NC0043532_Speculative Limits_20200127 (2)

ROY COOPER
Governor
MtCHAEL S. REGAN
Secretary
UNDA CULPEPPER
Director
Duane Wingo, PE
Stanly County Utilities Director
1000 N. First Street, Suite 12
Albemarle, North Carolina 28001
Dear Mr. Wingo:
NORTH CAROLINA
Environmental Quality
January 27, 2020
Subject: Speculative Effluent Limits
West Stanly WWTP
Permit No. NCO043532
Stanly County
Yadkin -Pee Dee River Basin
This letter provides speculative effluent limits for expansion to 2.5 MGD at the West Stanly
WWTP. The Division received the speculative limits request from the County in a letter dated
November 12, 2019. 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.
ReceivingStream. The Rocky River is located within the Yadkin -Pee Dee River Basin. The
Rocky River has a stream classification of C, and waters with this classification have a best
usage for aquatic life propagation and maintenance of biological integrity, wildlife, secondary
recreation and agriculture. The Rocky River has a summer 7Q10 flow of 29 cubic feet per
second (cfs), a winter 7Q10 flow of 51 cfs, and an annual average flow of 920 cfs.
The Rocky River is currently listed as an impaired waterbody on the 2018 North Carolina
303(d) hnpaired Waters List for dissolved copper and turbidity. This impairment may affect
future effluent limits for these parameters.
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. If there
are any identified threatened/endangered species, it is recommended that the applicant discuss
the proposed project with the US Fish and Wildlife Service to determine whether the proposed
discharge location might impact such species.
Speculative Effluent Limits. Based on Division review of receiving stream conditions and
water quality modeling results, speculative limits for the proposed expansion to 2.5 MGD are
presented in Table 1. A complete evaluation of these limits and monitoring requirements for
ig D E QP North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1617 Mall Service Center I Raleigh. North Carolina 27699-1617
^+v� 919.707.9000

metals and other toxicants, as well as potential instream monitoring requirements, will be
addressed upon receipt of a formal NPDES permit application. Some features of the
speculative limit development include the following:
• BOD/NH3 Limits. These speculative limits are based on freezing current permitted
BOD ultimate loading (i.e., facility will not be allowed to discharge oxygen -consuming
waste above what is currently permitted). Requests for seasonal limits in accordance
with 15A NCAC 02B .0404 will need to be supported by a QUAL2K or equivalent
water quality model. The resultant limits at expanded flows are considered
technologically -feasible.
TABLE 1. Speculative Limits for the West Stanly WWTP
Effluent Characteristic Effluent'! "imitations
�Monthl.y-eeklyP Deily
Avera a Arera a Maximum
Flow 2.5 MGD
BOD5 5.0 m 7.5 m
NH3asN 1.8m L mgIL
Dissolved Oxygen 5.0 m Daily Minimum Avera e
TSS 30.0 m L 45.0 m
TRC 28
Fecal coliform (geometric 200/100 ml 400/100 ml
Chronic Toxicity, Pass/Fail 4.6% '
(Quarterly test)
1. Subject to change. Updated flows will be determined upon receipt of application for
expansion.
Engineering 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 211.0105(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, 919-707-9045) 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
Page 2 of 3

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 David Hill at [phone].
Respectfully,
lie Grzyb
Supervisor, NPDES Complex Permitting Unit
Attachment: EAA Guidance Document
Hardcopy:
NPDES Permit File
Electronic Copy:
NC WRC, Inland Fisheries, [e-mail]
US Fish and Wildlife Service, Sarah [e-mail]
DWR/Mooresville Regional Office/Water Quality Regional Operations/Corey
Basinger
DWR/Modeling and Assessment Branch/Pam Behm
DWR/Basinwide Planning/ Ian McMillan
DWR/NPDES Server>Specs
Page 3 of 3

M
330.3 �bt�
�=MA
F 2,5 1.5x �,3N 4 2. 3y= 33c.5
y.sy� ,spy- Lsx
�I , •3.5Z-.3x
�✓ X=S=�2n\ �= I.ssb �1N�