a
A newsletter about soil, sediment, and ground-water characterization and remediation technologies
Issue 8
September 2003
Full-Scale Lasagne Demonstration Completed at
DOE Paducah Site
The "Lasagna Partnership," one of eight action
teams under the Remediation Technologies
Development Forum (RTDF), began developing
and testing an innovative technology in 1994
to address contamination in low-permeability
soil. Under this research partnership, the U.S.
Department of Energy (DOE) collaborated with
the U.S. EPA and private industry (Monsanto,
DuPont, and General Electric) in demonstrating
Lasagna™ technology on a commercial-scale
basis for treating trichloroethene (TCE)-
contaminated soil at DOE's Paducah Gaseous
Diffusion Plant in Paducah, K Y.
The technology uses an applied direct-
current electric field to drive contaminated
pore water through vertical treatment zones
containing iron filings and kaolin clay.
Contaminant passing through the treatment
zones is broken down into nonhazardous
compounds as it comes into contact with the
iron particles.
The demonstration took place in a 72- by 90-ft
area of the Paducah plant known as "solid waste
management unit (SWMU) 91." TCE used in
the mid 1960s for cylinder drop tests had spilled
during testing and eventually leaked into the
surrounding soil and shallow ground water.
Sampling conducted by DOE's Oak Ridge
National Laboratory in the early 1990s indicated
the soil contained an average TCE
concentration of 84 mg/kg and pure-phase
product (more than 1,500 mg/kg). The soil at
SWMU 91 is characterized as a clay loam with
apermeability of IxlO"6 cm/sec.
Phase I of the demonstration was conducted
over four months in early 1995 to collect site-
specific information from a 150-ft2 treatment
area. A follow-up, commercial-scale
demonstration (Phase Ila) was conducted over
12 months in 1996 on an adjacent 600-ft2 area
to refine die construction methods. Phase Ila
post-treatment analysis indicated that the
average TCE concentration in the treated soil
had decreased approximately 95%. Based on
these results, a full-scale system (Phase lib)
was constructed in 1999 to treat 6,480 ft2 of
contaminated soil covering the entire cylinder
drop area.
The Lasagna technology typically employs
electrode zones, multiple treatment zones, and
a water management system. At SWMU 91,
construction of the treatment system began
with the installation of the electrode zones
(Figure 1), which consisted of three 72-ft rows
of electrode assemblies placed at a depth and
spacing of 45 feet. Each assembly contained a
9-in by 40-ft carbon steel plate and a 4-in by
45-ft wick drain wrapped inside a geotextile
material. Construction of the treatment zones
involved offsite mixing of a 60:40 (by weight)
slurry of cast iron particles and kaolin. Acement
truck transported the slurry to the site, where it
was placed below the ground surface to create
two treatment zone sections consisting of eight
parallel 45-ft-deep curtains spaced at 5-ft
intervals. The water handling system consisted
of PVC piping, a collection sump, and a 400-gal
storage tank located in the center of the
treatment area.
Induced water flow (electro-osmosis) was
generated across the treatment zones using
direct current. The electrical field (initially set
at 450 volts and 800 amps and then converted
to 220 volts and 600 amps three months later)
caused the pore water to move uniformly from
[continued on page 2]
Contents
Full-Scale Lasagna
Demonstration
Completed at DOE
Paducah Site page 1
Large-Scale Bioslurping
Operations Used for
Fuel Recovery page 2
Propane Biostimulation
Barrier Demonstrated
in MTBE-Contaminated
Ground Water page 4
Phyto Demonstration
Enters 7th Year at
Carswell Naval Air
Station page 5
Research Needs
Identified Through 21M2
EPA's new Office of Superfund
Remediation and Technology
Innovation (OSRTI) has under-
taken an initiative to advance
monitoring and characterization
technologies for hazardous
waste sites. Known as 21 M2
(Measurement and Monitoring
Technologies for the 21st
Century), this initiative has
allowed OSRTI to identify ten
technology areas needing
additional research. Detailed
information on the research
needs, as well as overviews of
21 M2 projects that have already
been completed or are under-
way, is available at
www.cluin.ora/proarams/21 m2.
Recycled/Recyclable
Pnrted with Soy/Canola Ink on paper trial
contains at least 50% recyded liber
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[continued from page 1]
the anode toward the cathode through the
treatment zones. The pore water moved
more than 10 feet during the entire
operational period, forcing contaminants
through at least two treatment zones. Iron
filings in the treatment slurry degraded the
TCE to ethane (a nontoxic gas) and chloride
(a natural component of ground water), and
will remain in the ground to "polish" the
soil over time.
The system operated on a continuous mode
for approximately six months, at which time
the soil temperature reached 90°C. It then
was converted to a pulse mode to prevent
overheating. Pulsed operations allowed the
system to operate for 1-4 days until the
target temperature was reached, and then
to shut down for several days of cooling
before re-starting. Sampling conducted one
year after operations began showed that
TCE concentrations had declined from an
average pre-treatment concentration of 43.3
mg/kg to less than 1.5 mg/kg, and that the
highest concentration had decreased from
552 mg/kg to 27 mg/kg. Operations
continued for eight additional months.
Site inspections were conducted weekly.
The system ceased operation temporarily
for approximately eight weeks after 20
months of operation due to problems with
the rectifier converting incoming alternating
current into direct current. Minor problems
arising during operations involved:
> unscheduled power outages;
> installation of an above-ground water
reservoir tank in response to heavy
rain;
> removal of sediment from a water re-
cycling line;
> installation of a vent hose to prevent
false high sump readings caused by
trapped air; and
> spikes in the sump level sensor due to
electrical interference.
System operations were terminated in
December 2001 after a total of 24 months,
without the need for an additional one-year
option outlined in the project plans. Data
indicated the target cleanup level for TCE
(5.6 mg/kg) had been met. Sampling and
analysis conducted in Spring 2002 confirmed
that TCE concentrations had further
decreased, resulting in an average of 0.3 8 mg/
kg and a high of 4.5 mg/kg. A total of
approximately 10,000 yd3 of soil were treated
at a unit cost of $200/yd3.
The final remedial action report for this project
is available from the Remediation
Technologies Development Forum at
http://www.rtdf.org/public/lasagna/
lastechp.htm Planning of additional Lasagna
applications is underway, including use by
the State of Wisconsin for redevelopment
of a half-acre brownfields site at an estimated
unit cost of $110/yd3.
Contributed by Gary Bodenstein,
DOE/Paducah Site (270-441-6831 or
bodensteingw(q)oro.doe.gov) and Chris
Athmer, Terran Corporation (937-320-
3601 or dathmer
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[continued from page 2]
bioslurping system consists of a vacuum
pump connected by pipes to standard fuel
recovery wells. A dip tube is placed inside a
sealed well, with the straw inlet placed in the
water/floating fuel. The top of the dip tube
connects to pipes that carry the fuel and soil
gas drawn in by the vacuum pump. Soil gas
enters the well through a screened interval
above the water table. From the vacuum
pump, the fuel/water mixture is piped to a
separator where the fuel is removed and
collected for recycling. Vapors are discharged
directly to the atmosphere or treated, if
needed, and discharged. The bioslurping
system pulls oxygen-rich air from the
atmosphere into the unsaturated soils, thus
bioventing the unsaturated soil and fostering
aerobic microbial degradation of the
contaminants.
The first bioslurper at Diego Garcia was
installed in a grassy area near an airstrip and
included a vacuum pump and 1,100 feet of
4-inch PVC piping connected to six
downgradient recovery wells. Dip tubes were
placed approximately one foot into the water/
fuel during low tide. A10-horsepower vacuum
pump operated 24 hours per day to generate
a vapor flow rate averaging 50 fWmin. During
the first month of operation, 2,000 gallons of
fuel were recovered. Recovery rates over the
following 18 months averaged approximately
1,000 gallons of fuel per month. Recovered
fuel was used to power water heaters for
other onsite operations.
In 1997, a second bioslurper was added in a
nearby aircraft ramp area. The bioslurper
employed an identical vacuum pump that was
connected through manifolds to the original
vacuum pump. Piping was installed among
ten additional recovery wells and the vacuum
pump and connected to the existing pipe
system. Hose clamps and elastic couplers
were used for pipe connections to allow for
Figure 2. Bioslurping resulted in the recovery
of nearly 3,180 gallons of fuel at one of the
Diego Garcia target areas within 14 months.
rapid disassembly in the event of contingency
military activities. During the first month of
operation, 8,000 gallons of fuel were recovered
from the combined bioslurping systems. The
recovery rate averaged 5,000 gallons per
month over the following year, when
contingency aircraft operations took effect.
During this event, the bioslurper piping was
removed and the ramp was ready for aircraft
operations within four hours.
In 2000, the bioslurping system was further
expanded to remediate all areas of the site
known to contain fuel product in the
subsurface. The expanded system involves a
total of 50 bioslurper wells, some of which are
used only as biovents in areas that do not
contain floating fuel product. Within two to
three years of operation, the thickness of the
product decreased significantly inmost wells.
Between September 1998 andDecember 2000,
for example, the average product thickness in
10 wells in the aircraft ramp area decreased
100%, from an initial thickness of 1.26 feet.
Similarly, the volume of subsurface fuel at a
refueling pit within the ramp area decreased
more than 80% between July 2000 and
September 2001 (Figure 2).
While 25 recovery wells each contained more
than one foot of fuel accumulation prior to
treatment, only eight wells in the ramp area
had fuel accumulations exceeding one foot in
May 2002. None of the wells near the airstrip
contained any detectable fuel accumulation.
Overall, the rate of contaminant degradation
for this system is estimated at 1 pound of
hydrocarbon per 13 pounds of air introduced
into the soil.
The Air Force continues to conduct quarterly
sampling in the recovery wells and semi-annual
sampling of ground water to monitor
dissolved fuel contaminant concentrations
and indicators of natural attenuation. In
addition, soil gas is field tested at selected
locations to track the degradation of
contamination in the smear zone above the
water table. The bioslurper will continue to
operate until fuel recovery becomes
nonproductive, at which time operations will
convert to a bioventing mode until soil gas
tests indicate that aerobic degradation is
complete. Natural attenuation processes,
including tidal-mediated bioventing, are
expected to degrade the residual fuel in the
soil and the small quantities of fuel
constituents dissolved in the ground water.
AFCEE estimates that bioslurping will
remove the remaining recoverable fuel, which
exists at only one of the three treatment areas,
by the end of 2003. AFCEE also estimates
that the technology will cost approximately
5% of the amount required to excavate and
replace the entire site with clean fill-the
alternative cleanup remedy.
AFCEE recently assembled a mobile diesel-
powered bioslurping system that can be used
on an operational ramp while connected to
6-10 wells. The system allows fuel recovery
from wells to continue without disruption to
air operations. In field tests conducted at the
site earlier this year, the mobile bioslurper
recovered 260 gallons of fuel within four
months.
Contributed by Jerry Hansen, AFCEE
(210-536-4353 or jerry.hansenfa).
brooks.af.mil) and Donald Kampbell,
Ph.D., U.S. EPA/Office of Research and
Development (580-436-8564 or
kampbell.donald&epa.eov)
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Propane Biostimulation Barrier Demonstrated in MTBE-Contaminated Ground Water
The U. S. EPA's National Risk Management
Research Laboratory (NRMRL) and U.S.
Navy recently completed a technology
demonstration at the Naval Base Ventura
Comity (NBVC) inPortHueneme, CA. The
demonstration was undertaken to determine
whether biodegradation is reducing intrinsic
methyl tertian' butyl ether (MTBE) in
ground water to concentrations below state
criteria. Fifteen ground-water sampling
events were conducted over a 38-week
period. Analysis of intrinsic MTBE,
deuterated MTBE (d-MTBE), daughter
products, and geochemical parameters
demonstrated that the technology did not
meet the State of California's treatability
criteria (below 5ug/L).
From June 2001 to March 2002, the
demonstration was conducted at the NBVC
National Environmental Technology Test
Site, where approximately 10,800 gallons of
fuel had been released into ground water
from 1984 to 1985. The resulting ground-
water plume consists of approximately 9
acres of BTEX and 36 additional acres of
MTBE contamination. The plume extends
approximately 4,500 feet downgradient from
the release site. Pre-treatment data indicated
that MTBE concentrations in the
demonstration area, located midway
downgradient along the MTBE plume,
reached 5,000 ug/L.
The site is underlain by unconsolidated
sediment composed of sands, silts, clays,
andminor amounts of gravel and fill. Ashallow,
perched, unconfined aquifer is the uppermost
water-bearing unit. The aquifer consists of an
upper, 8-to 10-ft silty sand unit, an underlying
12- to 15-ft fine- to coarse-grained sand unit,
and a basal clay layer. The water table is
located 6-8 feet below ground surface, with a
saturated aquifer thickness of 16-18 feet
(reflecting 1-2 feet of seasonal variation). Pre-
demonstration study showed little ground-
water flow other than in the bottom portion of
the aquifer.
The demonstration tested the ability of a
propane biostimulation barrier to stimulate
cometabolism through the injection of oxygen,
propane, and MTBE-degrading bacteria into
the aquifer. Exogenous propane-oxidizing
bacteria (Rodococcus ruber strain ENV425)
were used to seed the aquifer at the
demonstration onset. Oxygen and propane
then were sparged intermittently into the
aquifer from separate sparging points at a rate
of 1-10 pounds/day and 0.1-0.5 pounds/day,
respectively.
Operations in the test plot began with the
injection of oxygen into eight oxygen injection
points (OIPTs) and propane into seven
propane injection points (PIPTs). Eight
bacterial injection points installed between the
OIPTs and PIPTs were used for a single release
of bacterial suspensions 16 days after the start
of oxygen injection. Only oxygen was injected
at eight OIPTs in the control plot. The ground-
water injection and tracer systems for the two
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plots together employed a total of 38 fully-
screened wells.
Deuterated MTBE and ground-water tracers
(bromide and iodide) were used to determine
the technology's efficacy. Tracer materials
were released into each well under the
natural gradient at a rate of 10 mL/day. The
ratio of tracers between downgradient
transects provided evidence of MTBE
dilution and degradation, while d-MTBE
ratios served as tracers of anthropogenic
MTBE. Critical evidence of biodegradation
was provided by measurement of d-MTBE
daughter products.
The first ten sampling events took place
biweekly in both the test and control plots
and monthly thereafter. Although sampling
was concentrated at the bottom well
screens, the middle and upper screens of
each well were sampled periodically. Both
the test and control plots contained very
low levels of daughter products (acetone;
acetone-d6,2-propanol; 2-propanol-d6,d8;
formaldehyde; tertiary butyl alcohol (TEA);
and tertiary butyl alcohol-d9,dlO). While
only TBA was detected at upgradient wells,
both TBA and d-TBA were detected in
downgradient wells; a determination of
whether biotic or abiotic processes
generated these products was not made.
The d-MTBE in both the test and control
plots increased throughout the evaluation
period.
Geochemical parameters in the upgradient
and downgradient portions of both the
control and test plots were analyzed after
the evaluation period. Analysis showed no
reduction in nutrients or in total and
[continued on page 5]
Figure 3. Intrinsic MTBE concentrations in
downgradient test plot wells indicated that
minimal biodegradation had occurred at the
NBVC test site as a result of propane
biostimulation.
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[continued from page 4]
dissolved organic carbon (electron donors)
in either plot, and no alkalinity change in the
downgradient portion of the test plot. These
results suggested little biodegradation was
occurring.
Throughout the 38 weeks of testing, intrinsic
MTBE concentrations in the upgradient
portion of the test plot and in both upgradient
and downgradient portions of the control plot
gradually decreased. MTBE concentrations
in the downgradient portion of the test plot,
however, remained at 300-600 jog/L throughout
testing (Figure 3). More information on this
evaluation is available in NRMRL's
innovative technology evaluation report
(EPA/600/R-02/092) at wwwepa. gov/ORD/
NRMRL/Pubsl
Contributed by Ann Azadpour-Keeley,
EPA/NWtRL (580-436-8890 or
keelev. atm&eva. eov)
Phyto Demonstration Enters 7th Year at Carswell Naval Air Station
An extensive interagency demonstration
of phytoremediation was initiated in 1996 at
the Carswell Naval Air Station RCRA site in
Fort Worth, TX. The system uses eastern
cottonwood trees, Populus deltoides, as
short-rotation woody crops to optimize in-
situ reductive dechlorination of
trichloroethene (TCE) and CM-1,2-
dichloroethene in shallow ground water.
Results after three years of monitoring
indicated that the planted trees had rooted
into the water table and begun to exhibit
hydraulic and geochemical influences at the
site.
Earlier this year, the U. S. Geological Survey
(USGS) and U.S. Air Force (USAF)
conducted a six-year review of the system
and found that the trees have significantly
increased biodegradation rates of TCE
beneath the center line of the plantations.
Associated with this increase in
biodegradation, or natural attenuation
capacity, is a substantial decrease in plume
stabilization distance (the extent to which
contaminants travel in the upper aquifer).
USGS modeling results suggest that solvent-
based contaminant mass flux decreases due
to in-situ microbial biodegradation will be
significantly larger than decreases due to
transpiration. A 20% decrease in mass flux
from transpiration alone during the peak of
each growing season is anticipated when
canopy closure is achieved.
The treatment area is located about one mile
from the main aircraft assembly building at
USAF Plant 4, where waste oil, solvents, and
fuels had been disposed at an onsite landfill.
Previous use of a pump and treat system and
steam-enhanced vacuum extraction
addressed only some of the site's solvent-
based source contamination. The area
encompasses 4.6 acres that were covered
primarily with grass prior to treatment. Surface
soil consists of a 12-to 18-in layer of silty clay
and clayey silt. Ground water is located 5-15
feet below ground surface, with an estimated
velocity of 0.62 ft/day. The underlying shallow
aquifer consists of silty fine sands and
hydraulically isolated lenses of coarser
material, with an estimated conductivity of
10"2 cm/sec. Prior to treatment, TCE
concentrations in the ground water
approached l,000ppb.
Approximately 960 trees were planted evenly
in two 60- by 250-ft plots positioned
perpendicular to the direction of ground-water
flow The plots are separated by a 50-ft buffer
zone (Figure 4). One plot is located directly
above a former waste trench, while the second
is located downgradient of the trench. Each
plot consists of seven rows of trees planted
4-8 feet apart. A drip irrigation system was
installed and used on a regular basis during
1996, the first year of tree growth, to help
establish them during a severe drought. The
irrigation system was used once during 1997;
since then, the trees' facultative
phreatophytes have used both ground water
and precipitation. Plant tissue analysis has
indicated that eventual disposal of the trees
as hazardous waste will be unnecessary.
Hydrologic and geochemical data collected
from 40 monitoring wells in August 1996
through September 1998 showed that
L
dissolved oxygen levels beneath the trees
had decreased. This suggested that the
trees are providing a sustained source of
the electron donors needed for reductive
chlorination. Data indicate that a
combination of hydraulic control and in-situ
microbially mediated reductive
[continued on page 6]
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5
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f\ t, Technology
News and Trends
p*
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(5102G)
EPA 542-N-03-005
September 2003
Issue No. 8
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[continued from page 5]
dechlorination is responsible for the mass
flux reduction.
The USAF anticipates follow-up data
collection through 2006, which will mark
the tenth year of tree growth. The estimated
full-scale cost for this application is
$466,000. EPA's National Risk Management
Research Laboratory is compiling detailed
cost information on this project in an
innovative technology evaluation report,
which will be available at www.epa.gov/ord.
hi addition, DOD will issue a final cost and
performance report later this year. If
warranted by the final results of this
application, the USAF anticipates the use
of phytoremediation for other ground-
water contaminants such as nitrates and
metals.
Contributed by Gregory Harvey, USAF
(937-255-3276 or
2reeorv.han>ev(a)wDafb.af.mil)
-400 Feet-
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Upgradient Zone
^TormerTCE Source AreJT^
Plantation #1
480 Trees
•
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Plantation #2
480 Trees
Downgradient Zone
«>
A
issing 960
cottonwood
e
ted for the
INAS
Direction of
Ground-water
Flow
New Ground-water Monitoring Well
New Piezometer
Soil Moisture Probe Nest
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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