NC0024333_Pretreatment_HWA_Letter_20211029

DocuSign Envelope ID: 6FECEA94-8C31-453D-B87C-C1 DF61 FB7F1 F
ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
S. DANIEL SMITH
Director
NORTH CAROLINA
Environmental Quality
10/29/2021
Via Electronic Mail ([e-mail])
Kyle Ketchum
WWTP Superintendent
City of Monroe
P.O. Box 69
Monroe, NC 28111
Subject:
Pretreatment Review of Headworks Analysis (HWA)
Program: City of Monroe
NPDES Permit No: NC0024333 - City of Monroe WWTP
Union County
Dear Mr. Ketchum:
The Municipal Unit of the Division of Water Resources has reviewed the Headworks Analysis (HWA) for
the City of Monroe for the City of Monroe WWTP - NC0024333. The HWA was received by the Division
on June 29, 2020. Additional information was received by the Division on August 30, 2021. We regret the
delay in providing these review comments.
The Division concurs with the HWA calculations for all pollutants of concern, with the observations
discussed below. These approved Maximum Allowable Headworks Loadings (MAHL), Maximum
Allowable Industrial Loadings (MAIL), and the basis for these values are found on the last page of the
attached HWA and Allocation Table (AT) spreadsheet which has the corrections marked.
1. HWA Calculations: Please feel free to contact the Municipal Unit if you have any questions or
concerns about the changes outlined below. All corrected spreadsheets were emailed to you for your
files, with the changes highlighted. Please ensure to replace or update POTW's HWA AT
spreadsheets and supporting documents with these approved ones.
a. Silver: The HWA as submitted showed a calculated over allocation based on the dissolved
metals stream standard. The uncontrollable load was larger than the MAHL, leaving no
allocation for the SAJs. Recently DWR has decided to allow POTWs the option of using zero
for data reported as below PQL (Practical Quantitation Limit) data when the PQL is
sufficiently low (best available PQL). All recent WWTP influent and effluent silver data was
below 1 µg/1 PQL. Based on this data, the HWA was revised to use 0 for the uncontrollable
which resolved the over allocation. If any future data shows a reported value above 1 µg/1
PQL, contact the Pretreatment staff of the Municipal Unit within 30 days to discuss the need
for future action.
b. Allocation Table: was updated to reflect the new S1U effective and expiration dates.
2. Next HWA Due Date: The HWA was based on DMR/LTMP data for the period of May 2017 through
April 2020. 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.
NORTH 1:tE
nepertment of Environmental jolek"
CAROLINA
North Carolina Department of Environmental Quality Division of Water Resources
512 North Salisbury Street 11617 Mail Service Center I Raleigh, North Carolina 27699-1617
919.707.9000

DocuSign Envelope ID: 6FECEA94-8C31-453D-B87C-C1 DF61 FB7F1 F
Regardless of this approval action today, within 180 days of the effective date of any reissued NPDES
permit (or any subsequent NPDES permit modification) 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) [NPDES Permit Section D, 4.]. This action may include revising,
updating or adding to the list of Significant Industrial Users (SIUs) and/or modification of SIU Industrial
User Pretreatment Permit (IUP) limits. 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.
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 cooperation with the Pretreatment Program. If you have any questions or
comments, please contact me at [phone] [email: [e-mail]] or Michael
Montebello, Unit Supervisor at [phone] [email: [e-mail]].
Sincerely,
1-DocuSigned by:
- C464531431644FE...
For S. Daniel Smith, Director
Division of Water Resources
ksl/Monroe.HWA.2020
Attachments:
Monroe_HWA_AT_approved_October_2021
Ec with attachments:
Mr. Kevin Keesler, Pretreatment Coordinator ([e-mail])
Municipal Permitting Unit
Wes Bell, Mooresville Regional Office
Cc without attachments:
Central Files (Laserfiche)
NORTH
Department of Emlr,nmentel Ovally
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