United States
Environmental Protection
Agency
Office of Research and Development (481)
Office of Solid Waste and
Emergency Response (5102G)
EPA 542-F-97-005
April 1997
SERA RTDF Updatef
A Progress Report on the Remediation Technologies Development Forum (RTDF)
Results are in for Several RTDF Field Studies
INSIDE
Intrinsic Bioremediation of TCE
at Dover Air Force Base 1
Accelerated Anaerobic
Bioremediation Pilot Underway 2
Cometabolic Bioventing Study
Initiated at Dover AFB 2
Lasagna™ Technology May be
Selected for Cleanup Effort at
DOE Facility 3
I INERT Action Team Plans Field
Study in Missouri 3
Permeable Barrier Field Study
Scheduled for 1997 4
Sediments Remediation Action
Team Investigates Potential Test
Sites 4
Upcoming Conferences of
Interest to RTDF
Members 4
About the RTDF
The Remediation Technologies
Development Forum (RTDF),
which was established in 1992, is
a consortium of partners from
industry, government, and
academia who are working
together to develop safer, more
effective, and less costly hazardous
waste characterization and
treatment technologies. For
information on the RTDF and
Action Teams visit the RTDF Home
Page at http://www. rtdf.org
\IlQr RecycledPaper
Intrinsic Bioremediation of TCE
at Dover Air Force Base
In 1995, the RTDF Bioremediation Consor-
tium initiated a Phase I field study at Dover
AFB to test the effectiveness of intrinsic bio-
remediation of chlorinated ethylenes in
groundwater. The goals of this four-year
intrinsic bioremediation study are to evaluate
whether trichloroethylene (TCE) is being
destroyed through intrinsic bioremediation, to
identify degradation mechanisms, and to
develop and validate protocols for implement-
ing the process at other sites.
The plume at Dover AFB occupies an area
approximately 9,000 feet long and 3,000 feet
wide and there are at least three sources of
TCE in the area. Intrinsic bioremediation of
perchloroethylene (PCE) and TCE is evident
from the presence of daughter products such
as ds-l,2-dichloroethene (DCE), vinyl chlo-
ride (VC), and ethene. Evidence for bio-
transformation is also supported by changes in
chloride ion concentration. While total
chloroethene concentrations decrease along
the plume from 15 ppm to below 1 ppm, the
dissolved chloride concentrations increase
from 10 ppm (background level) to over 40
ppm. This increase is large enough to account
for the entire observed loss of solvents. The
chemical composition of the groundwater
suggests that multiple biodegradation path-
ways are operating at the site. The central
region of the plume appears to be anaerobic
(dissolved oxygen is < 1 ppm), with iron
reduction and methanogenesis as the domi-
nant microbial processes. On the periphery of
the plume and downgradient from the anaer-
obic region, dissolved oxygen concentrations
increase from 1 to 5 ppm.
Microcosm studies conducted with materials
collected from three areas within the plume
confirm the potential for multiple degradation
pathways. Soil/water samples incubated un-
der anaerobic conditions exhibit reductive
chlorination of PCE to ethene, consistent
with the results of the groundwater analysis.
In addition, microcosms prepared under aer-
obic conditions indicated that DCE and VC
can also be oxidized by aerobic micro-organ-
isms to carbon dioxide. The latter ob-
servations may explain why DCE and VC,
although more mobile, have smaller lateral
distributions in the groundwater as compared to
TCE. The Consortium believes that there is
clear evidence of reductive dehalogenation of
TCE to DCE and that DCE is biodegraded
Multiple Biodegradation
Pathways Operating at
Dover AFB
Reductive Direct
Cometabolism Dehalogenation Oxidation
C02
C02
CO2
CO2
PCE
TCE
cis-DCE
VC
Ethene
CO,
CO2
CO2
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RTDF Update + April 1997
by a combination of oxidation, co-
metabolism, and reduction. The carbon
source for reductive de-halogenation at
the site is under investigation. In some
areas the carbon source appears to be
petroleum hydrocarbons; in other areas
it could be natural organic matter in the
soil.
The Consortium plans to conduct a
second intrinsic bioremediation field
study at the Strother Field Industrial Park
Superfund site in Winfleld, Kansas.
Based on the collaborative work accom-
plished to date and the expertise and
knowledge of the participating com-
panies and organizations, the Biore-
mediation Consortium has prepared a
principles and practice manual on
natural attenuation of chlorinated
solvents. The document presents an
overview of the current science and
practice of natural attenuation of
chlorinated solvents in an easy-to-use
question and answer format. It is
available on the World Wide Web
(http://www.rtdf.org) and in print form.
The Consortium plans to publish
guidance handbooks for accelerated
anaerobic bioremediation and co-
metabolic bioventing in the future.
Accelerated Anaerobic Bio-
remediation Pilot Underway
The RTDF Bioremediation Consortium
installed an accelerated in situ anaerobic
pilot system at Dover AFB in June 1996.
The goal of the pilot is to demonstrate
microbial degradation of groundwater
contaminated with PCE, TCE, and
daughter products (i.e., DCE, VC, and
ethene). Accelerated in situ anaerobic
bioremediation is a technology that
accelerates the indigenous anaerobic
degradation of the chlorinated
contaminants through nutrient addition
and enhancement of anaerobic
conditions in a controlled treatment
area. The objectives of the pilot project
are to: (1) demonstrate that degradation
of PCE and/or TCE can be stimulated in
the deep portion of the aquifer; (2) con-
firm that degradation will proceed
through biogenic intermediates to
nontoxic end products (e.g., ethylene);
(3) develop operation and cost data for
a full-scale system; and (4) document
methodologies for implementing the
technology at other sites. The
Consortium conducted laboratory
studies to identify optimal substrate and
nutrient concentrations to accelerate
degradation at the site.
The pilot consists of two phases. The
first phase involved laboratory testing of
various redox conditions, amendments,
and residence times to facilitate and
accelerate microbial anaerobic reductive
dehalogenation of the chlorinated
solvents in the groundwater. The
Consortium's efforts included laboratory
microcosm as well as soil column tests.
Installing Wells at the Dover
AFB Accelerated Anaerobic
Bioremediation Test Site
The second phase of the pilot study in-
volves hydrogeologic modeling and sys-
tem design. This includes an active
pumping system for adding amend-
ments to the subsurface via injection
wells and extracting the amended
groundwater from a downgradient
location for redrculation and reinjection.
The system has been designed to
operate at varying residence times,
varying flow rates and varying
amendment rates. Results from the
laboratory testing indicated that
bioaugmentation may be necessary to
enhance complete dehalogenation in
situ. This possibility has been discussed
with State of Delaware and EPA Region
3 officials. If normal operation does not
promote full dehalogenation,
bioaugmentation (using microorganisms
isolated from another site where active
TCE biodegradation is occurring) may
be pursued.
A numerical flow and transport model
was used to simulate the flow field
created by the injection/extraction
system. Substrate degradation kinetics
and dehalogenation degradation
kinetics, as well as hydrogeological
parameters were used in this model.
Various modes of injection (e.g.,
continuous, pulsed) were modeled and
investigated in the field to optimize
system performance. The pilot is
expected to continue through
December 1997.
The Consortium is currently preparing a
work plan for a second accelerated
anaerobic field study to be conducted at
Strother Field Industrial Park Superfund
site. This study will investigate the
accelerated anaerobic degradation of
both TCE and trichloroethane (TCA).
Cometabolic Bioventing
Study Initiated at Dover AFB
In June 1996, the RTDF Bioremediation
Consortium initiated a cometabolic bio-
venting study at Dover AFB. This study
is focused on the remediation of a TCE
source area in the vadose zone through
delivery of oxygen and a volatile cosub-
strate such as toluene, methane, or
propane. Microcosm studies were
conducted with soil collected from the
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RTDF Update
April 1997
3
Dover AFB site to determine whether
the indigenous microorganisms were
capable of cometabolically degrading
TCE under aerobic conditions in the
presence of a substrate. The laboratory
studies compared TCE degradation
rates using toluene, methane, propane,
or butane as substrates. Toluene,
methane, and propane were all shown
to induce cometabolic degradation of
TCE in the soil. Scale-up data, including
degradation rates for TCE and con-
sumption rates of toluene and propane
were determined from the soil column
studies. In these studies, the Consor-
tium also assessed the mode of addition
of substrate, comparing low flow contin-
uous to pulsed addition.
Based on laboratory study results, the
Consortium designed and began install-
ing the pilot-scale field study in March
1997. The test site is located adjacent
to the jet engine maintenance building at
Dover AFB, where TCE was used in the
past for degreasing operations. The
cometabolic bioventing system resem-
bles a typical bioventing installation ex-
cept that air is injected with the volatile
cometabolite. A second cometabolic
bioventing study is planned for Hill AFB,
Utah. Soil was obtained from the site in
February 1997, and laboratory studies
using this soil are underway.
Lasagna™ Technology May
be Selected for Cleanup
Effort at DOE Facility
Based on the success of the Phase I test
at the Department of Energy's Gaseous
Diffusion Plant in Paducah (PGDP), Ken-
tucky, the Lasagna™ Partnership initi-
ated a Phase Il-a study at PGDP to treat
a TCE-contaminated area 20 ft wide x
30 ft long x 45 ft deep. (Approximately
100 yd3 were treated in Phase I and
approximately 1,000 yd3 will be treated
in Phase Il-a.) If the Phase Il-a study is
successful, the Lasagna™ technology could
be used to remediate the entire Solid
Waste Management Unit (SWMU) at the
PGDP facility (Phase E-b).
For the Phase Il-a field test, three treat-
ment zones, each filled with 20% iron
by weight, were installed 5 feet apart.
This study will investigate alternative
emplacement methods, optimization of
the treatment zones and electrical and
hydraulic conductivity, the effectiveness
of coupling electroosmosis with iron
dechlorination, the mechanism and kin-
etics of dechlorination, and scale-up is-
sues. The Phase Il-a field study was
initiated in June 1996 and the unit was
stopped for a two-week sampling
period in September. The unit was
then restarted and will operate through
the spring of 1997.
Vertical Configuration of the
Lasagna™ Process
(4)
Electrode
ground surface
DeSr
7
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lation
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electFoameiic
cmihutiimtted,
soil x
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Df^rs
7,
ation
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^
APPLIED ELECTRICAL POTENTIAL
f-^'
Electrode
Note: Electroosmotic flow is reversed upon switching electrical polarity.
The results will be used to determine
whether the technology will be used to
remediate the SWMU. This decision
will also be based on cost projections
developed by the Lasagna™ Partner-
ship. If DOE selects the technology, the
Phase Il-b effort will be initiated. It is
expected that the test site will be 105 ft
wide x 60 ft long x 45 ft deep (approx-
imately 10,000 yd3 treated). Four elec-
trodes will be installed at 35 foot inter-
vals with a total of 18 treatment zones
between the electrodes. The Phase Il-b
system will operate at a rate sufficient to
treat one pore volume every 6 months
(required to observe a reduction in the
TCE concentration). A model will be
used to predict the voltage required to
circulate one pore volume in 6 months.
If initiated in 1997, the Phase Il-b study
could continue through 1999.
I INERT Action Team Plans
Field Study
The RTDF In-Place Inactivation and
Natural Ecological Restoration Technol-
ogies (IINERT) Soil-Metals Action Team
(in conjunction with the U.S. Depart-
ment of Agriculture, the Missouri De-
partment of Natural Resources, and
EPA Region 7) plans to initiate a field
study at a site in Joplin, Missouri.
IINERT refers to technologies that
chemically or physically inactivate soil
metals by reducing and essentially elimi-
nating their solubility and bioavailability
without the need for excavation.
The primary contaminants at the site are
lead and zinc. Mining was conducted at
the site until the early 1900s, followed
by smelting operations until the 1940s.
The one-acre test site, with lead levels
of approximately 1,000 to 5,000 ppm, is
located three to four blocks from the
primary smelter. Lead bioavailability has
been determined to vary significantly,
with values as high as 30%.
Preliminary tests performed by the U.S.
Department of Agriculture using lead-
contaminated soil from the Joplin site
(see graph on the following page) indi-
cate that various levels of iron and phos-
phorous amendments may be effective
in reducing the bioavailability of lead in
the soil.
Bench-scale tests will be performed to
identify the most promising IINERT
treatments for the Action Team's study.
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RTDF Update + April 1997
Effect of Different IINERT
Treatments on Joplin, MO
Lead-Contaminated Soil
0.1% P 0.32% P 1.0% P 3.2% P
Percent Phosphorous
•Control "0.5% Fe + P
Dl.0% Fe + PD2.5% Fe + P
The Action Team expects to investigate
two different treatments via a micro-
swine study, which will follow the EPA
Region 7 protocol. A control, lead
acetate addition, and treatments at
three amendment levels will be
investigated. Five microswine will be
used for each test unit (a total of 25
microswine will be required per treat-
ment investigation). The microswine
study is expected to be completed 3 to
4 months after it is initiated. The
amended soils fed to the microswine
will be highly homogenized to establish
a benchmark, against which the field
results may be compared. In addition to
the microswine study, the Action Team
plans to investigate other surrogates,
including rats and in vitro studies, to
determine human bioavailability from
soil ingestion. The Action Team also is
considering an investigation of IINERT
technology at a second site that is
contaminated with mine tailings.
Permeable Barrier Field
Study Scheduled for 1997
A design team for the RTDF Permeable
Barriers Action Team has been advising
the Air Force Environics Directorate on
a field study to be conducted at Dover
AFB to test the effectiveness of granular
iron permeable zones to treat plumes
contaminated with chlorinated solvents.
The project is being funded by the
Department of Defense Strategic
Environmental Research and
Development Program (SERDP). The
original project proposal called for a
side-by-side comparison of two funnel-
and-gate systems, one containing
granular iron and one containing
another material. Candidates for the
second gate would include iron plated
with a small amount of a catalytic metal
and iron mixed with a mineral such as
troilite or pyrite that would serve to
moderate the pH of the reactive bed,
thereby decreasing the precipitates
formed. The RTDF design team
evaluated the existing laboratory studies
of such materials and determined that
none has yet been demonstrated to be
worthy of in situ field testing. Therefore,
the design team recommended that the
focus of the pilot be shifted toward
testing a novel means of installing a gate
filled with granular iron, aimed at
dramatically reducing the cost of
installing permeable reactive barriers.
Specifically, the design team recom-
mended a side-by-side comparison of a
gate installed by conventional excavation
and one installed by jetting a slurry
containing granular iron under high
pressure— a modification of high-
pressure jet grouting technique. The
final pilot design is still being developed,
with field installation expected in Fall
1997.
The RTDF Update
Copies of the RTDF Update and
factsheets on the RTDF and its Action
Teams can be obtained by faxing a
request to FAX: (301) 670-3815 or by
downloading the files front the RTDF
Home Page at http://www.rtdf.org.
Sediments Remediation
Action Team Investigates Po-
tential Test Sites
The RTDF Sediments Remediation
Action Team held its third meeting at
the Army Corps of Engineers
Waterways Experiment Station in Vicks-
burg, Mississippi, in late October 1996.
Several Navy sites (including Port Huen-
eme) and some private sites are being
considered for a collaborative sediments
remediation field test.
Upcoming Conferences
In Situ and On-Site Bioremediation
The Fourth International Symposium
April 28-May 1, 1997
New Orleans, Louisiana
Tel: 1-800-783-6338
97th General Meeting of the American
Society for Microbiology
May 4-8, 1997
Miami, Florida
Tel: 202-942-9248
U.S. EPA National Conference on
Management and Treatment of
Contaminated Sediments
May 13-14, 1997
Cincinnati, Ohio
Tel: 617-674-7374
The First International Conference on
Remediation of Chlorinated and
Recalcitrant Compounds
May 18-21, 1997
Monterey, California
Tel:l-800-783-6338 or 614-424-5461
IBC's Second Annual International
Conference on Phytoremediation
June 18-19, 1997
Seattle, Washington
Tel: 503-481-6400
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