NC0085359_Permit (Issuance)_20060626

NPDES DOCUMENT 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:
June 26, 2006
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content on the re‘rernse !side

WArF7 Michael F. Easley
`C. QG Governor
co r William G. Ross, Jr., Secretary
j 1 North Carolina Department of Environment and Natural Resources
0 Alan W. Klimek, P.E., Director
Division of Water Quality
June 26, 2006
Ms. Christie Putnam
Union County Public Works
400 North Church Street
Monroe, North Carolina 28112
Subject: NPDES Permit Issuance
Permit No. NC0085359
Twelve Mile Creek WWTP
Union County
Dear Ms. Putnam:
Division personnel have reviewed and approved Union Co ity's Twelve Mile
Creek WWTP Site Specific Metals Development Water Effect Ratio (WER) Study for
Copper and Zinc Effluent Limits submitted to our office. Accordingly, we are
forwarding the attached NPDES discharge permit. This permit 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 May 9, 1994 (or as subsequently amended.)
This final permit authorizes Union County Public Works Department to
discharge 2.5 MGD -of treated wastewater from the Twelve Mile Creek WWTP, with an
expansion. phase to 6. MGD. Discharge limitations and/or monitoring for flow,
biochemical oxygen demand (BOD), total suspended solids (TSS), ammonia, fecal
coliform bacteria, total phosphorus, pH, total residual chlorine, chromium, copper and
zinc are included in the permit.
The *following modifications are included in the final permit:
• Effluent limitations for copper and zinc have been modified based on the results
of the site -specific criteria study that was conducted by Union County. A
reasonable potential analysis showed that the discharge had the potential to
exceed these site -specific standards.
At 2.5 MGD, the weekly average limit for copper is 13.2 ug/1, and the daily
maximum limit is 18.5 ug/1. At 6.0 MGD, the weekly average limit for copper is
13.0 ug/1 and the daily maximum limit is 18.5 ug/l.
At 2.5 MGD; the daily maximum limit for zinc is 175 ug/l. At 6.0 MGD, the
daily maximum limit for zinc is 172 ug/I. There is no weekly average limit at
either permitted wasteflow.
- N. C. Division of Water Quality / NPDES Unit
1617 Mail Service Center, Raleigh, NC 27699-1617
Internet h2o.enrstate.nc.us
Phone: [phone]
fax [phone]
DENR Customer Service Center 1 800 623-7748

Letter to Ms. Putnam
Page 2
If any parts, measurement frequencies or sampling requirements contained
in this permit are unacceptable to you, you have the right to an adjudicatory
hearing upon written request within thirty (30) days following receipt of this letter.
This request must be in the form of a written petition, conforming to Chapter 150B
of the North Carolina General Statutes, and filed with the office of Administrative
Hearings, 6714 Mail Service Center, Raleigh, North Carolina 27699-6714. Unless
such a demand is made, this permit shall be final and binding.
Please take notice that this permit is not transferable. The Division may
require modification or revocation and reissuance of the permit. This permit does
not affect the legal requirements to obtain other permits, which may be required by
the Division of Water Quality, or permits required by the Division of Land
Resources, Coastal Area Management Act, or any other Federal or Local
governmental permits may be required.
If you have any questions or need additional information, please contact Ms.
Jacquelyn Nowell at telephone number [phone], extension 512.
Attachments
cc: Mooresville Regional Office / Surface Water Protection Section
Aquatic Toxicology Unit
EPA/ Region IV attn. Marshall Hyatt
Jeff deBessonet/ Bureau of Water DHEC, 2600 Bull St. Columbia SC 29201
James N. Struve, P.E./ Hazen and Sawyer, P.C. 4944 Parkway Plaza Blvd.
Suite 375 Charlotte NC 28217
U.S. Fish and Wildlife Service :Attn: Contaminants Specialist.
PO Box 33726 Raleigh, NC 27636-3726
NC Wildlife Resources Commission :Division of Inland Fisheries Attn: Shannon
Deaton 1721 Mail Service Center Raleigh, NC 27699-1721
Central Files
Permit File

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
3104 Providence Road South
Waxhaw
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, II and III hereof.
This permit shall become effective August 1, 2006.
This permit and authorization to discharge shall expire at midnight on June 30, 2010.
Signed this day June 26, 2006.
f
an W. Klimek, P.E., Director
Division of Water Quality
By Authority of the Environmental Management Commission

Permit NC008$359 s
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 2.5 MGD wastewater treatment facility that includes
the following components:
> Self-cleaning influent filter screen
> Vortex grit chamber
> pH adjustment
> Two oxidation ditch systems
> Two final clarifiers
> Dual tertiary sand filters
> Ultraviolet disinfection
➢ Cascade post aeration
> Two sludge storage tanks with diffused aeration
> Sludge digester (1.0 MGD)
> Alum and polymer feed systems
> Stand-by power generator
This facility is located at the Twelve Mile Creek Wastewater Treatment Plant off
Providence Road South near Waxhaw in Union County.
2. Upon issuance of ' an Authorization to Construct permit by the Division and
submission of the engineer's certification for expansion, operate a wastewater
treatment facility up to a design flow of 6.0 MGD and,
3. 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.

Facility Information
Latitude: 34°57'Ol" Sub -Basin 03-08-38
T.. thtiat 80°45'44"
HIVE
Stream Class; C
Jieoeiving Stream: Twelve Mile Cheek .
Twelve Mile CreekWWTP
NC0085359
Union County
Facility
Location
North

Permit NC0085359
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [2.5 MGD]
During the period beginning on the effective date of the permit and lasting until expansion above 2.5
MGD or expiration, the Permittee is authorized to discharge from outfall 001. Such discharges shall
be limited and monitored by the Permittee as specified below:
PARAMETER
LIMITS
. MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample Type
Sample Locations
Flow
2.5 MGD
Continuous
Recording
Influent or Effluent
BOD, 5-day, 20°C
(April 1 - October 31) 2
5.0 mg/L
7.5 mg/L
Daily
Composite
Influent & Effluent
BOD, 5-day, 20°C
(November 1 - March 31) 2
10.0 mg/L
15.0 mg/L
Daily
Composite
Influent & Effluent
Total Suspended Solids 2
30.0 mg/L
45.0 mg/L
Daily
Composite
Influent & Effluent
NH3 as N
(April 1 — October 31)
2.0 mg/L
6.0 mg/L
Daily
Composite
Effluent
NH3 as N
(November 1 — March 31)
4.0 mglL
12.0 mg/L
Daily
Composite
Effluent
Dissolved Oxygen3
Daily
Grab
Effluent
Dissolved Oxygen
(June through September)
3/Week
Grab
Upstream & Downstream'
Dissolved Oxygen
(October through May)
1/Week
Grab
Upstream & Downstream'
pH
> 6.0 and < 9.0 standard units
Daily
Grab
Effluent
Total Residual Chlorine4
17.0 pg/L
28.0 pg/L
Daily
Grab
Effluent
Total Nitrogen (NO2+NO3+TKN)
Monthly
Composite
Effluent
Total Phosphorus 5
Monthly Average: 41.70 pounds/day
12 Month average: 20.85 pounds/day
Monthly
Composite
Effluent
Temperature, °C
Daily
Grab
Effluent
Temperature, °C
(June through September)
3/Week
Grab
Upstream & Downstream'
Temperature, °C
(October through May)
1/Week
Grab
Upstream & Downstream'
Fecal Coliform (geometric mean)
200/100 ml
400/100 mi
Daily
Grab
Effluent
Fecal Coliform (geometric mean)
(June through September)
3/Week
Grab
Upstream & Downstream'
Fecal Coliform (geometric mean)
(October through May)
1/Week
Grab
Upstream & Downstream'
Conductivity
Daily
Grab
Effluent
Conductivity
(June through September)
3Mleek
Grab
Upstream & Downstream'
Conductivity
(October through May)
1lWeek
Grab
Upstream & Downstream'
Total Chromium6
Monthly
Composite
Effluent
Total Copper
13.2 pg/l
18.5.g/I
Weekly
Composite
Effluent
Total Zinc
175 Ng/l
Weekly
Composite
Effluent
Chronic Toxicity7
Quarterly
Composite
Effluent
Annual Pollutant Scan8
Annually
See A.(5.)
Effluent
Notes on following page:

Permit NC0085359
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [2.5 MGD]
[continued]
1. Upstream: 50 feet upstream from the outfall. Downstream samples shall be collected at two
locations. D 1: One quarter mile downstream from the outfall, before confluence with the first
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.
5. Part A. (4.) describes the methodology for calculation of the monthly average and 12-month limits.
6. Monitoring requirement may be deleted upon written notification from the permitting authority.
7. Chronic Toxicity (Ceriodaphnia) P/F @ 90% with testing in February, May, August and November
(see A. (3.)).
8. See Special Condition A. (5.)
There shall be no discharge of floating solids or visible foam in other than trace amounts.

Permit NC0085359
A. (2.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [6.0 MGD]
During the period beginning upon expansion above 2.5 MGD 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°C
(April 1 - October 31) 2
5.0 mg/L
7.5 mg/L
Daily
Composite
Influent & Effluent
BOD, 5-day, 20°C
(November 1 - March 31) 2
10.0 mg/L
15.0 mg/L
Daily
Composite
Influent & Effluent
Total Suspended Solids 2
30.0 mglL
45.0 mg/L
Daily
Composite
Influent & Effluent
NH3 as N
(April 1 — October 31)
1.0 mg/L
3.0 mg/L
Daily
Composite
Effluent
NH3 as N
(November 1— March 31)
2.0 mg/L
6.0 mg/L
Daily
Composite
Effluent
Dissolved Oxygen3
Daily
Grab
Effluent
Dissolved Oxygen
(June through September)
31Week
Grab
Upstream & Downstream'
Dissolved Oxygen
(October through May)
1/Week
Grab
Upstream & Downstream'
pH
> 6.0 and < 9.0 standard units
Daily
Grab
Effluent
Total Residual Chlorine4
17.0 pg/L
Daily
Grab
Effluent
Total Nitrogen (NO2+NO3+TKN)
Monthly
Composite
Effluent
Total Phosphorus 5
Monthly Average: 41.70 pounds/day
12 Month average: 20.85 pounds/day
Monthly
Composite
Effluent
Temperature, °C
Daily
Grab
Effluent
Temperature, °C
(June through September)
3/Week
Grab
Upstream & Downstream'
Temperature, °C
(October through May)
1/Week
Grab
Upstream & Downstream'
Fecal Coliform (geometric mean)
200/100 ml
400/100 ml
Daily
Grab
Effluent
Fecal Coliform (geometric mean)
(June through September)
3/Week
Grab
Upstream & Downstream'
Fecal Coliform (geometric mean)
(October through May)
1/Week
Grab
Upstream & Downstream'
Conductivity
Daily
Grab
Effluent
Conductivity
(June through September)
3lWeek
Grab
Upstream & Downstream'
Conductivity
(October through May)
1/Week
Grab
Upstream & Downstream'
Total Chromium6
Monthly
Composite
Effluent
Total Copper
13.0 pg/I
18.5 pg/I
Weekly
Composite
Effluent
Total Zinc
172 pg/I
Weekly
Composite
Effluent
Chronic Toxicity7
Quarterly
Composite
Effluent
Annual Pollutant Scan8
Annually
See A.(5.)
Effluent
Notes on following page:

Permit NC0085359
A. (2.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [6.0 MGD]
-[continued]
1. Upstream: 50 feet upstream from the outfall. Downstream samples shall be collected at two
locations. D 1: One quarter mile downstream from the outfall, before confluence with the first
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. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
5. Monitoring requirement and limit applies only if chlorine is added for disinfection.
6. Part A. (4.) describes the methodology for calculation of the monthly average and 12-month limits.
7. Monitoring requirement may be deleted upon written notification from the permitting authority.
8. Chronic Toxicity (Ceriodaphnia) P/F @ 90% with testing in February, May, August and November
(see A. (3.)).
9. See Special Condition A.(5).
There shall be no discharge of floating solids or visible foam in other than trace amounts.

Permit NC0085359
SUPPLEMENT TO EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
SPECIAL CONDITIONS
A. (3.) CHRONIC TOXICITY PASS/FAIL PERIVIIT 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 Branch
1621 Mail Service Center
Raleigh, North Carolina 27699-1621
Completed Aquatic Toxicity Test Forms shall be filed with the Environmental Sciences Branch 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 beno 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 Branch 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 1
A. (4.) 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 Mass Loading (pounds/day)= >TPma +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 first worksheet is due with the DMR 12 months from the effective date of the TP limit
(referenced in A. (1)).
In the period between the effective date and the requirement to submit the attached
worksheet, the TP monthly average mass loadings should be reported on the appropriate
monthly DMR.
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
Reporting Month:
Beginning Month:
Ending Month:
Union County
Twelve Mile Creek WWTP
Nutrient Worksheet
NPDES Permit NC0085359
(Month 1)
(Month 12)
Monthly Average Total Phosphorus
pounds/day
Month 1
Month 2
Month 3
Month 4
Month 5
Month 6
Month 7
Month 8
'Month 9
Month 10
Month 11.
Month 12
12-Month Mass Loading
Note: The TP mass loadings for the current reporting month should be entered for Month 1.

Permit NC0085359
A. (5.) EFFLUENT POLLUTANT SCAN
The permittee shall perform an annual Effluent Pollutant Scan for all parameters listed in the table
below (in accordance with 40 CFR Part 136). The annual effluent pollutant scan samples shall
represent seasonal (summer, winter, fall, spring) variations over the 5-year permit cycle. Unless
otherwise indicated, metals shall be analyzed as "total recoverable." Additionally, the method detection
level and the minimum level shall be the most sensitive as provided by the appropriate analytical
procedure.
Ammonia (as N)
Chlorine (total residual, TRC)
Dissolved oxygen
Nitrate/Nitrite
Illeldahl nitrogen
Oil and grease
Phosphorus
Total dissolved solids
Hardness
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
Lead
Mercury
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-dichloroethane
1,2-dichloroethane
Trans-1, 2-dichloroethylene
1,1-dichloroethylene
1,2-dichloropropane
1,3-dichloropropylene
Ethylbenzene
Methyl bromide
Methyl chloride
Methylene chloride
1,1,2,2-tetrachloroethane
Tetrachloroethylene
Toluene
1,1,1-trichloroethane
1,1,2-trichloroethane
Trichbroethylene
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
Benzo(k)fluoranthene
Bis (2-chloroethoxy) methane
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
Fluorene
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclo-pentadiene
Hexachloroethane
Indeno(1,2,3-cd)pyrene
Isophorone
Naphthalene
Nitrobenzene
N-nitrosodi-n-propylamine
N-nitrosodimethylamine
N-nitrosodiphenylamine
Phenanthrene
Pyrene
1,2,4-trichlorobenzene
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. A copy of the report shall be submitted to Central
Files at the following address: Division of Water Quality, Surface Water Protection Section,
1617 Mail Service Center, Raleigh, North Carolina 27699-1617

ADDENDUM TO THE FACTSHEET AMENDMENT 6 / 21 / 2006
The Division of Water Quality (DWQ) has completed its review of Union County's
Twelve Mile Creek WWTP Site Specific Metals Development Water Effect Ratio (WER)
Study for Copper and Zinc Effluent Limits. We have also evaluated the subsequent
supplemental information that addressed SCDHEC's comments and request for
monthly average copper limits.
Union County's NPDES permit contains a schedule for daily maximum copper and
zinc limits that would have become effective on June 1, 2006. Currently at the
permitted wasteflows of 2.5 MGD and 6.0 MGD, the copper limits would have been
10.5 fig/ L and 10.3 pg/L, respectively; the zinc limits would have been 94 fig/ L and
93 fig/ L, respectively.
After evaluation of the study results, DWQ has determined to accept the WER site -
specific values calculated in the report. The limits based on dissolved partitioning will
not be considered. The dissolved partitioning conversion and WER conversions should
*not* be applied to water quality criteria in series as submitted in the February 2006
report. The WER results provide the most direct estimation of copper and zinc toxicity
to aquatic life in Twelve Mile Creek.
The WER results for Copper are:
Site specific CCC= 12.86 fig/L
Site specific CMC= 18.52 fig/L
The WER result for Zinc is:
Site specific CMC= 170.6 fig/L
DWQ staff conducted a reasonable potential analysis using the values above as input
for the copper and zinc standards, and effluent data from January 2003 through
December 2005. Results at both flows indicated that with the WER site -specific
values, there was still reasonable potential for both copper and zinc to exceed the
allowable effluent concentrations. The Union County permit will be modified to
include the revised copper and zinc limits developed from the WER study. The new
limits will be as follows:
At 2.5 MGD
Total Copper = 13.2 fig/L (weekly average); 18.5 fig/L (daily maximum)
Total Zinc = 175 fig/ L (daily maximum)
At 6.0 MGD
Total Copper = 13.0 ug/1 (weekly average); 18.5 fig/L (daily maximum)
Total Zinc = 172 fig/ L (daily maximum)
Supplemental information from Union County and an updated reasonable potential
analysis for copper and zinc was forwarded to SCDHEC and EPA Region IV.
Comments were to be submitted June 16, 2000. No adverse comments to the
modification to these new limits was received. DWQ will issue a modified permit to
Union Co ty with the site specific limits for total copper and total zinc
NAME*
DATE: 0/200
Union County -Twelve Mile Creek WWTP Fact Sheet
NPDES Renewal
Page 10

Union County North Carolina
Twelve Mile Creek WWTP
Site Specific Metals Development
Water Effect Ratio Study for Copper and Zinc Effluent Limits
Supplemental Information
The Union County Twelve Mile Creek WWTP is a 2.5 mgd facility which discharges a
highly treated effluent into Twelve Mile Creek about 1 mile upstream of the North
Carolina / South Carolina border. The effluent has an NPDES permit with the following
general permit limits:
Parameter
Twelve Mile Creek Permit Limits
Monthly Average Weekly Average
Flow, mgd 2.5 N/A
Copper, ug/L 2.75 3.6
Zinc, ug/L N/A 35.6
BOD, mg/L April — Oct. 5.0 7.5
BOD, mg/L, Nov. — March 10.0 15.0
TSS, mg/L 30 45
The permit is issued by the North Carolina Department of Environment and Natural
Resources (NCDENR) with United States Environmental Protection Agency (USEPA)
oversight.
Because the facility discharges only a modest distance upstream of South Carolina
jurisdiction, South Carolina Department of Health and Environmental Control (DHEC)
had concerns with the copper and zinc permit limits and provided concerns with the
metal limits as developed by the NCDENR protocols. After a series of meetings,
discussions, and a site specific study, the regulatory agencies concurred that a Water
Effect Ratio Study for copper and zinc would address outstanding concerns. This report
presents the WER study results and proposed effluent limits which are in accordance
with the guidelines of all three regulatory agencies.
The water effect ratio approach is based on the toxicity test results of the standardized
laboratory water and a simulated stream water (sim stream). Comparing the results of
the two laboratory tests allows a ratio to be developed, known as the water effect ratio
1

(WER) which can be used to multiply the National numerical criteria for a metal and
derive a site specific alternative criterion (SSAC) for the parameter.
The standardized laboratory water was the basis for the original development of the
numerical standards for the metals. However, this synthetic laboratory water does not
exist in nature and the use of the natural water with the real world chemical
characteristic is considered more representative of the actual in stream conditions.
Also, SCDHEC provides guidance for evaluating the partitioning of the dissolved fraction
of the metal. This approach is important as only the dissolved fraction is considered a
source of toxicity for the metals of interest. It is also important to recognize that all of
these approaches are fully protective of the environment. Because the Twelve Mile
Creek WWTP has consistently passed the whole effluent toxicity tests, a high level of
confidence is present that the metals are not toxic.
The study results are presented as the (CCC) criterion continuous concentration which
corresponds to the monthly average value and the criterion maximum concentration
CMC which corresponds to the weekly average. Because copper has both monthly and
weekly average permits limits the study developed CCC and CMC values. Because zinc
only has a weekly average value, the study develops the CMC values. The results are
presented in the following table:
Parameter
12 Mile Creek WWTP
WER and Dissolved Metals Partitioning Study Results
Water Effect Ratio Dissolved Partitioning
Copper, ug/L
Monthly Average 12.86 43.06
Weekly 18.52 61.99
Zinc, ug/L
Weekly 170.6 738.2
Because zinc has the same concentration for both CCC and CMC in the SCDHEC water
quality standards, it is reasonable to assume the monthly and weekly allowable
concentrations are the same. To determine if permit limits are really necessary, a
reasonable potential evaluation is used. The reasonable potential evaluation consists of
a statistical evaluation and determination of maximum projected values which is known
as the reasonable potential value. The reasonable potential value can be compared with
the site specific alternative criteria (SSAC) and if the reasonable potential value is less
than the SSAC, there is not a need for a permit limit for that parameter.
The copper reasonable potential evaluation was conducted on 140 data points from May
2003 to December 2005 which includes periods of plant upset when the maximum
2

effluent copper concentration was 18 ug/L and also periods when the metal sampling
was conducted with conventional techniques. Using the EPA procedures and NC and
SC acceptable protocol, the maximum projected weekly effluent concentration is 37.8
ug/L of total recoverable copper, which is well below the CMC value for copper of 61.99
ug/L. Using a monthly average approach, the maximum monthly average value
determined by the reasonable potential evaluation is 16.5 ug/L. This is well below the
monthly average CCC value of 43.06 ug/L determined by the WER. Thus there is not a
justification for a permit requirement for copper. Should a permit limit for copper be
implemented the dissolved partitioning derived values which indicate the monthly
average should be 43.06 ug/L and the weekly average be 61.99 ug/L.
For zinc, using the same data base of 140 samples, the reasonable potential evaluation
shows the maximum projected value is 1,512 ug/L. Hence, the weekly maximum of
738.2 ug/L is appropriate for a zinc monthly average. Because no sample ever
exceeded this value, a high rate of compliance is anticipated.
Using a monthly average approach, the reasonable potential highest projected
concentration for zinc is 461.5 ug/L which is well below the CCC/CMC value for zinc of
738.2 ug/L. Hence a monthly average zinc permit condition is not warranted.
In summary, the 12 Mile Creek WWTP effluent copper and zinc were evaluated to
determine site specific alternative criteria for these metals using the WER and dissolved
partitioning approaches. Based on the study data, the SSAC for copper is 12.86 ug/L
based on a WER approach and 43.06 ug/L based on a dissolved partitioning approach
for a monthly average value. This dissolved partitioning value is appropriate for
reasonable potential evaluation. The reasonable potential evaluation indicates a permit
limit is not necessary for copper for either weekly or monthly monitoring. If a copper
permit limit is necessary, the limit should be a monthly maximum of 43.06 ug/L of copper
and the weekly maximum criterion should be deleted. Also, if after twelve months of
collecting data using clean techniques and the results indicate little potential, then the
monitoring frequency should be reduced to a monthly frequency or eliminated all
together.
For zinc, the WER and dissolved partitioning approaches indicate the weekly maximum
SSAC are 170.6 ug/L and 738.2 ug/L, respectively. The reasonable potential evaluation
indicates the zinc permit limit of 738.2 ug/L as a weekly maximum is warranted.
Because this limit is somewhat above the highest of 140 samples, it is envisioned there
will be a high rate of compliance. The monthly average maximum projected
concentration for zinc is only about 62.4% of the allowable zinc dissolved derived
allowable concentration of 738.2 ug/L. Therefore, there is no justification for a monthly
average zinc permit limit. If after twelve months of collecting data using clean
techniques and the results indicate no reasonable potential for exceedances, then
monitoring frequency should be reduced or eliminated all together.
3

REASONABLE POTENTIAL ANALYSIS
Union County -Twelve Mile Creek
< NC0085359 >
Time Period 01/2003-12/2005
Ow (MGD) 2.5
7Q10S (cfs) 0.1
7Q10W (cfs) 1.5
3002 (cfs) 3.2
Avg. Stream Flow, QA (cfs) 72.7
Rec'ving Stream Twelve Mile Creek
WWTP Class 4
IWC (%) ® 7Q10S 97.484
0 7Q1OW 72.093
3002 54.77
@ QA 5.0604
Stream Class C
Outfall 001
Qw = 2.5 MGD
TYPE
(1)
STANDARDS &
CRITERIA (2)
PQL
Units
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
PARAMETER
NC WQS/
Chronic
t4 FAV/
Acute
n
I DeL Alex Pled Cw Albwabie Cw
Copper
NC
12.86
AL
18.52
ug/L
158
67
25.7
Acute:
_ _ _ _
Chronic:
18.5
_ _ _ --
13.2
Shows RP to exceed site specific standard. Recommend
weekly avg and daily max. limit for protection of SC WQ std
-------------------------------
Zinc
NC
170.6
AL
170.6
ug/L
155
151
1,072.8
Acute:
_ _ _
Chronic:
171
_ _ _ --
175
Shows RP to exceed site specific standard. Recommend
daily max. Limit for protection of SC WQ standard
-------------------------------
• Legend:
C = Carcinogenic
NC = Non -carcinogenic
A = Aesthetic
Freshwater Discharge
85359rpa2006wer2.5, rpa
5/18/2006

REASONABLE POTENTIAL ANALYSIS
Union County -Twelve Mile Creek
< NC0085359 >
Time Period 01/2003-12/2005
Ow (MGD) 6
7Q 10S (cfs) 0.1
7Q 10W (cfs) 1.5
30Q2 (cfs) 3.2
Avg. Stream Flow, QA (cfs) 72.7
Rec'ving Stream Twelve Mile Creek
WWTP Class 4
1WC (%) 7Q10S 98.936
6, 7Q10W 86.111
@ 30Q2 74.4
• QA 11.341
Stream Class C
Outfall 001
Qw=6 MGD
PARAMETER
TYPE
{1)
STANDARDS &
CRITERIA (2)
POL
Units
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
NC WQS /
Chronk
% FAY/
Acute
n
f DeL Max Fred Cw Alkwable Cw
Copper
NC
12.86
AL
18.52
ug/L
158
67
25.7
Acute:
_ _ _ _
Chronic:
18.5
_ __
_ _ _
1
Shows RP to exceed site specific standard. Recommend
weekly avg and daily max. limit for protection of SC WQ std
-- _---- —--------- --- --- ---
Zinc
NC
170.6
AL
170.6
ug/L
155
151
1,072.8
Acute:
_ _ _ _
Chronic:
171
_ _ _ __
172
Shows RP to exceed site specific standard. Recommend
_— daily max. limit for protection of SC WQ standard
_—_—_—_—_—_—_—_—_—_—_—_—_—____
• Legend:
C = Carcinogenic
NC = Non -carcinogenic
A = Aesthetic
Freshwater Discharge
85359rpa2006wer6, rpa
5/18/2006

15
Copper
Zinc
Date Data BDL=1/2DL Results
2 1.0 Std Dev.
2 1.0 Mean
2 1.0 C.V.
8.8 8.8 n
5.8 5.8
4.4 4.4 Mult Factor =
6 6.0 Max. Value
2 1.0 Max. Pred Cw
Apr-2005
Jan-2005
Jan-2005
Dec-2004
2 1.0
8 8.0
6 5.5
2 2.1
2 1.0
2 1.0
13 13.0
18 18.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
2 1.0
3 3.1
6 6.3
2 1.0
2.3073
2.3025
1.0021
158
1.4300
18.0 ug/L
25.7 ug/L
1
2
3
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
135
36
Date Data BDL=1/2DL Results
5.0 Std Dev.
5.0 Mean
57.0 C.V.
12.0 n
28.0
14.0 Mult Factor =
61.0 Max. Value
13.0 Max. Pred Cw
5.0
5.0
10.0
87.0
67.0
48.0
47.0
100.0
110.0
50.0
42.0
38.0
43.0
39.0
51.0
50.0
51.0
48.0
62.0
42.0
52.0
72.0
63.0
48.0
60.0
32.0
69.0 85359rpa2006wer6]
71.0
Apr-2005 < 10
10
57
12
28
14
61
13
10
10
10
87
67
48
47
Jan-2005 100
Dec-2004 110
50
42
38
43
39
51
50
51
48
62
42
52
72
63
48
60
32
69
71
67.6683
57.2194
1.1826
155
1.4900
720.0 ug/L
1072.8 ug/L

Dec-2003
• 2
3
• 2
• 2
• 2
3
4
7
• 2
• 2
2
3
• 2
• 2
• 2
3
2
3
3
• 2
• 2
• 2
• 2
• 2
• 2
4
7
2
2
• 2
6
2
2
< 2
2
3
3
2
2
2
2
• 2
1.0
2.6
1.0
1.0
1.0
3.0
4.4
7.1
1.0
1.0
2.0
2.9
1.0
1.0
1.0
2.5
2.4
3.3
2.9
1.0
1.0
1.0
1.0
1.0
1.0
4.1
7.1
2.4
2.1
1.0
6.3
1,0
1.0
1.0
2.3
2.7
2.8
1.0
1.0
1.0
1.0
1.0
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
Z7
78
35
72
56
62
61
66
65
67
69
70
64
Jul-2004 720
60
61
47
66
60
63
49
Apr-2004 430
72
42
52
59
61
70
120
35
38
52
53
59
60
43
Dec-2003 74
69
48
57
62
69
65
65
35.0
72.0
56.0
62.0
61.0
66.0
65.0
67.0
69.0
70.0
64.0
720.0
60.0
61.0
47.0
66.0
60.0
63.0
49.0
430.0
72.0
42.0
52.0
59.0
61.0
70.0
120.0
35.0
38.0
52.0
53.0
59.0
60.0
43.0
74.0
69.0
48.0
57.0
62.0
69.0
65.0 85359rpa2006wer6]
65.0

1.0
5.6
2.2
1.0
1.0
1.0
1.0
1.0
3.6
3.4
5.3
2.2
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
3.6
7.4
1.0
1.0
1.0
1.0
2.3
1.0
1.0
1.0
2.8
1.0
1.0
2.7
3.5
2.5
3.4
5.3
2.1
3.6
4.3
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
-1� 9
120
36
56
37
61
46
65
61
67
54
14
48
22
65
26
17
20
24
25
15
25
28
25
24
24
29
23
23
13
28
22
17
30
24
260
32
30
27
24
35
43
37
38
36.0
56.0
37.0
61.0
46.0
65.0
61.0
67.0
54.0
14.0
48.0
22.0
65.0
26.0
17.0
20.0
24.0
25.0
15.0
25.0
28.0
25.0
24.0
24.0
29.0
23.0
23.0
13.0
28.0
22.0
17.0
30.0
24.0
260.0
32.0
30.0
27.0
24.0
35.0
43.0
37.0 85359rpa2006wer6J
38.0

3
4
3
May-2005 < 2
2
2
3
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
3
3
2
3
5
3
2
Dec-2005 2
3.4
4.2
3.4
1.0
1.0
2.2
3.4
2.0
1.0
1.0
2.1
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
2.2
1.0
1.0
2.2
2.8
1.0
2.5
2.6
2.0
3.3
5.3
3.3
1.0
2.0
3 2.6
7 7.3
4 4.3
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
1459
May-2005
Dec-2005
15
38
40
58
31
45
69
56
42
33.0
44.0
50.0
48.0
49.0
53.0
49.0
53.0
64.0
69.0
65.0
50.0
64.0
80.0
62.0
120.0
96.0
69.0
77.0
110.0
65.0
68.0
61.0
68.0
32.0
31.0
15.0
38.0
40.0
58.0
31.0
45.0
69.0
56.0
42.0
33.0
44.0
50.0
48.0
49.0
53.0
49.0
53.0
64.0
69.0
65.0
50.0
64.0
80.0
62.0
120.0
96.0
69.0
77.0
110.0
65.0
68.0
61.0
68.0
32.0
31.0
85359rpa2006wer6]

Union County, North Carolina
Twelve Mile Creek Wastewater Treatment Plant
Copper and Zinc Reasonable Potential Analysis
Chronic Toxicity
Copper Copper Deter * Monthly Average Zinc Zinc Deter * Monthly Average TSS Result Date
Date (mg/1-) (ug/L) (ug/L) (mg/L) (ug/L) (ug/L) (mg/-)
1-May-2003 <.002 1 0.025 25 1.8
8-May-2003 0.0023 2.3 0.024 24 <1.0
15-May-2003 <.002 1 0.024 24 1.6
22-May-2003 <.002 1 0.029 29 <1.0
29-May-2003 <.002 1 1.26 0.023 23 25 1
5-Jun-2003 <.002 1 0.025 25 <1 !:s` ice`'
12-Jun-2003 0.0036 3.6 0.015 15 3.2
19-Jun-2003 0.0074 7.4 0.025 25 2.6
26-Jun-2003 <.002 1 3.25 0.028 28 23.25 <1
1-Ju1-2003 <.002 1 0.026 26 1
10-Jul-2003 <.002 1 0.017 17 2
17-Jul-2003 <.002 1 0.017 17 <1
24-Ju1-2003 <.002 1 0.02 20 1.6
31-J u1-2003 <.002 1 1 0.024 24 20.8 1.2
7-Aug-2003 <.002 1 0.014 14 4.4
14-Aug-2003 <.002 1 0.048 48 1.8
21-Aug-2003 0.053 5.3 0.022 22 <1
28-Aug-2003 0.0022 2.2 2.375 0.065 65 37.25 <1
4-Sep-2003 <.002 1 0.065 65 2
10-Sep-2003 <.002 1 0.061 61 1.2 r lc ° Ra 0-;':8 ' IL, .,,='r
18-Sep-2003 0.0036 3.6 0.067 67 <1
25-Sep-2003 0.0034 3.4 2.25 0.054 54 61.75 <1
2-Oct-2003 0.0056 5.6 0.036 36 1.6
9-Oct-2003 0.0022 2.2 0.056 56 <1
16-Oct-2003 <.002 1 0.037 37 <1
23-Oct-2003 <.002 1 0.061 61 <1
30-Oct-2003 <.002 1 2.16 0.046 46 47.2 1.2
6-Nov-2003 <.002 1 0.062 62 <1
13-Nov-2003 <.002 1 0.069 69 1.4
20-Nov-2003 <.002 1 0.065 65 1.6
25-Nov-2003 <.002 1 1 0.065 65 65.25 1.4
4-Dec-2003 0.0023 2.3 0.074 74 <1
11-Dec-2003 0.0027 2.7 0.069 69 <1
18-Dec-2003 0.0028 2.8 0.048 48 <1 L2L4Pnwast='71Fitteliti
22-Dec-2003 <.002 1 0.057 57 <1
30-Dec-2003 <.002 1 1.96 0.058 58 61.2 <1
8-Jan-2004 <.002 1 0.053 53 <1
15-Jan-2004 <.002 1 0.059 59 <1
22-Jan-2004 0.0063 6.3 0.06 60 1
29-Jan-2004 <.002 1 2.325 0.043 43 53.75 1.2
4-Feb-2004 0.0041 4.1 0.07 70 1
5-Feb-2004 0.0071 7.1 0.12 120 <1
12-Feb-2004 <.002 1 0.035 35 1.4
19-Feb-2004 0.0024 2.4 0.038 38 1.8

Union County, North Carolina
Twelve Mile Creek Wastewater Treatment Plant
Copper and Zinc Reasonable Potential Analysis
Chronic Toxicity
Copper Copper Deter * Monthly Average Zinc Zinc Deter * Monthly Average TSS Result Date
Date (mg/L) (ug/L) (ug/L) (mg/L) (ug/L) (ug/L) (mg/L)
26-Feb-2004 0.0021 2.1 3.34 0.052 52 63 1.2
4-Mar-2004 <.002 1 0.042 42 <1
11-Mar-2004 <.002 1 0.052 52 1.2
18-Mar-2004 <.002 1 0.059 59 <1
25-Mar-2004 <.002 1 1 0.061 61 53.5 1 Pass 2-3/2-7
1-Apr-2004 <.002 1 0.06 60 1.8
8-Apr-2004 0.0024 2.4 0.063 63 <1
15-Apr-2004 <.002 1 0.049 49 <1
22-Apr-2004 0.0033 3.3 0.43 43 <1
29-Apr-2004 0.0029 2.9 2.12 0.072 72 57.4 <1
4-May-2004 <.002 1 0.06 60 <1
13-May-2004 <.002 1 0.061 61 <1
20-May-2004 0.0025 2.5 0.047 47 <1
27-May-2004 <.002 1 1.375 0.066 66 58.5 <1
3-Jun-2004 <.002 1 0.069 69 <1
10-Jun-2004 <.002 1 0.07 70 1.4
17-Jun-2004 0.002 2 0.064 64 <1
24-Jun-2004 0.0029 2.9 1.725 0.72 720 230.75 12.4
1-Jul-2004 <.002 1 0.056 56 <1 Pass 5-17/5-21
8-Jul-2004 <.002 1 0.062 62 1.2 ChV=92.5% 5/18/2004
15-Jul-2004 <.002 1 0.061 61 <1
22-Jul-2004 0.003 3 0.066 66 <1
29-Jul-2004 0.0044 4.4 0.065 65 <1
30-Jul-2004 0.0071 7.1 2.92 0.067 67 62.83 <1
5-Aug-2004 0.0063 6.3 0.069 69 <1
12-Aug-2004 0.0026 2.6 0.071 71 1.2
19-Aug-2004 <.002 1 0.035 35 1
26-Aug-2004 <.002 1 2.725 0.072 72 61.75 1.2
2-Sep-2004 <.002 1 0.072 72 1.2
9-Sep-2004 <.002 1 0.063 63 3.4
16-Sep-2004 <.002 1 0.048 48 <1
23-Sep-2004 0.0031 3.1 0.06 60 <1
30-Sep-2004 <.002 1 1.42 0.032 32 55 7.8
7-Oct-2004 <.002 1 0.048 48 1.2
14-Oct-2004 0.002 2 0.062 62 1.6 Pass 8-15/8-20
21-Oct-2004 <.002 1 0.042 42 <1 ChV=95% 8/17/2004
28-Oct-2004 <.002 1 1.25 0.052 52 51 <1
4-Nov-2004 <.002 1 0.039 39 1
11-Nov-2004 <.002 1 0.051 51 1.2
18-Nov-2004 <.002 1 0.05 50 <1
23-Nov-2004 <.002 1 1 0.051 51 47.75 <1
2-Dec-2004 <.002 1 0.11 110 1.2
9-Dec-2004 <.002 1 0.05 50 1
21-Dec-2004 <.002 1 0.038 38 1.4

Union County, North Carolina
Twelve Mile Creek Wastewater Treatment Plant
Copper and Zinc Reasonable Potential Analysis
Chronic Toxicity
Copper Copper Deter * Monthly Average Zinc Zinc Deter * Monthly Average TSS Result Date
Date (mg/L) (ug/L) (ug/L) (mg/L) (ug/L) (ug/L) (mg/L)
28-Dec-2004 <.002 1 1 0.043 43 60.25 4
6-Jan-2005 <.002 1 0.067 67 1.4
13-Jan-2005 <.002 1 0.048 48 2.4
20-Jan-2005 0.013 13 0.047 47 66
27-Jan-2005 0.018 18 8.25 0.1 100 65.5 182
3-Feb-2005 <.002 1 <.01 5 16.4 Pass 11-8/11-12
10-Feb-2005 0.008 8 0.087 87 63 ChV=>100% 11/9/2004
17-Feb-2005 0.0055 5.5 0.01 10 17.5
24-Feb-2005 0.0021 2.1 4.15 <.01 5 26.75 5.4
3-Mar-2005 0.0058 5.8 0.028 28 60
8-Mar-2005 <.002 1 0.014 14 6.4
17-Mar-2005 0.0044 4.4 0.061 61 4
23-Mar-2005 0.006 6 0.013 13 3.6
31-Mar-2005 <.002 1 3.64 0.017 17 26.6 2.4
7-Apr-2005 <.002 1 <.01 5 3.8
14-Apr-2005 <.002 1 <.01 5 10
21-Apr-2005 0.0088 8.8 0.057 57 95
28-Apr-2005 <.002 1 2.95 0.012 12 19.75 2
5-May-2005 <.002 1 0.015 15 5.44
12-May-2005 <.002 1 0.038 38 3.4
19-May-2005 0.0022 2.2 0.04 40 14.2
26-May-2005 0.0034 3.4 1.9 0.058 58 37.75 7.8
2-Jun-2005 0.002 2 0.031 31 10.2
9-Jun-2005 <.002 1 0.045 45 7.6
16-Jun-2005 <.002 1 0.069 69 9.2
23-Jun-2005 0.0021 2.1 0.056 56 4.6
30-Jun-2005 <.002 1 1.42 0.042 42 48.6 5.8
7-Jul-2005 <.002 1 0.033 33 11.4
14-Jul-2005 <.002 1 0.044 44 7.4
21-Jul-2005 <.002 1 0.05 50 6
28-Ju1-2005 <.002 1 1 0.048 48 43.75 3.6
4-Aug-2005 <.002 1 0.049 49 2
11-Aug-2005 <.002 1 0.053 53 13.8
17-Aug-2005 <.002 1 0.049 49 2.4
25-Aug-2005 <.002 1 0.053 53 2.2
20-Aug-2005 <.002 1 1 0.064 64 53.6 2.8
6-Sep-2005 0.0022 2.2 0.069 69 3
15-Sep-2005 <.002 1 0.065 65 6.4
23-Sep-2005 <.002 1 0.05 50 1
28-Sep-2005 0.0022 2.2 1.6 0.064 64 62 5.2
6-Oct-2005 0.0028 2.8 0.08 80 <1.0
13-Oct-2005 <.002 1 0.062 62 1
20-Oct-2005 0.0025 2.5 0.12 120 <1.0
27-Oct-2005 0.0026 2.6 2.225 0.096 96 89.5 1.6

Union County, North Carolina
Twelve Mile Creek Wastewater Treatment Plant
Copper and Zinc Reasonable Potential Analysis
Chronic Toxicity
Copper Copper Deter * Monthly Average Zinc Zinc Deter * Monthly Average TSS Result Date
Date (mg/L) (ug/L) (ug/L) (mg/i.) (ug/L) (ug/L) (mg/L)
1-Nov-2005 0.002 2 0.069 69 <4.0
8-Nov-2005 0.0033 3.3 0.077 77 <4.0
15-Nov-2005 0.0053 5.3 0.11 110 <4.0
22-Nov-2005 0.0033 3.3 0.065 65 <4.0
29-Nov-2005 <.002 1 2.98 0.068 68 77.8 <4.0
6-Dec-2005 0.002 2 0.061 61 <4.0
14-Dec-2005 0.0026 2.6 0.068 68 6.2
20-Dec-2005 0.0073 7.3 0.032 32 30
29-Dec-2005 0.0043 4.3 4.05 0.031 31 48 28.5
Average 2.260 2.269 55.667 56.149
Standard Deviation 2.393 1.444 60.616 35.925
Co Variance 1.06 0.636 1.09 0.6398
No. of Samples 140 32 140 32
Max Conc 18 8.25 720 230.75
Multiplier 2.1 2 2.1 2
Max Predicted Conc 37.8 16.5 1512 461.5

Union Co. Twelve Mile Cr. WWTP Site Specific Cu & Zn
Subject: Union Co. Twelve Mile Cr. WWTP Site Specific Cu & Zn
From: Matt Matthews <[e-mail]>
Date: Thu, 18 May 2006 12:56:07 -0400
To: Susan A Wilson <[e-mail]>, Jackie Nowell <[e-mail]>,
Connie Brower <[e-mail]>
I called Jim Struve following our meeting today. He acknowledged that applying a WER adjustment and
the TSS translator was probably "reaching a bit." There was no heartburn whatsoever with us applying
the WER adjustment alone to determine a limit. He asked about possibly reverting back to a monitoring
requirement for the metals at some point should the data warrant it. I told him (after talking with Jackie)
that this was indeed a possibility at the next permit renewal.
We both agreed that a face-to-face meeting was unnecessary at this point.
My question is: will we input the WER-adjusted numbers for their permit limit or will we want to wait
for review by SC and Region 4?
Matt Matthews
NC DENR/Division of Water Quality
Point Source Branch
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
v-[phone], ext. 517
f-[phone]
[e-mail]
http://h2o.enr.state.nc.us/swps/
1 of 1 5/23/2006 2:10 PM

REASONABLE POTENTIAL ANALYSIS
Union County -Twelve Mile Creek
< NC0085359 >
Time Period 01/2003.04/2005
Ow (MGD) 6
7010S (cfs) 0.1
7Q10W (cfs) 1.5
3002 (cfs) 3.2
Avg. Stream Flow, OA (cfs) 72.7
Rec'vrng Stream Twelve Mile Creek
WWTP Class 4
PVC (%) ® 7Q10S 98.936
7Q10W 86.111
® 3002 74.4
® QA 11.341
Stream Class C
Outfall 001
Qw = 6 MGD
PARAMETER
TYPE
(1)
STANDARDS &
CRITERIA (2)
POL
Units
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
NCWQs/ ffFAV/
Charge Acute
n /0 t. Mir Pod Or AllowabteCw
Arsenic
NC
ug(L
1 0
Note: n<12
Limited data
WA
set
Acute: WA
_ ____— ---
._51
Chronic:
-------------------•—•_---•—•—
50 g
Beryllium
C
6.5
ug/L
1 0
Note: n<12
Limlted data
NIA
set
Acute: N/A
_ _ _
• Chroni_c: - 8.7 —-------------------
--- ------- —•—
Cadmium
NC
2 15
ug/L
1 0
Note: n<12
Limited data
WA
set
Acute: 15
_
• Chron__ ic: 2.0— --
- — - — - — - — — - — - — - — - — -------------
Chromium
NC
50 1,022
ug/L
2 1
Note: n<12
Limited data
245.8•
set
Acute: 1.022
_ _ -____---------
Chronic: 51
_ -- —
Copper
NC
10.2 AL 7.3
ug/L
123 50
28.6
Acute: 7.3
_ _ __ _
• Chronic: i0.3
Shows RP to exceed site specific standard. Recommend
weetdy avg and max. limit for_protectlon of SC WQ std
laity.---- — -- - - —
Cyanide
NC
5 N 22
10
ug/L
0 0
N/A•
Acute: 22
_ _ __
Chronic: 5.1--
——•----- - ----
— — — -- — — — —
Fluoride
NC
1,800
ug/L
0 0
N/A•
Acute: WA
_ _ __ _ _
Chronic: 1,819
--—--
------- — -
Lead
NC
25 N 33.8
ug/L
1 0
Note: n<12
Limited data
N/A•
set
Acute: 34
_ _ _-_ _
Chronic: 25.3
_ _.—.--- _--------•---
Mercury
NC
0.0002
ug/L
2 2
Note: n<12
Limited data
0.0030
set
Acute: N/A
_ _ _ _
Chronic: 0.0121
- ------•—•---.—.—•—•—•—_—.—•—
-- -
0.012 .
Molybdenum
A
ug/L
1 0
Note: n<12
Limited data
WA•
set
Acute: WA
_ __
Chronic: S#4##4##
_ _----------_ -----—•-------
3.500 C'
Nickel
NC
88 261
ug/L
1 0
Note: n<12
Limited data
WA
set
Acute: 261
_ _ -__---------.—_—_—_—.—.—.—.—.—_—_--^
Chronic: 86.9
Phenols
A
ug/L
0 0
N/A
Acute: WA
_ -_ _ _-------------------------------•—
Chrontc: 8.8
1 N V'
Selenium
NC
5.0 56
ugr.
1 0
Note: n<12
Limited data
WA
set
Acute: 56
._________---________--------------
Chronic: 5.1
Silver
NC
0.06 AL 1.23
uglt.
1 0
Note: n<12
Limited data
WA
set
Acute: 1
_ _
Chronic: --0.06 -------
--------- ------------- -----
Zinc
NC
92 AL 67
ug/L
120 116
1260.0
Acute: 67
Shows RP to exceed site specific standard. Recommend
daily max. ilmtt for protection of SC WQ standard—_—.^
.—•—.—.
• Legend:
C a Carcinogenic
NC = Non -carcinogenic
A = Aesthetic
Freshwater Discharge
85359rpa2005.sssalldata6.updflo, rpa
5/18/2006

REASONABLE POTENTIAL ANALYSIS
Union County -Twelve Mile Creek
< NC0085359 >
Time Period 01/2003-04/2005
Ow (MGD) 2.5
7Q10S (cfs) 0
7010W (cfs) 1.5
3002 (cfs) 2.5
Avg. Stream Flow, OA (cfs) 69
Reeving Stream Twelve Mlle Creek
WWTP Class 4
/WC (%) ®7Q10S 100
7Q10W 72.093
3002 60.784
® QA 5.3173
Stream Class C
Outfall 001
Qw = 2.5 MGD
PARAMETER
•
TYPE
(1)
STANDARDS &
CRITERIA (2)
POL
Units
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
NCWQS/ 1 FAV/
Chronic Acute
n IDA Max Prod Cr, Mows,* Qv
Arsenic
NC
ug/L
1 0
Note: n<12
Limited data
N/A_~
set
Acute: N/A
Chronic: 50�
--------•-----------------------
50 =
Beryllium
C
6.5
ug/L
1 0
Note: n<12
Limited data
N/A
set
Acute: N/A
_ __ _------------------------•---------
Chronic: 10.7
Cadmium
NC
2 15
ug/L
1 0
Note:n<12
Limited data
WA
set _
Acute: 15
_ _ __ _ —
Chronic: 2.0
—•-------.---�—�—�---.—•—•----- —
Chromium
NC
50 1,022
ug/L
2 1
Note: n<12
Limited data
245.8
set
Acute: 1,022
_ _ __
Chronic: •_.—• 50---------
-----�—.---�----- —•— -
Copper
NC
10.2 AL 7.3
ug/L
68 24
16.7
Acute: 7
_ _ ___ _ _~.-----.—.—.—.—•—.---.—.—.—_—_---
Chronic: 10.2
Cyanide
NC
5 N 22
10
ug/L
0 0
N/A_
Acute: 22
Chronic: 5.0
---------------•-----------------
Fluoride
NC
1,800
ug/L
0 0
WA
Acute: WA
-----------------•—•-------------
Lead
NC
25 N 33.8
ug/L
1 0
Note: n<12
Limited data
WA
set
Acute: 34
_ -_ _ _---------------------------------
Chronic: 25.0
Mercury
NC
0.0002
ug/L
2 2
Note: n<12
Limited data
0.0030
set
Acute: N/A
_ _ __ _-------------------------------•—
Chronic: 0.0120
�
0.012 Imo`
Molybdenum
A
ug/L
1 0
Note: n<12
Limited data
N/A
set
Acute: N/A
_ _ __ _ __----------------------------•---
Chronic: ########
3.500 (><
Nickel
NC
88 261
ug/L
1 0
Note: n<12
Limited data
N/A
set
Acute: 261
._________—_---.---.—.—.---.—.---
Chronic: 88.0
Phenols
A
ug/L
0 0
N/A
Acute: WA
_oni-_ _ _~--•--------------------
Chrc: 18.8
-- ------—
1 N >.
Selenium
NC
5.0 56
ug/L
1 0
Note: n<12
Limited data
N/A_~.
set
Acute: 56
Chronic: 5.0
---•---------------------------
Silver
NC
0.06 AL 1.23
ug/L
1 0
Note: n<12
Limited data
WA_
set
Acute: 1
-^.—_-----.---.—_—_—_—.—_—_—•—_—_—
Chronic: 0.06
Zinc
NC
92 AL 67
ug/L
65 61
119.2
Acute: 67
_ _ ---92•—•
Chronic:
---------------•—•-----------• ---
• Legend:
C = Carcinogenic
NC = Non -carcinogenic
A = Aesthetic
Freshwater Discharge
85359rpa2005.v4sss.noouts, rpa
5/18/2006

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Union County Site Specific Metals Development - Supplemental Infor...
Subject: Union County Site Specific Metals Development - Supplemental Information for SC DHEC
From: "Struve, James N." <[e-mail]>
Date: Thu. 30 Mar 2006 06:16:31 -0500
To: <[e-mail]>
CC: <[e-mail]>, <[e-mail]>, <[e-mail]>, <[e-mail]>, "Fergen,
Robert E." <[e-mail]>
Jackie,
Per our discussion yesterday, I am emailing you this supplemental information in response to a verbal comment
received from Mike Montebello of SC DHEC. Mr. Montebello's requested that a reasonable potential analysis of the
data be performed not only for the weekly condition but also for the average month condition. Upon review by you
and your staff, we would like to schedule a meeting to discuss the results of this study and the potential changes in
may have on Union County's NPDES permit.
As a reminder, please note that the proposed daily maximum metals limits for copper (10.5 ug/L) and for zinc (94
ug/L) are to become effective at the Union County Twelve Mile Creek WTP on June 1, 2006. Consequently, we
respectfully request that we can meet prior to the effective date with the hope of coming to a resolution and hopefully
obtaining additional relief.
Please let me know if you need additional information to facilitate your review.
I look forward to hearing from you.
Regards,
Jim
James N. Struve, P.E.
Senior Associate
Hazen and Sawyer, P.C.
4944 Parkway Plaza Boulevard, Suite 375
Charlotte, NC 28217
Office [phone]
Direct [phone]
Fax [phone]
Email jstruvehazenandsawyer.com
Content -Description: Supplemental Information Exec Summary
(March 29th).doc
Supplemental Information Exec Summary (March 29th).doc Content -Type: application/msword
Content -Encoding: base64
Union County 2006 Reasonable Potential Analysis (Max Month and Average).xls
Union County 2006
Content -Description: Reasonable Potential
Analysis (Max Month
and Average).xls
Content -Type: application/vnd.ms-excel
Content -Encoding: base64
1 of 1 5/18/2006 9:31 AM

Re: WER Report Twelve Mile Creek
• .e
Subject: Re: WER Report Twelve Mile Creek
From: Jackie Nowell <j ackie.nowell @ ncmail.net>
Date: Thu, 02 Mar 2006 14:34:31 -0500
To: Michael Montebello <MONTEBMJC dhec.sc.gov>
Michael Montebello wrote:
Ms. Nowell, I've received the WER package from Hazen & Sawyer dated 2/23/06, for
copper and zinc.
I spoke to Mr. Stuve (Hazen & Sawyer) and indicated that they should assess both
the monthy average and daily maximum concentrations for both copper & zinc, rather
than assessing the daily maximum alone. On the previously issued permit, you
included only a daily maximum limit, which was acceptable since it was more
restrictive than the monthly average value that we would have used.
In this case, however they want to drop the daily max limit based on the WER
results. Both the monthly data and the daily maximum data would need to be
reviewed to determine if there is RP for either limit. Mr. Struve indicated he
would provide this assessment.
Thank You,
Mike Montebello
Michael Montebello, Manager
Domestic Wastewater Permitting Section
Phone [phone]
Fax [phone]
[e-mail]
Mr. Montebello,
Thank you for your response. DWQ staff is still reviewing the document submitted by
Hazen and Sawyer. I will forward your comments to them, so that they will anticipate
the updated information from Mr. Struve. Jackie Nowell
1 of 1 3/8/2006 3:27 PM

floZ359
HAZEN Ali D SAWYER
Environmental Engineers & Scientists
February 2, 2006
Ms. Susan Wilson
Supervisor of NPDES Western Region
North Carolina Division of Water Quality
1617 mail Service Center
Raleigh, NC 27699-1617
Re: Twelve Mile Creek WWTP
Site -Specific Metals Development
WER Final Report
H&S Job No. 30873
Dear Ms. Wilson:
Hazen and Sawyer, P.C.
4944 Parkway Plaza Blvd.
Suite 375
Charlotte, NC 28217
704 357-3150
Fax: [phone]
3 2006
Hazen and Sawyer was directed by Union County, North Carolina to provide technical
assistance in the development of site -specific standards known as site specific alternative
criterion (SSAC) for copper and zinc at their Twelve Mile Creek Wastewater Treatment Plant
(NPDES Permit NC0085359). As a result, Hazen and Sawyer has developed these site -
specific alternative criterion in accordance with USEPA's "Interim Guidance on Determination
and Use of Water — Effect Ratios for Metals", February 1994 (EPA-823-B-94-001) and the
South Carolina Department of Health and Environmental Control "Toxic Control Strategy"
May 1999. Additionally, a reasonable potential evaluation was conducted using the SSAC
developed from the WER and Dissolved Partitioning based SSAC procedures. The results
from the reasonable potential evaluation indicate that permit conditions are not warranted for
copper and the permit limit for zinc is a daily maximum value of 738.2 ug/L.
At your convenience, we would therefore like to schedule a meeting with you and your staff
to discuss the findings of this study with the objective of revising the metal limits in the Union
County Twelve Mile Creek WWTP NPDES Permit. For your convenience, we are also
forwarding a copy of this report to Mr. Matt Matthews and Ms. Connie Brower as directed by
Ms. Jackie Nowell of your staff.
S Wilson 02 3 06 IV (2).doc
New York, NY • Armonk, NY • Upper Saddle River, NJ • Raleigh, NC • Charlotte, NC • Vienna, VA • Hollywood, FL • Boca Raton, FL • Fort Pierce, FL • Jupiter, FL • Miami, FL • Bogota, U.E. Colombia

Ms. Susan Wilson
February 2, 2006
Page 2
Please contact me at [phone] or email me at istruvec hazenandsawyer.com to
schedule this meeting. We eagerly await your reply.
Very truly yours,
HAZEN AND SAWYER, P.C.
o✓v -w -n•
James N. Struve, P.E.
Senior Associate
REF/db
Enclosures
cc: Mr. Matt Matthews, NC DWQ
Ms. Connie Brower, NC DWQ
Mr. Mark Tye, Union County
Ms. Laura Shealy, Shealy Environmental
Mr. Bob Fergen, Hazen and Sawyer

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..,on County, NC0085359
Subject: re Union County, NC0085359
From: [e-mail]
Date: Fri, 30 Sep 2005 12:37:01 -0400
To: [e-mail]
contingent on the final permit containing a daily max fecal limit of
400/100 ml to meet SC WQS (unless a subsequent conversation with SC
indicates a less stringent value meets SC WQS), I will be sending a no
comment letter.
thanks!
1 of 1 10/3/2005 2:32 PM