NC0088722_Speculative Effluent Limits_20170726

Water Resources
ENVIRONMENTAL QUALITY
July 26, 2017
Mr. Don Chamblee, Public Works Director
Lincoln County
115 West Main St.
2nd Floor Citizens Center
Lmcolnton, North Carolina 28092
Dear Mr. Chamblee
ROY COOPER
Goi e, not
MICHAEL S REGAN
Secs emit
S JAY ZIMMERMAN
Du ecloi
Subject. Speculative Effluent Limits
Kilhan Creek WWTP
Permit No. NCO088722
Lincoln County
Catawba River Basin
This letter provides speculative effluent limits for 4 9 MGD and 6.6 MGD at the Killian Creek
WWTP The Division received the speculative In -nits request in a letter dated February 20, 2017.
Please recognize that speculative limits may change based on future water quality initiatives, and
it is highly recommended that the applicant verify the speculative limits with the Division's
NPDES Unit prior to any engineering design work.
Receiving Stream. Killian Creek is located within the Catawba River Basin. Killian Creek has a
stream classification of C Waters with C classification have a best usage for aquatic life
propagation and maintenance of biological integrity, wildlife, secondary recreation and
agriculture. The USGS provided flow statistics for Killian Creek on June 2, 2017. For the
discharge location the summer 7Q10 flow is 3.1 cfs, winter 7Q10 flow is 7.5 cfs, and an annual
30Q2 is 10.8 cfs. Please note these values are slightly different than previously used in the
permit The previous permit listed the drainage area as 36 nll2. This area corresponds to the area
at the Killian Creek USGS station near Mariposa. The drainage area at the point of discharge
was verified as 46.8 nue.
Killian Creek is not currently listed as an impaired waterbody on the draft 2016 North
Carolina 303(d) Impaired Waters List.
Based upon a review of information available from the North Carolina Natural Heritage
Program Online Map Viewer, there are not any Federally Listed threatened or endangered
aquatic species identified within a 5 mile radius of the proposed discharge location.
Speculative Effluent Limits. Based on Division review of receiving stream conditions,
speculative hnuts for the proposed expansion to 4.9 and 6.6 MGD are presented in Table 1. A
complete evaluation of these limits and monitoring requirements for metals and other
toxicants, as well as potential instream monitoring requirements, will be addressed upon
State of North Carolina I Environmental Quality I Water Resources
1617 Mail Service Center I Raleigh, North Carolina 27699-1617

receipt of a formal NPDES permit application. Some features of the speculative limit
development include the following:
BOD/NH3 Limits. A level B model was developed to evaluate limits for BOD and
ammonia The model predicted that effluent concentrations of 5 mg/1 BOD and 1 mg/1
ammonia will not cause exceedances in the dissolved oxygen instream standard for
both proposed flow scenarios.
Total Nitrogen/Total Phosphorus. The Division developed a Nutrient Management
Strategy for Lake Wylie in 1995 due to eutrophic conditions in the lake. The Lake Wylie
Nutrient Management Area encompasses Lake Wylie and its tributaries including the
Catawba River and its tributaries below Mountain Island Dam. Killian Creek is a
tributary to the Catawba River within the Lake Wylie Management Area. The strategy
for expansions of existing discharges presented in the 1995 Catawba River Basin Plan
recommends the use of advanced nutrient removal technology. For expanding
facilities with permitted flows greater than 1 MGD the strategy recommends monthly
average limits of 1 mg/l Total Phosphorus (TP) and 6 mg/l Total Nitrogen (TN) (TN
applies April to October only).
TABLE 1. Speculative Limits for the Killian Creek WWTP (Proposed Expansion to 4.9
MGD and 6.6 MGD)
Effluent Characteristic
Effluent Limitations
Monthly Average
Weekly Average
Daily
Maximum
Flow
4.9 MGD / 6.6 MGD
BOD5
5 m /L
7.5 m /L
NH3asN
1m /L
3m /L
Dissolved Oxygen
(minimum)
5.0 mg/L
TSS
30 m /L
45 mg/ L
TRC
28 ug/1
Fecal coliform
(geometric mean)
200/100 ml
400/100 ml
Total Nitrogen
6 mg/l (April - October)
Total Phosphorus
1 mg/1
Chronic Toxicity
Pass/Fail (Quarterly
test)
71%/77%
I
I
Engineermg Alternatives Analysis (EAA). Please note that the Division cannot guarantee that
an NPDES permit for a new or expanding discharge will be issued with these speculative
limits. Final decisions can only be made after the Division receives and evaluates a formal
permit application for the new/expanded discharge. In accordance with North Carolina
Administrative Code 15A NCAC 21-1.0105(c), the most environmentally sound alternative

should be selected from all reasonably cost effective options. Therefore, as a component of
all NPDES permit applications for new or expanding flow, a detailed engineering alternatives
analysis (EAA) must be prepared. The EAA must justify requested flows and provide an
analysis of potential wastewater treatment alternatives. A copy of the Division guidance for
preparing EAA documents is attached.
State Environmental Policy Act (SEPA) EA/EIS Requirements. A SEPA EA/EIS document
may be required for projects that: 1) involve $10 Million or more of state funds; or 2) will
significantly and permanently impact 10 or more acres of public lands. Please check with the
DWR SEPA coordinator (David Wainwright, 919-807-6442) as to whether your project
requires SEPA review. For projects that are subject to SEPA, the EAA requirements discussed
above will need to be folded into the SEPA document. Additionally, if subject to SEPA, the
NPDES Unit will not accept an NPDES permit application for a new/ expanding discharge
until the Division has approved the SEPA document and sent a Finding of No Significant
Impact (FONSI) to the State Clearinghouse for review and comment.
Should you have any questions about these speculative limits or NPDES permitting
requirements, please feel free to contact Teresa Rodriguez at [phone] or Julie Grzyb at
[phone].
Respectfully,
1"�'
6,iIie Grzyb
Supervisor, NPDES Complex Permitting Unit
Attachment: EAA Guidance Document
Hardcopy:
Central Files
NPDES Permit File
Electronic Copy:
DWR/Mooresville Regional Office/Water Quality Permittmg
DWR/Basinwide Planning, Ian McMillan
DWR/NPDES Server>Specs