NC0021024_Draft Permit_20230628

Mr. Gary Perlmutter, MSc.
Environmental Specialist II
NCDEQ/ Division of Water Resources
NPDES Municipal Permitting Unit
Dear Mr. Perlmutter:
City °rRoxboro RECEIVED
JUJ , 8 Z;;23
NCDEQ/DWR/NPDES
Subject: Draft NPDES Permit NCO021024
Roxboro WWTP
Person County
Grade IV Biological WPCS
SIC Code 4952
The City of Roxboro NC would like to offer the following comments concerning the DRAFT NPDES permit
NCO021024 for its WWTP.
Mr. Andrew M. Oakley is no longer the City of Roxboro's Public Services Director. Mr. Kenneth Griffin is
the new City of Roxboro Public Services Director and the process of naming Mr. Griffin "permittee" will
begin as soon as possible.
Page 2 of 11 of the Draft permit list both current and future components at the Roxboro WWTP. An
updated list was emailed to you on 4/28/23, it included this notable change;
1. 1.5 sludge drying beds...( the sludge dewatering facility utilized one of these beds and the two
new aerobic digesters used'/ of another)
We request that notification be given when EPA publishes 40 CFR part 136 Final PFAS Method for
wastewater in the Federal Register in -order to meet the I" full calendar quarter following six (6) months
after publication monitoring requirement included in the draft permit.
Conductivity. Downstream conductivity is just 5% higher than upstream therefore we don't see why
monitoring our effluent for it is necessary. At a minimum we request that the monitoring be reduced to
once per week which is 250 plus samples/data points over the five year permit term.
105 S. LAMAR STREET - PO BOX 128 - ROXBORO, NORTH CAROLINA 27573 - [phone] - FAX
[phone]
«tivw. c i tyo&oxboro. com

Ammonia. The City of Roxboro request that the modified compliance Special Condition A. (1) Effluent
Limitations and Monitoring Requirements, Footnotes 3 and 4 that expired on November 30, 2021 be
reinstated through March of 2024. Completion of the Roxboro WWTP upgrade which began on July 23`d
of 2018 continues to be delayed due to construction related issues with the Oxidation Ditch. A repair
resolution was approved and the repair work to the structure was started on April 3rd 2023, the
Oxidation Ditch repair is scheduled to be completed in late 2023. Once this occurs the biological
treatment process will be transferred from the existing activated sludge basins to the Oxidation Ditch.
The requested March 2024 compliance schedule would also allow time to get the new system up and
running efficiently after the projected solids transfer.
Additionally, the City of Roxboro had an outside consultant (AquaLaw) compare our data (Nh3, ph,
temp.) against EPA's 2013 Freshwater NH3-N criteria. Their findings and recommendations are as
follows:
Roxboro objects to the ammonia ("NH3-N") limits, as proposed, and requests different numeric limits for
the following reasons. The proposed limits (summer 1.0 mg/I monthly average/3.0 weekly; winter 1.8
mg/I/5.4) are unnecessarily stringent for protection of aquatic life, arbitrary and unsupported legally. We
note that we have had no ammonia toxicity as verified through our passing all of our WET tests during the
prior permit cycle.
EPA's 2013 Freshwater NH3-N criteria ("EPA 2013") are the nationally recommended criteria for NH3-N
toxicity. Those criteria are so stringent that many states have not adopted them (also pointing to the fact
that WET testing results demonstrate no need for more stringent NH3-N criteria). EPA's recommended
criteria are highly pH and temperature dependent. We propose the application of EPA's 2013 creiteria
with the pH and temperature inputs set at the upper 75`h percentile values. The upper 75`h percentile
represents a reasonable, largely worst -case, application of EPA 2013.
We compiled the daily pH and temperature records for our facility for 2020, 2021 and 2022, and then
ranked the data separately for the DE4-defined summer and winter tiers. The data are included in the
tables following, including values for a more stringent 90"' percentile approach (although we believe that
the 75`h percentile is adequately conservative, particularly as used with both variables for EPA 2013
criteria):
Summer 2020-2022 Effluent Data
Max
75`h
90`h
pH
7.4
7.2
7.3
T
26.4
24.2
25.1
Winter 2020-2022 Effluent Data
Max
75`h
90th
pH
7.4
7.1
7.1
T
20.8
15.3
16.7

The approximate EPA 2013 criteria values are the following:
EPA 2013 NH3-N WQC (mg/1)
Summer Acute/Chronic
Winter Acute/Chronic
75`h
9.7/1.3
22/2.4
90`h
7.9/1.2
20/2.2
For permit limits Roxboro requests that DEQ use an approach recommended by U.S. EPA in its Technical
Support Document for Water Quality -Based Toxics Control ("TSD"). The first TSD option is to use the
criteria values themselves as limits. Under this approach (and using upper 751h percentile pH and
temperature), the summer NH3-N limits would be 1.3 mg/I monthly average and 9.7 mg/I weekly average.
The wintertime limits would be 2.4 and 22 mg/I, monthly and weekly. Again, considering the use of
conservative 751h percentile values for both the pH and temperature input variables, these resulting NH3-
N limits will be highly conservative and protective of aquatic life. This has been confirmed by our extensive
WET testing.
EPA's TSD alternate statistical procedure for limits calculations generally produces similar numeric values
to the direct use of wasteland allocations/criteria. We have not calculated those alternate values but it
generally appears that in this case the permit limit values would be comparable.
Total Copper limits. As the copper data below demonstrates, we had issues in the second half of 2020,
especially during December that were construction related. We strongly believe the December 151 2020
and December 22"d 2020 copper results were related to three things.
1. One of the three final clarifiers being off-line due to the plant upgrade.
2. MI due to heavy rain.
3. In anticipation of the Oxidation Ditch coming on-line, the contractors installed an influent
diversion box in August of 2020. This diversion box allows influent flow to the OD through a 36"
pipe and flow to the equalization basins through a 24" telescoping valve. Since installation and
currently the 36" pipe to the OD is plugged so all of our flow since August of 2020 goes through
the 24" telescoping valve to the existing activated sludge basins which eventually become
equalization basins after the OD comes on-line. The 24" telescoping valve was not designed to
carry all the influent flow so during heavy rain events it creates a "funnel" effect and water
backs up.
With the installation of the influent diversion box in August of 2020 there was a learning curve for our
staff that resulted in two bypass events from the diversion box and how they had to manage heavy rain
events like those from December 2020. Since that time, we have had heavy rain that resulted in high
flows on many occasions but we haven't had another bypass or copper result anywhere near the 32 ug/I
from 12/1/2020. Since that time, you can see that our copper average has come down steadily and our
maximum value since 1/1/21 is 10 ug/L. We do not believe there is reasonable potential if DEQ would
simply base the review on the data since 1/1/21. We believe these data are the more representative

data because the 2020 data came when the facility was in an upset condition due to the construction
issues mentioned above. Thus, we ask DECL to rerun the RP calculations using data from 1/1/21 and with
recognition of the significant downward trend since 1/1/21 in both the max and annual values. That
trend is due to the lessons learned and the management strategies applied as a result of high flows
during heavy rain events after the influent diversion box tie-in and the resulting stabilization of the
operation of the facility. We believe this stabilization of operation will continue to improve with the
Oxidation Ditch & Final Clarifier coming online and the completion of the WWTP upgrade. Again, the
second half of 2020 copper data are not representative of the plant performance going forward.
Date
ug/I
Date
ug/I
Date
ug/I
Date
ug/l
1/7/2020
6
1/5/2021
8
1/5/2022
3.6
1/10/2023
6
2/4/2020
9
2/3/2021
6
2/1/2022
7
2/7/2023
5
3/3/2020
8
3/2/2021
8
3/8/2022
5
3/7/2023
6
4/7/2020
11
4/6/2021
8
4/5/2022
6
4/4/2023
6
5/8/2020
8
5/10/2021
10
5/4/2022
7
5/2/2023
6
5/18/2020
10
6/7/2021
6
6/5/2022
5
Avg.
5.8
6/3/2020
7
7/5/2021
8
7/5/2022
7
Max.
6
7/7/2020
8
8/3/2021
6
8/2/2022
6
8/4/2020
it
9/14/2021
9
9/13/2022
7
9/22/2020
7
10/5/2021
8
10/4/2022
6
10/6/2020
8
11/2/2021
6
11/8/2022
9
11/3/2020
10
12/9/2021
5.6
12/6/2022
7
12/1/2020
32
Avg.
7.383333
Avg.
6.3
12/8/2020
13
Max.
10
Max.
9
12/10/2020
12
12/11/2020
12
12/22/2020
18
12/29/2020
8
Avg.
11
Max.
32

Fact Sheet NPDES Permit No. NCO021024 6.6. Mercury Statewide TMDL Evaluation pg. 7 & 8 of 11
We disagree with including an annual limit of 12ng/I because of the reported maximum conc. of 51.9
ng/I from August 2018 monitoring. This 51.9 ng/I was reported on the August 2018 eDMR as instructed
the RRO (Raleigh Regional Office), the original lab result of 92.8 ng/I was averaged with a second
analysis on the same sample which came back as 11.0 ng/I. Please see the attached file (LLHG August
2018 5 26 23), it includes email correspondence between Roxboro WWTP Supt. Derek Clayton and
NCDENR Environmental Program Consultants Vanessa Manuel and Danny Smith. Additional emails
(attached) between the Division of Water Resources PERCS Unit Supervisor Deborah Gore and City of
Roxboro WWTP Lab Supervisor / PT Coordinator Crystal Shotwell indicate that she had talked to Teresa
Rodriguez who issued our current NPDES permit and concluded there was plenty of historical data
showing the original lab result for the August 2018 sample of 92.8 was an anomaly. Also, in the
attached file is a copy of the comments submitted with version 4.0 of our August 2018 eDMR. We
believe that PERCS Unit Supervisor Deborah Gore and permit writer Theresa Rodriguez were correct and
the original sample result of 92.8 was indeed an anomaly based on the historical data and therefore
should have been considered invalid. Based on the information provided here and in the attached file
we request the LLHG 12 ng/I annual limit be removed from the final permit.
Upstream and Downstream DO, Temp., and Conductivity. Since the instream sampling is not required
under the federal program nor by any other State the we are aware of and the City has been doing this
monitoring for years we don't feel that it is necessary to continue it in the new permit. Therefore, we
request that this requirement be removed from the final permit.
Chronic Toxicity. The Roxboro WWTP passed 17 of 17 Chronic Toxicity and all four second species WET
test during the last permit cycle, based on these results we request that this monitoring requirement be
removed from the final permit.
Thank you for taking the time to consider the above requests, we look forward to your assistance in
continuing to protect our local environment.
Sincerely,
Allen Brooks Lockhart
City Manager
City of Roxboro

i1e m- Manual• Vanewas ........ Of
:i9ii.••-:' RE- [E(teffaq fioxwo WwTP LOW LAYER M!feury
Oats: October 2. 2018 at 903 AM
T•:: Derek Clayton :ic r.,.r Srntr, penny _
Cs: Tommy Warren t ....:. cry" srtotwet Andrew Qdcley
Oerek —
Because permittees are required to report all monitoring data from samples collected from the
effluent, you should revise the eDMR to include the additional monitoring data, add a comment to the
eDMR noting your concerns with the data result(s) and attach a copy of your email to the signed eDMR
(2 copies) you submit to Central Files. Your comments and attachment, as included on the eDMR, will
be part of the final record for the monitoring report.
If you have additional questions, please feel free to contact me.
Vanessa E Manuel
Environmental Program Consultant
Division of Water Resources — Raleigh Regional Office
Department of Environmental Quality
919 791-4255 office
anes§a rranues,tJnccQgru goy
Physical: 3800 Barrett Drive, Raleigh, NC 27609
Mailing: 1628 Mail Service Center, Raleigh. NC 276WI628
_..:a:i :•. �r,�cl.... 't; a:tc, ;•ra. �_._.. jl.�'t?'S� =� ss. ..r .!•?
,';i% .:3; Jl:.;d .'_: i,i _ ?•_���'•':� i. c': _' n:+tY .r?y � t� _.. ,. �i`•� •. ,
From: Derek Clayton <dclayton@citycftoxboro_com>
Sent: Tuesday, October 02, 2018 7:16 AM
To: Manuel, Vanessa <vanessa.rnanuel@ncdenrgov>; Smith, Danny <[e-mail]>
Cc: Tommy Warren <[e-mail]>; Crystal Shotwell <cshotweliLOcityofroxboro_com>;
Andrew Oakley <[e-mail]>
Subject: (External] Roxboro WWIP Low Level Mercury
Good morning Vanessa and Danny,

On 9/20/18 I had a phone conversation with Danny eonoeming both influent and effkMA low level Hg
sarnples that were u*en in mid AuWst I followed up the phone cab with an ernad on the same day. As a
result we submitted our August 2018 edror witthout dim rewits knowing that once we did get them we
would WKkAde them in a version 2.0 edmr:
Due to orgotrg lab equipment issues our eorrrrrercial lab (Merl Inc) was unable to analyze the samples
so they stripped ttrem to Pace Analytical. I received the results of these samples via email on 9/27118 while
on vacation and fore atrded the results to our Lab Supervisor (Crystal Slobveif) asking her to deck with our
oDmmemiai lab because the effluenk results were 3OX higher than average. Please review the foN w&* as to
why we feel these results are not valid
1. We were gold that we were not the only municipality that received results way higher than normal on
samples that Merit ch Inc. had forwarded to Pace Anakyticai during the same time frame.
2. Field blanks higher than nomiaL
3. Roxboro tow Level Ng plant hisbory...2012 avg. 1.67 ng/l, 2013 avg. 2.13 ngjl, 2014 avg. 3.71
ng/t, 2015 avg. 3_M #W& 2016 avg. SA& ng/ki, 2017 avg. 3.71 h9/1, 3!6/18...L62 ng/L
The 2012 - 3/2018 average dfkm t rrremcuy for our facility is 3.07 ng/t and tine rnaxintum for the
same period was 10.9 rWl so when I saw an effluent bw level Hg result from 8/13/18 at 92.3 ng/l I was
and AN am very skeptiCaL An influent sample was Wm on the same date and it was reported at 42.3 n9/i.
Based on this information I woad hike to kknm how NCDEW would like me to use these results. Should I
report them in a version 2.0 edw as we had planned and attach a copy of this emall? Or is there something
else we should do7 Our Lab Supervisor / PT Coordna0or will also be consulltirig with her NCDENR
Pretimbrrerk contacts to get guidance on using or not using this effluent result: in our Prebeabnent LTMP.
We contacted Pace Labs yesterday and asked 9 our 8/13/18 samples were snit there and informed #Ann that
we wound blue bD have them back if they are. tWre still waiting to find out whether they are or not VVe also
Nave anattrer set of Influent and Hf[uent low level mercury samples Ud m on 9/li/18 that were seek bo
Merttech UX.. These samples have been shipped to Summit Labs in Ohio for analysis.
I look forward to your response concerning this ntiat n and t you need additional information pleam don't
heskabe to cal.
Derek Clayton
WWTP Suet.
C,ty of RoodxxD
336 599 8232

From: CrpvW Shobv * crbowesC citycrroxboro.com
Subject: Fwd: [E4enhal] Low level Hg for August LTM
Date. October 26, 2018 at 8Z5AM
To: Derek Cbgton ddayton,4ctyofroxboro.com
Begin forwarded message
Fronk 'Gore, Deborah' <de0wrah.aore4nFtlgnr.gQ_v>
Subject RE: [External] Lour Level Hg for August LTM
Dabs: October 26. 2018 at 8:06:35 AM EDT
To: Crystal Shotwell <,c:rbotves-#cityofroxbcro.com>, "Hassan, Monti' <rr.onti.hassanCncdenr.gov>
Cc 'Zavng, Chong' <c; g zhanq*ncdanr.g. v_>, 'Manuel, Vanessa' <vaneSSa.manue*ncdenr.ggv_>
Good Morning,
As far as using the data in the HWA I would allow the use of the second value. 11.o ugrl, based on historical data. Now as to what to report
on the DMR... I'm not sure.
There is no unit for mercuy, but the nunhbers are used in the RPA. Teresa Rodriguez just issued the permit so I talked to her about how
they use the numbers and she said that the permit would probably decide the same as PERCS would for the HWA. Plenty of historical data
showi gt that the 928 is an anomaly. Still she didn'trealty know the answer to what to put on the DMA.
d possible I would put both numbers in the coil and explain on the back 111192.81 But I doubt the system will allow that So then, my
recommendation is that Roxboro report the average on the DMR with an explanation and both values on the beck
I have copied the RRO to see rf they have an alternate suggestion since they are the ones who really review the data and lake the action.
Deborah Gore
PERCS Ling Supervisor
Division of Wafer Resowces
Department of Environmental Quality
9IW707-3624 office
919-807.6489 fax
deborah.gorgtg nodenr.goy
1617 Mad Service Center
Raleigh, NC 27699-1617
Email correspondence to and from this address is subject to the North Caro ina Public Records taw and may be disclosed to third parties
---Onginai Message ---
From: Crystal Shotwell <crbowes0cityo1roxboro.com>
Serf: Thursday. October 25, 2018 1 29 PM
To: Hassan, Monti vranti.hassanOncdem.gov>
Cc: Gore, Deborah <deborah.gore0ncdenr.gov>
Subject: [External] Low Level Ng for August LTM
CAUTION External email. Do not dick links or open attachments urdess verdied. Send a3 suspicious email as an attachment to Report
Spam <nwIto:report.spam<Pnc.gov>
Good afternoon Monti.
! collected my LTM samples in August and shipped them to Mentech to have there anWyzod. They were having issues with their Low Level
-ig machine and were not able to run our samples. Without ctmcking with us, they shipped our samples to Pace Analytical and had them to
tnaiyze the samples and we received a 92.8 ng& on our effluent sarnple. We irrtnedhately, knew this could riot be right and argued this with
Mer4ech and Pace. Pane stood by it. So we had Mentech get our sample back from Pane and ship it to SumnV Labs and have them
malyze A. Summit analyzed it and the result was 11.0 ng2, which is still highet than normal but more believable than the first
Ay question to you is, can I throw out that first number and use 11.0 nq& or do I have to average the two numbers Would this be
*nsidered a split sample')
;iystat Shotwell
'retreatment CoordinatorlLaboraviry Supervisor City of Roxboro WWTP
56-59M232

NPMS PMMff NO- MM1024
v
FUMff VERS10Pi_ 4.0
—
PERMfI' SFATM Eked
FACILITY NAhL: Roxbow WWTP
CLASS: 11,W-4.
COUNTY: Pcmn
OWNER HAMS: City of Roabow
ORC: Derck Lym Cl"
ORC CERT NUMBER: 9264
MAD& W W-4.
ORC tt" CHANGED: No
eDMRPERIOD: 09-2014(Aurm201E)
VDRSiON:4.0
SfATVS:PtaccoW
Rgml Commeoft
I had a phoa corrmudoa wilt Dasry Smth of M IANR on 912WI9 and fabwW is up with w anti exp6jowS dot vee were wis&ietg t" low W%yl _
hg nmpFa for LdiurYtd
and F:Muatt. These are not NPUFS Permit required bat part ofar Picutalmcrt Larg Tar Mamoru* Pin. Our commwcW lab had w etltripatte m min and had to send the
samples to m!w hb for arri . Becow of this and me being on vacwkm mad vjmk D wmy said 1 ewdd certify and mrLmi versioe t.0 m& dw more A mcmd edmr (version
2.0) wtll be s AmiNed pith the restlltc oam nw ved Vasion 2.0 Added low keel hs sevah, far [t ww and aw ce t Crtroeoe_3 do &ot befwm tie d&.t to. kwd
hg retest m vtm= 2 0 is vd id. pkaae see atbdmmt included with oopia that vMM MMW in DC Verdun 3 0 The or trl IErg sartpk (mot a cedes saarpk) vas reuicved
hm the &U wom mud lab who up&rkd the rinds 30X highs dram the historical avg for our 4' at 92.E W and at out mgwm shipped the amok to a wcad isb who
i and ftpoftd 11.0 . Our Pmkcd netts Coordmukw / Lab Srpeviwreawuled the more PERCS Unit and Deborah Gore snored e reVoua dal we would be &Rowed
to ttm the setwod vshre bwed an the mmwd of mAcriwl data gpiog the 42..E as an aaawn)y Sic also tdked to Taaa Radr9m (pm" wailer) aced sit said that they world
rrub 1y decide 6e same as PFRCS. (anal attsdied) Nawew ow RRO contact Vwcm Manuel has mmumed tore to ropwt so bob tore ladlucrt and Efuntt llhg .
rartpk tsxrks fiane Eli3I l E irrehsded in this vessim 3.0 &rc averages of the two lab erardb on the same samples Gam l/13/18 1 an Ar el0tratt average of S 19„del at
it sbwocd bet 1 oompkuly agmc w * PEtfCS dw based as auomt of hwaxd duce avaltsbk tart rwoo tie 92.E srf/E or the 519 ne w& mpcewats em aeewl arrant of
wArcwy in ow cffi rtoud/13/l R DC I/M9 Veraioa 4.0 added rticixl molt dial was tot kmkrdtd in previous veasiom. DC