NC0069841_Speculative Limits_Comments_ADI_20240628

DocuSign Envelope ID:A6A34A48-5776-429F-B5C2-EC90B33C9C60
ROY COOPER cd _
Governor d C
ELIZABETH S.BISER ;e
Secretary •E .
RICHARD E.ROGERS,JR. NORTH CAROLINA
Director Environmental Quality
June 28,2024
Brian Matthews, County Manager
Union County
Planning&Resource Management Director
500 N. Main St., Suite 70
Monroe,NC 28112
Subject: Speculative Limits Request
Crooked Creek WRF
NPDES Permit No.NCO069841
Union County
Yadkin-Pee Dee River Basin
Dear Mr. Matthews:
On March 7,2024,the Division received a letter from Black&Veatch requesting verification of direction
from the January 11,2024 meeting for a new discharge location for Crooked Creek WRF (CCWRF). The
Division has the following comments,recommendations, and requests:
• The Division affirms that a new wastewater discharge permit will not be able to be permitted at the
locations along Crooked Creek where flow and effluent limits cause downstream dissolved oxygen
concentrations to fall below the 5.0 mg/L dissolved oxygen standard(15A NCAC 02B .0211).
In the October 24,2023 Modeling Review letter to Union County,the Modeling and Assessment Branch
(MAB)noted the following concern:
One significant issue is that the predicted dissolved oxygen(DO)downstream of the proposed
CCWRF falls below 5 mg/L.According to the modeling report,the minimum summertime DO
between the South Fork Crooked Creek confluence and the Highway 601 crossing(referred to as
"Old Debris Dams")was predicted to be 3.9 mg/L under the CCWRF's maximum permitted
discharge scenario(we have additional concerns with this model estimate discussed below).
Originally the predicted DO stays above 5 mg/L downstream of the approved LCCWRF speculative
limits until Crooked Creek's confluence with Rocky River.
• The Division also affirms that Union County Water needs to re-evaluate discharge locations and identify
a final location that will meet the above requirements in order for NC DEQ to provide a final response to
the Request For Speculative Limits at Site B. Water Quality modeling results should be submitted which
demonstrate compliance with the dissolved oxygen standard based on the discharge location.
The Division also provided the following recommendation in the October 24, 2023 letter:
We recommend that Union County evaluate the option of moving the outfall closer to the confluence
with the Rocky River(as was proposed and already given speculative limits for LCCWRF). This
location would alleviate the concerns expressed above with both model scenarios and the physical
characteristics of Crooked Creek.
North Carolina Department of Environmental Quality I Division of Water Resources
NORTMcna 512 North Salisbury Street 11617 Mail Service Center I Raleigh,North Carolina 27699-1617
a E ��rsi ffi 919.707.9000
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DocuSign Envelope ID:A6A34A48-5776-429F-B5C2-EC90B33C9C60
For Site B Speculative Limits,between Highway 601 and the original Site A,we request that the original
Lower Crooked Creek model submitted for the 2021 Speculative Limits be revised for the new location
and the latest flows.
• The March 7,2024 letter from Black&Veatch also requested that the Division verify that the July 12,
2021 Speculative Limits for Site A were still valid. We affirm that 2021 speculative limits are still valid
only for the Site A location with the proposed expansions to 4.6 MGD and 8.2 MGD. However, it was our
understanding that this discharge location was no longer available to the County. Additionally,the
speculative limits request on January 4,2023,was for an expansion to 6.0 MGD and 12.0 MGD. The
2021 Speculative Limits would not be valid for the latest flows requested. If the County intends to expand
to the latest flows of 6.0 MGD and 12.0 MGD for Site A,the original Lower Crooked Creek model
submitted for the 2021 speculative limits request would have to be revised for latest flows.
• To issue speculative limits,the Division requests additional information for the basis of the expansion to
6.0 MGD and 12.0 MGD. Projected expansions typically are based on 20-year population increases. The
Engineering Alternatives Analysis(EAA) Guidance Document is attached. Steps 1 and 2 in the guidance
document provides information that you will need to determine if the discharge is allowed and to provide
reasonable projections for population&flow. Please provide this information along with the updated
model files.
Please let us know if you have any questions regarding these comments and we will schedule a meeting to
discuss. Should you have any questions,please feel free to contact Derek Denard at(919) 707-3618/
[e-mail].
Respectfully,
DocuSigned by, Al• ''
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C464531431644FE...
Michael Montebello
NPDES Program Branch Chief
ec: NPDES Files[Laserfiche]
Union Couty/Brian Matthews,County Manager[[e-mail]]
Aubrey Lofton,Planning&Resource Management Director[[e-mail]]
Hyong Yi,Water Administrator[[e-mail]]
John Shutak,Engineering Division Manager [e-mail]]
Josh Brooks,Operations Director[[e-mail]]
Christopher Clark,Water&Wastewater Director[[e-mail]]
Jonathan Jordan,WRF Superintendent[[e-mail]]
Black&Veatch/Kent Lackey[[e-mail]];Mike Osborne[[e-mail]];
Chris deBarbadillo[[e-mail]]
Tetratech/Trevor Clements[[e-mail]];Hillary Yonce[[e-mail]]
Tedderfarm Consulting/Steve Tedder[[e-mail]]
DWR MAB/Pam Behm[pamela.behm@ deq.nc.gov];
Adugna Kebede[[e-mail]];Bongghi Hong[[e-mail]];
Andy Painter[[e-mail]];
DWR MRO/Andrew Pitner[[e-mail]];Roberto Scheller[[e-mail]]
DWR Basin Planning/Nora Deamer[[e-mail]];Michelle Raquel[[e-mail]];
Ginny Baker[[e-mail]]
DWR NPDES/Kristin Litzenberger[[e-mail]];Nick Coco[[e-mail]];
Anjali Orlando[[e-mail]]
D E Q�� North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1617 Mail Service Center I Raleigh,North Carolina 27699-1611
NORTH CAROUNA _
o,p,�„F r��,�wla,\ /./ 919.707.9000