le ,

1-14/\/'
lAY.7277_c4M
AMB STATION
DATE
DO (mg/L)
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
09819500
C9819500
09819500
09819500
09819500
09819500
09819500
09819500
04/06/1999
05/11/1999
06/28/1999
07/21/1999
08/19/1999
09/13/1999
10/18/1999
11/18/1999
01/19/2000
02/03/2000
03/06/2000
04/04/2000
05/10/2000
06/22/2000
14 i Al
UPSTRM DATE
8.1
8.7
6.7
5.5
2.2 UPSTRM
3.4 UPSTRM
6.3
6.0
10.9
12.3
10.2
7.2
7
6.2
09819500 07/25/2000 7.1
C9819500
C9819500
09819500
09819500
09819500
09819500
C9819500
C9819500
C9819500
09819500
09819500
09819500
09819500
09819500
09819500
08/14/2000
09/11/2000
1- 10/17/2000
11/20/2000
12/12/2000
01/04/2001
02/07/2001
04/05/2001
05/03/2001
06/12J2001
07/10/2001
08/06/2001
09/06/2001
10/02/2001
12/10/2001
UPSTRM
UPSTRM
UPSTRM
UPSTRM
UPSTRM
UPSTRM
UPSTRM
5.9 UPSTRM
UPSTRM
5.9 UPSTRM
UPSTRM
7.1 UPSTRM
UPSTRM
9.2
9.6
13.4
11.7
9.8 UPSTRM
6.9 UPSTRM
4.5 UPSTRM
4.6 UPSTRM
2.8 UPSTRM
5.3 UPSTRM
5.5 UPSTRM
2.4
09819500-Twelve Mi. Creek @ Hwy 16 nr Waxhaw
Upstrm- 50 ft above VVVVTP
Dwn1-1/4 mi. below VVVVTP
Dwn2 - @ NCSR1301
SC Dwn- @ SC State Road 55
Twelve Mile Creek Instream DO data
, 57?;,1 ;. IToi
DO (mg/L)
DWN1 DO (mg/L) DWN2
8/18/99 2.1 DWN1
9/13/99 3.31 DWN 1
4.36 DWN2
5.3 DWN2
DO (mg/L)
Sc
SC DWN DATE
4.77 CW-083 8/19/99
6.25 CW-083 9/23/99
DO (mg/L)
3.4
6.6
5/10/00 6.46 DWN1 5.4 DWN2 6.65 CW-083 5/8/00 8.3
6/22/00 4.47 DWN1 3.79 DWN2 4.46
6/14/00 4.49 DWN1 3.78 DWN2 4.67 CW-083 6/14/00 5.2
7/24/00 3.85 iDWN1 4.84 DWN2 4.83
7/26/00 4.77 pwN1 5.44 DWN2 5.5
7/17/00 4.06 bWN1 5.36 DWN2 5.33 CW-083 7/18/00 4.7
7/19/00 3.32 DWN1 5.1 DWN2 5.15 CW-083 7/18/00 4.7
8/14/00 4.76 ,DWN1 6.1 DWN2 6.33 CW-083 8/16/00 4.7
8/16/00 3.75 DWN1 5.5 DWN2 5.8 CW-083 8/16/00 4.7
9/11/00 3.66 ,DWN1 5.42 DWN2 5.53
9/6/00 6.16 DWN1 6.46 DWN2 6.5 CW-083 9/6/00 5.8
10/16/00 5.42 'DWN1 6.81 DWN2 6.62
10/9/00 4.87 pwNi 6.69 DWN2 6.94 CW-083 10/11/00 8.3
4/2/01 10.2 DWN1 10.1 DWN2 10.08
5/7/01 6.18 DWN1 6.74 DWN2 6.96
6/12/01 3.73 DWN1 5.33 DWN2 5.84
7/9/01 4.39 DWN1 5.9 DWN2 5.78
7/11/01 3.35 5.23 5.25
8/6/01 3 DWN1 5.5 DWN2 5.16
9/9/01 5.5 DWN1 5.86 DWN2 5.96
10/2/01 4.71 DWN1 6.85 DWN2 6.88

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Union County Twelve Mile Creek WWTP Projected TP Limits
57)
Design Flow
Total Phosphorus Limit
2.5 MGD
,1 mg/1 (20.85 lbs/day)
3 MGD
6 MGD
9 MGD
12 MGD
0.83 mg/I (20.85 lbs/day)
0.41 mg/I (20.85 lbs/day) 0J-it•
0.28 mg/I (20.85 lbs/day)
0.21 mg/I (20.85 lbs/day)
("Al 15 &)
fir /1"frAtr--et'srM ah-4j .4AL-7
-rt 13

AMB STATION
DATE
DO (mg/L)
C9819500
C9819500
C9819500
09819500
C9819500
09819500
C9819500
C9819500
C9819500
C9819500
09819500
09819500
09819500
09819500
1C9819500
04/06/1999
05/11/1999
06/28/1999
07/21/1999
08/19/1999
09/13/1999
10/18/1999
11/18/1999
01/19/2000
02/03/2000
03/06/2000
04/04/2000
05/10/2000
06/22/2000
07/25/2000
C9819500
09819500
C9819500
08/14/2000
09/11/2000
10/17/2000
Twelve Mile Creek Instream DO data
UPSTRM DATE DO (mg/L) DWN1
DO (mg/L)
DWN2
DO (mg/L)
SC DWN DATE
DO (mg/L)
8.1
8.7
6.7
5.5
2.2 UPSTRM 8/18/99 2.1 DWN1 4.36 DWN2 4.77 CW-083 8/19/99 3.4
3.4 UPSTRM 9/13/99 3.31 DWN1 5.3 DWN2 6.25 CW-083 9/23/99 6.6
6.3
6.0
10.9
12.3
10.2
7.2
7 UPSTRM 5/10/00 6.46 DWN1 5.4 DWN2 6.65 CW-083 5/8/00 8.3
6.2 UPSTRM 6/22/00 4.47 DWN1 3.79 DWN2 4.46
UPSTRM 6/14/00 4.49 DWN1 3.78 DWN2 4.67 CW-083 6/14/00 5.2
7.1 UPSTRM 7/24/00 3.85 DWN1 4.84 DWN2 4.83
UPSTRM 7/26/00 4.77 DWN1 5.44 DWN2 5.5
UPSTRM 7/17/00 4.06 DWN1 5.36 DWN2 5.33 CW-083 7/18/00 4.7
UPSTRM 7/19/00 3.32 DWN1 5.1 DWN2 5.15 CW-083 7/18/00 4.7
5.9 UPSTRM 8/14/00 4.75 DWN1 6.1 DWN2 6.33 CW-083 8/16/00 4.7
UPSTRM 8/16/00 3.75 DWN1 5.5 DWN2 5.8 CW-083 8/16/00 4.7
5.9 UPSTRM 9/11/00 3.55 DWN1 5.42 DWN2 5.53
UPSTRM 9/6/00 6.16 DWN1 6.46 DWN2 6.5 CW-083 9/6/00 5.8
7.1 UPSTRM 10/16/00 5.42 DWN1 6.81 DWN2 6.62
____
UPSTRM 10/9/00 4.87 DWN1 6.69 DWN2 6.94 CW-083 10/11/00 8.3
C9819500 11/20/2000 9.2
09819500 1 12/12/20061 9.6
09819500 01/04/2001 13.4
09819500 02/07/2001 11.7
09819500 04/05/2001 9.8 UPSTRM 4/2/01 10.2 DWN1 10.1 DWN2 10.08
09819500 - 05/03/2001 6.9 UPSTRM 5/7/01 6.18 DWN1 6.74 DWN2 6.96
C9819500 06/12/2001 4.5 UPSTRM 6/12/01 3.73 DWN1 5.33 DWN2 5.84
C9819500 07/10/2001 4.6 UPSTRM 7/9/01 4.39 DWN1 5.9 DWN2 5.78
7/11/01 3.36 5.23 5.25
C9819500 08/06/2001 2.8 UPSTRM 8/6/01 3 DWN1 5.5 DWN2 5.16
C9819500 09/06/2001 5.3 UPSTRM 9/9/01 5.5 DWN1 5.86 DWN2 5.96
09819500 10/02/2001 5.5 UPSTRM 10/2/01 4.71 DWN1 6.85 DWN2 6.88
09819500 12110/2001 2.4
09819500-Twelve Mi. Creek @ Hwy 16 nr Waxhaw
Upstrm- 50 ft above WWTP
Dwn1-1/4 mi. below WVVTP
Dwn2 - @ NCSR1301
SC Dwn- @ SC State Road 55

AMB STATION
DATE
DO (mg/L)
C9819500
C9819500 -1
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
C9819500
04/06/1999
05/11/1999
06/28/1999
07/21/1999
08/19/1999
09/13/1999
10/18/1999
11/18/1999
01/19/2000
02/03/2000
03/06/2000
04/04/2000
05/10/2000
06/22/2000
07/25/2000
8.1
8.7
6.7
5.5
UPSTRM DATE
Twelve Mile Creek Instream DO data
DO (mg/L)
DWN1 DO (mg/L) DWN2
DO (mg/L)
SC DWN DATE
DO (mg/L)
2.2 UPSTRM 8/18/99 2.1 DWN1 4.36 DWN2 4.77 CW-083 8/19/99 3.4
3.4 UPSTRM 9/13/99 3.31 DWN1 5.3 DWN2 6.25 CW-083 9/23/99 6.6
6.3
6.0
10.9
12.3
10.2
7.2
7 UPSTRM 5/10/00 6.46 DWN1 5.4 DWN2 6.65 CW-083 5/8/00 8.3
6.2 UPSTRM 6/22/00 4.47 DWN1 3.79 DWN2 4.46
UPSTRM 6/14/00 4.49 DWN1 3.78 DWN2 4.67 CW-083 6/14/00 5.2
7.1 UPSTRM 7/24/00 3.85 DWN1 4.84 DWN2 4.83
UPSTRM 7/26/00 4.77 DWN1 5.44 DWN2 5.5
UPSTRM 7/17/00 4.06 DWN1 5.36 DWN2 5.33 CW-083 7/18/00 4.7
UPSTRM 7/19/00 3.32 DWN1 5.1 DWN2 5.15 CW-083 7/18/00 4.7
08/14/2000 5.9 UPSTRM 8/14/00 4.75 DWN1 6.1 DWN2 6.33 CW-083 8/16/00 4.7
UPSTRM 8/16/00 3.75 DWN1 5.5 DWN2 5.8 CW-083 8/16/00 4.7
09/11/2000 5.9 UPSTRM 9/11/00 3.66 DWN1 5.42 DWN2 5.53
UPSTRM 9/6/00 6.16 DWN1 6.46 DWN2 6.5 CW-083 9/6/00 5.8
10/17/2000 7.1 UPSTRM 10/16/00 5.42 DWN1 6.81 DWN2 6.62
UPSTRM 10/9/00 4.87 DWN1 6.69 DWN2 6.94 CW-083 10/11/00 8.3
11/20/2000 9.2
12/12/2000 9.6
01/04/2001 13.4
02/07/2001 11.7
04/05/2001 9.8 UPSTRM 4/2/01 10.2 DWN1 10.1 DWN2 10.08
05/03/2001 6.9 UPSTRM 5/7/01 6.18 DWN1 6.74 DWN2 6.96
06/12/2001 4.5 UPSTRM 6/12/01 3.73 DWN1 5.33 DWN2 5.84
07/10/2001 4.6 UPSTRM 7/9/01 4.39 DWN1 5.9 DWN2 5.78
7/11/01 3.35 5.23 5.25
08/06/2001 2.8 UPSTRM 8/6/01 3 DWN1 5.5 DWN2 5.16
09/06/2001 5.3 UPSTRM 9/9/01 5.5 DWN1 5.86 DWN2 5.96
10/02/2001 5.5 UPSTRM 10/2/01 4.71 DWN1 6.85 DWN2 6.88
12/10/2001 2.4
C9819500-Twelve Mi. Creek @ Hwy 16 nr Waxhaw
Upstrm- 50 ft above VVVVTP
Dwn1-1/4 mi. below VVVVTP
Dwn2 - @ NCSR1301
SC Dwn- @ SC State Road 55

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Union County -Twelve Mile Creek WWTP Meeting
April 25, 2002
10:30 am
Raleigh, NC
Agenda
chri 1) Introductions
v 2) Speculative effluent limits, including total uP", for a permitted flow
of 6 mgd
a
a
a
0
(,,`;• )-V1,\t,
3) Potential effluent limits or requirements not in the current NPDES
permit — Cui, ZAI -1,0#-L'i) .v-,-1-nril . -r.'„_(-;,.),),-, (t.,,,, ,./ fitr-ih
4nformation that will be required to support the request for an
expanded permit (engineering analysis of alternatives, etc.)
\CP (16)Specific requirements of the E/A for the WWTP
(6) Requirements of the County to hold public hearings-1,
(71c,
3-/
7) Timeline for the NPDES permit process
pric-6,- k-
fl 8) Any additional information McKim & Creed/or Union County can
supply in support of the new permit
tio 1-e-sm "
/1fr,
c,
Ft)
.011,,,v1 9) Review the procedures for re -rating the existing 12 Mile Creek
WWTP from 2.5 to approximately 3.0 mgd
0 Since the County's NPDES Permit renewal is past due, does
DENR prefer to renew the existing permit or process a new permit
with new limits, including phosphorous, at a new flow of around
6.0 mgd?
Miscellaneous/Closing

4??fr McKIM&CREED
April 30, 2001 00771.0021 (10)
Ms. Jackie Nowell, Environmental Engineer
Division of Water Quality
NC DENR
1617 Mail Service Center
Raleigh, NC 27699-1617
RE: Request for NPDES Speculative Limits
Union County Twelve Mile Creek, NC 0085359
Dear Ms. Nowell,
At the suggestion of Michael Myers, I am submitting information regarding long range
capacity needs for Union County's Twelve Mile Creek Wastewater Treatment Plant. McKim
& Creed has completed a draft of the Master Sewer Study for Union County. Part of this
effort has involved a detailed analysis of population trends and flow capacity needs for each
of the County's major drainage basins. The attached Executive Summary summarizes
information for each of these basins, including Twelve Mile Creek.
As noted, it is anticipated that the Twelve Mile Creek basin, which is currently served by the
Twelve Mile Creek treatment facility, rated at 2.5 MGD, will grow rapidly in the next decades.
The master planning effort suggests that the treatment plant should be re -rated immediately,
and that the County should proceed expeditiously to increase the capacity of the plant to
approximately 6 MGD. It is estimated that the long range capacity needs for the Twelve Mile
Creek basin will range between 12 and 15 MGD, based upon current land use and zoning.
On the basis of these needs, Mr. Jon Dyer, PE, Director of Union County Public Works
submitted a letter requesting speculative limits for capacity ranges up to 12 MGD. I hope the
attached information will support this need, and allow the Division of Water Quality to
expediently process Union County's request and to submit speculative limits to the County
for their consideration. If you have any questions regarding the request or the flow capacity
requirements for the Twelve Mile Creek basin, please feel free to contact our office at 704-
841-2588. We appreciate your assistance in this significant endeavor.
RespectfuHy,
McKIM & CRT),PA
William S. Riddick, Jr., PE
Senior Project Manager
pc: Mr. Jon Dyer, PE
r • -
r
2300 SARDIS ROAD NORTH, SUITE A, CHARLOTTE, NORTH CAROLINA 28227
TEL [phone] Fax [phone] www.mckimcreed.com
AA0002667