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/A newsletter about soil, sediment, and ground-water characterization and remediation technologies
Issue 35
Both light and dense nonaqueous phase liquids (LNAPLs and DNAPLs) are prevalent
environmental contaminants. NAPL contamination may occur as free product, sorbed
to the matrix, and in the dissolved phase plume. Increasing understanding of the
different phases and locations in which contamination may occur at NAPL sites-and
their interactions-has led to increasing use of several treatment technologies operat-
ing in parallel or in series as a treatment train. More frequently, treatment trains for
NAPL include innovative remedies such as in-situ thermal, in-situ chemical oxidation,
and in-situ bioremediation in addition to or instead of tradtional remedies such as
excavation and pump and treat. Technologies may be adapted over time as remediation
progresses. Remedy implementation often provides additional insight into the true
nature and extent of subsurface contamination.
April 2008
Adaptive Treatment Strategy Addresses Extensive DNAPI Contamination |
The Oregon Department of
Environmental Quality (OR DEQ) is
working with a site owner to remediate
a 47-acre operative manufacturing
facility near Troutdale, OR, using a series
of innovative technologies to address
trichloroethene (TCE) in the unsaturated
zone and ground water. Initial cleanup
efforts focused on pump and treat (P&T)
with air stripping and subsequent
installation of an interception trench
(French drain) with air stripping to treat
the upper gravel aquifer. Since the 1989
issuance of the record of decision
(ROD), several additional remedies have
begun operating: dual-phase extraction,
soil vapor extraction (SVE), air sparging,
phytoremediation, biostimulation, and a
bioremediation barrier wall.
Cascade Corporation has manufactured
forklifts at the site since 1956. Activities
over the years have included product
painting, parts and hydraulic cylinders
assembly, nickel and chrome
electroplating, vapor degreasing, and
mechanical maintenance. Spent TCE
was discharged to the ground, resulting
in DNAPL source zones at locations now
covered by the expanded facility. In
addition, sludge from the degreaser tank
and cutting oils containing TCE were
disposed near a former underground
storage tank (UST) and the edge of a
parking lot that was subsequently
expanded. As a result, separate TCE
plumes formed beneath the manufacturing
building and paved parking lot.
Near the former UST, LNAPL was
detected in 1995 in two monitoring wells.
Analyses of the LNAPL revealed TCE
concentrations of up to 26,000 parts per
million (ppm). The LNAPL serves as a
long-term source of dissolved-phase
volatile organic compound (VOC)
contaminants and petroleum constituents
in ground water, including downgradient
private wells.
The site is immediately underlain by a 15-
foot deposit of unconsolidated gravel with
silt, sand, and clay. The underlying
Troutdale Gravel Aquifer is a 50-foot-thick
unconsolidated deposit of silty/sandy gravel
with cobbles and boulders that transitions
to an indurated sandstone at variable
depths. A 15- to 50-foot-thick leaky
aquitard separates the Trout Gravel Aquifer
from the underlying Troutdale Sandstone
Aquifer. Ground water in the Troutdale
Gravel Aquifer is shallow and discharges
in the form of springs at an erosional face.
[continued on page 2]
Contents
Adaptive Treatment
Strategy Addresses
Extensive DNAPL
Contamination page 1
Sodium Persulfate
and Hydrogen
Peroxide Injections
Achieve Ground-Water
Cleanup page 2
Integrated Technology
Approach Used to
Remediate Site
Contaminated by 56
Chemicals page 4
Upcoming TIFSD
Conferences page 5
CLU-IN Resources
EPA's CLU-IN website offers a
range of resources to help
characterize and remediate sites
with DNAPL. The DNAPL "issue
area" contains case studies,
guidance documents, and
technical reports prepared by
EPA as well as other federal or
state agencies. The issue area
focuses on halogenated alkenes
and multi-component wastes
(e.g, coal tar and creosote), but
will enventually be expanded to
cover other DNAPLs. Visit the
issue area at: http://cluin.org/
issues/default.focus/sec/
Dense Nonaqueous Phase Liquids
(DNAPLsVcat/Overview/.
Recycled/Recyclable t
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[continued from page 1]
Installed in 1998, a 21-well SVE system
continues to remove VOCs from the
unsaturated zone with assistance from
capping provided by the existing building
and paved parking lot. The system was
augmented with a dual-phase extraction
system to remove the LNAPL and air
sparging wells to strip high-concentration
VOCs from source-area ground water.
The air sparging system was found to
contribute minimally to contaminant
removal, and thus was terminated the
following year. The entire SVE system
was shut down months later due to
asymptotic recovery rates but restarted
the following summer using pulse
pumping. Activated carbon is used to
treat offgases.
To enhance biodegradation of
contaminants in the sub-building
source zone, full-scale biostimulation
was conducted in mid 2006. More than
82,509 gallons of an emulsified oil/
water solution were administered in
one area of the subsurface, and a
sodium lactate solution in another area.
The solutions were injected at locations
immediately outside the manufacturing
building, without disruption to ongoing
activities. Two additional biostimulation
events were planned, but only one was
necessary to sufficiently reduce VOC
concentrations.
Aggressive treatment of the source zone
resulted in contaminant concentrations
sufficiently lowered to allow
implementation of less costly passive
technologies. In 2006, the ground-water
interception trench was expanded by 80
feet and converted to a mulch biobarrier.
The biobarrier was added to the
treatment train due to its low operation
and maintenance cost and ability to
augment P&T operations addressing the
sand/gravel aquifer's high volume of
water. Since barrier startup, P&T costs
have decreased and ground-water flow
to the springs has increased. The
maximum TCE concentration in the
springs last fall was 2.6 (J.g/L, which is
below the cleanup target.
Figure 1. Trees at the Cascade Corporation
site in Troutdale OR, have grown about 25
feet over 10 growing seasons, allowing for
metabolism, transpiration, and
rhizode gradation of TCE.
Phytoremediation is employed as a
polishing step for residual
contamination in the portion of the
Troutdale Gravel Aquifer located
between the biobarrier and the springs.
In 1998, approximately 800 poplar
trees were planted downgradient of the
interceptor trench but upgradient of the
springs. The trees were planted in a
configuration sufficiently long to
provide a root zone capable of
capturing ground water (Figure 1).
Average TCE concentrations
measured in 2006 near onsite source
areas had decreased 22-61% over the
previous year. The aggressive steps
taken to biostimulate contaminant
degradation in the sub-building source
area resulted in reduction of TCE
concentrations to an average below the
5 |0.g/L cleanup goal. At locations
between the biobarrier and onsite
P&T wells, ground water
concentrations of TCE have
decreased to an average of 5.2 u,g/L.
As a result, the OR DEQ is initiating
steps to confirm that the cleanup goal
is met for all target areas.
Contributed by Mavis Kent, OR
DEQ (kent.mavis.d@deq.state.or.us
or 503-229-5071)
Sodium Persulfate and Hydrogen Peroxide Injections Achieve Ground-Water Cleanup
The California Regional Water Quality
Control Board (RWQCB), Los
Angeles Region, oversees remediation
of a 2.8-acre area known as the
"Former Sta-Lube" site in Rancho
Dominquez, CA. Cleanup technologies
employed at this site since 1997 include
SVE, P&T, and soil excavation with
offsite disposal. In 2005, another
excavation and addition of in-situ
chemical oxidation (ISCO) quickly
addressed a previously unknown
DNAPL zone serving as a continued
source of dissolved contamination.
Industrial activities at the site from 1968
until 1986 included the manufacture of
paint, varnish remover, fuel additives,
degreasers, and petroleum-based
lubricants. Site investigations indicated
VOC-contaminated soil and ground
water, with methylene chloride as the
primary chemical of concern. Leakage
of methylene chloride from a former
UST resulted in a dissolved plume
estimated at 200 feet long and 80 feet
wide as of 1995. Ten years later, the
plume had shrunk to 80 by 30 feet, most
[continued on page 3]
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[continued from page 2]
of which was located under the
remaining building, which continues to
operate for administrative purposes.
The maximum concentration of
methylene chloride detected in ground
water was 3,000 mg/L.
The site is located within the Central
Groundwater Basin, which is part of
the Los Angeles Coastal Plain. Near-
surface sediment comprises primarily
fine-grained silt and clay to a depth
of approximately 45 feet below
ground surface (bgs). Ground water
is encountered at approximately 40
feet bgs. The upper aquifer extends
approximately 140 feet bgs, and is
separated from a lower (450-700 feet
bgs) aquifer by several clay-lens
aquitards. The aquitards limit vertical
migration of contaminants to the
lower aquifer, a high-quality drinking
water source.
A P&T system operated from 1997
until 2003 to treat the dissolved-phase
ground-water plume. From early
2000 until late 2001, an SVE system
supplemented with hot-air
injections treated vadose-zone soil.
Concentrations of methylene chloride in
pumping wells had decreased to below
100 (Xg/L, and both soil and ground water
nearly attained closure from the
RWQCB. However, concentrations
rebounded significantly, suggesting
DNAPL presence. Hence, operation of
each system was suspended.
Results of a membrane interface probe
survey indicated that methylene
chloride DNAPL was trapped in sandy
stringers in a clay zone located 40-48
feet below the building. To remove
DNAPL, the area was excavated in
Figure 2. Although three of the four
ISCO monitoring wells showed slight
rebound at different times (likely due
to back diffusion from clay),
methylene chloride concentrations in
all four wells remained steadily below
50 ug/L one year after the injections.
2003 to a depth of 48 feet using large-
diameter augers. More than 266 yd3
were excavated and disposed offsite.
The Los Angeles RWQCB's efforts to
accelerate dissolved-phase cleanup
were initiated in 2005 after soil
excavation/disposal and six years of
SVE and P&T operations. The primary
cleanup goal set at that time was
attainment of methylene chloride
concentrations below 50 p.g/L in ground
water. Based on the results of a more
detailed site investigation identifying
additional DNAPL directly below the
facility's building, ISCO was selected as
a remedy enhancement.
A total of 23 ISCO injection wells were
installed at the site, of which 16 were
placed inside the building and 7 outside
the building, each with an estimated 8-
to 12-foot radius of influence.
Approximately 7,700 gallons of 22%
sodium persulfate solution were injected
over six days in mid 2005, followed by
injection of 12,044 gallons of 17.5%
hydrogen peroxide over 14 days to
activate the persulfate. Downhole
thermocouples monitored subsurface
temperature to ensure a temperature of
120-160T for optimum generation of
hydroxyl radicals with minimal
decomposition of the hydrogen peroxide.
Logistical challenges include using angled
wells to minimize disruption of business
operations and operating the wells safely
within the building. Injection flows were
optimized to control the reactions and to
minimize the potential for treated ground
water and vapor to migrate to the ground
surface through existing soil crevices.
An additional 16 injection wells
surrounding the 23 chemical injection
wells were used for hydraulic control
by injecting (dripping) tap water to
prevent outward migration of the
injected chemicals. Two vapor control/
extraction wells were also installed and
operated during the chemical oxidation
to prevent vapor migration into the
industrial/warehouse building.
ISCO application resulted in 94-97%
reduction in methylene chloride
concentrations within four months, and
to concentrations below the 50 |J,g/L
cleanup goal within five months
(Figure 2). In particular, one well
experienced a concentration decrease
from 15,000 to 18 |Xg/L. Most recent
results of quarterly monitoring indicate
that methylene chloride concentrations
are below 33 )J.g/L. Accordingly, the
Los Angeles RWQCB has initiated
closure of the Former Sta-Lube site.
Contributed by Gary Cronk, Jag
Consulting Group, Inc.
(gary@jagconsultinggroup.com or
714-241-7722), Pinaki Guha-
Niyogi, California EPA
(pguha@waterboards.ca.gov or
213-576-6731) and Mehmet
Pehlivan, Leighton Consulting, Inc.,
(mpehlivan@leightongroup.com or
949-250-1421 ext. 4264)
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Integrated Technology Approach Used to Remediate Site Contaminated by 56 Chemicals
EPA Region 9 is using several
technologies to treat soil and ground
water at the Pemaco Superfund site
in Maywood, CA. Cleanup began in
2005 with placement of a
conventional soil cover over the entire
1.14-acre site to establish plant
growth and stabilize soil. Full-scale
treatment began last summer through
use of a P&T system containing
granular activated carbon (GAC), and
startup of an electrical resistance
heating (ERH) system shortly
thereafter to vaporize VOC hotspots.
A portion of the integrated system's
high electricity demand is met through
solar energy. Intermediate results as
the remedy progresses indicate that
ground-water concentrations have
been reduced significantly and are on
a downward trend. Air emissions
have met standards throughout
remedy implementation.
The site is located on the grounds of a
former chemical mixing facility in a
light industrial and residential area.
Following 1991 closure, a fire
destroyed the facility in 1993 and
emergency actions were taken to
remove the remaining 10,000- to
20,000-gallon chemical and fuel
storage containers. Removal actions
included offsite disposal or recycling
of six 55-gallon drums, several above-
ground storage tanks, and 31 USTs.
Subsequent site assessment indicated
past releases of 56 chemicals including
aromatic solvents, flammable liquids,
oils, specialty chemicals, and metals.
The largest contaminant plume,
approximately 1,300 feet long and
750 feet wide, occurs in a lower
aquifer situated 80-100 feet bgs. The
plume consists almost entirely of TCE
and its degradation products.
Maximum TCE concentrations were
3,300 Hg/kg in the upper vadose zone
(2-30 feet bgs), 2,100 fig/kg in the
lower vadose zone (35-65 feet bgs),
680 |J,g/L in perched water (20-40 feet
bgs), and 22,000 |J,g/L in the aquifer.
Investigations also revealed LNAPL
consisting of 20-30% gasoline-range
hydrocarbons.
An initial SVE system was installed in
early 1998 to treat contaminated soil in
the former UST area. The system
comprised 16 extraction wells, a pre-
treatment GAC filter system, and a
portable thermal oxidizer operating at
temperatures exceeding 1,400SF. During
incineration, most contaminants were
reduced to byproducts such as carbon
dioxide and water. The system treated
72 tons of contaminated soil, removing
68 tons of contaminants. Due to
insufficient data on potential dioxin
emissions from the thermal oxidizer and
related community concerns, the SVE
system was shut down after 16 months
of operation.
Selection of the final cleanup remedy,
as formalized in a 2005 ROD, involved
determination that remediation goals
could be met through a strategy
combining several technologies. The
strategy includes enhancement to the
initial SVE system and additional means
to address contaminant hotspots.
Target zones and treatment
technologies now include:
> Surface and near-surface soil: En-
hanced revegetation of the soil cover,
> Upper vadose soil and perched
ground water. A high-vacuum dual-
phase extraction system using GAC
for water, and a high-temperature
flameless thermal oxidation (FTO) unit
and GAC for vapor treatment, and
> Lower vadose soil and exposition
ground water: An ERH system to
treat approximately 30,000 yd3 of soil
at a depth of 35-95 ft bgs; vapor ex-
traction and subsequent GAC and
FTO treatment; vacuum-enhanced
P&T employing GAC; and monitored
natural attenuation (MNA).
The full-scale system includes 89 vapor
extraction wells, 58 ERH electrode
wells, and 30 thermocouple wells. The
selected FTO is capable of heating
contaminated vapor to temperatures of
1,400-1,700SF.
Prior to startup, a vapor conditioning
package that includes a heat exchanger
and additional GAC adsorption units
was installed to the post-exhaust side
of the FTO unit to minimize possibility
of dioxin release. The final monitoring
plan also calls for enhanced indoor and
neighborhood ambient-air monitoring
as well as direct sampling of FTO
emissions, including dioxin and furan
concentrations.
For ground-water and soil-vapor
treatment, 20 two-phase extraction
wells with high-vacuum pumps were
installed in an area of the plume with
TCE concentrations of 1,000-10,000
u,g/L. An additional fifteen extraction
wells were installed along the leading
edge of the plume (with TCE
concentrations greater than 10 (0,g/L but
less than 1,000 u,g/L) for contaminant
containment. MNA is used to evaluate
portions of the leading edge with TCE
concentrations at or below 10 |J.g/L.
Construction of the underground
conveyance piping, ground-water
extraction wells, and vapor extraction
wells was coordinated with the City
of Maywood's development of
infrastructure for a riverfront park. The
entire treatment system, including the
aboveground treatment plant, was
completed within one year. Incremental
operational startup began with April
2007 commencement of the ground-
water system, followed by the vapor-
treatment system the following month
and the ERH system another three
months later. Sodium lactate was
injected directly into the ground-water
plume during the startup phase to
stimulate in-situ bioremediation.
As part of Region 9's Cleanup-Clean
Air Initiative, a 3-kW photovoltaic
system was installed on the roof of the
treatment building last year to meet part
of the treatment system's electricity
[continued on page 5]
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Figure 3. After the first nine months,
the Pemaco ERH system removed a
cumulative TCE mass exceeding
13,000 pounds.
[continued from page 4]
demand. The system generates
approximately 375 kWh of electricity
each month, preventing an estimated
carbon dioxide emission totaling 4,311
pounds each year. After nine months
of operation, the system generated
enough electricity to pay for one month
of operating the treatment plant. At this
payback rate, capital cost of the solar
system will be recovered in one year.
After approximately 120 days of ERH
operation, temperatures in the source
zone averaged 208T. Cumulative
electricity consumption of the ERH
system approached 3.35 MkWh, or
111.7 kWh per cubic yard of treated
soil. In early February of this year,
performance monitoring indicated a
vapor-mass removal rate of 0.32 Ib/day
at a vapor extraction rate averaging
504 ftVmin (Figure 3). TCE
concentrations of P&T influent
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averaged 320 |J.g/L, while effluent
concentrations averaged 1 |J.g/L. TCE
mass removal from ground water
averaged 0.12 Ib/day.
Pemaco cleanup is expected to cost
approximately $17 million, including
more than $3 million for site assessment.
Operation of the ERH system, estimated
to cost $67/yd3, is expected to continue
until this spring. The city has nearly
completed construction of the
Maywood Riverfront Park, which will
become part of the Los Angeles River
Greenway.
Contributed by Rose Marie
Caraway, EPA Region 9
(caraway.rosemarie@epa.gov or
415-972-3158)
Upcoming TIFSD Conferences
EPA's Technology Innovation and Field Services Division (TIFSD) and the University of Massachusetts-
Amherst's Environmental Institute will jointly sponsor Triad Investigations: New Approaches and
Innovative Strategies on June 10-12, 2008, in Amherst, MA. Best practices and lessons learned
will be woven together throughout the conference to help participants use the Triad approach for
improved decision-making regarding hazardous site characterization, remediation, and redevelopment.
The conference includes 54 platform presentations, technical posters, equipment demonstrations,
and specialized Triad training sessions with opportunity for continuing education credits.
Workshops will address:
> Anatomy of a well-structured project,
> Best practices for efficient soil-sampling designs,
> Use of 3-D and 4-D site characterization and visualization techniques,
> Flux-based site management, and
> Spatial Analysis and Decision Assistance (SADA) tools.
Advanced training also will cover design application and data analysis for field-portable X-ray fluorescence and
characterization, and long-term management of contaminated ground-water plumes.
An interactive "tool room" will be available for hands-on use of new automated systems for data collection, continuous
monitoring, and long-term monitoring. Participants may use tools such as:
[continued on page 5]
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Solid Waste and
Emergency Response
(5203P)
EPA 542-N-08-002
April 2008
Issue No. 35
United States
Environmental Protection Agency
National Service Center for Environmental Publications
P.O. Box42419
Cincinnati, OH 45242
Presorted Standard
Postage and Fees Paid
EPA
Permit No. G-35
Official Business
Penalty for Private Use $300
TCCHHNOLOQY
[continued from page 5]
> Scribe configurable integration and migration software,
> SADA software for environmental assessment decision-making, and
> Rapid Assessment Tools Software (RATS) for real-time field mapping.
The exhibit hall will host nearly 30 booths offering analytical instrumentation,
environmental software, monitoring tools, equipment for excavation or
remediation, and related information or services. An outdoor courtyard also
will host vendor demonstrations of equipment such as direct-push probes and
samplers. Poster sessions will showcase site-specific strategies that have been
used to apply Triad principles in remedial systems and to improve remedial
performance through real-time feedback.
Conference content and activities are overseen by a scientific advisory board
comprising representatives of both government and industry organizations. More
information is available online at http://www.umass.edu/tei/conferences/triad.html:
registration may be completed on Trainex (http://www.trainex.org).
Other major events co-sponsored by TIFSD this year include the:
International Environmental Nanotechnoloy Conference, October 7-9, 2008,
in Chicago, IL, through partnership with the U.S. Department of Defense, U.S.
Department of Energy, National Science Foundation, and additional federal
agencies; http://emsus.com/nanotechconf/index.htm.
Remediation of Abandoned Mine Lands Conference, October 2-3, 2008,
Denver, CO, in cooperation with the National Ground Water Association;
http://www.ngwa.org/development/conferences/details/0810025019.asDx.
Contact Us
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is on the NET!
View, download, subscribe,
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http://www.epa.qov/tio
http://cluin.org/newsletters
Technology News and Trends
welcomes readers' comments
and contributions. Address
correspondence to:
John Quander
Office of Superfund Remediation
and Technology Innovation
(5203P)
U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Ave, NW
Washington, DC 20460
Phone:703-603-7198
Fax:703-603-9135
EPA is publishing this newsletter as a means of disseminating useful information regarding innovative and alternative treatment techniques and
technologies. The Agency does not endorse specific technology vendors.
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