NC0024571_Pretreatment_Headworks_Review_20191231

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
LINDA CULPEPPER
Director
NORTH CAROLINA
Environmental Quality
December 31, 2019
Sent via email ([e-mail])
Ms. Beverly Allen
Pretreatment Coordinator
City of Lumberton
P.O. Box 1338
Lumberton, NC 28359-1388
Subject: Pretreatment Review of Headworks Analysis (HWA)
City of Lumberton, NPDES Permit No: NCO024571
Robeson County
Dear Ms. Allen:
The Pretreatment, Emergency Response, and Collection Systems (PERCS) Unit of the Division of Water
Resources has reviewed the Headworks Analysis (HWA) for the City of Lumberton. This HWA was
submitted by The Wooten Company, the POTW's Consultant, and received by the Division on August 20,
2019, with additional information received on November 20, 2019.
The Division concurs with the HWA calculations for all pollutants of concern, with corrections 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 attached HWA
spreadsheet, which has the corrections highlighted. The results of the HWA are also listed in the bottom
section of the Allocation Table.
HWA Corrections: Please feel free to contact PERCS if you have any questions about the changes outlined
below or if the POTW does not agree with the modifications. None of the corrections caused any over
allocation that were not resolved by another correction. All corrected spreadsheets were emailed to you
and your consultant for your files, with the changes highlighted. Please ensure the POTW's paper and
electronic HWA, AT, and other supporting documents contain these corrected documents, especially the
Allocation Table. As needed, please mark any original documents as "replaced" or "voided."
1) Sludge % Solids: was updated to 3.055 based on the calculations of the average of the Marchand July
2018 event.
2) Stream Standards: reasonable potential analysis calculator was used to apply dissolved metal
standards, which was effective for NPDES permits issued since April 2016. Please see attached
calculator.
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North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1617 Mail Service Center I Raleigh, North Carolina 27699-1617
919.707.9000

3) Inhibition Concentration: for Chromium, Molybdenum, Selenium and Zinc were updated using the
data received on November 19, 2019.
4) Mercury: It was noted that Mercury was not sampled quarterly at influent and effluent as specified
in the LTMP, based on the data submitted and the DMR data. Please make sure as least ALL effluent
data submitted in DMR or start to sample Mercury quarterly at the influent and effluent. NPDES limit
(cell B33) was removed per the NPDES permit. PERCS chose to use literature removal rate because
there were method differences in collecting influent and effluent samples and the mercury removal
was not able to be demonstrated through the last several samples — the data shows that all influent
data were below detection level of 1 ng/L while a couple effluent was above the same detection level.
5) Detection level: for Cu was 0.002 mg/L in the approved LTMP. It was noted in the review that 0.01
mg/L was sometimes used for the effluent. Please make sure all future Cu samples use the detection
level of 0.002 mg/L.
6) Uncontrollable mass balance: The influent concentrations for Mercury and Silver has been chosen for
the uncontrollable concentration. Literature values are not as accurate as the detection levels getting
lower and lower. In this case, PERCS believes that the influent data is more representative for Mercury
and Silver.
7) Allocation table: Zinc limit for Elkay Southern Corp. and TSS limit for Robeson County Landfill were
updated according to the current permits.
8) Next HWA Due Date: The HWA was based on January 2014 — 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 September 1, 2024.
Thank you for your continued cooperation with the Pretreatment Program. If you have any questions or
comments, please contact me at [phone] [email: [e-mail]].
Sincerely,
DocuSigned by:
Vivien Zhong, PERCS Unit
E42E88CDBD404A7...
vz/Lumberton. H WA.2019
Attachments: HWA.AT, Calculator
Ec: PERCS Unit with attachments
Miles Galloway, The Wooten Company, with attachments
Kirsten Slodysko, FRO
Central Files (LF)