United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-OO-005
August 2000
Issue No. 38
»B* raff TRENDS
CONTENTS
Cometabolic Bioventing _.
Field Test Conducted at
Dover Air Force Base page 1
Anaerobic/Aerobic
Composting for Removal
of Pesticide
Contaminants page 2
Anaerobic
Bioremediation of Soil
on Tribal Lands page 3
Upcoming Monitoring
Technology Conference page 3
New Resources
Available on EPA's
CLU-IN Web Site page 4
The Applied Technologies
Newsletter for Superfur,
Removals & Remedial
Actions & RCRA Corrective
Action
ABOUT THIS ISSUE
This issue highlights
innovative bioremediation
technologies used to treat
contaminated soils.
Cometabolic
Bioventing Field Test
Conducted at Dover Air
Force Base
by Gregory Sayles, Ph.D., EPA/
National Risk Management
Research Laboratory ;
Under stewardship of EPA's government/
industry collaboration, the Remediation
Technologies Development Forum (RTDF)
Bioremediation Consortium, a cometabolic
bioventing demonstration was conducted
during 1998-1999 at Dover Air Force Base
in Dover, DE. Results of the demonstration
have shown that 99% of the chlorinated
organic contamination was removed
through cometabolic bioventing. RTDF
researchers are continuing to compile and
disseminate information on the lessons
learned during this demonstration, and to
conduct similar testing at Hill Air Force
Base in northern Utah.
-Cometabolie-bioventing-is the injection of •-
air and a cosubstrate into the vadose zone
to promote in situ biodegradation of
chlorinated solvents. Although the use of
cometabolism for ground water treatment
has been studied in the field for several
years, the RTDF study is the first known
field test of cometabolic bioventing.
The demonstration occurred adjacent to a
jet engine maintenance area (Building
719) contaminated with trichloroethylene
(TCE), l,l,l-trichloroethane(TCA),and
1,2-cis dichloroethylene (DCE). Early
laboratory tests using soil from this
location showed that propane and toluene
each performed well as cosubstrates, and
propane was chosen for the demonstration.
Testing indicated that 30 moles of propane
were required to promote biodegradation
of one mole of TCE.
The field system consisted of three
injection wells screened to 10 feet below
- ground surface, which was the lowest
expected elevation of the water table.
Thirteen soil gas monitoring points, each
of which were equipped with two gas . .
probes, also were installed to monitor soil
gas conditions throughout the demonstra-
tion. An additional 11 temporary soil gas
monitoring points were installed for use
during initial air permeability testing and
for soil gas monitoring during operation of
the system. Operation began with pulsed
injection of propane in air over a three-
month period in order to acclimate the
microbial environment of the 600 square-
foot test plot. Over the following 14
months, continuous injection of 0.03% (v/
v) propane in air was applied at a rate of
1.0 feetVminute.
Statistical analysis showed that TCE, TCA
and DCE were removed significantly
during the test, with most final concentra-
tions reaching below the detection limit of
6 ug/kg. As a product of chlorinated
solvent biodegradation, deposition of
chloride was used to demonstrate overall
contaminant biodegradation. Chloride ion
was found to accumulate at a median rate
of 58 mg/kg of soil, for a total chloride
accumulation rate of 10 times the initial
amount present at the test plot. Based on
these rates, it is estimated that a total of 13
kg of chlorinated solvents (in TCA
equivalents) biodegraded as a result of the
cometabolic bioventing process. Figure 1
provides histograms of the initial and final
TCE and chloride concentrations during
the demonstration.
Researchers found that an initial
cosubstrate acclimation period prior to full
operation of the system is required for
effective use of propane as a cosubstrate
[continued on page 2]
Recycled/Recyclable
Printed with Soy/Cano]a Ink on paper that
contains at least 50% recycled liber
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Figure 1. Histograms of Initial and Final TCE and Chloride Concentrations
U
I
Frequency
3 S
«,- •
°
Sot) TCE Lavols (mg/kg)
Soil Chloride Levels (mg/kg)
[continued from page I]
during the bioventing process. It was also
recognized tliat reliance on the use of
indirect measures of biodegradation (such
as chloride accumulation) rather than direct
measures highlights the need for innovative
approaches to proving that biodegradation
otcurs in the field.
Although detailed costing of this technol-
ogy is not yet available, aerobic bioventing
of fuel contamination typically costs $5-
25/yard'. Cometabolic bioventing incurs
additional costs for elements such as the
cosubstrate and additional monitoring, but
these expenses are expected to be less than
$10/yard\
Dover Air Force Base is considering full-
scale application of this technology to
complete vadose-zone remediation at
Building 719. Visit the RTDF Web site at
www.rtdf.org for more information, or
contact Dr. Gregory Sayles (EPA/National
Risk Management Research Laboratory) at
513-569-7607 or e-mail
sayles.gregory@epa.gov.
Anaerobic/Aerobic
Composting for
ftemoval of Pesticide
Contaminants
by Brad Jackson, EPA/Region 4,
and Frank Peter, Stauffer
Management Company
Field demonstration of a unique
composting process was completed recently
at the Stauffer Management Company
(SMC) Superfund site in Tampa, FL. This
process, known as Xenorem™, uses
anaerobic and aerobic cycles to
bioremediate pesticide-contaminated soil
via indigenous bacteria and the addition of
amendments. The demonstration resulted
in an overall destruction rate of 90% for all
contaminants of concern (chlordane, DDD,
DDE, DDT, dieldrin, toxaphene, and
molinate). Based on these results, this
technology now is being used to remediate
approximately 16,000 cubic yards of soil at
the SMC Tampa site and in other full-scale
commercial applications.
The field demonstration was conducted in
an enclosed warehouse at the SMC Tampa
manufacturing facility using soil taken
from two areas with high concentrations of
pesticides. Preparation for the tests
included the installation of an odor
abatement system and an ambient air
monitoring system. Tests began in June
1997 with the construction of a uniformly-
mixed, 905 cubic-yard pile of the
excavated soil, which had been run through
a two-inch screen. Locally-available cow
manure and straw were added as amend-
ments to the soil to create an environment
with high levels of nutrients and to
maintain desired conditions of temperature,
oxygen, pH, and nutrient availability.
The pile was covered with a 40 mil 30-by-
60-foot woven tarp to begin the anaerobic
cycle. The testing period was extended
until September 1998 in order to provide
sufficient time for experiencing hot and
cold weather operations, assessing the
quality of the amendments, and using
various mixing equipment such as a loader,
roto-tiUer, and Fecon and SCAT turners.
Amendments were added at weeks 0,14,22,
33, and 48 to create a total volume of 1,193
cubic yards after week 48. Aerobic condi-
tions in the pile were created by either
mechanically mixing and turning the .
windrow or by injecting compressed air
through injectors spaced 15 feet apart along
the length of the pile. Aerobic and anaero-
bic operating cycles were varied to
maximize contaminant destruction rates.
Key operating parameters of the process
included a pH of 5-9, residence time of less
than six months, temperatures of 35-60°C,
and a moisture content of 30-90%. :
Soil samples were collected weekly from
four locations of the pile, and analyzed for
pesticide content, inorganic composition,
microbial enumeration, moisture and dry
matter, organic matter, pH, surface tension,
thiocarbamates, and water-holding capac-
ity. Laboratory analysis indicated that
targeted cleanup levels, as specified in the
site's record of decision, were achieved for
the primary contaminants of concern. In
particular, concentrations had dropped
significantly for chlordane (47.5 mg/kg to
5.2 mg/kg), DDD (242 mg/kg to 23.1 mg/
kg), DDT (88.4 mg/kg to 1.2 mg/kg), and
toxaphene (469 mg/kg to 29 mg/kg).
Figure 2 illustrates the typical DDT
destruction rate observed during this
demonstration.
[continued ori~page~3J
Figure 2. Typical DDT Destruction Rate
at the SMC Tampa Site
40 50
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[continued from page 2]
Of the five amendment periods employed,
two were identified as operating under
optimal environmental/process conditions.
Researchers found that the mixing equip-
ment and duration of mixing steps is critical
to the efficiency of this technology. (The
SCAT turner proved to serve as the more
efficient turner of the composted material.)
Although costs are very site-specific, SMC
estimates that the cost for cleanup using
- Xenorem^eomposting at a project such as
this is $192/yard3.
Based on its successful use in pesticide
destruction, application of Xenorem
technology has been extended to include
nitro-aromatics (TNT, RDX, and MX),
polyaromatic hydrocarbons, polychlori-
nated biphenyls (in development) and other
persistent compounds. For more informa-
tion, contact Brad Jackson (EPA/Region 4)
at 404-562-8925 or e-mail
jackson.brad@epa.gov, or Frank Peter
(SMC) at 302-239-9222 or e-mail jfpeter®
aol.com.
Anaerobic
Bioremediation of Soil
on Tribal Lands
by Jefflnglis, EPA/Region 9, and
George Padilla, Navajo Nation
Superfund Program ___ __
The Navajo Nation, through its Superfund
Program, has teamed with the U.S. EPA's
Region 9 Office and the Environmental
Response Team (ERT) to remediate soils on
tribal lands contaminated with toxaphene,
the active constituent of livestock dipping
solutions used in the past. At these sites,
anaerobic bioremediation through the
addition of a multi-part amendment to
excavated soils is resulting in a minimum
of 80% reduction of toxaphene.
Remediation using this process is complete
at 22 dip vat sites located on the Navajo
Nation lands.
In the 1930s, the Department of the Interior
established laws and programs for livestock
grazing, and the Bureau of Indian Affairs
(BIA) began administering and managing
these programs on many tribal lands.
Toxaphene was used by the BIA and the
Navajo Nation as a pesticide at 250-300 dip
vat sites on Navajo lands from 1948 to
1982, when it was banned by the EPA.
During this time, sheep and cattle were
driven routinely through concrete-lined
vats that were positioned partially below
grade level and filled with pesticide
solutions for the control of ectopic para-
sites. Approximately 20,000 gallons of the
pesticide solution was used each year, and
" then discharged on-site into ground-level "
pits. These management practices ceased in
the 1980s, but toxic residues had accumu-
lated over the years as a result of pesticide
discharge. This pattern was repeated at
several other reservations in the Southwest.
In 1992, the Navajo Superfund Program
expressed its concerns regarding these sites
to EPA's Region 9 Office. As a result, the
ERT began researching the potential for an
in-situ or on-site bioremediation method to
treat the sites. A comparison study was
conducted to evaluate the effectiveness of
anaerobic processes versus combined
anaerobic/aerobic processes. Study results
indicated that an anaerobic process would
achieve the targeted toxaphene cleanup
level (25 parts per million for buried soil) in
the most cost-effective manner.
In 1994, the EPA Region 9 Emergency
Response Office began implementing this
anaerobic process for treatment of soils at a
..4iE.site.locaJted.at Nazlini Chapter, near
Window Rock, AZ. WiTSTtoxaphene levels
as high as 33,000 parts per million, this site
ranked Mghest on the BIA's list of 22
priority sites. In the area of each dip vat,
remediation efforts began with soil screen-
ing to determine the horizontal and vertical
extent of contamination, followed by
excavation of up to four feet of soil and its
transfer to a poly vinyl chloride (PVC)-lined
treatment cell. A slurry consisting of 10%
manure, 5% lime, 5% blood meal, 0.75%
disodium phosphate, 0.25% monosodium
phosphate, and 79% contaminated soil was
mixed with water and poured into the
treatment pit. The pit then was sealed with
a PVC cover, and vents were installed to
allow for gas emissions.
Over the following 12-month resting
period, indigenous bacteria were allowed to
multiply while feeding on the toxaphene.
Quarterly samples were taken to ensure the
progression of contaminant biodegradation.
Once target levels were achieved, the pits
were opened, drained, left to dry, backfilled,
and revegetated. Follow-up sampling has
confirmed that toxaphene cleanup levels
have been maintained.
Based on the successful results at Nazlini,
this anaerobic bioremediation process was
applied at the remaining 21 high-priority
dip varsites"ln^treatment'cells'as long as
300 feet. The Navajo Superfund Program
has evaluated an additional 48 dip vat sites
on Navajo lands, and currently is working
with the BIA to develop a long-term
cleanup plan for the remaining sites. It is
anticipated that this approach to anaerobic
bioremediation may be applied success-
fully to the remediation of other chlorinated
solvents and pesticides, such as DDT. An
environmental videotape on this work
(Navajo Vats IT) is available through the
ERT products line offered at www.ert.org.
For more information, contact Jefflnglis
(EPA/Region 9) at 415-744-2348 or e-mail
inglis.jeff@epa.gov, or George Padilla
(Navajo Nation Superfund Program) at 520-
871-6861 or e-mail ggpad@cia-g.com.
[This technology, using a more refined
slurry recipe, also has been piloted at two
aerial pesticide spraying facilities and used
to treat dip vat sites on the Zuni and Pueblo
Reservations. Information on using this
technique for treatment of pesticide-
contaminated soil on the Zuni Reservation
is available from Michael Torres (EPA/
Region 6) at 214-665-2108 or e-mail
torres.michael @ epa.gov.]
Upcoming Monitoring
Technology Conference
On September 19 and 20,2000, EPA will
sponsor the National Environmental
Monitoring Technology Conference at the
Hynes Convention Center in Boston, MA.
More than twenty panel sessions will be
held on topics such as surface water, ground
water, and watersheds; ozone and air
monitoring; innovative technology
verification; hazardous substance
[continued on page 4]
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View or download it from:
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Tech Trends welcomes comments, contributions,
and new subscriptions. Address correspondence
to:
Tech Trends,
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Silver Spring, Maryland 20910
Fax:301-589-8487
[continued from page 3]
monitoring in soils; and technology
commercialization.
EPA program offices will be represented by
plenary speakers from the National
Exposure Research Laboratory, Technology
Innovation Office, Environmental
Monitoring Public Access and Community
Tracking Program, Environmental
Technology Verification Program, Small
Business Innovative Research Program, and
Center for Environmental Industry and
Technology.
During the conference, over 100 exhibitors
will display information on environmental
monitoring and related technologies. To
register for exhibit space at the trade show,
call 1-888-EPA-7341. Conference registra-
tion information is available on the Internet
at www.epa.gov/regionl.
New Resources
Available on EPA's
CLU-IN Web Site
The Hazardous Waste Clean-up Information
(CLU-IN) Web site, which is managed by
EPA's Technology Innovation Office,
provides information on innovative
treatment technologies to the hazardous
waste remediation community. Visit CLU-
IN at www.clu-in.org to obtain more
information on resources such as these:
An Analysis of Barriers to Innovative
Treatment Technologies: Summary of
Existing Studies and Current Initiatives.
This report (publication number EPA
542-B-00-003), which was published in
March 2000, presents a summary of
existing studies on barriers that have
historically impeded the successful
commercialization of innovative treatment
technologies. Users may download the
document at http://clu-in.org/publ.htm.
Innovative Remediation Technologies:'
Field-Scale Demonstration Projects in
North America, 2nd Edition. This
updated system provides a searchable
database of information about innova-;
tive remediation technology field
demonstration projects conducted in
North America. Users may search or
browse the system at http://clu-in.org/
pub 1.htm.
Upcoming Courses and Conferences.
This feature of CLU-IN'pfovides' users
with the capability to search for courses
and conferences by date, name, location,
or description from among 172 cur-
rently-posted events. Users also may
suggest the addition of an event not yet
listed in the system. This feature is
available at http://clu-in.org.
Errata
The correct Web site for the Sediment
Management Work Group, as
referenced in the February 2000 issue
of Tech Trends, is: www.smwg.org.
Mention of trade or commercial products does not constitute endorsement by the U.S. Environmental Protection Agency.
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TECH TRENDS
EPA 542-N-00-005
August 2000
Issue No. 38
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