NC0021156_NOV-2019-PC-0370 Response_20190516

May 16, 2019",40:�.
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Mr. W. Corey Basinger, Regional Supervisor
Water Quality Regional Operations Section
Division of Water Resources, NCDEQ
610 East Center Avenue, Suite 301
Mooresville, NC 28115
Re: Notice of Violation — Compliance Evaluation Inspection
NOV-2019-PC-0370
City of Mount Holly
NPDES Permit No. NCO021156
Gaston County
Dear Mr. Basinger:
I am in receipt of your certified letter dated May 2, 2019 concerning the results of your April 30,
2019 WWTP inspection. Your Notice of Violation included two violations requiring our
immediate attention:
1. Clean Out Basin #3
As you may remember we met in your office in mid-2017 disclosing the failure of Basin 3. We
also agreed that with the Charlotte Water Regionalization plans moving forward we could
decommission our plant in its entirety once the CW pump station and force main became
operational.
We also discussed that Basin 3 would not be put back in service and if the basin needed to be
cleaned out due to public outcry, we would do so prior to the decommissioning. We have
complied with the conclusions of our discussion. We have not received any citizen complaints
and Basin #3 is NOT in service. Any rain water that needs to be pumped out is pumped into the
influent splitter box at the headworks of the plant. From May 6th to May 1 Oth our WWTP staff
pumped our 5-ft. of rainwater from Basin 3.
We certainly would prefer to wait on the removal of the sludge and deconstruct the basin once
the City's flow is discharged to CW sometime at the end of 2021. We will receive better
P.O. Box 406 Mount Holly, North Carolina 28120

contractor pricing as we decommission the entire plant at one time rather than segments at a
time. Of course, if there should be any issues that surface in the interim, we will implement the
proper solution.
2. Clarifier 4 weir had a low spot and maintenance is required
In March 2019 the City had both clarifier drives replaced. The weirs were leveled by our
contractor on May 14th and May 15, 2019. Thus, in our opinion the deficiency cited during the
inspection has been taken care of.
You also asked us to inspect and review the inactive mechanical drum screen and correct any
downstream issues. This mechanical drum screen has had limited use because of its unreliability
and constant problems. There are four (4) manual bar screens which are cleaned every hour or as
necessary to ensure the plant is operating at its optimal level. The inspection report highlighted
observance of solids and grit in downstream treatment units. This is not a normal occurrence and
we will make sure the manual bar screens are monitored more closely during peak use.
The other issue was a non -reoccurring event that resulted in the freeboard being less than 2-ft in
the lower digester. We will change our SOP to maintain a 34-inch freeboard which will provide
ample storage for rain or unusual flow events.
The above plan of action is underway except for the Basin 3 sludge removal. We remain
consistent with our approach to decommission the plant all at once. We would appreciate your
consideration and approval of this approach since we have not received any citizen complaints
and the approach is practical and cost effective for the City. Thank you.
Best Regards,
1
Da 'd E. John on, PE, FASCE
Utilities Direcor / City Engineer
CC: D. Jackson, City Manager
M. Braswell, Assistant City Manager
R. Clemmer, Deputy Utilities Director
D. Stoutd, WWTP ORC
P.O. Box 406 Mount Holly, North Carolina 28120