United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-97-004
September 1997
Issue No. 25
vvEPA Ground Water Currants
ii
Biodegradation of TCE through
by Perry L. McCarty, Sc.D.,
Stanford University
The Western Region Hazardous Sub-
stance Research Center (HSRC) recently
completed a full-scale in situ demonstra-
tion of successful trichloroethylene
(TCE) biodegradation in contaminated
ground water at Edwards Air Force Base
(AFB), CA. Through the addition of
toluene and oxygen in treatment wells,
cometabolism by toluene-using microor-
ganisms caused TCE concentrations
ranging between 1,000-1,400 p.g/1 in the
influent aquifer water to fall by 85%
with each pass through the wells.
Following several passes at flow rates of
25-38 liters per minute, TCE concentra-
tions in ground water ranged from 25-50
jig/1, indicating 95-98% TCE removal.
This 12-month demonstration project
encompassed a 22-meter-square treat-
ment zone and a 60-meter-wide influent
ground water plume. Stanford Univer-
sity researchers designed a two-well
treatment system spanning two aquifers.
Toluene, gaseous oxygen, and hydrogen
peroxide were injected into each well
and mixed with pumped-in contaminated
ground water from one aquifer. The
mixture then entered the other aquifer,
where toluene and TCE biodegradation
occurred. Ground water circulated
between the two wells and between the
two aquifers.
Static mixers at each well dissolved 7-14
mg/1 of toluene and a mixture of pure
oxygen and hydrogen peroxide to
provide the dissolved oxygen concentra-
tion of 30-40 mg/1 required for toluene
degradation. Hydrogen peroxide, added
to prevent excessive bacterial growth
near the well screens, dissociated in the
aquifer to provide part of the required
dissolved oxygen. The system added
oxygen and peroxide continuously, with
additions of toluene in a pulse only once
per day over a 2-hour period to achieve
more uniform distribution away from the
treatment well.
Prior to initiation of this project, regula-
tory agencies required positive assurance
that toluene was actually biodegraded to
a level below regulatory concern. Results
of an earlier pilot demonstration con-
ducted at Moffett Federal Air Field in
Mountain View, CA, showed that this
system reduced toluene through biologi-
cal activity to below 1 p.g/1.
Biodegradation of ICE lough Toluene Injection
1PL Solubilization through Single-Phase Itroemulsion and Insolvents
Calendar
In Situ Oxidation Destruction of DNflPL
Resources
flddress Change for Technology Practices Manual Requests
NeujTIO Publications
In the Edwards AFB demonstration,
toluene concentrations leaving the
treatment zone averaged 1.6 \igfl, with a
maximum measurement of 18 jig/1,
which was far below health effects
standards (100 \igfl for California and
1000 jig/1 for EPA) and below taste and
odor thresholds (25-40 \igfl).
The HSRC conducted this demonstration
in cooperation with the Armstrong
Laboratory, U.S. Air Force; Edwards Air
Force Base; Earth Tech; Woodward-
Clyde; and EPA's Robert S. Kerr
Research Laboratory. For additional
information, contact Dr. Perry L.
McCarty (Western Region HSRC) at
650-723-413 lor e-mail
McCarty@CE.Stanford.edu.
About this Issue
This issue features
results of field- and
full-scale demonstra-
tions of in situ pro-
cesses under study for
their potential effec-
tiveness in cleaning
up sites contaminated
with solvents, non-
aqueous phase liquids
(NAPLs), and dense
nonaqueous phase
liquids (DNAPLs).
Recycled/Recyclable
Printed with Soy/Canola Ink on paper that
contains at least 50% recycled fiber
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NiLSolubiizalionlhroihSiile~
by Stephanie Fiorenza, Ph.D.,
Rice University, and Michael
Annable, Ph.D., University of
Florida
University of Florida researchers completed
a field-scale demonstration of the effective
use of a surfactant/cosurfactant mixture.
The surfactant/cosurfactant solution forms a
water-continuous, low-viscosity
microernulsion when it comes into contact
with a nonaqueous phase liquid (NAPL).
This microernulsion can be diluted in water
and transported through porous media as a
single-phase, low-viscosity fluid. With
microernulsification of a NAPL, complete
solubilization of NAPL components should
occur without selectivity.
The U.S. Department of Defense (DOD)
Advanced Applied Technology Demonstra-
tion Facility (AATDF) program, the
Strategic Environmental Research and
Development Program (SERDP), Hill Air
Force Base (AFB) in Utah, and EPA's
National Risk Management Research
Laboratory supported this single-phase
microernulsion (SPME) project. The
demonstration took place in a sheet pile-
enclosed test cell at Hill AFB, Operable
Unit 1. The 2.8-by-4.6-metertest cell
extended to a depth of 11.7 meters below
ground surface, 3.7 meters into a clay
confining unit.
Researchers flushed nine pore volumes of a
solution consisting of 3% surfactant—Brij
97 n(polyoxyethylene (10) oleyl ether)—
and 2.5% cosurfactant—n-pentanol—
through the test cell. Soil cores were
collected before and after the addition of the
surfactant/cosurfactant mixture, and testing
of pre- and post-flush partitioning tracers
was conducted.
NAPL removal was estimated using soil
core data, tracer test data, and the mass of
target analytes collected in extraction wells.
Comparison of target analyte concentrations
in pre- and post-treatment soil cores yielded
an estimated 91-96% reduction in the three
most dominant NAPL constituents (decane,
1,3,5-trimethylbenzene, and undecane).
Initial examination of tracer test data
indicated an average NAPL removal of
75%. When the mass of target analytes
recovered at the extraction wells was
compared to initial NAPL mass estimates
provided by soil core data or partitioning
tracer data, the estimated removal of NAPL
was >90% or 60-80%, respectively.
At a recent meeting of the Remediation
Technologies Development Forum In Situ
Flushing Action Team, AATDF and SERDP
researchers compared these SPME results
with a cosolvent test conducted in a
different cell at the same operable unit. The
flushing agent used in the cosolvent test
consisted of 70% ethanol and 12% pentanol.
Upper and lower layers of the cell showed
different performance levels. For example,
99% removal of 1,2-dichlorobenzene was
observed at a 16.25-foot depth, while 75%
removal was detected at a 20-foot depth.
Researchers believe this difference is
attributable to higher NAPL saturations in
the lower zone and the difficulty of direct-
ing a low-density flushing agent to reach
deeper layers.
Comparison of the SPME and cosolvent
studies concluded that the efficacy of the
two methods is comparable, but the flushing
agent in the cosolvent study contained more
chemical additives that increased costs. For
additional information about these two
studies, contact Dr. Michael Annable
(University of Florida) at 352-392-3294.
Eleven additional projects are nearing
completion under the four-year AATDF
program. Processes under evaluation
through the program include the use of a
surfactant/foam process for aquifer
remediation and passive and semi-passive
techniques for ground water remediation.
DOD initiated the program in 1993 by
awarding a $19.3 million grant to a univer-
sity consortium of research centers led by
Rice University. Participating universities
include Stanford University, the University
of Texas, Rice University, Larnar Univer-
sity, the University of Waterloo, and
Louisiana State University. For additional
Remediation Technologies Development Forum (RTDF) Permeable Reactive Barriers Action Team Meeting; September 18-19,
1997; Sheraton OceanFront Hotel, Virginia Beach, VA; 617-674-7347 or the World Wide Web at http://wvw.rtdf.org (click on
Permeable Reactive Barriers Action Team).
Water Environment Federation 70th Annual Conference & Exposition; October 18-22,1997; McCormick Place, Chicago, IL;
800-666-0206, confinfo@wef.org (e-mail), or World Wide Web at http://www.wef.org.
Groundwater Foundation "Priming the Pump" Workshop and Annual Groundwater Guardian Designation Conference; Novem-
ber 22-24,1997; McDonald's Corporation, Oak Brook, EL; 800-858- 4844 or the World Wide Web at http://www.gmundwater.org.
IBC's Annual Natural Attenuation Conference; December 8-10,1997; Raddison Resort Scottsdale, Scottsdale, AZ; 508-481-6400
ext. 281, pcanney@ibcusa.com (e-mail), or the World Wide Web at http://wwya.ibcusa.com/conf/attenuation.
The Eighth Annual West Coast Conference on Contaminated Soils and Ground Water; March 8-12,1998; Embassy Suites
Hotel, Oxnard, CA; 413-549-5170, bknowles@aehs.com (e-mail), or the World Wide Web at http://www.aehs.com.
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Electronic Sources
Commonly referenced World Wide Web sites containing additional information on hazardous waste issues include:
EPA
EPA Superfund Program
EPA/Technology Innovation Office (TIO)
Hazardous Waste Cleanup Information (CLTJ-IN) System
EPA/Office of Research and Development (ORD)
EPA/ORD Environmental Technology Verification (ETV) Program
EPA Brownfields Program
Ground-Water Remediation Technologies Analysis Center (GWRTAC)
http://www.epa.gov
http://www.epa.gov/superfnd
http://www.clu-in.com
http://www.epa.gov/ord
http://www.epa.gov/etv
http://www.epa.gov/brownfields
http://www.gwrtac.org
information on the AATDF program,
contact Dr. Stephanie Fiorenza (Rice
University) at 713-527-4725.
InSiluOxidalionDeslruclionofliL
by Karen Jerome, Westinghouse
Savannah River Company
The U.S. Department of Energy (DOE)
Office of Science and Technology (Subsur-
face Contaminant Focus Area) recently
completed a full-scale demonstration of the
use of hydrogen peroxide and iron to
convert chlorinated solvents and hydrocar-
bons to nontoxic end products such as
carbon dioxide, chloride ion, and water
(Fenton's reaction). Through a cooperative
venture that included Westinghouse
Savannah River Company and Geo-
Cleanse International, Inc., DOE achieved
a destruction efficiency of 94% on a
64,000-cubic-foot site containing nearly
600 pounds of dense nonaqueous phase
liquid (DNAPL) at the Savannah River Site
in Aiken, SC. A cost evaluation concluded
that "hot spot" treatment yields the most
cost-effective use of this technology for
treating DNAPL.
Researchers determined that a DNAPL
pool at a depth of 155 feet should contain
11,000 pounds or more of DNAPL for this
technology to be considered more cost
efficient than a conventional pump-and-
treat system, a baseline technology for
DNAPL-contaminated ground water. If
time is a key factor in the decision-making
process, however, this technology can
remove contamination faster than pump-
and-treat methods (weeks versus years).
The demonstration deployed this technol-
ogy to destroy DNAPL below the water
table. The DNAPL, consisting of solvents
such as trichloroethyiene (TCE) and
tetrachloroethyiene (PCE), was located
approximately 140 feet below ground
surface in unconsoiidated sediments.
Address Change for Technology
Practices Manual Requests
Rice University requests that readers
interested in obtaining copies of the
Technology Practices Manual for Surfac-
tants and CoSolvents (referenced in the April
1997 issue) fax the following information
to Donald F. Lowe, PhD. (Rice University)
at 713-285-5948:
name
company
mailing address
telephone number
fax number
e-mail address
The first edition of the manual is currently
available on the World Wide Web at
www. ch2m. com/ch2mhill/services/environ/
RICEMANUAL/TOC.htm. The second
edition is scheduled for release in Fall 1997.
Treatment involved incremental injection of
a total 4,200 gallons of hydrogen peroxide,
along with ferrous sulfate. Increased
chloride concentrations in ground water and
decreased concentrations of TCE and PCE
in both ground water and soil served as
indicators of DNAPL destruction.
Chloride ion concentrations increased from
an initial concentration of 4 ppm to a final
concentration of 25 ppm. Post-treatment
analysis indicated that PCE and TCE
concentrations in ground water fell to nearly
zero from 120 mg/1 and 20 mg/1, respec-
tively. Pie- and post-tests showed that the
total estimated DNAPL quantity dropped
from 593 pounds to 36 pounds.
Under its DNAPL remediation program,
DOE's Subsurface Contaminant Focus Area
soon will complete demonstrations of three
additional technologies. At the Portsmouth
Gaseous Diffusion Plant, field tests are
evaluating the use of potassium permangan-
ate to degrade pure-phase TCE in saturated
aquifer sediments using recirculation as a
reagent delivery technique. Additionally,
researchers are studying the use of stacked
horizontal fractures propped with a new
permanganate particle grout to form a
permeable reactive barrier at the Portsmouth
Plant. At a commercial wood treatment
facility in California, DOE also is testing
the use of hydrous pyroiysis/oxidation for
use on DNAPLs and dissolved organic
components. Contact Karen Jerome
(Westinghouse Savannah River Company) at
803-725-5223 for additional information on
the Savannah River Site demonstration, and
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Dr. Thomas Early (Oak Ridge National
Laboratory) at 423-576-2103 for information
on DOE's in situ oxidation work.
Neiiil Publications
EPA's Technology Innovation Office (TIO)
recently issued three new publications. The
eighth edition of Innovative Treatment
Technologies: Annual Status Report (EPA
542-R-96-Q10) provides information on
Superfund sites at which innovative technolo-
gies are in use or are selected for use. The
companion information system, Innovative
Treatment Technologies: Annual Status
Report Database (TTT Database) (Version 2.0)
(EPA 542-R-96-002) will be released later this
Fall.
TIO also updated Cleaning Up the Nation s
Waste Sites: Markets and Technology Trends
(EPA 542-R-96-005), which describes the
future demand for remediation services on all
major cleanup programs in the U.S., including
Superfund, RCRA corrective actions,
undeiground storage tanks, DOE, DOD, and
other federal or state programs.
Partnerships for the Remediation of Hazard-
ous Wastes (EPA542-R-96-006) provides
potential private sector partners interested in
development of new and innovative hazardous
waste technologies with information on
opportunities for entering into joint public-
private development projects.
Copies of these publications may be obtained
from EPA's National Center for Environmen-
tal Publications and Information at 513-489-
8190 or downloaded from TIO's CLU-IN site
at http://www.ciu-in.com.
United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-96-004
September 1997
Issue No. 25
&EPA Ground Water Currants
in
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