NC0021920_HWA Approval_20220512

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ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
RICHARD E. ROGERS, JR.
Director
NORTH CAROLINA
Environmental Quality
5/12/2022
City of Whiteville
Newlyn McCullen, Utility Director
P.O. Box 607
Whiteville, NC 28472
Transmitted via email to [e-mail]
Subject: HWA Review
Program: City of Whiteville
NPDES Permit No NC0021920, 3.0 MGD
Land Application of Class B Residuals No WQ0000048
City of Whiteville WWTP
Columbus County, WIRO
Dear Permittee:
The Municipal Unit of the Division of Water Resources has reviewed the Headworks Analysis
(HWA) for the City of Whiteville for its wastewater treatment plant (WWTP) working under the
NPDES Permit No NC0021920 (effective on February 1, 2021). The Division initially received
the HWA on August 19, 2020, followed by more information and revisions on February 7, 2022,
March 7, 2022, and March 9, 2022. We regret the delay in providing this review.
The Division concurs with the HWA calculations for all pollutants of concern, with the corrections
and observations discussed below. The approved Maximum Allowable Headworks Loadings
(MAHLs), Maximum Allowable Industrial Loadings (MAILs), and the basis for these values are
found in the enclosed HWA and Allocation Table (AT) spreadsheet, which has the updates,
corrections, and observations highlighted. Please ensure to replace or update the POTW's HWA
AT spreadsheets with this approved one.
HWA Corrections
a. Sludge to Disposal Flow was updated from 0.0016 MGD (based on the 2012 Annual
Report of 595,200 gallons) to 0.0015 MGD, based on the 2018 Annual Report of
539,400 gallons. The 2020 Annual Report value was not recommended since it would
limit excessively the Sludge Ceiling Load. The 2019 and 2021 Annual Reports noted no
land application for both years. The Facility has a storage container for sludge.
b. Sludge Site Area was updated from 460 acres to 399 acres based on the 2018 Sludge
Permit and its approved 2020 Modifications.
c. Formulas for Sludge Ceiling Load and Cumulative Sludge Loading were included in the
spreadsheet.
d. Removal Rates for TSS, ammonia, lead, mercury, zinc, total nitrogen, and total
phosphorous were updated according to the updated removal rates submitted on
February 7, 2022.
e. NPDES Limits for lead, mercury, cobalt, and tin were removed following the current
2021 NPDES permit limits.
f. Water Quality Stream Standards for copper, lead, mercury, molybdenum, nickel, silver,
and zinc were updated to use the site -specific water quality standards (WQS) used in

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the current NPDES permit reasonable potential analysis (RPA). (See 2021 RPA
included in the HWA-AT Sheet from the NPDES Fact Sheet).
g Inhibition concentration was included for zinc and removed for cobalt since no literature
value has been published.
h. Uncontrollable Concentrations in the HWA were updated to use the most conservative
available option. Uncontrollable sampling values in the Mass Balance Sheet were
corrected to use the current values reported in the LTM Sheet and additional literature
values were included from Metcalf & Eddie. (See SIU.Mass.Bal included in the HWA-
AT Sheet).
i. Silver has been hidden in the HWA's uncontrollable concentration section and
the Allocation Table since this is not a pollutant of concern defined by the
Facility's LTMP.
2. HWA Observations
a. Design Values: The Facility calculated the ammonia design value based on the TKN
design value using the 40:25 ratio from Metcalf & Eddie. This literature value is
acceptable at this time. The Facility also based the TN design value on the TKN design
value. This approach is acceptable at this time, since there is no TN NPDES limitation.
If an NPDES TN limit is assigned, the Facility must develop a site -specific TN Design
Value.
b. Removal Rates for molybdenum, selenium, and silver were not calculated following the
approved 2019 LTMP sampling plan. It is acceptable to leave silver out of the
monitoring plan since there is no requirement for it; however, the LTMP sampling needs
to be updated to include influent and effluent sampling for molybdenum and selenium;
these are pollutants of concern (POC) due to sludge. Please follow the POC definition
outlined in the Comprehensive Guidance Chapter 4.
c. Sludge Site Life: The 2011 and 2016 HWA were approved with a Site Life of 15 years.
Per the current HWA, the update of this value does not alter the MAHL; therefore, the
Division will maintain it as it is. If the City wishes to update this value in the future,
please consult the median site life with the land application site managers and submit
the proposed sludge site life.
d. Age of Sludge Site: For informational purposes only. Currently based on the permit life.
e. Uncontrollable Concentration value for mercury was taken from the mass balance,
instead of the uncontrollable sampling. This approach is acceptable since there is no
NPDES limit or monitoring requirement for mercury.
3. Required Updates
a. IUP renewal: In the HWA review process, it was noted that the Industrial User Permit
(IUP) for Columbus Regional Healthcare expired on 03/15/2021. Please submit the IUP
renewal as soon as possible.
b. LTMP updates
Submit the updated Long -Term Monitoring Plan (LTMP) by July 14, 2022, addressing:
i. The Division recommends including the following pollutants of concern (POC)
in the LTMP: TN and TP. These are POCs per the current NPDES permit
monitoring requirements.
ii. The Division recommends updating the PQL for the following parameters:
arsenic (from 10.0 to 2.0 µg/1), lead (from 10.0 to 2.0 µg/1), and nickel (from
10.0 to 5.0 µg/1).
iii. The Facility shall update the Sampling Plan (Section F) to include influent and
effluent sampling for the pollutants of concern (POC) listed under Section B.

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Please update Section B following the POC definition outlined in the
Comprehensive Guidance Chapter 4.
4. Next HWA Due date: The HWA approved today is based on DMR/LTMP data for the period
of January 2015 through December 2019. Unless conditions at the POTW change
significantly and thus warrant an earlier submittal (see Comprehensive Guide, Chapter 5,
Section B), the POTW must submit an updated site -specific HWA by January 30, 2026 (after
the reissue of the next NPDES permit renewal).
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 IWS/L-STMP/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
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. 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 [[e-mail]], or the
Unit Supervisor, Michael, at[[e-mail]].
Sincerely,
LeA1 ADo'clu.d
Signed by1:,t ` A
eta
C464531431644FE..
for Richard E. Rogers Jr., Director
Division of Water Resources
dy/ whiteville_21920_hwa_2022
Attachments:
Whiteville 21920 HWA-AT.2022
cc with attachments:
City of Whiteville — Pretreatment Coordinator/Brandon Rich
City of Whiteville — ORC/ Daniel Clinton Ward
DWR - Wilmington Regional Office/Tom Tharrington and Chad Coburn
Municipal Unit File and Central Files (Laserfiche)