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[continued from page 3]
reductions of 62 percent, 50 percent,
31 percent, 20 percent, and 24
percent for the 2, 3, 4, 5, and 6-ring
PAHs, respectively. These numbers.
may change after further evaluation,
but any changes would be minimal
and are not expected to alter the
project conclusions.
This demonstration also confirmed
earlier understanding of the applica-
bility of aerobic bioventing
technology to degrade high-molecu-
lar weight hydrocarbons in situ in
vadose zone soils. Suitable soil
conditions include:
• high levels of CO2 (greater than
1 percent)
• low levels of oxygen (less than
5 percent)
• PAH contaminant concentrations
- -^ML^2Mb^J£3U"R^£L_=______
increased growth of native" "
microorganisms
• unsaturated, unconsolidated soil,
and
• sufficient quantities of nitrogen
and phosphorous to support new
cell growth and development.
Final project details will be available
this Fall through EPA's Superfund
Innovative Technology Evaluation
(SITE) Program, which sponsored the
demonstration. Contact Dr. Paul
McCauley (EPA National Risk
Management Research Laboratory) at
513-569-7444 or E-mail
mccauley.paul@epa.gov for addi-
tional information.
Conference on Present and
Future Technology
Developments
The U.S. EPA will sponsor the
conference Innovative Clean-Up
Approaches: Investments in
Technology Development, Results, &
Outlook for the Future at the Indian
Lakes Resort in Bloomingdale, EL,
^NovernBer^-^rl 9997^Stakeholders
in hazardous waste site remediation
projects, including EPA's partners
from other government agencies,
academia, and the private sector, will
have an opportunity to share the
latest information on technology
development, demonstration, and
commercialization. Participants also
will evaluate the success of past
efforts and discuss future research
and information needs. Workshops
will be available to provide
information on the SITE Program,
Brownfields Program, funding
sources, and electronic information
resources. On-line program
information, including an updated
conference agenda, is available on
the Internet at www.epa.gov/ttbnrmrl
or by calling 412-741-5462.
United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-99-005
August 1999
Issue No. 34
EPA TECH TRENDS
-------
Figure 2. Biodegradation ofcis-DCE and Production/Degradation of Daughter
Products: Estimated Minimum Biodegradation Rates to Fit Curve to
Monitoring Point (MP) 35-D Data
220 240 260 280 300 320 340 360 380 400
Tlmo (days since background sampling event)
/continued from page 2]
that arsenic generally is being
immobilized in the anaerobic portion
of the treatment zone. In most
locations, arsenic is entering the
anaerobic zone at levels in the range
of 50-200 ppm and leaving at
concentrations below the interim
cleanup level of 50 ppm. It is
believed that co-precipitation with
sulfides is the mechanism for arsenic
removal in the anaerobic zone.
This bioremediation demonstration is
anticipated to continue through the
year 2001. For more information,
contact Craig Lizotte (Envirogen) at
781-821-5560 or E-mail
Hzotte@envirogen.com, or Andrew
Hoffman (State of New Hampshire,
Department of Environmental Ser-
vices) at 603-271-6778 or E-mail
a_hoffman@des.state.nh.us.
BJoventdng for
Enhanced Degradation
of PAHs
by Paul McCauley, Ph.D., U.S.
EPA National Risk Management
Research Laboratory
Pilot-scale testing of an aerobic
bioventing process for enhanced
degradation of polynuclear aromatic
hydrocarbon (PAH) contaminants in
soil has been completed at the Reilly ,
Tar site in St. Louis Park, MN. Dem-
onstration results show that
continuous, slow injection of atmo-
spheric air into the soil subsurface can
stimulate the growth of indigenous
microorganisms capable of contami-
nant consumption. After almost five
years of treatment, bioventing re-
duced the total PAH concentrations at
the treatment plot by 37 percent,
while the reduction in PAH concen-
tration at the control plot was only 11
percent.
Between 1917 and 1972, the 80-acre
Reilly Tar site was used for coal tar
distillation and wood preserving
operations. Wood preserving
solutions were estimated to consist of
60-70 percent creosote oil and
petroleum oils. Soils at this site
consist of approximately 0.6 meters
of a topsoil cover underlain by an
asphaltic layer, below which coarse
sand extends to the water table at
approximately 3 meters below ground
surface. Sandy soils within the
demonstration area were
contaminated with PAHs in
concentrations as high as 873 ing/Kg.
The simple bioventing process used
at the Reilly Tar site consisted of a
single, 5-cm injection well sur-
rounded by a network of four tri-level
soil gas/soil temperature monitoring
stations and a piezometer. The
screened injection well was installed
in the center of the 15.2 meter-square
treatment area, and connected to a
nearby 2.5-horsepower blower
capable of injecting air at a rate of
0.3-5.7 m /hour. During installation
and after shutdown of the system,
120 soil cores were collected from
each plot at a depth of 1.2-2.4 meters.
Respiration tests conducted after two
years of system operation suggested
that initial oxygen utilization
correlated to concentration reductions
in the more readily degradable carrier
oils (23 percent for naphthalene).
Concentrations of the three- and
higher-ring PAHs, however, remained
unchanged. Final soil data collected
in 1997 after five years of treatment
showed, that bioventing significantly
treated the higher-ring PAHs as well.
Data analysis indicated concentration
[continued on page 4]
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Figure 1. Distribution of Lead Concentrations in the Top 6
Inches of Soil
^| Before Treatment
-1
After Treatment
57%
<400 400-800 800-1,200 >1,200
Lead Concentration (parts per million)
AerOblC in
Treatment
System
, ^ . -r .
by Craig Lizotte,
.
Envirogen, and
Andrew
based on the results of ground water
quality data, hydrogeologic investiga-
tions, and treatability testing. The
aquifer is found in overburden
materials of sand with silt clay lenses.
Located at the toe of the landfill, the
, . . . . - ,, '
treatment zone consists of a 61- by
9i-meter area with two amendment
injection systems. The anaerobic
New Hampshire,
Department of
Environmental
Service
[continued from page 1]
sunflowers was measured at an
average concentration of 400 mg/Kg.
All three of these average values
exceeded the minimum project
objective of 200 mg/Kg (dry weight).
This demonstration confirmed earlier
findings that the use of Indian
Mustard plants to extract metals is
most applicable to intermediate levels
of lead contamination (less than
1,500 mg/Kg), soil pH levels of 4.3-
8.3, and moderate climates.
phytoextraction for soils covering a
10-acre site typically requires 6-8
crops over three growing seasons.
Harvesting of this quantity of crop is
anticipated to ultimately result in the
disposal of approximately 500 tons of
biomass from 0.3 meters of top soil.
This represents 0.25% of the 20,000
tons of contaminated soil that other-
wise would require excavation and
landfilling. For more information,
contact Steven Rock (EPA National
Risk Management Laboratory) at
513-569-7149 or E-mail
rock. Steven @ epa. go v.
Early results of a pilot-scale enhanced
bioremediation project operating at a
former municipal landfill site in
Dover, NH, since January 1998 are
demonstrating that enhanced degra-
dation of contaminants is occurring.
The project involves the sequential
use of anaerobic treatment to degrade
chlorinated volatile organic com-
pounds (VOCs) and aerobic treatment
for non-chlorinated VOC degradation
and arsenic immobilization. This
demonstration was undertaken to
evaluate the effectiveness of en-
hanced bioremediation as an
^alternative 1:6 the more costly "con-"
sanction of a landfill cap and leachate
pump and treat system (which are
required in the site's existing record
of decision) and to obtain necessary
design data for possible full-scale
implementation.
Although contaminant concentrations
site-wide have decreased naturally
over time, the treatment zone is
located in an area that exhibited the
greatest diversity and some of the
highest levels of contaminants
remaining at the site. The precise
location, orientation, and design of
the treatment zone were selected
61 meters of the gradient, was
designed to add electron donor
compounds for enhancement of
chlorinated compound degradation.
Following laboratory testing, sodium
benzoate was selected to serve as the
electron donor, at a target application
level of 3.7 mg/L. The aerobic
system, which is located hydraulically
downgradient from the anaerobic
area, completes the final 30-45 meters
of the gradient within the treatment
zone. Gaseous oxygen is injected at
a series of injection points to achieve
a dissolved oxygen target concentra-
tion of 2 mg/L in the aerobic zone.
Preliminary data collected from
selected monitoring points in the
that en-
hanced biodegradation rates for
cis-l,2-dichloroethene (DCE) and
vinyl chloride could be as high as 4 x
10'3 day1 and 2 x 10~2 day1, respec-
tively (Figure 2). Prior to the
demonstration, anaerobic biodegrada-
tion rates in this area were
approximately zero.
Data on aerobic biodegradation rates
will be collected and analyzed over
the next 6 to 12 months. Although
arsenic was to be a target for removal
in the aerobic zone through co-
precipitation with iron, data indicate
[continued on page 3]
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United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-N-99-005
August 1999
Issue No. 34
CONTENTS
Phytotechnology for
Metal-Contaminated
Surface Soils
pagel
Sequential Anaerobic/
Aerobic In Situ
Treatment System page 2
Bioventing for Enhanced
Degradation of PAHs page 3
EPA Plans Capstone
Conference on
Technology Development
see page 4 for details
The Applied Technologies
Newsletter/or Superfund
Removals & Remedial
Actions & RCRA Corrective
Action
ABOUT THIS ISSUE
This issue highlights the use of
innovative biological
technologies for remediating
sites with organic and metal
contaminants in soils.
TRENDS
Phytotechnology for
Metal-Contaminated
Surface Soils
by Steven Rock, EPA National Risk
Management Research Laboratory
The use of phytoextraction to
remediate surface soils contaminated
with metals was demonstrated
recently at the Magic Marker site in
Trenton, NJ. Preliminary results of
the demonstration, which took place
between May 1997 and November
1998 under EPA's Superfund Innova-
tive Technology Evaluation Program,
indicate that specially selected plants
successfully accumulated significant
amounts of lead and other metals.
Comparison of post-treatment soil
concentrations to baseline soil
concentrations indicated an average
20 percent reduction of lead in the
top 15.2 centimeters of soil.
Contamination at the Magic Marker
site resulted from various manufac-
turing activities, including lead-acid
battery production, that were con-
ducted between 1947 and 1987. The
site soil consisted of gravelly sand
with miscellaneous debris. Earlier
investigations identified lead in the
surface soils exceeding the regula-
tory limit for residential areas (400
parts per million).
The demonstration evaluated a total
of three crops grown in a 9.1- by
17.4-meter treatment plot, compared
against a 9.1- by 12.2-meter control
plot. Two crops of Brassica juncea
(Indian Mustard) plants were grown
and harvested over the spring and
summer of 1997. One crop of
sunflower plants was grown in the
summer of 1998. Harvested plant
tissue samples were collected to
evaluate the amount of lead uptake
in each crop. Prior to the first crop
plant and immediately following
harvest of the third crop, soil samples
also were collected to evaluate the
change in lead concentrations in the
root zone. To solubilize the metals
into a form that the plant tissues
could absorb, and consequently
increase the efficiency of phyto-
extraction, ethylenediaminetetra-
acetic acid and other amendments
were added to the soil.
Figure 1 shows the distribution in
soil lead concentration before and
after phytoextraction was applied.
Results show that treatment
increased the portion of the treatment
area with lead concentrations below
400 mg/Kg from 31% to 57%. The
average lead concentrations
accumulated in the above-ground
plant tissue samples from the two
Brassica crops were 830 mg/Kg and
2,300 mg/Kg. (These differences in
lead uptake between the two
Brassica crops are attributed to
amendment optimization.) Lead in
the above-ground plant tissues of the
[continued on page 2]
Recycled/Recyclable
Printed with Soy/Canola Ink on paper thai
contains at least 50% recycled fiber
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