5
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Ti
o
/A newsletter about soil, sediment, and ground-water characterization and remediation technologies
Issue 19
This issue o/Technology News and Trends looks back to find lessons learned from projects described in
earlier issues of the newsletter.
July 2005
Chitin Emplaced Using Hydraulic Fracturing Enhances
Bioremediation of Ground Water
Following a successful pilot-scale field test in 2002.
full-scale application of "biofracing" was conducted
over a 26-month period in 2003-2005 to remove
chlorinated solvents from ground water at the Distler
Brickyard Superfund site near West Point, KY (For
information on site conditions and details concerning
the pilot, see the January 2003 issue of Technology
News and Trends.) Anatural hiopolymer derived from
shrimp and crab shells, chitin was injected into a tight
aquifer using hydraulic fracturing to provide a source
of volatile fatty acids (VFAs) that served as electron
donors for anaerobic reductive dechlorination (ARD).
The frill-scale results continued to show that the
technology effectively delivered chitin within the site's
low-permeability subsurface, generated highly
reducing geochemical conditions, and significantly
stimulated natural biodegradation of chloroethenes.
The full-scale test application was designed to further
evaluate the effectiveness and longevity of chitin-
stimulated biodegradation in the field and to
concurrently evaluate the perfomiance of various
grades of chitin under laboratory conditions. Using
techniques similar to those of the pilot test, a larger
network of 33 hydraulic fractures was initiated from 10
direct push holes within an expanded (0.4-acre)
treatment area. Approximately 4,800 pounds of chitin
were mixed with sand in a guar slurry and in] ected into
the aquifer, creating hydraulic fractures that extend
15-20 feet through the area's fine-textured sediment.
Monitoring focused on VFA concentrations, redox
indicators, and concentrations of trichloroethene
(TCE) and its degradation products in ground water.
Visual examination of soil cores helped to document
the fracture network geometry and evaluate changes
in chitin over time.
Soil cores collected one week after chitin emplacement
showed that the location of chitin- and sand-filled
fractures highly corresponded to locations inferred
by inverse modeling of data obtained from a network
of tiltmeters. Visual examination of a second set of core
samples collected eight months later showed that chitin
degradation was accompanied by development of
strongly reducing conditions. Sediment near the
fractures tod changed in color from tan to dark gray,
and the presence of a black precipitate (likely a sulfide
mineral) was observed in the fractures. These changes
suggest that the strongly reducing conditions needed
for ARD ID occur were generated near chitin-filled
fractures.
Ten rounds of ground-water monitoring data
demonstrated that VFA production began almost
immediately after chitin emplacement and continued
over the following year (Figure 1). Total VFA
concentrations one week after chitin emplacement
ranged from 8.4 to 5,020 mg/L, with a median
concentration of 109 mg/L.
VFA production was accompanied by development
of strongly reducing conditions, as indicated by lower
sulfate concentrations and higher methane
concentrations. Production of the highest
concentration of methane (25 mg/L) occurred
approximately eight months after the chitin was
emplaced. when maximum c-is-dichloroethene (DCE)
concentrations also were observed Overall, increased
concentrations of ds-\2 DCE and ethene (Figure 2)
show that biodegradation of TCE was significantly
stimulated by chitin emplacement. Concentrations of
ethane, as a final TCE degradation product, peaked
nearly four months after chitin placement and
[continued on page 2]
Contents
Chitin Emplaced Using
Hydraulic Fracturing
Enhances Bioremediation
of Ground Water pagel
Continued Triad
Approach for NAPL
Removal Expedites Fort
Lewis Cleanup page 2
Field Tests Show
Enhanced
Bioremediation
following Cyclodextrin
Flushing page 4
"Supermulch"
Amendment Expedites
Revegetation at Mining
Sites page 5
CLU-IN Resources
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Figure 1. Representative data from one of
17 monitoring wells showed that injection
ofchitin in Distler Brickyard ground
water produced a range ofVFAs that were
available to serve as electron donors for
enhanced bioremediation.
[continued from page 1]
remained elevated to various degrees
throughout the project period.
Concurrent laboratory column studies were
conducted at Pennsylvania State University to
compare VTA production, chloroethene
degradation, and chitin longevity for three
grades of chitin (SC-20, SC-40, and SC-80).
While the most refined grade of chitin (SC-80)
demonstrated superior performance in terms of
VFA production and chloroethene degradation,
the least refined grade (SC-20) performed nearly
as well. The intermediate refined grade (SC-40)
performed slightly lower. Based on these results
and an estimated factor of 2.5 cost differential
500
400-
S 300-
c
I 2oo^
CD
o
c
o
O
100-
chitin
emplacement
v
-+- acetate
-+- propionate
-*- butyrate
° valerate
v hexanoate
AugOS Dec 03 Apr 04 Aug 04 Dec 04
between the SC-20 and SC-80, researchers
recommend the use of SC-20 in future
applications.
Full-scale biofracing at this site was estimated to
cost $500,000, which was provided by the
National Science Foundation under an
innovative technology grant for small businesses.
It is estimated that chitin accounted for only 2.5%
c
o
'•*-•
CD
-t—»
C
CD
O
C
o
O
20
15-
10
chitin
emplacement
TCE
c/s-DCE
frans-DCE
vinyl chloride
ethene
Apr 03 AugOS Dec 03 Apr 04 Aug 04 Dec 04
of the total project cost. Other agency support
was provided by the U. S. EPARegion 4, which
provided analytical services. The State of
Kentucky, now holding lead responsibility for
cleanup at the Distler Brickyard, anticipates that
ground-water monitoring will continue for
several years until cleanup goals are met.
Contributed by Ken Logsdon, Kentucky
Department for Environnental Protection
(502-564-6716 or
kenneth.logsdoniSky.gov), Femi Alrindele,
U.S. EPA Region 4 (404-562-8809 or
akindele.femi&epa.gov), and Bob Stair,
North Wind, Inc. (208-557-7878 or
bstarnS'nortlnvind-inc.com)
Figure 2. TCE breakdown was observed
consistently over an 18-month period
following chitin emplacement at the
Distler Briclcvard.
Continued Triad Approach for NAPL Removal Expedites Fort Lewis Cleanup
Aggressive treatment of a nonaqueous-phase
liquid (NAPT) source area at the Fort Tewis
Togistics Center near Tacorna, WA, was
undertaken last year following use of a Triad
approach for characterizing contaminant migr-
ation in the area's dual aquifer system In 2002, the
Fort Tewis Public Works and U. S. Army Corps of
Engineers (USAGE) had completed site
characterization involving a dynamic
investigation approach, systematic planning, and
real-time data collection (described in the July 2004
issue of Tedmology News and Trends). They then
installed and operated an in-situ electrical resistance
heating (ERH) system to sequentially treat three
NAPT source areas of the logistics center's "East
Gate Disposal Yard"
The Triad approach was continued during the
remediation stage to maximize removal of NAPT
containing TCE and associated volatile organic
compounds (VOCs) from soil and ground water
at the first of die three source areas. Sequential
treatment will allow lessons learned from one
source area to be applied to the next through an
adaptive site management approach. In the first
treatment area, anonsite gas chromatograph/mass
spectrometer (GC/MS) and other field-based
technologies such as vibrating-wire transducers
were used during ERH operations. Such onsite
[continued on page 3]
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[continued from page 2]
methods facilitate a dynamic strategy for
measuring contaminant recovery rates and mass,
ensuring hydraulic containment goals are met,
modifying the treatment system as needed, and
optimizing the treatment system's efficiency.
In the first treatment area, heat was applied across
a 25,500-ft2 zone using 106 electrodes installed at
depths extending 39 feet below grade. Each
electrode contained a co-located multiphase
extraction well that was plumbedto otherelectrode
wells, resulting in six separate liquid and vapor
recovery regions. The system's original operational
requirements included a constant temperature of
100°C in the saturated zone, 90°C in the vadose
zone soil, and sustained temperatures at these
levels for 60 days. Temperatures during system
operations were monitored with 224
thermocouples.
During active treatment, the onsite GC/MS
produced water and air data within 24 hours of
sample collection and the data were posted to an
online system accessible by all project staff. A
total of 870 air samples and 858 water samples
were analyzed Offsite laboratories analyzed split
samples and selected primary samples, including
58 air samples and 46 water samples.
Monitoring indicated that the goal of sustaining a
toiling temperature throughout the entire saturated
zone for 60 days was unnecessary due to
diminishing return of chlorinated solvent mass
recovery The conceptual site model consequently
was refined to reflect a tetter understanding of
contaminant distribution. After three months of
ERH operation, the remediation strategy was
modified to focus onmaintaining 100°Cinsmaller
areas where evidence of NAPL was noted during
pre-remediation sampling and system installation
The presence ofNAPL had been identified earlier
through use of photoionization and ultraviolet
methods, sheen tests, and specialized soil test
kits. This information was used during ERH
operations alongside wellhead-specific vapor data
Figure 3. Distinct changes in chlorinated
VOC concentrations in ground water
began occurring 2-3 months after ERH
startup at the East Gate Disposal Yard.
to determine whichmulti-phase extraction wells were
producing the largest mass of contaminant and to
direct electrical power toward those areas.
Approximately 95% of the thermocouples reached
the TCE boiling point (77-89=C) below the ground-
water table, and 86% reached Hie project's target
temperatures. Failure to achieve the desired
temperatures at 31 of the thermocouples was
attributed to an unexpected presence of distinct,
highly permeable paleochannels at depths of 16-21
feet, which introduced steady streams of cold water.
Thermocouples that reached the TCE boiling point
were maintained an average of 97 days. Those that
reached project target temperatures were maintained
an average of 70 days.
Temperature data also were used to detemrine the
point of system shutdown, which occurred after
eight months of operation. At that point,
temperatures in the NAPL hot spots had been
maintained above the toiling point of TCE in water
for an average of 97 days. Subsurface temperatures
at 193 of the 224 thermocouples had reached 9QPC
in the vadose zone and 100°C in the saturated zone,
and subsurface VOC concentrations had decreased
more than 90%.
Ground-water quality data from wells inside, outside,
and below the treatment area have not indicated
contaminant rebound within the treatment area
following shutdown of the ERH system Similarly,
contaminant migration beyond the treatment area
after shutdown has not been observed.
Use of ERH resulted in a total mass removal
(including vapors, dissolved-phase liquid, and
NAPL) of 2,576 kg of TCE, 405 kg of DCE, and
40,171 kg of total petroleum hydrocarbons. Vapor
data indicated that recovery of vapor-phase TCE
peaked approximately four months after system
start-up. At the same time, ground-water data
showed that TCE concentrations peaked as
NAPL transitioned to the dissolved phase. TCE
concentrations dropped over the following four
months to levels below starting concentrations
(averaging 383 |Jg/L). These estimates do not
include degradation occuring in-situ during
treatment.
Data from nine ground-water monitoring wells
showed significant reductions in chlorinated VOC
concentrations following ERH treatment (Figure
3). The highest ground-water concentration of
TCE priorto treatment was 1,500 |lg/L. Thoughit
increased to a maximum of 950,000 |Jg/L during
heating, the average concentration decreased to
57 (jg/L and is expected to continue declining.
Post-treatment monitoring confirms that no
contaminant rebound lias occurred in saturated
or vadose zone soil and that significant TCE
NAPL no longer exists in the treatment area.
The Triad work strategy is being modified as
lessons are learned throughout the remediation
process. Cleanup at the second source area
recently began, and remediation of the third area
is scheduled to begin in the spring of 2006.
Optimization of the site's existing pump-and-treat
system will continue for removal of remaining
dissolved-phase contaminants from the ground
water. Adetailed technical profile on this and other
Triad projects is available from the on-line Triad
Resource Center at http://wwwtriadcentral.Qrg.
[continued on page 4]
Time (months)
Interior Shallow Wells
~*~ MWE07A1
-•- MWF03A1
MWF14A1
MWH06A1
a MWI08A1
t MWJ04A1
MWJ10A1
~^~ MWL07A1
" MWL10A1
MWL10A1
Begin ERH
End ERH
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[continued from page 3]
Fort Lewis currently is designing and implement-
ing an area-wide treatment performance
assessment to evaluate thermal treatment system
impacts on contaminant flux. In addition, an
Environmental Security Technology Certification
Program (ESTCP) demonstration is underway to
evaluate bioremediation and enhanced mass
transfer for dense nonaqueous-phase liquid
(DNAPL) source treatment
Contributed by Kira Lynch, USAGE
(206-764-6918 or
Iara.v.lvnch®nws02.usace.armv.mil)
Field Tests Show Enhanced Bioremediation following Cyclodextrin Flushing
The U.S. Department of Defense (DOD)
conducted a four-month field demonstration
in 2002 to evaluate cyclodextrin-enhanced in-
situ removal of organic contaminants from
ground water at the Naval Amphibious Base
Little Creek in Virginia Beach, VA(see January
2003 Technology News and Trends). Under its
ESTCP, DOD more recently analyzed the
project's cost and performance data. The}" found
that TCE concentrations in DNAPL declined
an average of 77.3% from pre-treatment levels;
initial aqueous TCE concentrations increased
nine-fold; and solubility for 1,1,1 -trichloroethane
(TCA)increasedupto 19-fold. OverallDNAPL
saturation in the treatment wells decreased
70-81%.
The cost of cyclodextrin-enhanced flushing
(CDEF) was evaluated based on two
deployment methods: injection and extraction
(I/E) of cyclodextrin solutionusing several wells,
and application of cyclodextrin in a multi-well
push-pull (CPPT) mode. The CPPT approach
cost approximately half of a comparable I/E
system. While the cost of full-scale
implementation of CDEF was found to be
similar to other technologies, significant cost
savings are associated with CDEF due to its
ability to shorten remediation time.
Researchers concluded that the use of other
technologies may be required in conjunction
with CDEF at some sites, such as those involving
free-moving NAPL. In addition, CDEF may be
Figure 4. Increased cyclodextrin
concentrations in the subsurface correlated
highly with increased CVOC concentrations
during the Denver brownfield pilot project,
and were followed by concentration declines
caused by both biodegradation and other
attenuation processes.
most effective in initially lowering extremely
elevated concentrations of contaminant, followed
by a remediation approach to further reduce
concentrations to below MCLs. (The complete
ESTCP cost and perfonnance report [publication
number CU-0113] is available at http://
www.estcp.org.)
CDEF technology was used more recently at a
fonner dry cleaning site in Denver, CO, as part of a
voluntary cleanup and brownfield redevelopment
effort. Enhanced reductive dechlorination (ERD)
was implemented at this site through a series of
moksses injections into a subsurface comprising
relatively tight sand, clay, and silt These conditions
required hydraulic fracturing to enhance ground-
water flow and ensure delivery of the carbohydrate
material needed for anaerobic microbial
degradation. Through a network of 65 borings,
119 fractures at depths of 12-37 feet were initiated
over the extent of a ground-water plume of
tetrachlorethene (PCE) exceeding 5 mg/L. A
mixture of sand, guar gum, and chemical stabilizers
was introduced into the subsurface during
hydrofracturing to create highly permeable fractures
in each of the two water-bearing zones. The
hydraulic radius of influence for these fractures
ranged from less than 5 to 75 feet
Once data confirmed the ERD system was
mature, a pilot-scale CDEF test was conducted
to evaluate the use of cyclodextrin to enhance
chlorinated VOC (C VOC) desorption from soil
while acting as a carbohydrate source to
stimulate the reductive dechlorination process.
The area's downgradient dissolved-phase
plume was already being treated using an in-
situ reactive zone (IRZ) strategy. In this "inject-
leave" application, any CVOC mobilization in
ground water resulting from cyclodextrin
injection would be treated in the downgradient
ERZ. Preliminary results suggest that
cyclodextrin increased the aqueous-phase
concentration of total CVOCs at this site by
approximately 350% (Figure 4).
A follow-up pilot study is underway at a second
commercial site in Colorado where mixed
solvents (including 1,1,1 -TCA, TCE, methylene
chloride, and petroleum distillates) had leaked
from underground storage tanks. The study is
further evaluating the effectiveness of using
cyclodextrin inapush-pull application to remove
DNAPL and to lower source area
concentrations to levels eventually treatable by
[continued on page 5]
VOC concentrations
enhancement
cyclodextrin
concentration
0%
0 20 40 60 80 100
Time Since Cyclodextrin Injection (Days)
120 140
4
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[continued from page 4]
natural attenuation. In contrast to conventional
application based on a "line-drive" hydraulic
strategy involving multiple injection wells and
distant extraction wells, the push-pull strategy
allows cyclodextrin solution to be injected into a
single treatment well and extracted from the same
well after a short residence time. The push-pull
method avoids high rates of agent dilution (up
to 90%) that are common to the line-drive
method as well as the extensive ground-water
flow modeling required for line-drive
implementation In addition, operational costs
are lowered by the use of only a single well and
by the conservation of costly but recyclable
cyclodextrin agent.
Contributed by Assoc. Prof. Ttwmas Boving,
University of Rhode Island Department of
Geosciences (401-874-7053 or
boving&uri.edu), Craig Divine, Ph.D.,
ARCADIS G&M (720-344-3500 or
cdivine(ci>arcadis-us.com) and Juli Park,
ARCADIS G&M (720-344-3500 or
ivark(a)arcadis-us. com)
"Supermulch" Amendment Expedites Reueyelation at Mining Sites
In 1997, the U.S. Department of Agriculture
(USDA) and University of Washington began
conducting a series of revegetation experiments
and demonstrations at the Bunker Hill Mining and
Metallurgical (Superfund) Site in central Idaho
(detailed in the July 2003 Technology News and
Trends). Amixture of municipal biosolids and wood
ash, called "Supermulch," was applied to an
approximate seven-acre ground surface
encompassing a fomier impoundment andhillsides
surrounding a formerzinc smelter. Througha unique
partnership, amendment materials for a portion of
the hillside remediation were provided by the City
of Coeurd'Alene and Avista Utilities. Theprqject's
innovative technical andbusinessstrategiesmerited
an award of engineering excellence from the
American Council of Engineering Companies
earlier this year.
Long-temimonitoring indicated that tissue samples
from plants grown in the Supermulch remained
within nomral ranges and that revegetation was
achieved on 100% of the amended plots. For
example, zinc concentrations in soil of the amended
plots ranged from 2,500 to 19,000 ppm, while zinc
concentrations in plant tissue ranged from 45 to 74
ppm-well within normal plant concentrations.
Analysis of seed germination as another key index
of revegetation showed that no germination had
occurred during the same time in control plots.
The revegetation approach developed at Bunker
Hill has since been employed at other sites. In
1998, University of Washington researchers
assisted EPAs Environmental Response Team
(ERT) in designing an amendment mixture for
alluvial tailings deposits at the California Gulch
Superfund site inLeadville, CO. Disposal or erosion
of high-pyrite tailings into the Arkansas River over
the past 100 years had created a 10-mile stretch of
barren mine deposits with high acidity and elevated
metal concentrations in soil, including 1,500-3,500
ppmlead,9-27ppm cadmium, and 1,500-3,400 ppm
zinc. In addition, high metal concentrations in
irrigated pastures had contributed to elevated rates
of plant toxicity and high mortality in grazing
livestock Removal of the tailings was not feasible
due to the potential for tailings to enter the river
during field activities, the high cost of replacement
topsoil, and the difficulty of locating an acceptable
repository for contaminated soil.
The Bunker Hill revegetation strategy was modified
at California Gulch to use higher rates of lime
amendment to neutralize the acidity of the tailings,
and to apply the Supermulch amendment directly
into (rather than atop) the tailings at a depth of 6-12
inches using a bulldozer and toothed ripper.
Inexpensive biosolids again were obtained partially
through a municipal partnership, with Denver
Metro, the public wastewater treatment authority'
in Denver, CO.
Seven years later, approximately 35 acres of the
ten-mile riverside stretch have been restored and
now support dense vegetation (subject to recent
drought conditions). Analytical sampling
conducted by EPA and USDA indicates that
although total soil concentrations of metals of
concern have notchanged,extractable and available
lead, cadmium, and zinc are now below regulatory
standards. For instance, toxicity characteristic
leaching procedure (TCLP)-extractable cadmium
in the top foot of soil decreased from 1.32 ppm in
the untreated tailings to 0.06 ppm within two years
after amendment addition
ERT conducted a four-year ecological risk
assessment of the treatment area, finding that metals-
relatedriskto wildlifeno longer exists. Inadditionto
standard extracts such as TCLP and the multiple
extraction procedure (MEP), die assessment
evaluated ecosystem endpoints' 'from the soil up;'
including microbial populations and activity in soil;
earthworm communities and metal uptake; plant
germination and metal concentration; field plant
species diversity; small mammal populations and
metal body burden; and fat head minnow survival
in re-entrained tailings of the upper Arkansas
[continued on page 6]
Contact Us
Technology Ne\vs and Trends
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Technology News and Trends
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and contributions. Address
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Ann Eleanor
Office of Superfund Remediation and
Technology Innovation
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U.S. Environmental Protection Agency
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Washington, DC 20460
Phone: 703-603-7199
Fax:703-603-9135
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Solid Waste and
Emergency Response
(5102G)
EPA 542-N-05-004
July 2005
Issue No. 19
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
[continued from page 5]
River. The evaluation found that biosolids and
lime amendment had reduced metal toxicity
sufficiently to restore ecosystem function for all
endpoints, as highlighted by key findings:
> Mcrobial function in the biosolids-amended
tailings (as measured by carbon dioxide evo-
lution) in the first year after amendment addi-
tion was 10 times higher than in untreated
tailings and four times higher than in uncon-
taminated soil.
^ Earthworm survival averaged 80% in the
treated tailings, as compared to 1992-2000tests
showing 0% in the untreated tailings and 99%
in the laboratory control soil.
> SmaflmanmTalpopuktiaTsweresimilartothose
in offsite regions, and laboratory analysis of
small mammal target organs showed no signs
of malfunction or damage.
As a result of Supemiulch amendment, cattle-
grazing has resumed on land that was barren for
more than 80 years, aiidapubHcparkwithafishing
area now operates on one of the fonner tailings
deposits. Similar results have been observed after
this technology was initiated at the Qronogo
Duenweg Mining Belt site in Jasper County, MO,
in!999-2001. The approachnowis under evaluation
for use at a wetland tailings repository at the Bunker
Hill site and at alluvial tailings deposits outside of
Prescott, AZ.
Contributed by Salfy Brown, University of
Washington (206-616-1299 or
slb(a)UM'ashington. edit) arid Harry Compton,
U.S. EPA- ERT (732-321-6751 or
comvton. harr\(Sieva. sov)
Superfund Turns 25
This year marks the 25th
anniversary of the Superfund
program. To commemorate this
milestone, the U.S. EPA is
developing a series of oral and photo
projects covering Superfund history,
its social complexity, and important
events, and will launch a national
discussion ofthe program's
changing nature. Information on
participation in these projects or
future viewing ofthe anniversary
documentation is available athttp://
epa .qov/superrund/25anniversarv.
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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