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/A newsletter about soil, sediment, and ground-water characterization and remediation technologies
Issue 42
o/Techno logy News and Trends highlights innovative applications of soil
vapor extraction (SVE) and bioventing for removal of volatile organic compounds
(VOCs). SVE has accounted for approximately 25% of the in situ technologies used for
source control over the past 25 years, and recent years have shown rising interest in
bioventing technology.
| Full-Scale SVE System Operates in Tandem with Ground Water Treatment
Since 1993, SVE has been implemented
using two designs at the TP Industrial,
Inc. (TPI) site in Gardena, CA, to treat
soil contaminated with chlorinated
solvents. The SVE system was modified
in 1997 to improve emissions control
efficiency by using carbon adsorption
units that treat effluent from an air-
stripping system for treating site ground
water. By the end of 2007, SVE had
removed a cumulative halogenated
organic compound (HOX) mass of
approximately 25,000 pounds.
The former TPI facility was used from
1964 through 1986 for solvent
reprocessing, which involved storage of
chemicals in aboveground and
underground tanks. Investigations by the
California Regional Water Quality Control
Board in the early 1980s identified 1,1-
dichlorothene, tetrachloroethene (PCE),
1,1,1-triehloroethane (TCA), methylene
chloride, trichloroethene (TCE), and
1,1,2-trichlorotrifluorethane. All were
found in both the saturated and
unsaturated zones of two areas, with
representative high concentrations
reaching 1,790 mg/kg for PCE and 725
mg/kg for TCA. Site characterization
indicated that the vadose zone consists of
well-stratified layers of silty sand, clean
sand, sandy and/or clayey silt, and silty
clay. Ground water is approximately 75 feet
below ground surface (bgs).
In 1986, the California Department of
Toxic Substances Control (CA DTSC)
began managing the site's corrective
actions. Ground water treatment began in
1988 through use of an air stripping
system. Site closure activities included
removal of three underground tanks and
offsite disposal of approximately 2,000
yd3 of soil excavated from depths
extending to 30 feet bgs. CA DTSC
determined that additional excavation
was infeasible, and in 1990 tested and
selected in situ SVE as the most feasible
remedial technology for removing the
remaining HOX.
SVE operation began in 1993. The SVE
network encompasses eight 2-inch-
diameter vapor extraction wells screened
between 16 and 66 feet bgs in two of
the previously excavated areas. The wells
are connected to a knock-out pot and a
single 7.5-hp rotary blower that extracts
soil gas from the well network at 100-
130 scfm. Initial design of the system
relied on refrigeration technology to
condense and control VOC emissions.
After removing approximately 10,000
pounds of HOX, operation was suspended
in April 1996 due to failure of the
refrigeration system compressor and
difficulties in attaining an emissions control
efficiency of 90%, in accordance with
South Coast Air Quality Management
[continued on page 2]
May 2009
Contents
Full-Scale SVE
System Operates in
Tandem with Ground
Water Treatment page 1
Bioventing Systems
at Alaska Air Force
Base Achieve
Cleanup Closures page 3
SVE Interim
Remedial Measure
on Long Island
Meets Response
Action Goals page 4
Superfund
Redevelopment
Webinars page 6
Upcoming ITRC
Training page 6
Online Resources
Soil vapor extraction and
bioventing are two of 19
remediation technologies
addressed in the U.S. Envi-
ronmental Protection Agency
(EPA) CLU-IN web forum.
Visit http://www.cluin.org/
remediation/ for information
about SVE or bioventing
applications at other sites as
well as guidance from EPA,
U.S. Department of Defense
services, and state regula-
tory agencies.
Recycled/Recyclable
Printed with Soy/Canola Ink 01 paper that
contains at least 50% recycled fiber
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Figure 1. SVE at the
TPI site steadily
removed HOX from
1993 through 2007,
except for temporary
shutdowns to
accommodate
conversion to the
GAC-based air
emission control
system and later
replacement of the
air blower.
Cumulative Mass of Halogenated Organic Compounds (HOX) Removed by Soil Venting
30,000
•*j- in to (o K oo oo
g g o g 5 CD eg
^OCOCMOKCMCO
!C@ۤICCts@
T- O) If) O ID C\J O
Date
Calculated HOX Removed (based on measured composition of combined extraction gases fed to treatment system)
Liquid Solvent Recovered (as measured in drums and condensate tank)
Calculated HOX Removed (based on measured compositions of gases extracted from wells)
[continued from page 1]
District requirements. Efficiency
reduction was attributed directly to
the significant VOC concentration
reductions in extracted soil gas. Over
the three years of operation, the
system had extracted 9,200-10,300
pounds of HOX and recovered 6,700
pounds of liquid solvents that were
drummed and delivered to an offsite
reclamation facility.
As a consequence, the SVE system was
reconfigured in July 1996 to reroute
SVE gases to the existing carbon
adsorption units used to treat effluent
from the ground water air stripper. Soil
gas is delivered to a series of three
carbon adsorbers, each containing
approximately 5,500 pounds of activated
carbon. Air from the carbon adsorbers
is exhausted to the atmosphere through
the facility's 60-foot stack.
SVE performance monitoring is
conducted through 50 shallow semi-
permanent vapor probes and eight deep
multi-level nested vapor probes to
measure soil gas concentrations across
the entire site. Performance tests rely
on use of a flame ionization detector
(FID) for field detection of VOCs in soil
gas extracted by each well. The FID
sample line is connected directly to a
sample port on the well while isolating
the well from the rest of the system.
Due to consistent field screening results,
fixed-laboratory analysis is not required.
Over 10 years of operation, the modified
SVE system successfully removed an
additional 15,000 pounds of HOX (Figure
1). In general, measured HOX
concentrations decreased as much as
80% in soil and as much as 50% in
ground water. Performance monitoring
in the first half of 2008 indicated that
the system was operating at a flow rate
averaging 110 scfm. VOCs were being
removed at an average rate of 0.07 Ibs/
hr, slightly higher than the previous six-
month period. The system had
performed without interruption for
4,368 hours, with soil gas extracted
continually from five of the eight SVE
wells. An estimated 292 pounds of HOX
were removed from the subsurface in the
first half of 2008, the majority of which
were captured by the carbon adsorption
Installation costs for the project are
estimated at $312,00. Operation of the
combined treatment system costs
approximately $33,000 each year,
including $3,000 for electricity plus an
annual change-out of carbon in the air
stripping system (at a material cost of
$5 per pound).
Contamination in the capillary fringe
and ground water continues to serve as
a source of VOCs in the soil gas. As a
result, CA DTSC is negotiating an interim
measure using in situ chemical
oxidation (ISCO) to attack the most
recalcitrant HOX contaminants, in this
case chlorinated compounds such as
PCE and TCE. The SVE system will
continue operating until ISCO is
implemented and possibly afterward if
ISCO mobilizes additional contamination.
Rebound testing and risk-based soil and
soil gas remediation levels may be
considered if mobilization does not occur.
Contributed by Richard Allen
(rallen2(a)dtsc.ca.gov or 818-717-6607)
and Andy Cano (acano(a),dtsc. ca. gov
or 818-717-6620), CA DTSC
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Bioventing Systems at Alaska Air Force Base Achieve Cleanup Closures
The U.S. Air Force and Alaska
Department of Environmental
Conservation (ADEC) collaborated in
installing and operating seven full-scale
bioventing systems overthe last 10 years
to address hydrocarbon and VOC
contamination at the King Salmon
Airport (KSA) in Alaska. Five of the
systems achieved cleanup closure
within five years of operation, and
another is currently under closure
review. The remaining system will
continue operating to address light non-
aqueous phase liquid (LNAPL) for an
additional five years, after which
sampling data will be reviewed to
determine if regulatory cleanup
standards have been met.
The KSA is located on the Alaska
Peninsula adjacent to Bristol Bay and
Katmai National Park and Preserve.
approximately 280 miles southwest of
Anchorage. KSA had been used as a
World War II military fuel and support
base and subsequently became part of a
permanent state-wide air defense
system. Hazardous materials formerly
used and stored at the facility include
diesel fuel, gasoline, oil, antifreeze.
cleaning solvents, pesticides, and
electrical transformers containing
poly chlorinated biphenyls (PCBs).
Storage tanks were suspected to be the
source for up to 400,000 gallons of fuel
released into the subsurface.
Investigations under the U.S. Department
of Defense Installation Restoration
Program during the late 1980s indicated
soil and ground water contamination at
several KSA sites, which were segregated
into seven treatment zones. High
concentrations for contaminants of
concern found in soil during 1994 and
1998 remedial investigations included
19,200 mg/kg for diesel-range organics
(DRO), 15,000 mg/kg for gasoline-range
organics (GRO), 27 mg/kg total BTEX
(benzene, toluene, ethylbenzene, and
xylenes), 0.26 mg/kg trichloroethene
(TCE), and 2.19 mg/kg PCE.
A seep collection system was installed in
1994 to capture any source material and
treat contaminated ground water before
it reached an adjacent surface water
body (Eskimo Creek). The collection
system was shown over years to be
ineffective in reducing the time to achieve
the remedial action objective (RAO) of
removing subsurface free product.
Evaluated or implemented treatment
methods to address the problem
included a reactive iron wall, in situ
biological treatment, bio-slurping, air
sparging, bioventing, diversion walls.
phytoremediation, capping, and monitored
natural attenuation. Bioventing was
selected in five of the seven treatment
zones as a lower cost alternative with a
shorter duration compared to other
remedial approaches.
Six bioventing systems were installed in
1998 through 2001. Each system consisted
of 1-11 venting wells extending 14-34 feet
bgs with a 10- to 20-foot radius of
influence perbiovent. Equipment for each
system consisted of an enclosed motor/
blower assembly generating approximately
5-15 cfm of continuous airflow into each
venting well. Four to eight vapor points
per site were installed for periodic
monitoring of soil gas.
Operation of the first system began in
1999, with the last going into operation in
2002 as part of a remediation process
optimization (RPO) for an existing SVE
system. The switch from SVE to
bioventing in this treatment zone was
estimated to save $2.8 million in project
costs, including an annual $890,000 for
operation and maintenance (O&M).
An additional RPO in 2004 resulted in
expansion of the site's radar approach
control building (RAPCON) bioventing
system to provide additional source
treatment of diesel-range organics and
free product. Expansion involved
installation of four bioventing wells.
which effectively enlarged the treatment
area (Figure 2). Results of ground water
sample analysis showed that bioventing
was accelerating attenuation. At one
RAPCON monitoring well, GRO and
TCE pre-treatment concentrations in
1996 were 13.071 mg/L and 0.0589 mg/L,
respectively. During a 2006 ground
water monitoring event, GRO and TCE
concentrations in the same well had
reached established cleanup goals, with
concentrations of 0.41 mg/L for GRO
and 0.0159 mg/L for TCE.
Follow-up monitoring was conducted
approximately two months after shutting
down each of the five bioventing
systems achieving cleanup objectives.
Activities included installing two or three
soil gas monitoring points and
conducting a soil gas survey at existing
vapor monitoring points to determine
oxygen utilization. From each soil gas
location, one soil sample was collected
to evaluate soil gas total petroleum
hydrocarbons and target contaminant
concentrations. Appropriateness of
system shutdown and site closure was
determined through application of
ADEC's "350 determination," otherwise
known as the "ten-times rule." This
determination allows for a site to be
considered closed once contaminant
concentrations attenuate below 10 times
the established cleanup level; it can be
applied only to soil-impacted areas
where ground water is non-potable.
RPO in 2004-05 indicated marginal
performance of the sixth bioventing
system, which had operated
intermittently since 2001 in the vicinity
of another building. Operational
problems involved blower and motor
overheating and inability to inject
[continued on page 4]
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[continued from page 3]
adequate oxygen, partially due to
surface water infiltration. Less
permeable soil, water-saturated soil,
and temporary leaks in system piping
combined to limit oxygen delivery in
this system. Piping repairs and
diversion of air flow to air injection
wells within the treatment area were
implemented but had limited effect. To
determine whether NAPL-saturated soil
could be limiting bioventing success, six
direct push borings equipped with an in-
situ probe for measuring laser-induced
fluoroescence (LIF) were advanced. LIF
results showed low average saturation
(2-4%) in the smear zone at a depth of
10-12 bgs. Based on recommendations
from the RPO team and finalization of
RPOs, ADEC recently granted approval
for conditional closure with long-term
monitoring and institutional controls.
The seventh bioventing system, which
continues to operate, combines a
bioventing curtain with a carbon-based
pump and treatment system. This system
was installed in 2003 to reduce LNAPL
mobility and reduce continuing migration
of hydrocarbons and TCE into the onsite
creek. The bioventing curtain focuses on
remediating the smear zone and
augmenting natural attenuation, which
was found to be occurring despite the
cold climate. It consists of wells
distributed across a contaminant plume
perpendicular to ground water flow, in
order to oxygenate ground water before
entrance to the creek. This combined
treatment strategy allowed complete
shutdown of the ground water seep
collection system, consequently reducing
annual O&M costs by approximately
$300,000 and potentially reducing long-term
project costs by an estimated $40 million.
Abandonment of all KS A bioventing wells
will be completed under a future base-wide
well abandonment and maintenance effort.
The U.S. Air Force Center for Engineering
and the Environment (AFCEE) estimates
that installation and operation of the five
bioventing systems reaching cleanup
closure cost approximately $1.2 million
and accelerated cleanup closure by
decades when compared to monitored
natural attenuation. More information
about AFCEE's bioventing initiative,
which has involved more than 150
bioventing systems at more than 30 sites,
is available at www.afcee.af.mil/
resources/technology transfer/.
Contributed by Lori Roy, U.S. Air Force
(lori.roy&elmendorf. af.mil or 907-552-
7697), Charley Peyton, U.S. Air Force
(charley.peyton&elmendorf.af.mil)
and Jonathan Schick, ADEC
(Jonathan.schick&.alaska. gov)
SVE Interim Remedial Measure on Long Island Meets Response Action Goals
Northrop Grumman Corporation (NGC)
is successfully implementing SVE as an
interim remedial measure (IRM) to
mitigate offsite migration of VOCs in
soil gas from the Bethpage Community
Park in the Town of Oyster Bay on Long
Island, New York. The IRM is being
conducted per an Order on Consent with
the New York State Department of
Environmental Conservation (NYSDEC)
and in conjunction with a pump and
treat IRM for ground water.
Performance and compliance
monitoring during the first year of
SVE operation have indicated that
response action goals are being met,
allowing parts of the IRM to be
rebalanced or eliminated.
The Bethpage Community Park was
previously the site of the former Grumman
settling ponds area, which received
chemical waste from the neighboring
Grumman Aircraft Engineering
Corporation (now NGC) property. NGC
donated the property to the Town of
Oyster Bay in 1962 for development of
the park. Since the 1960s, the 18-acre
park was open to the public for
swimming, ice skating, picnicking, and
other recreational activities. Discovery of
PCBs and metals above state guidelines
[continued on page 5]
4
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LEGEND
Full Scale Depression Weil
[continued from page 4]
in surface soil at the NGC property and
shallow soils in the park prompted closure
of portions of the park in 2002, excavation
of contaminated surface soil, and further
site investigations. Soil and ground water
at the park were found to contain VOCs
at elevated levels that raised concern for
potential inhalation risk to nearby residents.
Native soil at the site consists of sand
with interbedded lenses of silt, clay, and
gravel. Depth to ground water is
approximately 55 ft bgs, but perched
ground water is present locally atop a
low-permeability zone, which is
encountered 36 to 46 feet bgs and
ranges in thickness from 1 to 20 feet.
The average horizontal conductivity of
the upper glacial deposits is
approximately 270 ft/day, and shallow
ground water flows south-southeast at
about 1 ft/day. Some areas of the site
contain fill materials at varying depths.
Soil vapor samples collected in March
2007 were found to contain PCE, TCE,
and isomers of dichloroethene (DCE).
TCE was present at concentrations up
to 17,000 |J,g/m3, which exceeds
NYSDEC's short-term guideline
concentration (SGC) of 14,000 Hg/m3.
NGC completed installation of the SVE
system along the facility's access road
at the southern and western borders of
the park in early 2008 to prevent offsite
migration of VOC soil vapor (Figure 3).
Four depressurization wells and 10
vacuum monitoring wells were installed in
a line about 400-feet long along the western
access road, while 14 depressurization
wells and 37 vacuum monitoring wells
(VCMs) were installed in a line about
1,300-feet long along the southern access
road. The clustered depressurization wells
have 5- to 20-foot-long screens, while the
VCMs have 1-foot screens. Depths of the
wells range from 7- to 50-feet bgs.
Two 20-hp and one 30-hp regenerative
blowers were installed to generate a
vacuum within the vadose zone and draw
the vapor stream through the emissions
control system. The system was designed
to maintain an average negative pressure
of -0.1 inches of water column (iwc)
along the access road to prevent offsite
migration of soil gas.
Three 52-gallon moisture separators were
installed to remove condensate from the
influent vapor stream and direct it to a 400-
gallon bulk storage tank for offsite
treatment. A heat exchanger conditions the
effluent vapors prior to passing it through
a vapor-phase granular activated carbon
bed (VPGAC) for treatment. Treatment
was to continue until all VOCs in the
influent vapor stream were less than the
NYSDEC annual guidance concentrations
(on a 12-month rolling average) and less
than SGCs for any given grab sample.
Once the final remedies are selected, NGC
will propose SVE closure criteria.
Figure 3. Vacuum
monitoring wells
and
depressurization
wells of the SVE
system line the
Plant 24 access
road along the
southern and
western
boundaries of
Bethpage
Commuity Park.
Continuous operation of the SVE system
began in February 2008 with brief
shutdowns due to routine maintenance
and troubleshooting. Performance
monitoring showed that the average
induced vacuum was about three times
greater than the -0.1 iwc design. As a
result, the system was rebalanced in
March 2008, and two of the blowers
and the heat exchanger were put on
standby. In addition, manifold control
valves were adjusted, as needed, to
lower or raise the vacuum and flow at
various wells to obtain values closer to
their design criteria.
Influent and effluent vapor streams were
monitored monthly at vapor sampling
ports from February through
December. Total concentrations of
VOCs in the influent vapor samples
decreased from a maximum of 20,622
|J,g/m3 at system startup to a minimum of
1,966 |lg/m3 in December. The
concentration of TCE was reduced from
above the SGC to 710 |j,g/m3.
VOC concentrations in effluent released
to the atmosphere also complied with
state criteria. A detailed air-emissions
regulatory review summary and site
status prepared in December 2008
demonstrated that untreated air
emissions from the SVE system met
applicable regulatory criteria.
Therefore, the VPGAC was deemed no
[continued on page 6]
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Solid Waste and
Emergency Response
(5203P)
EPA 542-N-09-003
May 2009
Issue No. 42
United States
Environmental Protection Agency
National Service Center for Environmental Publications
P.O. Box 42419
Cincinnati, OH 45242
Presorted Standard
Postage and Fees Paid
EPA "
Permit No. G-35
Official Business
Penalty for Private Use $300
[continued from page 5]
longer necessary to treat influent soil
vapors and was removed from service
in January 2009. The piping has been
modified accordingly.
The SVE system meets the design
criteria and prevents potential impacts
to nearby residences. The soil vapor
IRM will continue to operate according
to the rebalanced system parameters.
Now that the VPGAC bed has been
removed, having continuously met
influent and effluent criteria, NGC and
NYSDEC agreed to reduce sampling
frequency from monthly to quarterly.
Further information on the site is
available at http://www.dec.ny.gov/
chemical/3 5727 .html.
Contributed by Steven Scharf
(sxscharf(q).gw. dec, state, ny. us or
518-402-9620) NYSDEC
Superfund Redevelopment Webinars
EPA is hosting a series of monthly CLU-IN seminars on the redevelopment of
Superfund sites across the country, as part of a 10-year anniversary of the
Agency's Superfund Redevelopment Initiative. The opening seminar provided
an overview of different types of site reuse, such as parks and recreation.
ecological revitalization, renewable energy, residential, commercial, and multi-use.
In subsequent sessions, remedial project managers will describe redevelopment
case studies on sites such as the Pemaco Superfund site in Maywood, CA, and the
South Point Plant Superfund site in South Point, OH. Registration for upcoming
seminars is available at http://www.clu-in.org/sri/. Archived seminars (April 29 and
May 21) can be viewed at http://www.cluin.org/live/archive.
Contact Us
Technology News and Trends
is on the NET! View, download,
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www.epa.qov/tio
www.clu-in.orq/newsletters
Contributions may be submitted to:
JohnQuander
Office of Superfund Remediation
and Technology Innovation
U.S. Environmental Protection Agency
Phone:703-603-7198
quander.iohn@.epa.qov
Upcoming ITRC Training
The Interstate Technology and
Regulatory Council (ITRC) now offers
the two-day training course Vapor
Intrusion Pathway: A Practical
Guideline. Training will be held in
Sacramento on June 22-23 and Long
Beach, CA, on June 25-26. To
register or obtain more information,
visitwww.itrcweb.org/crt.asp.
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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