NC0024970_Other_20230928

DocuSign Envelope ID:86CFEEF8-B431-45D7-AB95-A5EA8E156136
of1Nc STATE�A'
ROY COOPER
Governor 2r
ELIZABETH S.BISER
Secretary
RICHARD E.ROGERS,JR. NORTH CAROLINA
Director Environmental Quality
September 26, 2023
Mr. Joseph Lockler, Operations Chief
Charlotte Water
5100 Brookshire Boulevard
Charlotte,North Carolina 28216
Subject: MODIFIED Letter of Understanding
North Plant Interim Fermenter Pilot Study
McAlpine Creek WWMF
Mecklenburg County
NCO024970
Dear Mr. Lockler:
A request for the continuation of an ongoing pilot study utilizing an Interim Fermenter at the North
Plant of the McAlpine Creek WWMF (NC0024970) was received on May 17, 2023 and a Letter
of Understanding (LOU) was issued on September 11, 2023, by the Division of Water Resources
(Division). On September 26, 2023, Charlotte Water requested modification to the September 11,
2023 LOU to remove the requirement to notify the Division if ferric chloride is fed along with the
reasoning behind its addition in the monthly report following incident. The rationale behind the
removal of this requirement is that Charlotte Water employs ferric chloride on a daily basis to
assist with enhanced biological phosphors removal in the South Plant,with final dewatering of the
plant's anaerobically digested biosolids, and even occasionally in the North Plant should it be
required by the treatment process,regardless of operation of the interim fermenter.
Due to the daily use of ferric chloride associated with varying purpose, the Division is providing
Charlotte Water the following Understanding to Conduct for:
Charlotte Water's ongoing pilot study at the McAlpine Creek WWMF utilizes the Interim
Fermenter as a sidestream process to create anaerobic conditions necessary for enhanced biological
phosphorous removal.
This Modified LOU is subject to the following conditions:
1. The project shall not cause or contribute to any violation of water quality standards in
McAlpine Creek, which is classified C waters in the Catawba River Basin. The NPDES
permit terms and conditions shall be complied with during the pilot study at the facility.
2. The facility shall keep ferric chloride onsite during the duration of the pilot study as a
backup means of phosphorous removal.
3. Monitoring and Reporting.
a. Collect weekly effluent water samples at the current effluent sampling point and
monitor parameters including Total Phosphorous, CBOD5, ammonia, pH,
temperature and DO.
b. Report the monitoring results mentioned in Condition 3.a monthly to the Division
via the electronic Discharge Monitoring Report (eDMR) system.
Pl E Q:> North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1611 Mail Service Center I Raleigh,North Carolina 27699-1611
919.707.9000

DocuSign Envelope ID:86CFEEF8-B431-45D7-AB95-A5EA8E156136
c. Charlotte Water shall report to the Mooresville Regional Office any noncompliance
that potentially threatens public health or the environment. Any information shall
be provided orally within 24 hours from the time Charlotte Water becomes aware
of the circumstances.A written report shall also be provided within five days of the
time Charlotte Water becomes aware of the circumstances. Occurrences outside
normal business hours may also be reported to the Division's Emergency Response
personnel at(800) 858-0368 or(919) 733-3300.
4. Charlotte Water shall make available upon the Division's request any monitoring results
or other information necessary to ensure compliance with this letter of approval.
5. Annual report on the performance of the Interim Fermenter and a final summary report for
the Interim Fermenter pilot study shall be made in writing prior to permanent installation
and sent to:
NCDEQ/DWR NPDES
Municipal Permitting Unit
Attn: Michael Montebello
1617 Mail Service Center
Raleigh,NC 27699-1617
and by email to: michael.montebellogdeq.nc.gov
6. Charlotte Water shall notify the Mooresville Regional Office by telephone and in writing
at least seven days prior to completion of permanent installation of the Interim Fermenter.
The Division may modify this LOU upon the written request of Charlotte Water.
The Division also reserves the right to modify or withdraw this LOU if the project does not
conform to the above conditions or results in unacceptable impacts to water quality. In such case,
the Division shall notify Charlotte Water in writing of its findings and identify actions required of
Charlotte Water.
This Modified LOU applies only to conducting the Interim Fermenter pilot study from September
26,2023 until a time in which a permanent installation can be commissioned and built. If Charlotte
Water elects to permanently install the Interim Fermenter,the Division will consider the results of
this study and the scope of work in order to determine whether the system will require other
permits.
This Modified LOU replaces the original LOU issued September 11, 2023. Please discard the
original LOU.
If you have any questions concerning this letter,please contact Michael Montebello at (919) 707-
3624 or at michael.montebellogdeq.nc.gov.
Sincerely,
DocuSigned byy:�Al•� 'e.''`
Aukhi"WW
C464531431644FE...
for Michael Montebello, Branch Chief
NPDES Municipal Permitting Unit
Hardcopy: NPDES Files
Ecopy: DWR/Mooresville Regional Office
Pl E Q:> North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1611 Mail Service Center I Raleigh,North Carolina 27699-1611
919.707.9000