NC0084212_Corrective Action Plan_20201120

Davie County Sparks Road Water Treatment Plant (NCO230015)
Plan for Reducing Water Plant Wastewater Discharges of Copper and Zinc
11 /25/20
In response to the requirements of NPDES Permit No. NC0084212 providing for the
discharge of wastewater from the Sparks Road Water Treatment Plant (NCO230015),
the Davie County Utilities Department (Utility) performed background sampling and
commissioned Mr. Gary A. Iverson, of Hazen and Sawyer to consider alternatives to
limit the discharge of Copper and Zinc in its wastewater. Mr. Iverson's suggestions and
comments are attached.to
In light of those considerations; the Utility proposes the following multi step plan:
1. Increase internal QA/QC sampling at various points including background river
sampling, terminal lagoon sampling, sedimentation basin influent and effluent
sampling (individually and combined) using available bench methods throughout
the period of study.
2. Optimize sedimentation performance in the wastewater settling basins to reduce
contaminant suspension and short circuiting.
3. Optimize dosing of Copper based algae control methods in the terminal reservoir
using bench testing methods now available. Change algaecides as needed.
4. Switch to an orthophosphate product that does not include Zinc if sedimentation
optimization does not provide sufficient reduction.
5. Evaluate progress at frequencies set forth in the permit.

Hazen
Memorandum
4011 Westchase Blvd
November 25, 2020
To: John Grey, P.E., Grey Engineering
From: Gary Iversen, P.E., Hazen and Sawyer
Raleigh, NC 27606
919-833-7152
Re: Sparks Road, Davey County, NC — Copper & Zinc NPDES Permit Compliance
NCDENR Contact List
1. Links to general permit information and dissolved metals concentration
calculator:
httr)s://deg.nc.gov/about/divisions/water-resources/water-resources-
perm its/wastewater-branch/n pdes-wastewater-permits
httr)s://deg.nc.gov/about/divisions/water-resources/water-resources-r)ermit-
guidance/npdes-industrial-stormwater/metals-calculators/option-1
2. Gary Hudson, Environmental Specialist
Gary. hudson(a)ncdenr.gov
3. The fact sheet for the 2019 permit is here:
https://edocs.deg.nc.gov/WaterResources/DocView.asr)x?id=885094&dbid=0&re
po=WaterResources
4. Sparks Road Permit written by: Joseph Corporon
0oe.corporon(a)ncdenr.gov
No phone number available
5. Charles Weaver, Environmental Specialist
Permitting Unit
Charles.weaver(a)ncdenr.gov
919-707-3616
6. Eric Hudson, Regional Engineer
Eric. Hudson(a)ncdenr.gov
336-776-9665
7. Dustin Rhodes, LCR Compliance
Dustin. Rhodes(a)ncdenr.gov

In discussions with Charles Weaver, the permit conditions must be complied with. I
asked why Sparks Road was required to monitor copper if they passed the whole
effluent toxicity test and Mr. Weaver replied that it was an old rule and copper
monitoring is now required and was included in the permit. North Carolina enacted the
requirement about 3 years ago in response to federal EPA regulations. Previously, if a
treatment plant passed the whole effluent toxicity test, compliance with copper, silver
and zinc standards was not required.
I also spoke with Eric Hudson, Regional Engineer at 226-776-9665 in Raleigh and he
thought I have a good case for not going back to original monitoring frequencies if the
zinc orthophosphate is replaced with a straight orthophosphate product. However, the
request must be submitted to Dustin Rhodes, LCR Compliance Manager
(Dustin. Rhodes(aDncdenr.gov) for approval. Eric Hudson also requested that I send an
email to Rhodes with a copy to him outlining the request.
Copper and Zinc Reduction Alternatives
Control of algae growth in the terminal reservoir is needed to help reduce taste and odor
and to prevent filter clogging algae from reducing filter run times.
Several options are available to help control algae and reduce effluent copper levels for
compliance with the NPDES permit. Each of the strategies are discussed.
Lagoon Settling and Solids Resuspension
Copper and zinc solids from filter and clarifier backwash settle in the lagoon and over
time could build up so they can be resuspended during a filter and/or clarifier backwash.
If compliance sampling of the supernatant takes place when the settled solids are
resuspended is likely that residual copper and zinc levels would be elevated causing a
violation.
Settled solids levels in the lagoon should be evaluated and it may be possible to remove
these solids periodically and avoid exceeding the copper and zinc limits.
It also may be possible to add baffles to the lagoon to help prevent filter and clarifier
backwash from disturbing the sediments.
Samples could be collected by plant staff before, during and after filter/clarifier
backwashes to determine if this is occurring. If this strategy is viable, periodic removal
of the settled solids could be an effective solution.
Protective Cover
One option that would provide a permanent solution to solve the problem of algae
growth in the terminal reservoir would be to provide a protective cover. Eliminate
sunlight and prevent algae growth. Hazen has provided assistance to Johnston County
and the City of Raleigh to prevent algae growth in their terminal reservoirs. This
2

strategy has been successfully used in Johnston County for the last 10 years and more
recently in Raleigh, NC for their terminal reservoirs.
The protective cover consists of floating balls; these floating balls annoy geese and
other birds and keep them off the reservoir and consequently are called "bird balls".
They are available locally from: EEC, Wilmington, NC, 910-799-4411. (http://eccllc.us/)
The terminal reservoir at the Sparks Road Water Treatment Plant is approximately
239,000 sf (5.5 acres). Preliminary cost estimates to cover the reservoir are
approximately $2.50 sf, plus delivery and installation. EEC can provide delivery
services and installation. Each truck can hold 100,000 balls which covers 10,000 sf.
Delivery from Wilmington to Sparks Road would be $450/truck with $250/truck labor for
installation. Cost details are presented below:
Parameter
Units
Totals
Reservoir
sf
239,000
Total
Cost/sf
$2.50
$597,500
Truck Capacity (sf)
sf
10,000
Total Truckloads
24
Delivery
$450
$10,800
Per/Truck
Installation
$250
$6,000
Per/Truck
Total Project Costs
$614,300
This strategy is the most expensive, but it would provide a permanent solution to the
algae issues and would not require any monitoring or compliance issues, as copper
would be eliminated.
Copper Sulfate Treatment
Currently Sparks Road is currently feeding Earthtec Copper Sulfate to the raw water
pumped to the terminal reservoir to provide algae control. Earthtec is a proprietary
copper solution designed to keep the copper suspended and not settle out, providing a"
better" control strategy than traditional copper sulfate solutions.
The fact that the Earthtec stays suspended in the water column of the terminal reservoir
may be contributing to the elevated copper levels.
Copper and zinc sample results and Earthtec feed rates are presented:
3

Total Copper results
Total Copper Limit Daily:10.47ug/I Monthly Avg:7.88ug/I
Date
Total Copper
7-Jan
4Feb
3-Mar
7-Apr
5-May
2-Jun
7-Jul
4-Aug
1-Sep
15-Sep
22-Sep
6-Oct
20-Oct
3-Nov
001 Effluent
4.00
4.50
6.00
6.40
10.00
<2.00
17.00
17.00
9.70
11.00
9.30
0.008
0.01
Lagoon 1
7.90
8.90
Lagoon 2
13.00
7.20
Settled
34.00
11.00
18.00
0.011
Raw YR
<2.00
8.50
2.70
0.004
<0.002
Clearwell
6.80
Earth Tec CuSO4
Off
Off
Off
12ml/min
20ml/min
25ml/min
38ml/min
24ml/min
25ml/min
Off
Off
20ml/min
Off
Off
Table Note: Oct, Nov results in mg/l. Other Results in ug/1
Earthtec or copper sulfate pentahydrate are needed to help control algae growth in the
terminal reservoirs. Based on the copper data and the Earthtec feed rates it may be
possible to provide algae control with reduced feed rates and not exceed the copper
limits.
As shown, when the Earthtec feed rate is 12 mL/min the 001 Effluent copper is less
than the monthly average limit of 7.88 uUmin.
Based on the copper level of 6.8 ug/L (Oct-6) in the clearwell, it appears that the filters
are removing nearly all the copper present in the settled water. When the filters are
backwashed, the copper held by the filters is transported to the lagoons and ultimately
back to the River exceeding the permitted copper limits.
Earthtec is a 20% copper sulfate solution with a specific gravity of 1.2. This provides a
copper sulfate concentration of 240 mg/mL. At a raw water flow rate of 2 mgd, a 12
mL/min solution feed rate would provide a concentration of approximately 0.5 mg/L
copper sulfate. One option would be to limit the Earthtec feed rate based on settled
water and Effluent copper levels so that the copper limits are not exceeded.
Traditional Copper Sulfate Crystals
Another alternative would be to use traditional copper sulfate pentahydrate crystals.
The copper sulfate crystals could be dissolved and mixed in a solution tank and fed to
the raw water flow to provide algae control. Copper sulfate would be expected to settle
out in the reservoir more quickly than the Earthtec. In this way, the copper would not
leave the terminal reservoir and would not be captured by the filters.
To maintain copper levels to below the NPDES limits, operating staff will need to
monitor copper levels in the field at the plant and make the necessary feed rate
4

adjustments as needed. Field test kits and test reagents are available from Hach that
would be compatible with the laboratory equipment at Sparks Road.
If this strategy is not effective because of the limited settling characteristics of Earthtec
then testing should be conducted using copper sulfate crystals until copper levels are in
compliance with the NPDES requirements.
A copper sulfate pentahydrate solution equivalent to the 20% Earthtec solution could be
made using a 50-gallon tank with a mixer. Add 156 lb of copper sulfate crystals to 50
gallons of water and mix until completely dissolved to provide a 20% copper sulfate
solution. Converting to copper sulfate crystals would be expected to reduce application
costs, as the crystals are less expensive compared to Earthtec. However, weighing,
adding, and mixing the crystals would require some additional labor, and the overall
costs may be similar.
Zinc Reduction Alternatives
Sparks Road currently uses zinc orthophosphate for corrosion control treatment. It is
assumed that the source of zinc causing exceedances in NPDES permit are due to the
current corrosion control treatment. The zinc sample results are presented below:
Total Zinc results
Total Zinc Limit Daily: 36.5ug/I Monthly Avg: 36.5ug/I
Date
Total Zinc
7-Jan
4-Feb
3-Mar
7-Apr
5-May
2-Jun
7-Jul
4-Aug
I 1-Sep
15-Sep
I 22-Sep
6-Oct
I 20-Oct
3-Nov
001 Effluent
21.00
31.00
33.00
25.00
6.40
<2.00
8.90
44.00
89.70
<2.00
39.00
25.60
<0.05
Lagoon 1
17.00
<2.00
Lagoon 2
16.00
6.80
Settled
<2.00
13.00
<2.00
23.30
Raw YR
<2.00
19.00
<2.00
25.20
<0.05
Clearwell
<2.00
All Results given in ug/I All Tests performed by Statesville Analytical State Certified Lab # 440
As shown the residual zinc levels were exceeded in August, September, and October.
If the source of zinc is due to the use of zinc orthophosphate for corrosion control
treatment, then it may be necessary to use a different corrosion inhibitor that does not
contain any zinc. Zinc Orthophosphates: Recent studies show no additional corrosion
control benefit due to zinc. However, the zinc can increase concentrations in
wastewater sludge.
Orthophosphates: PO4 3, are effective at pH values of 7-8, and form a protective coating
similar/identical to zinc orthophosphate, but without the zinc.
5

It would be straightforward to replace the zinc orthophosphate with a similar/identical
orthophosphate corrosion inhibitor and feed it to provide an identical concentration or
orthophosphate. However, changing the corrosion control treatment strategy will
require approval from DEHNR.
Often a change in corrosion control treatment will require the system to return to the
initial original lead and copper distribution system monitoring. Any corrosion control
treatment changes are reviewed by the State on a case by case basis. It may be
possible to make a case of changing the zinc orthophosphate treatment to
identical/similar orthophosphate treatment does not require a return to the original
sampling sites and frequencies. However, that will be determined by the State. Sparks
Road is currently monitoring 30 distribution system sites once every three years.
Original monitoring is considerably more expensive would require sampling from 60
sites every six months.
A recommended corrosion control treatment to replace the current zinc orthophosphate
would be a Carus 4000 straight orthophosphate product. Carus has been supplied with
water quality data and has recommended Carus 4500, a straight orthophosphate. They
have replied with product pricing and dosing recommendations, included in the
appendix of this report.
The local contact for Carus is: Eva Caspary, Regional Sales Manager, PhD
Cell Phone: [phone], eva.caspary(aDcarusllc.com, Carus LLC.
Consequently, a "Request for change in Corrosion Control Treatment Form" was filled
out and filed with NCDENR, and sent to Dustin Rhodes. Dustin Rhodes is the State
LCR Compliance Officer in Raleigh (Dustin.Rhodes(aDncdenr.gov). A copy of the form is
included in the Appendix of this report. In addition to the request form, an email letter of
explanation was included, requesting that the original LCR monitoring requirement be
waived.
Consequently, Dustin Rhodes approved our request for a change in corrosion control
treatment chemical to Carus 4500, and also approved the request for waiver of
returning to original monitoring requirements. Davie County will not be required to
return to original monitoring and will remain on reduced monitoring, sampling 30 sites
every three years. The next LCR monitoring event is June 2021.

11/19/2020
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North Carolina Department of Environmental Quality
Division of Water Resources, Public Water Supply Section
Request for Source Water and/or Treatment Changes Under the Lead and Copper Rule (LCR)
This form must be completed by the system owner or designated person in responsible charge and be submitted to the Public Water Supply Section's
LCR Rule Manager for approval at least 90 days prior to the planned date of change. This form is to be completed in addition to fulfilling the
requirements of 15A NCAC 18C Section .0300 "Submission of Plans: Specifications: and Reports.")
Water System Name: Davie County, Sparks Road
Water System Number:NCO230015
County: Davie
Date: 11/20/2020
Water Treatment Plant
Note: To help you properly complete this form, example entries are shown on our website at http://deg.nc,gov/about/divisions%water-resources/driRc
water. com fiance-services#1cr. See back of 'form for additional information.
SOURCE WATER CHANGES
TREATMENT CHANGES - CCT
TREATMENT CHANGES -
OTHER
List Existing
Source(s)
Source
Type
(SW,
GW
If currently pLand
water, provid
system namInactivated
number of s
Date to be
Existing Corrosion
Control Treatment (CCT)
Proposed Change #o CCT
Proposed
Change
Date
Existing Other
Treatment
Proposed
Change to
Other
Treatment
Proposed
Change
Date
= Zinc Orthophosphate Calcium Orthophosphate
List New Source(s)
Source
Type
(SW,
GW)
If plan to purchase
water, provide water
system name and
number of supplier
Proposed
Date to be
On-line
Proposed Corrosion Control Treatment
Proposed
Change
Date
Proposed Other Treatment
Proposed
Change
Date
Explanation of Source Water Change:
Explanation of CCT Change: Elimination of zinc for
compliance with zinc effluent limits in NPDES Permit
Explanation of Other Treatment
Change:
Form prepared by:
Ac.hAe l C. WEIR
Sign ure-
C
Phone:
336-998-9763
Email:
[e-mail]
System Affiliation: ( check box)
X Owner or ❑ Responsible person
(Print Name])
Return this form to: Public Water Supply Section, Attention: Lead and Copper Rule Manager, 1634 Mail Service Center, Raleigh, NC 27699-1634
0412019 Page t

ADDITIONAL INFORMATION ON SOURCE WATER AND/OR TREATMENT CHANGES
The Lead and Copper Rule requires prior State approval prior to changes/additions in source water and treatment as follows:
• Reference 15A NCAC 18C .1507 [§141.86(d)(4)(vii)]:
(vii) Any water system subject to a reduced monitoring frequency under paragraph (d)(4) of this section shall notify the State in writing in accordance with § 141.90(a)(3) of any
upcoming long-term change in treatment or addition of a new source as described in that section. The State most review and approve the addition of a new source or long-term change
in water treatment before it is implemented by the water system. The State may require the system to resume sampling in accordance with paragraph (d)(3) of this section and collect
the number of samples specified for standard monitoring under paragraph (c) of this section or take other appropriate steps such as increased water quality parameter monitoring or re-
evaluation of its corrosion control treatment given the potentially different water quality considerations.
Reference 15A NCAC 18C .1507 [§141.90(a)(3)]:
(3) At a time specified by the State, or if no specific time is designated by the State, then as early as possible prior to the addition of a new source or any long-term change in water
treatment, a water system deemed to have optimized corrosion control under §141. 81 (b)(3), a water system subject to reduced monitoring pursuant to § 14 1 . 86(d) (4), or a water system
subject to a monitoring waiver pursuant to §141.86(g), shall submit written documentation to the State describing the change or addition. The State must review and approve the
addition of a new source or long-temr change in treatment before it is implemented by the water system. Examples of long-term treatment changes include the addition of a new
treatment process or modification of an existing treatment process. Examples of modifications include switching secondary disinfectants, switching coagulants (e.g., alum to ferric
chloride), and switching corrosion inhibitor products (e.g., orthophosphate to blended phosphate). Long-term changes can include dose changes to existing chemicals if the system is
planning long-term changes to its finished water pH or residual inhibitor concentration. Long-term treatment changes would not include chemical dose fluctuations associated with daily
raw water quality changes.
REMEMBER: The State's Lead and Copper Rule Manager must review and approve a change in source water, the addition of a new source, or long-term change in
water treatment before it is implemented by the water system. Failure to notify the State and get approval before implementing the change is a violation (code 52) under
the Lead and Copper Rule. Systems should strive to submit their request 90 days before the change is desired to allow time to resolve any comments and questions.
Treatment changes to address a current MCL can be handled on a case -specific basis and the timeframes may necessarily be compressed.
General considerations:
• Monitoring Schedule Changes: Any necessary changes to a system's compliance monitoring schedule will be determined on a case -by -case basis.
• Addition of a new well: For a groundwater system, generally, the addition of a new well from the same aquifer will not require submitting a detailed formal request if
the water quality parameters (WQPs) are shown to be comparable to the other wells currently being used by that system. To demonstrate that the WQPS are
comparable, samples for WQPs should be collected from the new well and a nearby existing well on the same day. If this is the case, complete the information on
this form relating to the new source and attach those sample results to the form. The data will then be evaluated and approval will be handled via email from the Lead
and Copper Rule Manager. If the well draws water from a different aquifer or could be expected to have different water quality, more detail will be required to be
submitted with this form.
• Changes in source water or long-term changes in treatment: [Examples include: switching from ground water wells to a surface water source, switching secondary
disinfectants, switching coagulants (e.g., alum to ferric chloride), and switching corrosion inhibitor products (e.g., orthophosphate to blended phosphate)]:
Re-evaluation of the system's WQPs, chloride/sulfate ratios, if applicable, and the adequacy of corrosion control treatment, along with supporting documentation and
analytical results, will be required to be submitted with a request for any changes in source water or long-term treatment change. Depending on the size of system,
this may simply be the completion of a 141-C Form "Evaluation Form for Corrosion Control Treatment (CCT) For Small 1 Medium Systems" (updated January 2013).
Larger systems may be required to submit more information. [See November 3, 2015 memo from EPA's Peter Grevatt on "Lead and Copper Rule Requirements for
Optimal Corrosion Control Treatment for Large Drinking Water Systems" and Chapter 6 of EPA's "Optimal Corrosion Control Treatment Evaluation Technical
Recommendations for Primacy Agencies and Public Water Systems" (EPA 816-B-16-003, dated March 2016)]. Both documents and other valuable resource
materials and forms are located on our website at htt de .nc. ov about divisions water -resources drinkin -water corn liance-services#lcr.
0412019 Page 2

From: Rhodes, Dustin M Dustin. [e-mail] 6
Subject: RE: [External] Davie County, NC - Sparks Road Water Treatment Plant
Date: November 23, 2020 at 1:21 PM
To: Iversen, Gary A. [e-mail]
Cc: Hudson, Eric [e-mail], John Grey [e-mail], Wang, Michael mwang9haze nandsawyer.com,
Raynor, Linda [e-mail]
Dear Mr. Iversen,
Thank you for notifying us about the upcoming corrosion control treatment change at Davie
County Water System (NC 02-30-015).. We have reviewed the information provided in your
email. Because no effect is expected on the water system's corrosion control treatment and
water quality, we agree that the system may remain on its current reduced 3-year lead and
copper tap monitoring schedule.
The next sampling event is still scheduled to be 30 lead and copper tap samples collected
6/1/2021 —9/30/2021.
We appreciate the information you have provided us to document the water system's upcoming
change in treatment. If you have any questions, please do not hesitate to reach out to us. Thank
you!
Dustin
Dustin M. Rhodes, P.E
Lead & Copper Team Leader, DiWsion of Watex Resources
North Carolina Departluuerut of Emirontnendal Quality
D- E 919,707,9082 (Office)
919.715.6637 (Fax)
[e-mail]
bnW CLWt'S4X4%*4"� 1{1 It • : '',rrI Jr.+n h, ;re..'.t IY. i.,VL.SIZi pow PAXad'; Law aw
From: Iversen, Gary A.[mailto:[e-mail]]
Sent: Monday, November 23, 2020 9:59 AM
To: Rhodes, Dustin M <[e-mail]>
Cc: Hudson, Eric <[e-mail]>; John Grey <[e-mail]>; Wang,
Michael <mwang@haze nandsawyer.com>
Subject: [External] Davie County, NC - Sparks Road Water Treatment Plant
CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as
an attachment to [e-mail]
Dear Mr. Rhodes,
I am writing to request approval for a change in the corrosion control treatment chemical for
Davie County, North Carolina.
The County was issued a NPDES Permit No. NCO084212 (Joseph Corporon) in November 2019
that included monthly monitoring requirements for copper and zinc. The fact sheet for the
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id=885094&dbid=0&repo=WaterResources.
The County uses Earthtec Copper Sulfate to control algae in their terminal reservoir at the Sparks
Road Water Treatment Plant and zinc orthophosphate for corrosion control compliance with the
Lead and Copper Rule. Copper limits were exceeded in July, August, September and November
and zinc limits were exceeded in August, September, October, and November.
Accordingly, Davie County is required to develop an action plan to provide compliance with
copper and zinc limits.
The County is currently evaluating several alternatives for compliance with copper limits. For zinc
compliance the only source of zinc appears to be from the zinc orthophosphate corrosion
inhibitor. This product is a Brenntag zinc orthophosphate and it is fed at a dose of 1.6 mg/L and
is providing compliance with the LCR Rule.
To eliminate the source of zinc, the County is requesting approval to change to a Carus 4500,
straight orthophosphate (no zinc) at a dose of 2 mg/L. Normally a change in treatment will
require a return to the original number of sample sites and sampling frequency. Currently, Davie
County is under reduced monitoring with 30 sample sites every three years. A return to original
sampling would require sampling 60 sites every six months for one year before a request for
reduced sampling could be made.
The change from zinc orthophosphate to a straight orthophosphate is not expected to have any
effect on corrosion control or water quality. Consequently, Davie County is requesting a wavier
from returning to original monitoring.
I have included the data sheets for the current Brenntag product as well as the new Carus 4500.
In addition, I have included the request form for a change in treatment.
Please advise of any additional steps or information needed for consideration of this request.
Thank you for your consideration.
On behalf of Davie County;
Gary A. Iversen, PE
Hazen, Raleigh, NC
919-219-7744
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