5
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                         /A newsletter about soil, sediment,  and ground-water characterization and remediation technologies
                        Issue 30

TTz/'s /55Me o/Technology News and Trends highlights methods for harnessing energy from
renewable resources to reduce remediation costs and minimize the environmental footprint
left by remediation technologies. These methods currently are used to generate virtually no-
cost electrical power for low-energy remediation systems, to "polish " remediation following
aggressive baseline technologies, or to serve as baseline technologies addressing moderate
contaminant concentrations. Incorporation of renew able energy resources early in remediation
planning can significantly reduce long-term cleanup costs and allows site managers to evaluate
environmental tradeoffs of potential remedies.

           Solar Power Recirculates Contaminated Ground Water
                            in Low-Energy Bioreactor
  A pilot-scale recirculation bioreactor has
  operated at "Landfill 3" on Altus Air Force
  Base (AFB), OK, since late 2003 to address
  a hotspot of volatile organic compounds
  (VOCs) in ground water residing in fractured
  clay and weathered shale. A solar-powered
  pump operating  in the system's extraction/
  collection trench recirculates ground water
  through the 10,000-ft3 bioreactor and into the
  aquifer to generate high-carbon leachate and
  enhance VOCbiodegradation. Since startup,
  the system has transferred  approximately
  1,300 mVyr of organic  carbon-enriched
  leachate from the bioreactor into the aquifer.
  Ground water recirculation through the
  bioreactor has achieved a 98% reduction in
  trichloroethene (TCE) concentrations within
  the bioreactor and a 90-97% reduction in
  plume toxicity in hotspot wells between the
  bioreactor cell and the extraction trench.

  Prior to project startup, TCE concentrations
  in the hotspot were 19 mg/L, and the plume
  extended nearly  1,100 yds downgradient of
  the landfill. The bioreactor was constructed
  immediately upgradient of hotspot wells
  in a 30- by 30-ft excavation extending  11
  feet below ground surface (bgs). During
  excavation, landfilled materials were removed
  and disposed offsite as non-hazardous waste.
  The cell was backfilled with a 1:1 mixture of
  sand and  organic mulch  consisting  of
  municipally-obtained woody material and
                          cotton-gin trash, an inexpensive and locally
                          available byproduct of the cotton industry. At
                          the top of the cell a ground-water distribution
                          (irrigation) system operates between two layers
                          of geotextile fabric. The entire cell is capped
                          with two feet of soil and a native grass cover.

                          The bioreactor relies on recirculation of ground
                          water from downgradient of the  hotspot,
                          which is located in the shallow aquifer 10-18
                          feet bgs. Ground  water collected in a 2-ft-
                          wide by 30-ft-long trench extending 18 feet
                          bgs is recirculated through the bioreactor by a
                          single  solar-powered pump. Contaminant
                          degradation is monitored through a network
                          of 18 wells.

                          The site's remote location and average solar
                          radiation of 4-5  kWh/m2/day  prompted
                          investigation of solar power early in the project
                          planning process to reduce construction and
                          energy costs associated withlong-termpumping.
                          The selected photovoltaic (PV) array
                          comprises four single-crystal silicon panels,
                          each capable of delivering 50 watts to the pump
                          through a simple control box. The panels are
                          mounted in series  on a single frame oriented
                          due southard angledforrrmimum sun exposure
                          during winter months (Figure 1).

                          A 3-inch-diameter submersible pump, designed
                          specifically for solar applications, is suspended in

                                            [continued on page 2]
                                                                                            May 2007
                                                                                Contents
 Solar Power
 Recirculates
 Contaminated Ground
 Water in Low-Energy
 Bioreactor             page 1
 Wind Turbine Cost
 Study Shows Need
 for Redesigned
 Ground-Water
 Remediation Systems  page 2
 DOE Uses No/Low-
 Energy Approaches
 for Long-Term
 Remediation           page 4
 Sustainability Metrics
 Used to Evaluate
 Remedial Actions      page 5
     CLU-IN Resources
Environmentally sustainable
cleanup technologies commonly
include phytoremediation,
bioremediation, and monitored
natural attenuation but increas-
ingly involve modifications to
conventional technologies
relying on passive rather than
active mechanisms. Information
about other no- or low-energy
remediation technologies is
available in the U.S. EPA's
"Technology Focus" on CLU-IN
(http://cluin.org/techfocus/).
             Recycled/Recyclable
             Printed with Soy/Canola Ink on paper that
             contains at least 50% recycted fiber

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[continued from page 1]
a sump installed in the extraction trench.
The pump produces 2-3  gal/min during
peak sunlight hours but does not operate
overnight  or during low sunlight,
maintaining an average ground-water
flow  rate of  928 gal/day. Ground-
water velocity between the bioreactor
cell and the extraction trench likely
increased from the estimated area-
wide velocity of 0.1-1.2 ft/day due to
hydraulic mounding in the bioreactor. In
this case, downgradient water quality
data suggest that some recirculated ground
water may have bypassed the extraction
trench, potentially due to the shallow depth
and limited length of the trench and the
intermittent, low-rate nature of pumping.

The solarunit, pump, and auxiliary equipment
operated without breakdown and required
little maintenance over  three years of
operation; the lifespan of the PV system is
estimated at 20 to 30 years.  Capital costs
for the pump, controller, and PV array were
low, totaling approximately $2,300. Energy
cost savings achieved by the solar-powered
system are estimated at less than $1,0007
year but significantly higher savings were
realized by avoiding construction of electric
lines to connect to the local utility grid.
Though no enhancements to  the Altus PV
system are required, its performance suggests
that similar applications at other sites could
easily increase PV capacity through use of a
solar tracking device or larger PV array.

Evaluation of the bioreactor performance
indicates   dissolved  organic  carbon
concentrations increased from less than
6 mg/L priorto startup to 120 mg/L in shallow
wells and 30 mg/L in deeper wells. Increased
concentrations of c/s-l,2-dichloroethene, vinyl
chloride,  and ethene further indicate
reductive dechlorination of TCE occurs in
the bioreactor, and phospholipid fatty acid
analysis shows  a predominance of the
anerobic bacteria required for this process.
To achieve more  complete reductive
dechlorination of TCE, a semi-soluble
carbon substrate and a bioaugmentation
culture were added to the bioreactor last fall.

Results of the bioreactor's initial two-year
demonstration, including details on the solar-
powered pumping system, are  documented
in a final technical report to be  released this
summer from the Environmental  Security
Technology Certification Program (ESTCP)
(http://www.estcp.orgX The Air Force Center
for Environmental Excellence (AFCEE)
  Figure 1. Semi-arid conditions at Altus
  AFB contribute to solar radiation as high
  as 5-6 kWh/m2/day during summer months.
anticipates significantly increased use of solar
as well as wind energy to power low-energy
remediationsy stems suchasbioreactors across
the Department of Defense (DOD) complex,
particularly in remote  locations where
utility-grid connection is cost prohibitive.
Dyess AFB, anactivebaseinAbilene, TX,
recently converted the facility's entire
operation to exclusive use of wind energy,
and the Massachusetts Military Reservation
is investigating the use of a 660-kW wind
turbine to powerthe site's extensive ground-
water cleanup program.
Contributed by Jim Gonzales, AFCEE
(james.gonzales&.brooks.af.mil or
210-535-4255), Roger Wilkson, Air
Education and Training Command
(roger.wilkson&.randolph.af.mil). and
Jason Bidgood, Parsons
(jason. bidgood(a),parsons. com or
303-831-8100)
      Wind Turbine Cost Study Shows Need for Redesigned Ground-Water Remediation Systems
University of Missouri-Rolla researchers
recently evaluated the economic and
environmental benefits of a 10-kW wind
turbine  powering  a ground-water
circulation well (GCW) at the former
Nebraska Ordnance Plant  (NOP)
Superfund site in east-central Nebraska.
The project's first phase involved retrofit
installation and use of a grid inter-tie
system whereby electricity is provided by
the turbine during favorable weather.
The  local electric utility powers the
turbine during unfavorable weather.
Environmental benefits of the conversion
included a  potential  reduction  of
greenhouse gases associated with fossil-
fuel-generated electricity. When compared
to utility-only operation, monthly emissions
of carbon dioxide averaged 32% less during
the grid inter-tie phase.

In late 2006, the second project phase
converted the wind turbine  system to
off-grid operation powering  the GCW
submersible  pump. Utility power was
required for  the remaining GCW
components to meet energy demands during
mid-winter low temperatures.  Though
estimated carbon dioxide emissions during
off-grid operation were  higher than those
of the grid inter-tie phase due to cold
weather, monthly emissions averaged 24%
less than during utility-only operation.

The NOP site is located in an area with
winds averaging 6.5 m/s, which the DOE
considers suitable for wind turbine
applications (Wind Energy Resource
Atlas of the United States). The GCW
submersible pump extracts contaminated
water from the aquifer for above-ground
air stripping to  remove  TCE. After
treatment, ground water recharges the
aquifer through a different well interval.

               [continued on page 3]

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[continued from page 2]
As part of this project, researchers
evaluated the performance of the selected
10 kW-rated wind turbine as installed on a
30-meter tower. Electricity was delivered
from the turbine to the GCW through a
single circuit breaker, which eased the
system's retrofit for power from  an
alternative energy source. The grid inter-
tie system configuration resulted in monthly
energy generation ranging from 500-1,000
kWh.

Although the same wind turbine was used
for both study phases, an off-grid battery
system was  added for the second phase
to store energy  produced by the turbine.
Production capacity of the grid inter-tie
operating mode was rated at 7.5 kW, but
was 25% lower for the off-grid mode due
to reduced efficiency of the energy storage
system. As a result, stored energy allowed
the turbine to fully power only the 230-
volt, three-phase submersible pump,
which accounted for approximately one-
third of the  GCW's  total demand.
Additional modifications allowed the GCW
to operate either through exclusive use of
utility power or through intermittent use
of the  wind  turbine  to  power  the
submersible pump, supplemented by utility
power for remaining GCW components.

Economic benefits of the wind turbine were
evaluated through several measures.
Statistical comparisons were conducted on
comparable data collected when the GCW
relied on: (1) exclusively utility power, (2)
combined utility and grid inter-tie wind
power, or (3) combined utility power plus
off-grid wind power or utility power alone
(Figure 2). Results indicated that average
daily energy consumption from utilities
decreased 26% during the 17 months when
the turbine operated in grid inter-tie mode.
During two cold periods of the 6-month
off-grid operation, the cost of heating the
GCW to prevent freezing and associated
decreases in submersible  pump efficiency
contributed to significantly higher demand
for utility power.
Capital recovery was analyzed to evaluate
whether NOP utility-cost reductions could
offset wind turbine costs. Net capital costs
were estimated at $41,000 for the inter-tie
turbine system and $3 9,000 for the off-grid
system,  including turbine installation and
utility connection. Based on a GCW rate of
5.7 million liters of ground water treated
each month, the annual energy saved by
the turbine in grid  inter-tie mode was
estimated at $1,100. Results suggested that
less than 50% of the grid inter-tie system
cost would be recovered over 20 years.

Net cost of the off-grid  system, however,
would be recovered in 14 years if the GCW
were  significantly modified  to function
without incurring any utility costs. System
modifications would focus  on freeze-
proofrngthe GCW by automatically draining
the system to accommodate intermittent
operation during winter. Additional savings
for an off-grid system would be achieved
by using an alternate, low-energy treatment
technology such as bioremediation.

A total TCE mass of 50.6 kg, averaging
2.99 kg/month, was removed through air
stripping during the 17-month grid inter-tie
operational phase. The average TCE mass
removed during the six-month off-grid
phase was 2.53  kg/month.  Over both
phases, a combined total of 90.2 million
liters of ground water were treated
without any net loss of ground water to
the aquifer. The average reduction in
carbon dioxide emissions during treatment
was estimated at 437 kg/month during
the grid inter-tie phase and 317 kg/month
during the  off-grid phase, as  compared
to a potential emission of 1,600 kg/month
during utility-only operations.

Final results suggest that wind turbines
can be used to reduce operation and
maintenance (O&M) costs for long-term
ground-water remediation systems
such as pump-and-treat (P&T) while
significantly reducing carbon dioxide
emissions. Although the study indicates
that retrofit of existing GCWs with a wind
turbine  system is not cost effective, it
shows that an off-grid system may be
cost-competitive for  a new GCW
specifically designed to operate without
utility power. Results also illustrate the
need for wind-turbine GCW designs to
accommodate cold weather conditions.

Contributed by Curt Elmore, Ph.D.,
University of Missouri-Rolla
(elmoreac(q)umr. edu or 573-341-6784)
and Dave Drake, U.S. EPA Region 7
(drake, dove(q)epa. gov or 913-551-
7626)
                                    Grid inter-tie
                                    wind turbine
                                  plus utility dataset
             Off-grid
             wind turbine
             plus utility
             dataset
                                                        Figure 2. Mid-winter
                                                        utility power
                                                        consumption was
                                                        lowest during inter-tie
                                                        wind turbine operation
                                                        of the retrofit GCW
                                                        supporting NOP air
                                                        stripping.
         Jan-02
                   Jan-03     Jan-04     Jan-05     Jan-06     Jan-07
                  Months with Comparable Flow Rates (1.9 to 2.5 Us)

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                    DOE Uses No/Low-Energy Approaches I or Long-Term Remediation
The U.S. Department of Energy (DOE)
increasingly uses passive soil vapor
extraction (PSVE) and DOE laboratory
developments, such as the MicroBlower™
and  "GeoSiphon™," to address  sites
requiring long-term treatment. Use of these
no/low-energy technologies at the Savannah
River Site (SRS) significantly reduced
electricity  and  fossil-fuel  energy
consumption/costs and demonstrates their
ability  to  reduce  the  footprints  of
remediation strategies on the environment.

PSVE, also known as barometric pumping,
uses natural venting cycles between the
atmosphere and subsurface to extract
contaminants from soil. When atmospheric
pressure at the ground surface is higher
than subsurface soil gas pressure, airflows
downward  through wells  into  the
subsurface. When pressure at the surface
is lower than subsurface, air flows  from
the wells to the atmosphere. As a result, a
vadose-zone well crossing these pressure
differentials can remove gaseous-phase
VOCs from the subsurface without use of
a mechanical pump and associated power
sources. Prior to atmospheric discharge,
extracted vapors may require relatively low-
cost treatment such as carbon adsorption.
PSVE commonly is used to  inject air into
soil to stimulate bioremediation.

The SRS and Hanford Site  currently use
PSVE as a polishing technology to remove
VOCs from  permeable soil. At SRS, for
example, 52 PSVE wells  across three
separate areas have operated over the
past 10 years. Combined, these systems
have removed nearly 1,000 Ibs  of
tetrachloroethene (PCE) and 400 Ibs of
TCE. In addition, vapor concentrations
and gas-plume footprints have decreased
significantly. Although rates of contaminant
mass removal are declining due to reduced
concentrations of contaminants, the PSVE
systems are expected to continue operating
until soil cleanup targets are met. Results
at both  SRS and Hanford  confirm that
PSVE is  best applied where target
contaminants are in the unsaturated zone, and
is most effective in coarse soil with high
permeability or in soil layers separated from
the  atmosphere by a confining unit or by
depth.

SavannahRiver National Laboratory (SRNL)
researchers  are investigating PSVE
enhancements  such as wind turbine-
powered vacuum pumps to increase system
efficiency and further reduce cleanup costs
and environmental impacts of remediation.
One of the simplest methods for increasing
efficiency involves integration of a simple
one-way checkvalve capable of interrupting
airflow into PSVE wells when atmospheric
pressures reverse. Direct attachment of a
control valve such as the BaroBall™ to the
well casing at  ground surface permits
extraction of contaminants during reduced
barometric pressure, while eliminating
undesirable dilution caused by reinjectionof
clean air during periods of high barometric
pressure. This type of valve may be used in
other applications to inject air and/or nutrients
into  the   subsurface  for  enhanced
bioremediation, to control or confine
movement of a subsurface gas-phase plume
in the vadose zone, or to passively transfer
solar-heated, water-saturated air into the
subsurface for enhanced volatilization.

The MicroBlower™ is another no/low-energy
technology used to remove VOCs from the
subsurface. This system consists of a small 12-
or24-VDCvacuumblower connected directly
to a wellhead for extracting
or injecting gases into the
vadose zone. PV panels or
small  wind generators
typically supply electricity
to power  the  system,
enhancing its potential for
use in remote locations. Abattery bank can
be used for reserve power when sun or wind
is inadequate. Deployment is made easier
by the system's small pump, approximately
4 inches high by 3 inches wide (Figure 3).

TenMicroBlower systems currently operate
at SRS, each removing 0.1 to several
pounds  of solvent from  the subsurface
each week. The  cost of materials is
estimated at $1,500 per system, with
minimal installation and O&M expenses.
Performance results indicate that reliability
of a MicroBlower  system depends on a
pump lifespan of approximately one year.

Additional tests were conducted at SRS to
evaluate the feasibility of GeoSiphon, a
passive technology employing a siphon
made of HOPE tubing to induce ground-
water flow from the target portion of an
aquifer  toward a treatment cell. Once
primed, the upward arm of the siphon
draws water from the treatment cell,
inducing ground-water flow towards the
cell. The treatment cell consists of an 8-ft
diameter well containing approximately 25
tons of granular cast iron that abiotically
reduces chlorinated VOCs (CVOCs) to
ethene, ethane, methane, and chloride ions.
The downward arm discharges treated
water to the Savannah River.

Three  siphon configurations were
tested using l/i- to 2-inch HOPE tubing
               [continued on page 5]

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[continued from page 4]

on engineered and non-engineered
grades extending 223 to 1,032 feet on
different  slopes of the test site. All
configurations on engineered grades
maintained continuous, consistent
siphon  flow. When  needed,  an
automatic, solar-powered vacuum
pump  was   used  for  passively
recharging the system's air chamber
to remove gas bubbles.
The GeoSiphon  shows  potential for
significantly improving implementation of
permeable reactive barriers (PRBs) due to
its ability to increase and direct the flow of
water, resulting in less intrusive, less costly,
and more efficient deployment compared
to funnel-and-gate or continuous PRBs.

DOD has documented designs, costs, and/
or performance results of natural pressure-
driven passive bioventing at these DOE sites
as well as DOD sites under the ESTCP
 (http://www.estcp.orgX Both agencies
 anticipate additional remediation studies
 to investigate innovative methods for
 harnessing renewable energy from other
 natural resources such as ocean tide and
 geothermal forces.

 Contributed by Brian Riha, SRNL
 (brian.riha&srnl.doe.gov  or 803-725-
 5948) and Brian Looney, Ph.D., SRNL
 (brian 02. looney&srnl. doe, gov or
 803-725-3692)
                        Sustainability Metrics Used to Evaluate Remedial Actions
Savannah River National Laboratory
(SRNL) researchers are developing tools
to evaluate the need to power new or
existing remediation systems  with
renewable  energy sources. The tools
employ  Sustainability  metrics for
assessing energy  demand and storage
along with characteristics of the site and
contaminants. Early evaluation of these
parameters  can reduce the footprints of
many aggressive cleanup technologies.
which are now recognized increasingly as
secondary  impacts of environmental
contamination. It can also help identify risk
transfer across  environmental media and
associated regulatory programs.

This strategy was demonstrated last year
for a Savannah River Site (SRS) P&T
system operating since 1996 to treat TCE-
contaminated ground water. Following
extraction, ground water is treated by a
70-gpm air stripping system and ultimately
discharged to the Savannah River. Average
TCE concentrations in treatment influent
decreased from 600 u,g/L to 40 u,g/L after
eight years of P&T operation. These
dissolved CVOC concentrations (<50
u,g/L  or <0.0045% solubility) mark the
point at which media-specific benefits of
baseline technologies such as P&T and
in-situ chemical oxidation typically begin
to be outweighed by increased burdens
transferred to other environmental media.
otherwise known as the onset of collateral
environmental damage.
Common ground-water remediation
goals such as hydraulic containment of
contaminants, attainment of maximum
contaminant levels, contaminant mass
removal, risk reduction, and contaminant
flux   reduction  do   not  reflect
environmental burdens posed by cleanup
technologies. Typical  goals also do not
reflect the value of in-situ environmental
resource  services such as drought
buffering, prevention of land surface
subsidence, protection against salt-water
intrusion, and maintenance of ecological
diversity. Accordingly, the SRNL study
evaluated Sustainability goals considered
only minimally at the time of remedy
selection:
 > Resource conservation measured by
   "water intensity,"  or the amount of
   water necessary to remove one pound
   of contaminant,
 > Energy efficiency  measured by the
   amount of energy needed to remove
   one  pound of contaminant, and
 > "Carbon intensity" estimating the
   amount of CO2 emitted  for each
   pound of contaminant treated, based
   on power industry  standards.
During the first six months of air
stripping operations,  100,000-500,000
gallons of ground water were removed
for every pound of TCE removed.
Influent contaminant concentrations over
the following seven  years were more
moderate, decreasing from 100 u,g/L to
40 u,g/L. Water intensity during that
period increased to 3,000,000 gallons per
pound of contaminant removed. As of
early 2006, TCE concentrations persisted
at levels eight-fold higher than the 5 u,g/L
cleanup target.

Forecasts  estimate   that  influent
concentrations of TCE after 20 more
years of P&T operation would still be 15
u,g/L (three times the cleanup goal) and
               [continued on page 6]
            Contact Us
      Technology News and Trends
            is on the NET!
       View, download, subscribe,
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     welcomes readers' comments
       and contributions. Address
          correspondence to:
            John Quander
     Office of Superfund Remediation
       and Technology Innovation
               (5102P)
  U.S. Environmental Protection Agency
          Ariel Rios Building
       1200 Pennsylvania Ave, NW
        Washington, DC 20460
          Phone:703-603-7198
          Fax:703-603-9135

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                                                Solid Waste and
                                                Emergency  Response
                                                (5203P)
                               EPA 542-N-06-009
                               May 2007
                               Issue No. 30
United States
Environmental Protection Agency
National Service Center for Environmental Publications
P.O. Box 42419
Cincinnati, OH 45242
                              Presorted Standard
                              Postage and Fees Paid
                              EPA  "
                              Permit No. G-35
Official Business
Penalty for Private Use $300
   Figure 4. Modeling shows a growth of
   collateral environmental impacts
   associated with long-term operation of
   dilute ground-water plumes.
  [continued from page 5]
  water intensity would increase to 9,000,000
  gal/lb. The remediation system's carbon
  intensity also would increase exponentially
  to an estimated  50,000  Ibs of CO2 for
  each pound of contaminant removed,
  significantly increasing the rate of risk
  transfer  from ground water to the
  atmosphere (Figure 4).

  Recent  studies  by  the  Interstate
  Technology and Regulatory Council, the
  National Research Council, and other
  government organizations recommend
  addressing the diminishing environmental
  returns of  aggressive remediation
  technologies by:
                                               01
     700

     600

     500 -

     400 -

     300 -
   8 200
   111
   o
     100 -
       0 -
Air Stripper Influent Concentration
TCE Forecast
Water Consumption
COo Emissions
                                 Maximum Contaminant Level
                                                                                                       10
                                                                                                     - 6
                                                                                                     - 4
                                  - 2
                                                          - 0
                                       LU
                                       O
                                       E
                                       =3
                                       Q_
                            10     15     20
                          Elapsed Time (Years)
                                                 25
                                                        30
                                                                                                               - 100
- 80
                                                                                                               - 60
     a:
     O
                                                                                                               " 40  Jj
                                                                        jj
                                            - 20
                                                                   - 0
Evaluating collateral damages such as
energy use and loss of environmental re-
sources early in remediation planning.
Establishing alternative metrics for
tracking collateral impacts during active
remediation, and
Developing new economic models us-
ing sustainability metrics to balance
natural resource damages with resource
restoration.
                SRNL will continue developing innovative
                strategies for minimizing collateral damage
                during remediation polishing. Potential
                methods involve harnessing new forms of
                renewable energy and leveraging prevalent
                site conditions with natural processes.

                Contributed by Ralph Nichols, SRNL
                (ralph. nichols&srnl. doe, gov or
                803-725-5228)
EPA is publishing this newsletter as a means of disseminating useful information regarding innovative and alternative treatment techniques and
technologies. The Agency does not endorse specific technology vendors.

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