NC0021369_More Information (Requested)_20190329

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
LINDA CULPEPPER
Director
NC]RTH CAI-OLINA
Enpiranrtlwoof Quoury
March 29, 2019
CERTIFIED MAIL 7015 0640 0007 9833 6698
RETURN RECEIPT REQUESTED
Mr. Timothy Barth
Town of Columbus WWTP
PO Box 146
Columbus, NC 28722
Subject: Request for Additional Information
NPDES Renewal Application
Town of Columbus WWTP
NPDES permit NCO021369
Polk County
Dear Mr. Barth:
The Division has reviewed your application, received on February 20, 2018, for renewal of NPDES
permit NCO021369 and the response to our previous request for additional information regarding
lab data sheets. To enable us to complete our review in accordance with N.C.G.S. 143-215.1 and
15A NCAC 02H .0105, we need additional or revised information regarding your discharge. I
apologize for not requesting this information in the previous letter.
1. Please provide five (5) days of Total Hardness (CaCO3 or [Ca + Mg]) data for the wastewater
treatment plant effluent and upstream from Outfall 001 to the unnamed tributary to Whiteoak
Creek.
The NC 2007-2014 Water Quality Standard (WQS) Triennial Review was approved by the NC
Environmental Management Committee (EMC) on November 13, 2014. The US EPA subsequently
approved the WQS revisions on April 6, 2016 with some exceptions. The NC Division of Water
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North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11617 Mail Service Center I Raleigh, North Carolina 27699-1617
919.707.9000

Mr. Barth
NCO021369
March 29, 2019
Page 2 of 2
Resources NPDES Permitting Unit is required to implement the new dissolved metal standards in
all permits public noticed after April 6, 2016.
The new standards for most metals include acute standards. Further, the freshwater standards for
several metals are expressed as the dissolved form of the metals, and seven metals have hardness -
dependent equations. As a result, the NPDES Permitting Unit will need site -specific effluent
hardness data and instream hardness data, upstream of the discharge, for each facility monitoring
these metals in order to calculate permit limitations. The metals of concern for the Town of
Columbus WWTP are Total Copper, Total Silver, Total Zinc, Total Cadmium, and Total Lead.
If no response is received within 60 calendar days [per 15A NCAC 02H .0107(b)], the permit will
be renewed without the benefit of the additional information. Therefore, a default hardness of 25
mg/L (CaCO3 or [Ca + Mg]) will be used to calculate an effluent limit for the above metals of
concern, and which will give the following limits for Total Cadmium, Total Copper, and Total
Silver:
Daily
Monthly
Maximum Average
Cadmium
7.838 ug/L
1.589 ug/L
Copper
25.34 ug/L
21.23 ug/L
Silver
0.717 ug/L
0.162 ug/L
This information is required in order to continue processing the permit renewal request. If you have
any questions, please contact me at 919-707-3712 or via email at [e-mail].
Sincerely,
Sydney Carpenter
NPDES Program
cc: NPDES Permit Files
Central Files
DWR/ARO/WQROPS