NC0078115_Comments_20220914

A5. RECEIVED
An 4Essential Utilities Company SEP 14 2022
MCDEQIDINRINPDES
September 9, 2022
Certified Mail
Return Receipt Requested
Mr. Bradley Bennett
NCDEQ-DWR-Compliance and Expedited Permitting Unit
1617 Mail Service Center
Raleigh, North Carolina 27699
Re: Comments on Draft NPDES Permit NC0078115
Greystone Subdivision WWTP
Forsyth County
Dear Mr. Bennett:
On behalf of Aqua North Carolina (Aqua) I appreciate the opportunity to provide comment
on the above-referenced draft permit for the Greystone Wastewater Treatment Plant
(WWTP) and raise concerns about the proposed imposition of new limits for copper and
zinc, and the reduced dilution allowance for Whole Effluent Toxicity. As you know, Aqua
requested a complete file review and a copy of the Reasonable Potential Analysis in its
native format. As of this date, it does not appear we have received access to the complete
file or the Reasonable Potential Analysis in its native format (Excel). As such, we cannot
verify that the 7Q10 was reduced based upon new or appropriate information, or that
errors in the calculation of the reasonable potential analysis do not exist.
Aside from questions regarding validation of the reasonable potential analysis, Aqua also
has concerns regarding the feasibility to meet the proposed copper and zinc limits. the
Greystone WWTP is designed for the treatment of conventional pollutants (BOD5, TSS,
and Ammonia-Nitrogen) and is not designed for the removal of metals. The proposed two-
year timeframe to complete improvements prior to the effective date of the limits is
insufficient. During a recent discussion with you and John Hennessey, neither of you
provided any insight regarding treatment technologies used for removing metals from
similar small wastewater treatment plants. Large wastewater treatment plants are
required to evaluate and/or reduce their metal discharge concentrations through the
e
control of discharges from significant and categorical industrial users. However, typical
f
small wastewater treatment plants, Greystone WWTP primarily receives domestic
wastewater and the periods of higher copper and zinc concentrations in the effluent may
not correlate with the discharge of the hauled backwash water, nor may be effectively
reduced by eliminating that waste stream.
202 MacKenan Court, Cary, NC 27511 • 0: 919.467.8712 • F: 919.460.1788 • AquaAmerica.com

Aqua strives for one-hundred percent compliance and has shown significant improvement
in our wastewater treatment plant compliance in the last four years. I trust that NCDEQ/
DWR appreciates Aqua's efforts and does not wish to create a non-compliance situation
for Aqua without sufficient opportunity to study the issue and to implement a solution.
Aqua proposes to undertake the following:
1. Characterize each of the hauled wastewater sources to determine if those are
significant sources of the pollutants of concern (within three months of permit
issuance).
2. Review the corrosion control technology used for the water supply and determine
if a better alternative exists (within six months of permit issuance).
3. Based upon mass balances for the pollutants of concern, Aqua will determine if
source control for the pollutants of concern will reliably meet the proposed limits.
Examples of source control would be cessation of the hauled backwash water
contribution, or implementation of an improved corrosion control strategy (within
18 months of permit issuance). Source control is the preferred solution, but
dependent upon the source being controlled it may be many months before the
results are witnessed. Specifically, the formation of corrosion-protecting scale in
home plumbing is not instantaneous.
4. Aqua would monitor the concentrations of the pollutants of concern monthly as
prescribed by the permit and would statistically evaluate the data for changes
between the original condition and after source control. If the data is statistically
different, Aqua will submit the data to NCDEQ in support of a permit modification
to remove the subject permit limits. (within 48 months of permit issuance).
5. Concurrent with Item 4 above, Aqua will complete treatability evaluations for the
removal of the pollutants of concern. If these pollutants of concern are in a soluble
chelate form, treatment will be challenging and may require a process separate
from the existing wastewater treatment plant process. To Aqua's knowledge, there
is no domestic wastewater treatment facility in North Carolina operating a
wastewater treatment plant of this type and concerns would exist for Aqua
operating one of our facilities with this level of treatment. If needed to meet the
proposed permit limits, Aqua would complete treatability study, design, permitting,
and construction (within 60 months of permit issuance).
Aqua requests that you consider the option of either: (i) postponement of the
implementation of the new and revised limits until the next permit cycle with the known
expectation that these limits will be implemented; or (ii) incorporation of the proposal
above as a schedule within the permit.
Lastly, please be aware that our submission of these comments does not preclude the
right of permit appeal for the above stated reasons, or other reasons yet to be announced

or discovered. We are available to discuss these comments, and please feel free to
contact me at [phone].
Sincerely,
•
fi
os h Pearce PE
Director of Operations
cc: Shannon Becker
Amanda Berger