United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-98-006
June 1998
Issue No. 28
EPA Ground Water Currents
Vfcter Treatment
CONTENTS
Dynamic Underground
Stripping for
Creosote Removal Pg. 1
In Situ Steam Stripping
and Bioremediation
Used in Shallow Media
at Pinellas Pg. 2
Restoration Technology
Development for
DNAPL in Fractured
Bedrock Pg. 3
TSP Releases New
Issue Paper on
Steam Injection Pg. 4
About this Issue
This issue highlights
remediation methods
involving underground
stripping in deep and
shallow areas, in situ
anaerobic bioremediation,
and alternatives for DNAPL
removal in fractured
bedrock.
Dynamic Underground
Stripping for Creosote
Removal
by Eva Davis, Ph.D., U.S. Envi-
ronmental Protection Agency,
Robert S. Kerr Environmental
Research Laboratory
Underground steam injection at depths of
80-100 feet is underway at Southern
California Edison's Visalia, CA, Pole Yard
to recover creosote. The injected steam
displaces free-phase creosote to extraction
wells and increases its volatility and
solubility, and thus its recovery, in the
aqueous and vapor phases. In addition,
the increased temperatures resulting from
steam injection enhance in situ oxidation
of the creosote components through
biological and/or thermal degradation. To
date, it is estimated that 80,000 gallons of
creosote have been recovered or destroyed
since this technology was initiated in
May 1997.
Steam injection has been used for
enhanced oil recovery since the 1930s. In
the late 1980s, Dr. Kent Udell at the
University of California at Berkeley
pioneered the use of steam injection for
soil and aquifer remediation. In partner-
ship with Lawrence Livermore National
Laboratories, the process of dynamic
underground stripping (DUS) was
developed. The DUS process includes
steam injection into permeable areas for
the physical displacement and volatiliza-
tion of contaminants and electrical
heating of low permeability layers to
volatilize contaminants.
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
DUS is effective for volatile and
semivolatile organic contaminants and is
capable of recovering contaminants in
both the liquid and vapor phases. Electri-
cal resistance tomography is used for near
real-time monitoring of the subsurface
steam movement and allows daily control
of the steam injection process. In addition,
it has been found that many contaminants
will oxidize thermally at the subsurface
temperatures achieved through steam
injection.
A total of approximately 270 million
pounds of steam, at temperatures of 171 -
182"C, have been injected into a 2-acre
subsurface area at the Visalia site using a
cyclic process. Steam is injected through
11 wells that surround the free-phase
creosote, and recovered through seven
centrally located extraction wells.
Initially, the injected steam condenses, and
the resulting condensation heats the
subsurface. When the subsurface reaches
steam temperatures, the steam expands
radially from the well, displacing con-
densed steam and contaminants in front of
it. After steam breakthrough at the
extraction wells, injection is halted while
ground water and vapor extraction
continue. The steam zone then collapses,
and the water and vapors that had been
pushed away from the extraction area are
brought back toward the extraction wells
for recovery. The lower air phase pressures
resulting when steam injection is halted
allow increased recovery of contaminants
in the vapor phase.
Prior to the initiation of steam injection, a
ground-water pump and treat system
handling 400 gallons/minute was in place
at the Visalia site. Although the pump and
treat system reduced the size of the
dissolved phase plume effectively during
more than 20 years of operation, it
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contains at least 50% recycled fiber
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recovered less than 10 pounds per week of
creosote. Through steam injection, the rate
of creosote recovery was increased by more
than a factor of 1,000.
Currently, steam injection and the recovery
of free-phase creosote is continuing.
Planning is underway to install deeper
steam injection wells to recover creosote
trapped in a low permeability layer below
the current injection depth of 100 feet.
After recovery of free-phase creosote is
complete, ground-water monitoring is
expected to continue for two years. During
this time, the subsurface will remain at
elevated temperatures and in situ oxidation,
through both thermal and biological means,
is expected to degrade the remaining
dissolved phase contaminants.
To date, approximately $ 11 million have
been spent on the steam injection system,
and current estimates are that the total cost
will be $20 million. This compares
favorably with the site record of decision's
estimated cost of $45 million for enhanced
bioremediation. For additional informa-
tion, contact Dr. Eva Davis (U.S. Environ-
mental Protection Agency) at 580-436-
8548 or e-mail Davis.Eva@epa.gov, or
Craig Eaker (Southern California Edison) at
626-302-8531 or e-mail eakercl@sce.com.
In Situ Steam Stripping
and Bioremediation Used
in Shallow Media at
Pinellas
by Mike Hightower, Sandia Na-
tional Laboratories
Two field-scale operations focusing on the
lemediation of shallow soils and ground
water were completed recently at the
Pinellas Science. Technology, and Research
uSTAR) Center, formed) the U.S. Depart-
ment of Energ) \ fDOE's) Pinellas Plant in
Largo. FL A dual-auger rotary steam
stripping operation w as conducted to
reduce areas of high concentrations (500-
5,000 parts per million) of volatile organic
compounds (VOC's) below a shallow water
sable located less than 2 leet below ground
surface. At more moderate contaminant
levels (100-200 parts per million) the
potential application of in situ anaerobic
bioremediation then could be assessed.
In the second technology application,
bioremediation capabilities were tested
through the addition of nutrients to
stimulate in situ anaerobic degradation of
chlorinated solvents in the shallow,
anaerobic aquifer underlying the site.
Both technologies proved effective in
treating the site contaminants.
From 1956 to 1994, the Pinellas Plant
operations involved manufacturing of
neutron generators and other electronic
and mechanical components for nuclear
weapons. Application of the dual auger
rotary steam stripping technology took
place in an area of the site that was
formerly used as a waste solvent staging,
storage, and disposal area, where shallow,
saturated soil and ground water were
contaminated with high concentrations
(500-5,000 parts per million) of VOCs.
The dual auger system used at Pinellas
consists of a trackhoe modified to operate
two vertical, 35-foot long, hollow kelly
bars with 5-foot diameter augers, as
shown in Figure 1. Air and/or steam is
injected through the hollow kellys while
the augers drill into the subsurface,
liberating VOC contamination during the
churning and mixing of the soil. A large
shroud covers the auger hole to capture
the VOCs removed by this process for
treatment. A catalytic oxidation unit and
acid-gas scrubber were used to treat the
extracted VOCs.
During the system's 3-month operating
period, 48 auger holes were drilled to
depths of approximately 32 feet below
land surface, resulting in treatment of
approximately 2,000 cubic yards of
saturated soil and ground water. Treat-
ment rates varied from 1 to 5 holes/day, or
about 5-30 cubic yards/hour, depending
on the level of contamination encoun-
tered in each hole Overall, approxi-
mately 1.200 total pounds (if VOCs were
removed from (he soil and ground water
m the holes that were treated, and
contaminant levels generally were
reduced by 70-80' 'i. Treatment rate often
was limited to prevent the catalyst in the
catalytic oxidation unit from overheating
from the large quantities of VOCs
liberated by the augers. Operational costs
for the dual auger system ranged from $50-
400/cubic yard of treated soil and ground
water, or about $300-500/pound of
contaminant removed.
The in situ anaerobic bioremediation
demonstration was designed to evaluate the
use of nutrient injection in areas of moder-
ate ground-water contaminant concentra-
tions (100-400 parts per million), and to
obtain operating and performance data to
optimize the design and operation of a full-
scale bioremediation system. Preliminary
laboratory testing had shown significant
promise of using this technique for cost-
effective remediation at the site. The pilot
was located in an area with total chlorinated
contaminant concentrations in ground
water ranging from 10 to 400 parts per
million, with one monitoring well having
concentrations exceeding 2,900 parts per
million.
The bioremediation system consisted of
three 8-foot deep gravel-filled, surface
infiltration trenches and two 240-foot long
horizontal wells with 30-foot screened
intervals. The horizontal wells, directly
underlying and parallel to the middle
surface trench, were at 16- and 26-foot
depths. The study area was about 45 feet
Figure 1: Rotary Steam Stripping at the
Pinellas Plant
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by 45 feet and extended from the surface
down to a thick, clay confining layer 30
feet below the surface. Ground water was
extracted from the upper horizontal well
and recirculated via the surface trenches
and the lower horizontal well to create a
vertical recirculation cell. Sodium ben-
zoate, sodium lactate, and methanol were
added to the recirculated water as nutrients
to enhance the degradation of the chlori-
nated VOCs by the indigenous bacteria.
During the bioremediation pilot's six
month operating period, ground water was
extracted and recirculated at a rate of about
1.5 gallons/minute. Approximately
250,000 gallons of water (about two pore
volumes) were circulated during the pilot
study. Tracer and nutrient monitoring data
indicated that nutrients were delivered to
90% of the central treatment area during
operations. Significant declines in total
chlorinated VOC concentrations (70-99%)
were observed in the wells where nutrient
breakthrough was identified. Degradation
rates of as high as 1 -2 parts/million/day
were observed in high concentration areas.
Monitoring data showed that the bacterial
dechlorination process did not stop at any
intermediate compounds and that contami-
nant reductions to regulatory levels can be
obtained.
These technology applications were
sponsored by the Innovative Treatment
Remediation Demonstration (ITRD)
Program coordinated by DOE's Sandia
National Laboratories. The ITRD Program
is a joint effort between DOE and EPA to
reduce barriers to the use of new technolo-
gies. Through the ITRD Program, DOE,
EPA, industry, and regulatory agency
representatives worked with the Pinellas
Environmental Restoration Program on
these innovative technology applications.
Cost and performance reports on these two
applications are available. For more
inform;!; .in. ...intact Mike Hightower
(Saudi; \Ui.inal Laboratories) at 505-844-
5499. ! ; ; ...Me (Pinellas STAR Center) at
815-54 •'),- or the ITRD Web site http//
\\w\vc ii •. .'ov'itrd.
Restoration Technology
Development for DNAPl in
Fractured Bedrock
by J. Edward O'Neill, Smithville
Phase IV Bedrock Remediation
Program
The complexities of removing dense non-
aqueous phase liquids (DNAPLs) from
fractured bedrock at a former hazardous
waste storage and disposal facility in
Smithville, Ontario, Canada, have led to the
formation of a unique public/community
partnership for restoring the site. The
Managing Board of Directors of the
Smithville Phase IV Bedrock Remediation
Program (the Board), formed in 1993,
consists of representatives from Ontario's
Ministry of Environment and Energy, the
Township of West Lincoln, Ontario, and a
public liaison group known as the Chemi-
cal Waste Management Liaison Committee.
The Board is charged with selecting a
preferred remedial alternative for this site.
Recognizing that no technologies have
proven effective yet for remediating
DNAPLs in fractured carbonate bedrock,
the Board developed a 10-step approach for
selecting a preferred remedial alternative
(Figure 2). Aggressive efforts to solicit
community involvement through an active
stakeholder working group and extensive
outreach mechanisms are incorporated into
each step.
Chemical Waste Management Limited used
this site for operation of a primary waste
transfer facility for polychlorinated
biphenyls (PCBs) from 1978 to 1980, at
Figure 2: Steps in the Decision-Making Process
input/review
Finalize decision-making process '*r
Set goals and indicators
Develop site conceptual model
Establish alternatives
Ind Review
--• OH) Board ',
Public
IR
• Board
Public
IR
• Board
Public
STEP 5 ,
Studies to confirm
site conditions
Develop solutions
(containment/
remediation)
Predict effects of alternatives
Assess risks of alternatives
t wiluate and compare alternatives
Identify preferred alternative(s)
IR
Board
IR
Board
Public
\ssess confidence
T
Report to Province
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Ground Water Currents
welcomes readers' comments and contributions.
Address correspondence to:
Ground Water Currents
8601 Georgia Avenue, Suite 500
Silver Spring, Mary land 20910.
which time the U.S. border was closed to
shipment of hazardous wastes. The
facility's inventory, consisting of PCBs
stored in drums, tanks, and (leaking) tank
trucks, filled to capacity and the site
became known as Canada's largest PCB
storage area. It is estimated that about
30,000 liters of PCB liquid migrated
through the clay overburden into a shallow,
bedrock aquifer. This PCB oil, mostly
present as undissolved DNAPL, comprises
approximately 42% (by weight) PCB, 13%
chlorobenzenes, 2% trichloroethylene, and
43% other hydrocarbons.
Currently, the Board is collaborating with
the U.S. EPA; the University of Waterloo,
Ontario; Environment Canada; McMaster
University; and the University of Utah in
&EPA
United States
Environmental Protection Agency
EPA Publications Clearinghouse
PO Box 42419
Cincinnati, OH 45242
site characterization efforts through
application of an existing fracture flow
model (FRAC3DVS). TheFRAC3DVS
model will be expanded to investigate
capture zones in fractured carbonate
rocks. In addition to facilitating
decision-making for the Smithville site.
it is anticipated that these modeling
results will create an extensive site
characterization data bank that will be
useful for remedy selection at other
sites with similar geologic conditions.
In 1989, a pump and treat system was
installed aroune1 rH ^WAPT plume to
control migratio ,d con-
taminants. An aqu iess porous
rock appears to have prevented DNAPL
from migrating from the shallow
aquifer into intermediate and deep
aquifers; however, monitoring results
indicate that dissolved contaminants are
present in the deeper aquifers.
The Board has been using the 10-step
decision-making process over the last year
and recently has completed Step 4,
"Establish Alternatives." The remedial
alternatives identified include one natural
attenuation alternative and eight engi-
neered alternatives that potentially are
viable for application at this site. The eight
engineered alternatives include thermal
wells (combined with a ground-water
barrier technology); excavation and ex situ
treatment; hydromill excavating; ground
freezing; permeation grouting; secant
piling (megadrilling); extraction wells; and
integrated permeation grouting and
extraction wells. A comparative evaluation
of these nine alternatives (Step 9) is
scheduled to occur in late 1998 and early
1999 to identify the preferred alternative(s).
All of these technologies suffer from
potential adverse effects; however, none has
been tested in fractured bedrock. Final
selection of the preferred remediation
alternative is planned for late 1999.
For more information, contact J. Edward
O'Neill (Smithville Phase IV Bedrock
Remediation Program) at 905-957-4077, or
visit the Web site http://www.niagara.com/
sp4/.
TSP Releases New Issue
Paper on Steam Injection
In January 1998, EPA's Technology Support
Project (TSP) released an issue paper titled
Steam Injection for Soil and Aquifer
Remediation. The paper provides basic
technical information on the use of steam
injection for remediation of soils and
aquifers that are contaminated by volatile
or semivolatile organic compounds. Topics
include the process of steam injection,
applicable contaminant and subsurface
conditions, general design and equipment
considerations, and laboratory and field-
scale experimental results. The document
can be read or downloaded from the web
site http://www.epa.gov/ada/issue.html.
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