NC0063860_Permit Modification_20160907

WaterResources
ENVIRONMENTAL QUALITY
September 7, 2016
CERTIFIED MAIL 7009 2250 0000 80871290
RETURN RECEIPT REQUESTED
Mr. Shannon V. Becker, President
Aqua North Carolina, Inc.
202 MacKenan Court
Cary, North Carolina 28640
Dear Mr. Becker:
PAT MCCRORY
Governor
DONALD R. VAN DER VAART
Secretary
S. JAY ZIM ERMAN
Subject: Request for Additional Information
NPDES Permit Modification Request
Harbor Estates WWTP
NPDES permit NCO063860
Mecklenburg County
Director
The Division has reviewed your application, received on March 21, 2016, for renewal of NPDES permit
NC0083470. To enable us to complete our review in accordance with N.C.G.S. 143-215.1 and 15A NCAC
211.0105, please provide additional or revised information to address the following comments:
1. Please provide five (5) days of Total Hardness (CaCO3 or (Ca + Mg)) data for the Harbor Estates
WWTP effluent.
2. Please calculate and provide the expected discharge concentration for all parameters given in the
application for filter backwash that had detection. The minimum flow for the Harbor Estates WWTP in
the past three (3) years should be used in this calculation.
3. Please provide the following information to describe each filter backwash source (these questions are
taken from NC Form C-WTP for water treatment plants):
a) type of WTP treatment plant: Conventional (Includes coagulation, flocculation, and
sedimentation, usually followed by filtration and disinfection), Ion Exchange (Sodium Cycle
Cationic ion exchange), Green Sand Filter (No sodium recharge) and/or Membrane Technology
(RO, nanofiltration)
b) describe the treatment processes for the raw water
c) describe the wastewater and the treatment processes for wastewater generated by the facility
d) plant design potable flowrate in MGD and backwash or reject flow in MGD
e) list all water treatment additives, including cleaning chemicals or disinfection treatments, that
have the potential to be discharged such as Alum / aluminum sulfate, Iron sulfate / ferrous
sulfate, Fluoride, Ammonia nitrogen / Chloramines, Zinc -orthophosphate or Sweetwater CP1236
or any other additives
f) provide a schematic of flow through the facility, including flow volumes at all points in the
water treatment process and showing the points of addition for chemicals and all wastestreams.
State of North Carolina I Environmental Quality I Water Resources
1617 Mail service Center I Raleigh, North Carolina 27699-1617
919 806 6100

Mr. Becker
September 7, 2016
Page 2 of 2
Please note that the NC 2007-2014 Water Quality Standard (WQS) Triennial Review was approved by the
NC Environmental Management Committee (EMC) on November 13, 2014. The US EPA subsequently
approved the WQS revisions on April 6, 2016 with some exceptions. The NC Division of Water Resources
NPDES Permitting Unit is required to implement the. new dissolved metal standards in all permits public
noticed after April 6, 2016.
The new standards for most metals include acute standards. Further, the freshwater standards for several
metals are expressed as the dissolved form of the metals, and seven metals have hardness -dependent
equations. As a result, the NPDES Permitting Unit will need site-specific effluent hardness data and instream
hardness data, upstream of the discharge, for each facility monitoring these metals in order to calculate
permit limitations.
If no response is received within 60 calendar days [per 15A NCAC 2H.0107(b)], the permit will be modified
without the benefit of the additional information. Therefore, a default hardness of 25 mg/L (CaCO3 or (Ca +
Mg)) will be used to calculate effluent limits for Total Copper and Total Zinc giving a daily maximum limits
of 7.9 gg/L and 125.7 gg/L, respectively. See attached spreadsheet for dissolved to total metal calculations
with maximum allowable effluent concentrations.
If you have any questions, please contact Derek Denard at 919-807-6307 or email at
derek. denard(a,ncdenr. gov.
4cery,
S. Jay Zimmerman, P.G., Director
Division of Water Resources, DEQ
he: &P-DES_Pemiit File`s
Central Files
DWR/MRO/WQROS
Mecklenburg Co. DEH
ec: DWR/MRO/WQROS, Corey Basinger [[e-mail]]
DWR/MRO/WQROS, Ori A Tuvia [[e-mail]]
Shannon Becker, Aqua North Carolina, Inc. [[e-mail]]
Laurie Ison, Agua North Carolina, Inc. [[e-mail]]
I Thurman Home, P.E., Horizon Engineering & Consulting, Inc. [[e-mail]]

Date: 8/11/2016
FACILITY: Harbor Estates WWTP-Aqua North Carolina, Inc.
NPDES PERMIT: NCO063860 Dissolved to Total Metal Calculator
In accordance with Federal Regulations, permit limitations must be written as Total Metals per 40 CFR 122.45(c)
(d) = dissolved metal standard. See 15A NCAC 02B.0211 for more information.
(h) = hardness -dependent dissolved metal standard. See 15A NCAC 02B.0211 for more information.
(t) = based upon measurement of total recoveable metal. See 15A NCAC 02B.0211 for more information.
The Human Health standard for Nickel in Water Supply Streams is 25 mg/L which is Total Recoverable metal standard
The Human Health standard for Arsenic is 10 pg/L which is Total Recoverable metal standard.
Receiving
Stream
summer
70)10 (CFS)
Receiving
Stream
summer 7Q10
(MGD)
Rec. Stream NPDES Total Suspended
1Q10 FloLimit Solids
w
-Fixed Value-
[MGD] MGD], (mg/L)
Combined
Hardness
chronic
(mg/L)
Combined
Hardness
Acute
j(mg/L);
InsVeam
Wastewater
Concentration
(Chronic)
Irrstream fluent
Wastewater Upstream
Concentration Hardness (mg/L)[Hamrdness
Median
(Acute) g/L)
100.0000 25 25
0.0000
1 0.0000 11
0.0000 0.0416 10
25.000
25.000
100.0000
(d) = dissolved metal standard. See 15A NCAC 02B.0211 for more information.
(h) = hardness -dependent dissolved metal standard. See 15A NCAC 02B.0211 for more information.
(t) = based upon measurement of total recoveable metal. See 15A NCAC 02B.0211 for more information.
The Human Health standard for Nickel in Water Supply Streams is 25 mg/L which is Total Recoverable metal standard
The Human Health standard for Arsenic is 10 pg/L which is Total Recoverable metal standard.
Upstream Hard 10th Percentile (mg/1) = 25
EFF Hard Med (mg/L) = 25
Dissolved Metals
US EPA
Translators- using
Maximum Allowable; Effluent Concentration COMMENTS (identify parameters to PERCS Branch to maintain in facility's LTMP/STMP):
(MAEC) as a TotelrMetal.
PARAMETER
Default Partition
.=Disadv«1 Malai+Translator
Chronic
Acute
Coefficients
Chronic Acute
Cadmium (d)
fuglil
0.15
rug/11streams)
0.82
0.252
[uqAl FugAl
0.59 3.24
Cd -Trout streams
0.15
0.51
0.252
0.59 2.01
Chromium III (d)(h)
24
183
0.202
117.73 905.08
Chromium VI (d)
11
16
1.000
11.00 16.00
Chromium, Total (t)
N/A N/A
Copper (d)(h)
2.7
3.6
0.348
7.88 10.47
Lead (d)(h)
0.54
14
0.184
2.94 75.49
Nickel (d)(h)
16
145
0.432
37.23 335.21
Ni - WS streams (t)
25 N/A
Silver (d)(h,acute)
0.06
0.301
1.0001
0.061 0.30
Zinc (d)(h)
36
361
0.2881
126.73 125.71
Beryllium
6:'5 ,
65
1 000: _
65 _ 65
Arsenic'(d)
1'501
34UI
1.00q
1501, 340'
(d) = dissolved metal standard. See 15A NCAC 02B.0211 for more information.
(h) = hardness -dependent dissolved metal standard. See 15A NCAC 02B.0211 for more information.
(t) = based upon measurement of total recoveable metal. See 15A NCAC 02B.0211 for more information.
The Human Health standard for Nickel in Water Supply Streams is 25 mg/L which is Total Recoverable metal standard
The Human Health standard for Arsenic is 10 pg/L which is Total Recoverable metal standard.