NC0069841_Comments_20240802

(019
UNIONCOUNTY
WATER
July 26, 2024 RECEIVED
Mr. Nick Coco, PE AUG 0 2 2024
NPDES Municipal Permitting Unit
North Carolina Department of Environmental Quality NCDEQ/DWR/NPDES
Division of Water Resources
1611 Mail Service Center
Raleigh, NC 27699-1611
Subject: Draft NPDES Permit Renewal, Permit NC0069841, Crooked Creek WWTP#2
Dear Mr. Coco,
Union County Water has received the draft NPDES permit for Crooked Creek WWTP#2, dated June 25,
2024. As part of the 30-day comment period, we are respectfully submitting the following comments.
Union County Water has concerns relating to the proposed new limits for cadmium, selenium, and
cyanide. The proposed limits are based on the results of the reasonable potential analysis; however,we
are concerned that the results of the analysis are affected by some data that may not be representative of
conditions at the facility. In addition, the results may also be impacted by analytical detection limits as
follows:
1. The results of the reasonable potential analysis for cadmium appears to be affected by a single
value of 53 ug Cd/L for the effluent sample collected October 4, 2023.A total of twenty-five data
points were used in the analysis and the remaining twenty-four values were all below 0.5 ug
Cd/L. Additionally,the sample collected from the Crooked Creek influent wastewater on the
same date had a much lower value of 0.5 ug Cd/L. We believe the October 4, 2023, effluent
sample was not representative of actual effluent wastewater characteristics. Union County
Water requests that NCDEQ require monitoring and reporting rather than applying a numerical
permit limit for this parameter.
2. The results of the reasonable potential analysis for selenium appear to be affected by the
laboratory method detection limit for this parameter. Union County Water utilizes external
laboratories for analysis of these parameters. Laboratory results from August 4, 2021;
November 2, 2022; February 8, 2023; and February 7, 2024,were each below the detection limit
of 10 ug Se/L. Laboratory results from November 8, 2023; December 6, 2023;January 10, 2024,
were each below the detection limit of 15 ug Se/L. The reasonable potential analysis utilizes
values of 1/2DL for any sample results below the detection limit. However, because the
detection limits were high for these analyses, the 1/2DL values were all higher than the
proposed effluent limit of 3.1 ug Se/L.The remaining eighteen samples were analyzed with
detection limits of<5 or<1 ug Se/L and the results for all were
Union County Water
500 North Main Street, Suite 400
Monroe, NC 28112
T 704.296.4210
unioncountync.gov/water

below these lower detection limits. Because of the effect of the higher detection limits on the
1/2DL and the results of the analysis, we believe this result is not representative of actual
characteristics of the Crooked Creek WWTP#2 effluent wastewater. Union County Water
requests that NCDEQ require monitoring and reporting rather than applying a numerical permit
limit for this parameter.
3. The results of the reasonable potential analysis for cyanide also appear to be affected by
detection limits. For all values lower than 10 ug CN/L a value of 5 ug CN/L is applied.The draft
NPDES permit proposes a month average limit of 5 ug CN/L.This does not appear to be fully
meaningful given all measured values would be interpreted as being 5 ug CN/L or higher. Union
County Water requests that NCDEQ require monitoring and reporting rather than applying a
numerical permit limit for this parameter.
In summary, cadmium, selenium, and cyanide are new parameters for Crooked Creek WWTP#2,and the
facility does not have processes designed for the control of these pollutants. As discussed above,Union
County Water believes that the analyses for the proposed limits were significantly affected by laboratory
method detection limits and that some of the data are not fully representative of Crooked Creek WWTP
#2 effluent characteristics.Union County respectfully requests that NCDEQ consider applying monitoring
and reporting requirements for this permit cycle rather than introducing numerical permit limits.
Thank you for your consideration of these comments. Please contact me at 704.296.4227 or
[e-mail] if you have questions concerning the comments above.
Sincerely,
1 .44a
Jonathan Jordan
Water Reclamation Facilities Superintendent
CC: Hyong Yi, Public Works Administrator
Christopher Clark, PE,Water& Wastewater Division Director
Josh Brooks, Water& Wastewater Assistant Division Director
Eric Franks,Treatment Plant Supervisor
Andrew Pitner, Water Quality Supervisor(DEQ)
Wes Bell, Environmental Specialist II (DEQ)
Michael Montebello,Branch Chief(DEQ)
unioncountync.gov/water