2017_07_26 Technology Review Response wo attachments_20170726

�r� DUKE
ENERGY7,
July 26, 2017
Ms. Debra Watts
NC DEu, Divisiun ut Water Resources
1636 Mail Service Centu,
Raleiyn, NG 27699-1636
Subject: Technology Review ut Water Filtration Systems
Dear Ms. Watts:
52o suaffl c;Fmm Street
Cliarlutte, IBC 28202
IGlailiMg Aatllea5
Dail L;aoe ECizJI P.U. 6ux 1006
Charlutte, NG 28201-1wo
t04.392.8768
r 704.907.86Z6
As requested in the Deparnment's July 19, 2017 lever addressed to Mr. Paul uraovitch, Duke
Eneryy is providing the enclosed infurmatiun u� � the water tiltration systems 6Ciny installed as
a permanent water solution under RB630.
Please let me Knuw at the number above or at jcssica.eednarciRgduRe-ener .c;cm if yuu
Have any question s.
Since, cly,
Jessica E. 6ednarcik, P.E.
GG: (via email) Eri4 SniitFi, NC:uEQ
Paul Draovit,,h, DuRe Eneryy

Response to NC DEQ's Request for Information on Water Treatment Systems,
Hexavalent Chromium and Vanadium
July 26, 2017
On July 19, 2017, NC DEQ requested the following from Duke Energy to allow the agency to perform a technology review
of the water treatment systems:
- All design documents, specifications, engineering reports, and vendor product information to demonstrate
removal of hexavalent chromium and vanadium, including the following:
o Targeted performance goals for hexavalent chromium and vanadium, whether expressed as
concentration in produced water or as a removal efficiency.
o Any testing results (including bench scale or pilot testing) or full-scale implementation data indicating the
inlet/outlet concentrations and removal efficiencies for hexavalent chromium and vanadium.
o Any industry standards for removal of hexavalent chromium or vanadium, and information indicating
whether the proposed systems have been or could be certified under such standards.
o Any other available documentation related to the performance of such systems regarding removal of
hexavalent chromium and vanadium.
Duke Energy is happy to provide the information below to assist in the agency's review of the technology chosen by
Duke Energy's water treatment experts to meet the performance standards set by NC DEQ. Duke Energy also
understands that NC DEQ is forming a science advisory board to evaluate health data and provide recommendations
that could result in updates to state groundwater standards. We recognize our plant neighbors want a safe and long-
term water supply and are eager for projects called for in NC House Bill 630 (HB 630) to be complete. It is our intent to
proceed with installing systems that meet the current performance standards unless NC DEQ advises otherwise. If state
groundwater standards change at a later date, we will ensure the systems meet those.
Duke Energy shares the state's objective in protecting drinking water near our facilities. From our perspective, a
thoughtful and holistic approach is critical in determining standards for hexavalent chromium and vanadium in North
Carolina groundwater. While these treatment systems affect just roughly 200 homes under the purview of HB 630,
safety standards should apply consistently to all well owners in the state and not just a small subset of Duke Energy
plant neighbors who happened to be among the first tested in North Carolina for these substances. Increasing data
demonstrate hexavalent chromium and vanadium occur naturally at varying levels across North Carolina, and many well
owners throughout the state would not be able to meet the 2015 NC DHHS health screening levels (SQ regardless of ash
basin operations. We defer to state officials on how best to bring clarity and consistency to this issue.
Based on testing and ongoing dialogue with water treatment vendors, the performance standards NC DEQ provided are
reasonable for the whole -home treatment systems to achieve consistently. These systems were selected following
substantial research and field testing and are among the most sophisticated systems available for residential or
industrial use.
Page 1 of 8

For additional background on vanadium and chromium, Duke Energy has included in this submittal (attachments 1-4):
• World Health Organization's vanadium chapter. The WHO chromium level is 50 parts per billion (ppb) in drinking
water and does not have a vanadium target.
• Water Quality Association Chromium Fact Sheet;
• EPA's 2012 Edition of the Drinking Water Standards & Health Advisories; and
• IRIS Database Information for chromium.
Review of Water Treatment Industry Data on Removal of Hexavalent Chomium and
Vanadium
Duke Energy's research in publications and with water treatment experts led us to explore ion exchange and reverse
osmosis technologies in more detail.
There are no industry standards that Duke Energy or our water treatment partners are aware of that certify drinking
water treatment systems. As stated in our June 27, 2017 submittal, treatment components, including the resin, are
tested and certified by the Water Quality Association against National Sanitation Foundation and ANSI standard for
material safety. There are no standards available that certify the systems as a whole because each system is designed
based upon the water chemistry present at the homeowner's well.
The following publications (attachments 5-8), which were found through online searches and provided by our treatment
vendors, indicate that both weak and strong base anion exchange resins have been successful technologies to treat
hexavalent chromium.
• American Water Works Association Chromium in Drinking Water: A Technical Information Primer
• Water Research Foundation Guidelines for Hexavalent Chromium Treatment Testing
• EPA Demonstration Project in Vale, OR Arsenic & Nitrate Removal from Drinking Water by Ion Exchange
(reduction of both chromium and vandium are mentioned in the report)
• Water Research Foundation Bench Scale Evaluation of Alternative Cr(VI) Removal Options for Small Systems
There are also technical papers available for the removal of chromium from groundwater (attachments 9-10):
• Department of Energy Chromate Removal at the Hanford Site (removal to U.S. EPA Maximum Contaminatn
Levles [MCL] of 100 ppb)
• Soil & Groundwater Magazine Superfund Site Cleanup of Chromate Contaminated Groundater (removal to MCL
Treatment data for removing vanadium was less available in our review, likely because no federal MCL exists and most
states do not regulate it in drinking water.
Duke Energy's Proposed Water Treatment Systems and Performance Goals
HB630 required Duke Energy to educate all neighbors on the permanent water supply options available to them by April
15, 2017. To fulfill this requirement, Duke Energy needed to have technologies identified and vendors under contract
for the water treatment systems prior to the community information sessions held in February 2017.
Page 2 of 8

Since the performance standards developed by NC DEQ for the water treatment systems were not made available to
Duke Energy until June 14, 2017, Duke Energy took a conservative path in their absence. The company requested that
vendors propose a system that would meet the federal U.S. EPA Safe Drinking Act MCLs. As stated in our December
2015 plans outlining the proposed permanent water supply solutions, Duke Energy also directed the vendors to meet
the target of one-half of the MCL or the appropriate state standard for the constituents identified in the 2015 "do not
drink letters" as having potential health concerns. For vanadium, the "appropriate state standard" provided was the
expired Interim Maximum Allowable Concentration (IMAC) of 0.3 ppb. For hexavalent chromium, the target was to get
as close to the 2015 NC DHHS health screening level of 0.07 ppb as they could. Therefore, the treatment targets
communicated to the vendors were more protective than federal drinking water standards, assuring a final water quality
consistent with or higher than public water supplies.
While the type of technology was not specified to the bidders, Duke Energy provided them with the testing data for
eligible well owners available at the time. The bid document also included the requirement that the performance
targets were to be met for the life of the media and/or components. The vendors were also aware that Duke Energy
was requesting performance standards from NC DEQ.
When discussing the performance standards and the 2015 NC DHHS SLs for hexavalent chromium and vanadium,
vendors and resin manufactures indicated that the levels were lower than typically seen for industrial uses, and that
these levels for drinking water applications were unprecedented. This is not surprising given that the federal MCL for
chromium is 100 ppb and no MCL exists for vanadium. No other state has evaluated a hexavalent chromium standard as
low as 10 ppb other than California, which was invalidatated by the courts earlier this year.
Seven companies were invited to bid on the project and three submitted bids. Two of the bids were for ion exchange
and one was for reverse osmosis; these technologies were based upon the vendor's experience with home treatment
systems and the ability to meet the targets with available technologies. Duke Energy conducted a thorough review of
the bids and selected ion exchange systems because of their treatment capability and because they avoid the substantial
backwash flow generated from reverse osmosis systems that would require management.
The vendor product information was submitted to NC DEQ on June 27, 2017, with the submittal of the Performance
Monitoring Plan. The vendor project information does not address hexavalent chromium and vanadium specifically
because the treatment systems will be custom designed based upon water chemistry and water usage consideration for
each installed system. For example, groundwater wells that do not contain any hexavalent chromium or vanadium in
the raw water would not require treatment of these constituents. Cation exchange resins reduce positively charged
contaminants such as calcium, magnesium, iron, manganese, lead, cobalt, copper, and others. Anion exchange resins
reduce negatively charged contaminants such as arsenic, vanadium, chromium, sulfates, antimony, barium, chlorides,
and others. The specific resins chosen will be based upon the water quality of the household where it is being installed.
The treatment systems will not have a pre -determined removal efficiency assigned to them, as the water quality,
household usage, and flow rates will all contribute to the rate at which the resins need to regenerate and/or be replaced
in order to meet the NC DEQ performance standards. The methods that will be used to monitor the performance
standards were provided in the Performance Monitoring Plan.
Duke Energy has included information on the primary types of resin that will be utilized for groundwater containing
hexavalent chromium and vanadium (attachments 11-13):
Page 3 of 8

• ResinTech ASM-10-HP,
• Purolite SST-60 and
• Purolite A-300.
While the ResinTech bulletin is specifically for arsenic, the same type of resin that treats arsenic also treats chromium
and vanadium.
Duke Energy has also made our vendors aware that NC DEQ may be contacting them for additional information on the
treatment systems.
Full Scale Implementation Data: Ion Exchange
Duke Energy began field testing whole home water treatment systems during the second quarter of 2016. The goal of
the field testing was to evaluate if ion exchange technology could be effective in reducing constituents to the NC NCAC
2L standards and the NC DHHS SLs that prompted the "do not drink" letters to be sent by NC DEQ and NC DHHS to plant
neighbors in 2015. Due to the limited sample pool it must still be determined if NC DHHS SLs can be consistently
achieved.
Systems from two separate water treatment companies, Culligan and AquaPure, were evaluated at the pilot locations.
Both systems utilize a combination of anion and cation exchange resins to reduce those constituents identified in the
"do not drink" letters from the groundwater. The systems were located at groundwater wells that contained
constituents that were similar in concentration to wells that received guidance not to drink. After AquaPure decided not
to bid on the project, analytical testing of their equipment was suspended in January 2017.
The following graphics of systems from both companies demonstrate that ion exchange technology is capable of
reducing vanadium and hexavalent chromium to levels near or below the 2015 NC DEQ SLs.
Notes
• Circled points indicated that the result was less than the laboratory reporting level. For vanadium, the
laboratory reporting limit is typically equal to the 2015 NC DHHS SLs. There are some cases where the
laboratory reporting limit for hexavalent chromium equals or exceeded the 2015 NC DHHS SLs. There are times
when matricies within the sample result in an elevated detection limit.
• The Y-axis concentration is in ug/L or parts per billion (ppb).
• The X-axis is date that the sample was collected.
• Hexavalent Chromium plots have the Y-axis ploted on log scale due to the low concenrations in the sample
results.
• Both the NC DEQ Water Treatement System Performance Standards, the 2015 NC DHHS SL for hexavalent
chromium and the retired vanadium IMAC have been shown on the graphs
• The square symbols are raw water samples. The triangle symbols are treated water samples.
• The AquaPure system is similar in design to the systems being installed by Water Purification Consultants.
Page 4 of 8

B K-TW-RAW-P 1
BK-TW-TR-P7
MM TW RAW P1
MM-TW-TR-P6
Gaoled point indicates Non -Detect.
Vanadium Plots
Clligan Les4Systems
'Jalladii.im.. total (ug/L)
Sample Date
NlY7FO P—F--n -p SfA (10 —d i )
1. (0.3 uc�L]
Page 5 of 8

■ AL-TW-RAW
■ AL-TW-TR
■ JQ-TW--RAW
■ JQ-TW-TR
Ckied paint indicates Non -Detect.
Aqua Pure Test Systems
Vanadium, total (ugjL)
Sample Date
NCDDEG Perform nee Std. [10 ugJL]
Page 6 of 8

■ BK-TW-RAW-Pl
■ BK-TW-TR-P7
■ MM-TW-RAW-Pi
■ MM-TW-TR-P6
10
0-1
0-01
Circled point indicates Nun -Detect.
Hexavalent Chromium Plots
Culligan Test Systems
Chromium. hexavalent (u4L)
Sample Date
lip
NCDEQ Pef.,--Std. (104Q
Page 7 of 8

■ AL-TW-RAW
■ AL-TW-TR
■ JQ-TW--RAW
■ J&TW--TR
0.1
0.01
Circled point indicares Non -Detect.
AquaPure Test Systems
Chromium, hexavalent (uqf L)
Sample Date
NCDEQ Performance Std.
Page 8 of 8