United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-99-002
March 1999
Issue No. 31
4yEPA Ground Water Currants
^ter Treatment
CONTENTS
Coal-Derived Humic
Acid for Removal of
Metals and Organic
Contaminants Pg. 1
Bioremediation Barrier
Emplaced through
Hydraulic Fracturing Pg. 2
Pilot-Scale Testing of
a Surfactant-Modified
Zeolite PRB Pg. 3
New Information
Network Formed
in Europe
Pg.4
I.S. Environmental Protection Agency
legion 5, Library (PL-12J)
7 West Jackson Boulevard, 12th Floor
hicago, IL 60604-3590
About this Issue
This issue features
innovative permeable
reactive barriers used to
remediate contaminated
ground water.
Coal-Derived Humic Acid
for Removal of Metals
and Organic
Contaminants
by David L. Schwartz, U.S.
Department of Energy
The use of coal-derived humic acid
material to remediate ground water
contaminated with mining wastes was
demonstrated recently by the U.S.
Department of Energy (DOE) using waters
from the Berkeley Pit in Butte, MT. This
demonstration was conducted under
DOE's Resource Recovery Project, which
focuses on the evaluation of technology
systems for reclaiming usable water and
the identification of marketable resources
from surface and ground water contami-
nated with heavy metals. Pilot-scale
demonstration results indicate that, in
addition to removing heavy metals,
application of this ion exchange/adsor-
bent polymer (HUMASORB-CSIM) can
produce a chelated micronutrient-
enriched fertilizer product suitable for
agricultural application.
The Berkeley Pit, which is an open-pit
mine that was designated a Superfund site
in 1987, has been filling with acidic,
heavy-metal laden water since pumping
operations ceased in 1982. Water enters
the Berkeley Pit at a rate of five million
gallons per day (MGPD) from both
ground water and surface water flows.
Ground water contributes about 70
percent of inflow into the Berkeley Pit
(3.5 MGPD) and surface water about 30
percent (1.5 MGPD). The surface water
flow has been diverted to minimize the
flow of surface water and reduce the
overall flow of water into the Berkeley Pit.
In the two-stage process used on Berkeley
Pit waters, the water first was treated with a
liquid HUMASORB product to remove
iron and other agricultural micronutrients
by formation of humates that are precipi-
tated as floes. The precipitated complex
was separated in a solid/liquid separation
unit and remaining metals then were
reduced using a cross-linked and immobi-
lized solid humic acid product
(HUMASORB-CS). Analysis of metals in
the Berkeley Pit water before and after
treatment indicated that concentrations
fell to near or below detection limits, as
shown in Figure 1.
Figure 1. Metal Concentrations in
Berekely Pit Water
Concentration
Range after
Initial Concentration HUMASORB-CS
(ppm) Treatment (ppm)
Aluminum
Cadmium
Copper
Iron
Nickel
Zinc
244 0 428-1 72
1 82 00015-00016
(below detection limit}
201 0 0437-0 239
660 0 0585-75 1
102 00182-0124
626 0 325-26 2
Product characterization tests conducted
by Montana State University indicated
that the micronutrients derived from the
Berkeley Pit waters are utilized by plants,
with no difference between the uptake of
Recycled/Recyclable
Printed with Soy/Canola Ink on paper that
contains at least 50% recycled fiber
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nutrients from the Berkeley Pit water versus
that obtained from a commercial source. In
addition, increased yields of 35 percent for
alfalfa and 20 percent for wheat were
identified following application of the
micronutrients.
Full-scale application of this technology for
the Berkeley Pit is estimated to cost $51
million with an internal rate of return of
33c/( and a pay-back period of less than
three years. For this application, the
Berkeley Pit water will be pumped from the
pit and treated with HUMASORB to
recover the precipitated micronutrient
complex.
Additional studies have been conducted to
evaluate the effectiveness of HUMASORB
at treating chlorinated organics and for in
situ permeable reactive banner applications.
Early batch tests with HUMASORB-CS for
treatment of simulated groundwater
contaminated with chlorinated organics
showed that the half-life was less than two
hours for trichloroethene and
tetrachlorocthene, in contrast to 15.3 and
6.3 hours using zero-valent iron technol-
ogy. Additional tests conducted by Temple
University researchers confirmed that the
humic acid material not only effectively
adsorbs chlorinated organic contaminants,
but also degrades the contaminants through
the process of reductive dehalogenation. In
addition, HUMASORB-CS is being
evaluated for effectiveness in a simulated
barrier system comprising barriers at depths
of 10 feet and 100 feet. A simulated waste
stream containing a mixture of metals,
organics, and radionuchdes was passed
through the barriers at pressures of 10
pounds per square inch gauge (psig) and
100 psig for more than eight months, with
no observed breakthrough.
DOE is considering implementation of a
full-scale, in situ demonstration of a
HUMASORB-CS bamer for an extensive
chlorinated organic ground water plume at
DOE's Paducah Plant near Paducah, KY,
during 1999. For additional information,
contact David Schwartz (DOE) at 412-892-
6298 or E-mail schwartz@fetc.doe.gov, or
Upcoming Optimization Conference
The Federal Remediation Technologies Roundtable will sponsor an optimization conference on
June 8-11, 1999. at the Adam's Mark Hotel in St. Louis, MO. The conference, titled
"Subsurface Remediation: Improving Long-Term Monitoring and Systems Performance
Assessment," will include presentations of practical approaches to reducing costs oflong-term
monitoring programs and new approaches to performance assessment and optimization.
Technologies to be discussed include pump and treat, soil vapor extraction, permeable walls,
above-ground treatment systems, bioremediation, and natural attenuation. Registration details
and [he conference agenda are available on EPA's CLU-IN Web site (http://clu-in.org).
Dr. H.G. Sanjay (ARCTECH, Inc.) at 703-
222-0280 or E-mail
envrtech@arctech.com.
Bioremediation Barrier
Emplaced through
Hydraulic Fracturing
by Sandra Stavnes, U.S.
Environmental Protection
Agency, Region 8
The U.S. EPA, General Services Adminis-
tration, and the State of Colorado jointly
sponsored a demonstration of an innova-
tive bioremediation barrier to remediate
both ground water and soil containing
total petroleum hydrocarbons (TPH) at the
Denver Federal Center in Denver, CO. This
approach was selected as an alternative to
expensive excavation and disposal
processes that otherwise would have been
required in the tightly-packed clay and
shale existing at the site. At the end of the
9-month demonstration, TPH concentra-
tions had fallen by an average of 91.5
percent.
Installation of a bioremediation barrier
through hydraulic fracturing provides an
excellent in situ environment for microbes
to metabolize contaminants in ground
water and soil. Hydraulic fractures are
constructed and kept propped open by the
simultaneous injection of small ceramic
pellets made from diatomaceous earth
(isolite). The pellets, which are 74 percent
porous, are saturated with a liquid inocu-
lum of selected indigenous microbes and
nutrients that degrade the contaminants. The
isolite pore spaces are small enough to
protect the selected degrading microbes, but
large enough to hold the nutrients, water, and
oxygen required for bioremediation. Using
this technology, isolite serves to transport
microbes into soil and groundwater, maintain
the opening and permeability of fractures,
and create a permeable reactive treatment
system that increases contact time with
contaminants.
Diverse government operations have been
conducted at the Denver Federal Center over
the years. Contaminants targeted during the
demonstration were derived from cutting oil
that had been released during the 1940s
when the Center served as a munitions plant.
The average TPH concentration prior to the
demonstration was 5.700 mg/kg.
The Denver Federal Center test area extended
approximately 80 by 40 feet on the surface,
and 22 feet deep. Fractures were created at
the base of pre-drilled cased wells of varying
depths. Using high pressure water jets, niches
were cut at the bottom of each well to initiate
horizontal fracturing. An aqueous guar gum
slurry carrying the isolite was introduced into
the boreholes and pumped under pressure to
extend and fill the fractures. Over a period of
two days, a total of six one-inch thick,
pancake-shaped, horizontal fractures were
created, each extending over 40 feet in
diameter and stacked 8-22 feet below ground
surface (Figure 2). The cased wells were
vented passively through the top of the
casing and recessed slightly below the
surface in concrete well covers to allow easy
access for future recharging, if necessary, and
to allow unrestricted traffic How.
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Figure 2. Schematic Diagram of Fracture Installation
Vent Pipe
Vent Pipe
The fractures were installed in the upper
layers of the tightly-packed clay. However,
perched ground water was present in the
clay, resulting in treatment of both soil and
ground water at the site. Data suggest that
the fractures had increased the soil perme-
ability significantly, thus causing trapped
water in the clay to flow through the
fractures. As the water passed through the
inoculated isolite, the cutting oil was
degraded biologically and the
"bioi'ractures" served as a permeable
reactive treatment system for the ground
water.
The success of the Denver Federal Center
biofracturing demonstration proved to EPA
Region 8 and the State of Colorado Oil
Inspection Section that this is a promising
technology for remediating tightly packed
soils and ground water contaminated with
TPH. Based on the demonstration results.
which were released in 1996. emplacement
of bioremediation barriers through the use
of hydraulic fracturing has been undertaken
recently at two commercial underground
storage tank sites in Colorado. Preliminary
data for one of these sites show an average
reduction in benzene concentration in
ground water ot 80 percent and a total
BTEX (benzene, toluene, ethylbenzene,
and xylene) reduction of greater than 85
percent.
Final analytical results of the demonstration
are available from Sandra Stavnes (EPA,
Region 8) at 303-312-6117 or E-mail
stavnes.sandra@epa.gov, or Seth Hunt
(FOREMOST Solutions, Inc.) at 303-271 -
9114 or E-mail foremost@earthlink.net.
Pilot-Scale Testing of a
Surfactant-Modified
Zeolite PRB
by Robert Bowman, Ph.D., New
Mexico Tech
Pilot-scale demonstration of the use of a
surfactant-modified zeolite permeable
reactive barrier (PRB) to remediate con-
taminated ground water was conducted
from July through October 1998 in a
contained, simulated aquifer at the Oregon
Graduate Institute of Science Technology
(OGIST) near Portland, OR. Testing in the
aquifer, which was constructed at the
OGIST's Large Experimental Aquifer
Program (LEAP) site, is
designed to quantify the
ability of a surfactant-modified
zeolite PRB to intercept and
retard the migration of a mixed
plume containing 22 mg/L of
chromate and 2 mg/L of
perchloroethylene (PCE).
base cations on the external exchange sites
of unaltered zeolite with a cationic surfac-
tant. The surfactant forms a bilayer on the
surface, resulting in a net positive charge on
the zeolite, and increases the organic
carbon content to about 5 percent by
weight. Sorption of oxyanions occurs via
ion exchange to this new surface; sorption
of cations occurs via ion exchange and
surface complexation to remaining zeolite
surface sites; and sorption of organic-
compounds occurs via partitioning into the
new organic stationary phase (Figure 3).
The modified zeolite has the ability to sorb
these three major classes of contaminants
simultaneously.
The simulated aquifer at the LEAP site is
filled with sand, with a hydraulic conduc-
tivity of 56.7 feet/day. In order to simulate
emplacement in front of an advancing
plume in a shallow, unconfined aquifer, the
surfactant-modified zeolite barrier hangs in
the center of the aquifer approximately
three feet above its base. The barrier system
is constructed of 12 tons of reactive
medium, and comprises three 6.5-foot
modules totaling approximately 20 feet in
length, 3 feet in thickness, and 6.5 feet in
depth. Injection and extraction wells
controlling the flow system penetrate the
entire saturated thickness of the aquifer.
Each injection/extraction location consists
of paired wells, one screened at the 0.0- to
4.9-foot depth and the other screened at the
4.9- to 9.8-foot depth. Contaminants are
introduced only into the upper injection
Zeolites are naturally occur-
ring aluminosilicates with
open, cage-like structures and
high internal and external
cation exchange capacities.
Surfactant modification of
zeolite constitutes replacing
Figure 3. Schematic Diagram of the Sorption
Mechanism
PCE
j Anion
I
(Organic
Partitioning
Zeolite Surface
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wells, simulating a shallow plume in the
upper half of the aquifer. This design
provides a full three-dimensional test of
plume captured by the PRB.
Performance of the barrier system was
monitored during a two-month period in
which the contaminant plume was injected
into the aquifer. Weekly sampling from a
network of 63 sample nests with 315
sample points in the aquifer and 18 sample
nests with 90 sample points within the
barrier was conducted. Test results indicate
that the barrier is performing according to
design specifications, with retardation
factors for chromate and PCE both on the
order of 50. The entire plume was captured
by the PRB. Based on these experiments,
researchers recommend a minimum 100-
fold permeability contrast between the PRB
and the aquifer material.
Costs for con1 irrier system,
which was fut; •• ' •• •. '^.Department
of Energy Morg^'C'1 • i ;.ergy Technology
Center, were approximately $100,000,
including $75,000 for design and $25,000
for installation. Full-scale implementation
of the surfactant- modified zeolite PRB is
anticipated, pending final analytical results
of the pilot-scale tests. Contact Dr. Robert
Bowman (New Mexico Tech) at 505-835-
5992 or E-mail bowman@nmt.edu for
additional information.
New Information Network
Formed in Europe
A new partnership among European
nations, including Belgium, Denmark,
France, Germany, the Netherlands, and the
United Kingdom, was formed during 1998
to provide an information network for
addressing treatment technologies and
demonstrations. This partnership, the
European Treatment Zones Team (ETZT),
aims to foster research needed for areas such
as developing reactive materials, designing
and modeling hydraulic systems, evaluat-
ing technical solutions for depths greater
than 10 meters, developing cost-effective
and accurate monitoring, and integrating
treatment systems.
In an effort to establish collaborative
projects, the ETZT will hold a joint
meeting during May 1999 in France with
the Remediation Technologies Develop-
ment Forum, a multi-agency and private
industry organization with similar goals in
the U.S. For more information on the ETZT.
contact Liyuan Liang (University of Wales)
at 441-222-874-579 or E-mail
liyuan@cs.cf.ac.uk.
United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-99-002
March 1999
Issue No. 31
EPA Ground Water Currents
^^ter Treatment
PATRICIA KRAUSE
US EPA
RFGIOH 5
77 y JACKSON BLVD
CHICASO, IL
12TH FLOOR
68604
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