NC0024201_Headworks Analysis_20191105

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
LINDA CULPEPPER,
Director
NORTH CAROLINA
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November 5, 2019
(Sent via email: [e-mail])
Isabelle Wilcoxon, Pretreatment Coordinator
Roanoke Rapids Sanitary District
135 Aqueduct Road
Weldon, NC 27890
Subject: Pretreatment Review of Headworks Analysis - Approved
Roanoke Rapids Sanitary District (NPDES Permit No. NC0024201)
Halifax County
Dear Ms. Wilcoxon:
The PERCS Unit of the Division of Water Resources has reviewed the Headworks Analysis (HWA) for the
Roanoke Rapids Sanitary District (RRSD). The HWA was initially received by the Division on May 1st, 2019,
followed by revisions received on August 15, 2019.
The Division concurs with the HWA calculations for all pollutants of concern, with the observation
discussed below. These approved Maximum Allowable Headworks Loadings (MAHLs), Maximum
Allowable Industrial Loadings (MAILS), and the basis for these values are found on the last page of the
enclosed HWA spreadsheet. The results of the HWA are also listed in the bottom section of the enclosed
Allocation Table.
1) Low level Mercury Method: It appears from the sampling data and currently approved LTMP, that
the POTW does not use low level method (EPA 1631E) for mercury effluent samplings. However, the
Permittee is required to use 1631E for effluent mercury pollutant scans, per NPDES permit. To be
consistent throughout the samplings, POTW needs to start using low level 1631E method for at least
LTMP Hg effluent samplings. Please update the current LTMP and submit to PERCS for review and
approval by December 31, 2019.
Next HWA Due Date: The HWA was based on January 2016 through December 2018 data. Unless
conditions at the POTW change significantly and thus warrant an earlier submittal (see Comprehensive
Guide, Section 8), the POTW must submit an updated HWA on or before July 1, 2025.
Thank you for your continued cooperation with the Pretreatment Program. If you have any questions or
comments, please contact Monti Hassan at [phone] [email: Monti. [e-mail]].
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Division of Water Resources
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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

M H/rrsd_H WA_008
Enclosures: HWA_AT_2019_Approved
CC: PERCS Unit (ecopy)
Cheng Zhang, Raleigh Regional Office (email)
Central Files (LF)