HomeMy WebLinkAboutNC0021873_HWA Approval_20220915DocuSign Envelope ID: E678AB22-9CCO-4869-A014-FCFE86AC4EB8
ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
RICHARD E. ROGERS, JR.
Director
NORTH CAROLINA
Environmental Quality
9/15/2022
Town of Mayodan
Attn: Melessa Hopper, Town Manager
P.O. Box 1279
Mayodan, NC 27012
Transmitted via email to mhopper@mayodannc.org
Subject:
Dear Permittee:
Review of Headworks Analysis
Program: Town of Mayodan
NPDES Permit No: NC0021873- Mayodan WWTP
Rockingham County
The Municipal Unit of the Division of Water Resources has reviewed the Headworks Analysis (HWA) and
Allocation Table (AT) for the Town of Mayodan's wastewater treatment plant (WWTP) working under the
NPDES Permit No NC0021873 (effective on August 1, 2018). The revised HWA was submitted on July 8,
2022, in response to the DWR's September 3, 2021, HWA Review Letter.
The Division concurs with the HWA calculations for all pollutants of concern, with the updates,
corrections, and observations discussed below. These approved Maximum Allowable Headworks
Loadings (MAHLs), Maximum Allowable Industrial Loadings (MAILs), and the basis for these values are
found in the enclosed HWA AT spreadsheet, which has the updates and corrections highlighted. Please
replace or update POTW's HWA AT spreadsheets and supporting documents with these approved ones.
1. HWA Updates and Corrections
a. Water Quality Stream Standards: The HWA was updated to use the site -specific water
quality standards (WQS) for cadmium, copper, lead, and zinc according to the WQS for
human health used in the reasonable potential analysis (RPA) Input table (See `WQS RPA
Input' Tab in the HWA AT Sheet).
b. Mercury Removal Rate was changed from 0.01% to 18.35% based on the additional
mercury sampling provided by the Town.
c. AT: All Industrial User Permits (IUPs) were renewed in January 2022. The AT has been
updated to reflect those changes.
d. The use of Headworks Addendum for Sludge Loadings (HASL) is deemed necessary for
nickel and selenium and has been delisted for cadmium since there is no overallocation
based on sludge ceiling for cadmium.
2. Next HWA Due date: The HWA approved today is based on DMR/LTMP data for the period of
March 2016 through June 2020. Including mercury data collected in 2021 and 2022. Unless
conditions at the POTW change significantly and thus warrant an earlier submittal (see
Comprehensive Guide, Section B), the POTW must submit an updated site -specific HWA by
October 1, 2025, as set by the DWR's September 3, 2021, Letter.
Regardless of this approval action today, within 180 days of the effective date of any
reissued/modified NPDES permit, the Permittee would be required to submit to the Division a
written technical evaluation of the need to revise local limits (i.e., an updated HWA or
documentation of why one is not needed) INPDES Permit Section D, 4.1. This action may include
revising, updating, or adding to the list of Significant Industrial Users (SIUs) and/or modifying SIU
Industrial User Pretreatment Permit (IUP) limits. In addition, any executed Special Order of
Consent (SOC) conditions or requirements related to pretreatment or pretreatment program updates
must be complied with separately from this approval action.
DocuSign Envelope ID: E678AB22-9CCO-4869-A014-FCFE86AC4EB8
Federal and State pretreatment regulations require the local delegated pretreatment program to effectively
control and document the discharge of wastewater from Significant/Categorical Industrial Users to the
POTW. It is the POTW's responsibility to ensure that these objectives are consistently met.
Thank you for your continued support of the Pretreatment Program. If you have any questions or comments,
please contact the Pretreatment Coordinator Keyes [keyes.mcgee@ncdenr.gov], or the Unit Supervisor,
Michael at[michael.montebello@ncdenr.gov].
Sincerely,
EDocuSigned by:
L
higUta kiNAl t g
C464531431644FE...
for Richard E. Rogers Jr., Director
Division of Water Resources
dy/Mayodanhwa 2022
Attachments:
2022 Approved HWA-AT
cc with attachments:
Nadine Blackwell, Pretreatment Coordinator
Jim Gonsiewski, Winston-Salem Regional Office
Municipal Unit File and Central Files (Laserfiche)