United States
Environmental
Agency
Protection
Solid Waste and
Emergency Response
(5102W)
EPA/542/N-93/010
December 1993
&EPA
The Applied Technologies Journal for Superfund Removals and Remedial Actions and RCRA Corrective Actions
Pneumatic Fracturing
Increases VOC Extraction Rate
by Uwe Frank, Risk Reduction Engineering Laboratory
The Pneumatic Fracturing Extraction
(PFE) process: (1) increases the rate at
which vapor extraction removes volatile
organics (VOCs), and (2) broadens the
range of vadose zones where soil vapor
extraction (SVE) can be used. The low
permeability of silts, clays, shales, etc.,
would otherwise make such formations
Soil Btoremediation
Publications
in this issue erf ?•. 8C& f&£tt&$ (j>»
for irtfot fttatioo o-n issaes aM re-
soils and detaiteiafeo tit a guide to
unsuitable for cost-effective SVE and
would require more costly approaches.
Pneumatic fracturing provides an inno-
vative means of increasing the perme-
ability of a formation, thus extending
the radius of influence that can be
reached to effectively extract contami-
nants that otherwise might not be
reached by conventional SVE. The PFE
was developed jointly by Accutech Re-
medial Systems, Inc. and the Hazardous
Substance Management Research Cen-
ter, located at the New Jersey Institute
of Technology. The PFE was evaluated
under the SITE (Superfund Innovative
Technology Evaluation) Program at an
industrial site in central New Jersey;
and, it demonstrated the removal of
chlorinated VOCs, specifically
trichlorethene (TCE). The PFE should be
equally suitable for other volatile con-
taminants, including hydrocarbons such
Superfund Remedial Actions
Application of Innovative Treatment Technologies
100
80
f 60
a.
•5
X 40
20
Soil Vapor Thermal
Bio-
In-SHu
Solvent
Soil
Extraction Desorption remediation Flushing Extraction Washing
Note: Data are from EPA's Innovative Technologies: Annual Status Report (Fifth
Edition)
VOCs
Fracturing
Soil
as benzene, toluene, ethyl benzene and
xylenes.
In the PFE process, fracture wells are
drilled in the contaminated vadose zone
and left open (uncased) for most of their
depth. A packer system is used to iso-
late small (2 feet) intervals so that short
bursts (-20 sec) of compressed air (less
than 500 pounds per square inch) can be
injected into the interval to fracture the
formation. The process is repeated for
each interval. The fracturing extends
and enlarges existing fissures and intro-
duces new fractures, primarily in the
horizontal direction. When fracturing
has been completed, the formation is
then subjected to vapor extraction, ei-
ther by applying a vacuum to all wells
or by extracting from selected wells,
while others are capped or used for pas-
sive air inlet or forced air injection.
Based on the results from the SITE
demonstration, PFE is both technologi-
cally feasible and cost effective. The PFE
process increased the extracted air flow
rate by >600% relative to that achieved
in the site formation prior to fracturing.
While TCE concentration in the ex-
tracted air remained approximately con-
stant (-50 parts per million), the
increased air flow rate resulted in TCE
mass removal rates after fracturing that
were an average of 675% higher over
the 4-hour test periods. Significantly in-
creased extracted air flow rates (700% to
1,400%) were observed in wells 10 ft.
from the fracturing well. Even in wells
20 ft. away, increases in air flow rates of
200% to 1,100% were observed. From
well pressure and tiltmeter (surface
heave) data, results suggest an effective
extraction radius of at least 20 ft.
(see PFE, page 2)
Recycled/Recyclable
Printed with Soy/Canola Ink on paper that
contains at least 50% recycled Iber
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Soil Washing Technology Removes Organics
from Fine and Coarse Grained Soil
by Annette Gatchett, Risk Reduction Engineering Laboratory
VOCs
Soil
| Washing
Soil
I he BioGenesis soil washing technol-
ogy was developed to remove organic
compounds from both fine- and coarse-
grained soil. The technology, demon-
strated under EPA s SITE (Superfund
Innovative Technology Evaluation) Pro-
gram, uses a proprietary solution called
BioGenesisSM cleaner to transfer organic
compounds from the soil matrix to a liq-
uid phase. The process involves high-
energy mixing of excavated
contaminated soils in a mobile washing
unit. The cleaner, a complex alkaline
blend of surfactants, is rapidly degraded
by soil microbes. Residual BioGenesisSM
solution remaining on soil particles
stimulates the biodegradation of soil
contaminants not removed by the wash-
ing process. The process does not re-
quire the screening out of particles
larger than 4 to 6 inches in diameter. In
this SITE demonstration, BioGenesis
was used as a stand-alone technology.
EPA s SITE demonstration occurred
at a refinery contaminated with crude
oil. Analytical results from a sample col-
lected from the untreated soil prior to
the demonstration revealed total recov-
erable petroleum hydrocarbon (TRPH)
concentrations as high as 11,000 parts
per million. After the initial soil wash-
ing, TRPH decreased by 65 to 73%. The
biodegradation process continued in the
treated soil; samples revealed that
TRPH had decreased by 85 to 88% after
120 days. BioGenesis expects that
TRPH levels in treated soil from this site
will eventually be reduced to levels that
meet regulatory requirements for use as
fill material. TRPH concentrations in
wastewater ranged from 76 to 1,500 mil-
ligrams/Liter (mg/L). Approximately
3,500 gallons of wastewater were gener-
ated during each run because the waste-
water was not recycled; rather, it was
treated at the refinery treatment facility.
The treatment cost calculated for
SITE demo ranged from $74 to $160
per cubic yard of soil. This cost can be
expected to vary depending on contami-
nation type, level and volume of soil
treated. Treatability studies are highly
recommended before large-scale
applications of the technology are con-
sidered. Because results may vary with
different waste characteristics, the
BioGenesis treatment system s perfor-
mance is best predicted with prelimi-
nary bench-scale testing. Additionally,
treatment residuals may require off-site
treatment.
The BioGenesis soil washing sys-
tem consists of several major compo-
nents: the wash unit, the volatile organic
compounds (VOC) emissions hood,
holding tanks, oil skimmers, strainers,
transfer pumps, the American Petro-
leum Institute oil/water separator, oil
coalescer, a bioreactor (not used at this
SITE refinery demonstration) and a flat-
bed trailer for ancillary equipment.
Once onsite, the treatment system can
be operational within one day if all nec-
essary facilities, equipment, utilities and
supplies are available. After the treat-
ment is completed, the treatment system
can be demobilized and moved offsite
within one day. Approximately 30,000
sq. ft. are needed to accommodate the
unit and support equipment, etc.
BioGenesisSM claims that the process
is capable of extracting volatile and non-
volatile hydrocarbons, including petro-
leum hydrocarbons, pesticides, PCBs
and polycyclic aromatic hydrocarbons
(PAH) from most soils. Soil containing
large amounts of silt, clay and humic
substances are not as effectively treated
by soil washing technologies as are soils
containing sand and other coarse mate-
rials. However, BioGenesis claims that
its technology may be effective for soils
containing high percentages of silt and
clay. The BioGenesisSM technology s silt
and clay cleaning capability is being
tested in Environment Canada s Con-
taminated Sediment Treatment Technol-
ogy Program. The technology was used
in June 1993 to treat sediments contami-
nated by wood treating activities at
Thunder Bay Harbour, Ontario, Canada.
Primary contaminants on site included
PAHs containing two to five aromatic
rings. Particle size distribution analysis
showed that 80% of the sediment con-
sisted of silt and clay sized particles.
BioGenesis used a field prototype
wash unit capable of treating two cubic
yards of sediment per hour. Results of
PAH analyses showed that removal effi-
ciencies from washing alone ranged
from 83.3 to 94.8% for the individual
PAHs. Average PAH removal from soil
washing was reported at 89.5%. BioGen-
esisSM is currently modifying its wash
unit and is manufacturing a unit ca-
pable of treating up to 40 cubic yards of
soil per batch.
For more information, call Annette
Gatchett at EPA s Risk Reduction Labo-
ratory at 513-569-7697. A SITE Technol-
ogy Capsule (Document No. 54O/SR-93/
510) and its companion Innovative Tech-
nology Evaluation Report (Document
No. EPA/540/R-93/510) can be or-
dered from EPA s Center for Environ-
mental Research Information at
573-569-7697.
PFE from page 1
Even higher increases in air flow
rates and TCE mass removal were ob-
served when one or more of the moni-
toring wells was opened to allow
passive air inlet. Under these condi-
tions, air flow rates increased an aver-
age of 19,000% and TCE mass removal
rates increased 2,300%.
The developer also has proposed
that catalytic oxidation (not demon-
strated during this SITE evaluation) can
be cost-effectively used for above
ground treatment of the extracted
VOCs, particularly when contaminant
concentrations are above ~50 to 100
parts per million. Catalysts suitable for
oxidation of chlorocarbons such as TCE
now are commercially available. In ad-
dition, Accutech has suggested injecting
the waste heat from catalytic oxidation
either directly or indirectly (using a heat
exchanger) into the formation to further
enhance volatilization and removal of
VOCs.
For more information, call Uwe
Frank at EPA s Risk Reduction Engi-
neering Laboratory at 908-321-6626.
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New for the
I here are three recent EPA publications
addressing soil remediation. Two of
these address issues and research re-
lated to bioremediation. The third is a
bioremediation resource guide. These
publications are briefly described
below.
In-situ Bioremediation
Although in-situ bioremediation has
been used for a number of years in the
restoration of ground water contami-
nated by petroleum hydrocarbons, it
has only recently been directed toward
contaminants in unsaturated subsurface
soils. EPA s Robert S. Kerr Environmen-
tal Research Laboratory, in conjunction
with Utah State University, has pre-
pared a document which provides an
overview of the factors involved in in-
situ bioremediation, outlines the types
of information required in the applica-
tion of such systems and points out the
advantages and limitations of this tech-
nology. The document focuses on pro-
cesses which are currently being utilized
or are in development to treat contami-
nated unsaturated subsurface soils in
place. It is based on findings from the
research community in concert with
experience gained at sites undergoing
remediation.
Specific environmental processes,
factors and data requirements for char-
acterizing and evaluating the applica-
tion of subsurface in-situ bioremediation
are addressed as are selected field-scale
applications of recovery and delivery
systems that enhance in-situ subsurface
soil bioremediation. Discussed are: in-
situ subsurface microbial processes and
controlling environmental factors; en-
hancement of in-situ subsurface biore-
mediation; making the saturated zone
(see Bookshelf, page 4)
Electra-Osmosis Holds Promise
for In-Situ Extraction
By Randy Parker, Risk Reduction Engineering Laboratory
Inorganic
VOCs
Electro-
osmosis
* Soils
Electrokinetics, Inc. has developed an
electro-osmosis (EO) process that prom-
ises to be an effective in-situ separation
technology for extracting heavy metals,
radionuclides and other inorganic con-
taminants, as well as some volatile or-
ganic compounds, from both saturated
and unsaturated zones in soils. The tech-
nology has already been evaluated for
lead recovery in a pilot-scale field study
under EPA s Emerging Technologies
SITE Program (Superfund Innovative
Technology Evaluation Program) at a
lead contaminated site in Baton Rouge,
Louisiana. The Electrokinetics process
was developed in conjunction with
Louisiana State University s Louisiana
Business and Technology Center. A full-
scale SITE demonstration will occur in
early 1994.
EO uses electricity to affect chemical
concentrations and ground water flow.
The Electrokinetics process employs di-
rect currents across electrodes; condi-
tioning pore fluids move with the
current across the electrodes and circu-
late at the electrodes where the contami-
nants are removed. The type of pore
fluids are based on remediation goals
and specific contaminants. The fluid
moves between the soil particles because
a constant, low direct current is
applied through the electrodes inserted
into a soil mass.
Studies indicate that an acid front is
generated at the anode. This acid front
eventually migrates from the anode to
the cathode. Movement of the acid front
by ionic migration and advection results
in desorption of contaminants. The con-
current mobility of the ions and pore
fluid under the electrical gradients de-
contaminates the soil mass. The con-
taminants are either deposited at the
electrode or removed from the fluid by
a purification process. These phenom-
ena provide an added advantage over
conventional pumping techniques for
in-situ treatment of contaminated fine-
grained soils.
The process leads to temporary acidi-
fication of the treated soil. However,
equilibrium conditions are rapidly
reestablished by diffusion when the
electrical potential is removed. If the
electrodes are made of carbon or graph-
ite, no residue will be introduced into
the treated soil mass.
The efficiency of electro-osmotic wa-
ter transport under EO varies with the
type of soil. EO can be an efficient pro-
cess for removing contaminants from
fine-grained, low permeability soils.
In addition to lead, bench-scale
laboratory data demonstrate the feasibil-
ity of removing arsenic, benzene,
cadmium, chromium, copper, ethylben-
zene, lead, nickel, phenol, trichloroeth-
ylene, toluene, xylene and zinc.
Bench-scale tests have also demon-
strated the feasibility of removing ura-
nium and thorium from kaolinite.
Limited field tests showed zinc and ar-
senic removal from both clays and satu-
rated and unsaturated sandy clay
deposits. Lead and copper were re-
moved from dredged sediments. Treat-
ment efficiency depended on the
specific chemicals, their concentrations
and the buffering capacity of the soil.
The technique proved 85 to 95% effi-
cient when removing phenol at concen-
trations of 500 parts per million. The
removal efficiency for lead, chromium,
cadmium and uranium, at levels up to
2,000 micrograms per gram, ranged be-
tween 75 and 95%.
For more information, call Randy
Parker at EPA s Risk Reduction and En-
gineering Laboratory at 513-569-7271.
-------
Bookshelf from page 3
unsaturated; recovery technologies such
as soil vacuum extraction and soil flush-
ing; and delivery techniques such as
currently used gravity/forced hydraulic
delivery and bioventing. Research on
hydraulic fracturing and radial drilling
are also discussed. Additionally, the
document covers waste, soil and site in-
formation requirements for evaluation
and management of in-situ bioremedia-
tion and a mass balance approach to in-
situ subsurface bioremediation.
A copy of Engineering Issue: In-situ
Bioremediation of Contaminated Unsat-
urated Subsurface Soils can be ordered
from EPA s Center for Environmental
Research Information (CERI) at 513-
569-7562. When ordering, please refer
to the Document Number: EPA/540/S-
93/501.
Bioremediation Using Land
Treatment Concepts
Bioremediation processes using the
land treatment concept, whereby con-
taminated soil is treated in place or
excavated and treated in prepared-bed
treatment units, are common soil reme-
diation technologies proposed for haz-
ardous waste sites. However, RSKERL
and other research and demonstration
studies have identified complex biologi-
cal, chemical and physical interactions
within contaminated subsurface media
which may impose limitations on the
overall effectiveness of bioremediation
processes utilizing the land treatment
concept. RSKERL has prepared a report
to summarize and discuss basic consid-
erations necessary to implement and
manage these types of bioremediation
systems to improve their efficiency and
effectiveness in reclaiming contami-
nated soils.
The report suggests design and op-
eration criteria in areas ranging from
pH control to tilling practices and mois-
ture and nutrient requirements. Con-
taminants commonly related to the
wood preserving and petroleum indus-
tries are addressed with respect to their
applicability to land treatment in terms
of treatability, loading rates and cleanup
levels. A bibliography containing
references for further information is
provided along with appendices cover-
ing soil properties important in land
treatment and a discussion of monitor-
ing procedures.
A copy of the report, Bioremedia-
tion Using the Land Treatment Con-
cept, can be ordered from EPA s CERI
at 513-569-7562. When ordering please
refer to the Document Number: EPA/
600/R-93/164.
Bioremediation Resource Guide
The Bioremediation Resource Guide is
intended to support decision-making by
those involved in evaluating cleanup al-
ternatives. The Guide directs readers to
bioremediation resource documents, da-
tabases, hotlines and dockets and identi-
fies regulatory mechanisms that have
the potential to ease the implementation
of bioremediation at hazardous waste
sites.
A copy of the guide, Bioremediation
Resource Guide, can be ordered from
EPA s CERI at 513-569-7562. When or-
dering please refer to the Document
Number: EPA/542-B-93/004.
To order additional copies of this or previous issues of Tech Trends, or to be included on the permanent mailing list, send a fax
request to the National Center for Environmental Publications and information (NCEPI) at 513-891-6685, or send a mail request to NCEPI,
11029 Kenwood Road, Building 5, Cincinnati, OH 45242-0419. Please refer to the document number on the cover of the issue if available.
Tech Trends welcomes readers' comments and contributions. Address correspondence to: Managing Editor, Tech Trends (5102W),
U.S. Environmental Protection Agency, 401 M Street, S.W., Washington, DC 20460.
United States
Environmental Protection Agency
National Center for Environmental
Publications and Information
P.O. Box 42419
Cincinnati, OH 45242-0419
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