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Tl
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/A newsletter about soil, sediment, and groundwater characterization and remediation technologies
Issue 47
7)zis is-SHe o/Technology News and Trends highlights site remediation projects using onsite renew-
able energy resources to power treatment systems or to offset the air emissions and costs associated
with consuming electricity generated by conventional power plants. Highlighted projects include
both large- and small-scale systems producing power from wind, landfill gas, and solar resources.
April 2010
Cape Cod Wind Resources Provide Energy for Long-Term
Groundwater Cleanup at MMR
The Air Force Center for Engineering and
the Environment (AFCEE) recently began
operating a 1.5-MW wind turbine to power
ongoing remedial actions at the 22,000-acre
Massachusetts Military Reservation (MMR)
on Cape Cod, MA. The wind turbine is
expected to meet 25-30% of the total energy
demand of remediation systems treating
approximately 14.5 million gallons of
contaminated groundwater per day. AFCEE
anticipates capital expense payback for the
$4.6 million turbine in six to eight years.
MMR has been used since 1911 for military
training and aircraft operation and
maintenance. Historical activities involved
use of hazardous materials such as
explosives, fuels, and cleaning solvents that
were released to the environment.
Contaminants of concern and highest
concentrations during 2009 in the 12 remaining
groundwater plumes include trichloroethene
(TCE, 1,740 |J,g/L), tetrachloroethene
(5 1 |J,g/L), carbontetrachloride (17|Og/L),and
ethylene dibromide (23 |Ig/L).
The site is located over a recharge area for
the Sagamore Lens, a sandy, 300-foot-thick
sole-source aquifer. Most of the contaminant
plumes migrated beyond the base boundary
and threatened drinking water wells in
surrounding towns. Several discharged to
freshwater bodies or nearby ocean harbors.
The largest plume is nearly four miles long,
over one mile wide, more than 100 feet thick,
and 100-300 feet deep.
Remediation of the site's source areas has
been completed through removal actions
or in situ air sparging/soil vapor extraction
and thermal treatment. To address
groundwater contamination, AFCEE
installed 105 extraction wells with 27 miles
of pipeline and constructed nine treatment
plants to treat extracted groundwater
through granular activated carbon (GAC)
media. Treated water is returned to the
aquifer through reinjection wells and
infiltration trenches or discharged to local
rivers. An optimization program initiated in
2003 determined that the existing treatment
systems collectively consumed 12,300
MWh of electricity each year, all of which
was supplied by conventional power
plants. This "upstream" power production
was estimated to annually emit over 6.7
tons of carbon dioxide, 11,833 pounds of
nitrous oxides, 11,443 pounds of sulfur
dioxide, and 418 pounds of particular
matter. Economic analysis revealed that this
amount of electricity, purchased at a rate
of $0.167 kWh, cost MMR over $2 million
each year.
In 2006, to offset the air emissions and costs,
AFCEE assessed wind turbine constructability
by evaluating the economic, design, and
environmental factors affecting potential
generation of electricity onsite. Results
indicated that, due to net metering under
the Massachusetts Green Communities Act,
transfer of wind-generated electricity to the
[continued on page 2]
Contents
Cape Cod Wind
Resources Provide
Energy for Long-Term
Groundwater Cleanup
atMMR page 1
Gas-to-Energy
System at Former
Landfill Generates
Power for Gas and
Leachate Treatment
Systems page 3
Solar-Powered
Recirculation
Accelerates
Bioreactor
Operations at
Travis AFB page 4
Program Expands for
Upcoming Green
Remediation
Conference page 6
CLU-IN Resources
Other applications of renewable
energy for site cleanup are
described in site-specific profiles
and reports available online at
CLU-IN's Green Remediation
Focus (www.cluin.org/
greenremediation). In addition,
information about developing
renewable energy on currently
or formerly contaminated land is
offered online by EPA's RE-
Powering America's Land
Initiative (www.epa.gov/
renewableenergvland).
Recycled/Recy cl abl e
Printed with Soy/Canola Ink on paper that
contains at least 50% recycled fiber
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[continued from page 1]
local utility in exchange for credit on
electricity purchases offered the
greatest economic advantage. Initial
funding was available through the Defense
Environment Restoration Account and a
$300,000 renewable energy grant from the
Massachusetts Technology Collaborative.
Design analysis indicated that a 260-foot
turbine hub height with a 253-foot-
diameter rotor would maximize wind
capture. Together, the system's three 123-
foot rotor blades would sweep an area of
approximately 50,676 square feet. Selection
of blades made of epoxy and fiberglass
provided durability while minimizing
weight and increasing system efficiency.
The system was designed to operate at a
"cut-in" wind speed as low as 6.7 mph and
suspend operation at a "cut-out" wind
speed of 45 mph, which accommodated the
area's average wind speed of 14.6-15.8 mph
at a 260-foot height. System design called
for turbine survival at wind speeds
reaching 134 mph. A maximum power
output of 1,500 kW would be achieved at
a wind speed ranging from 25 mph to the
cutout speed.
Preferential siting factors included
sufficient open space to minimize
interference from nearby structures and
close proximity to an existing 23-kV power
line for interconnection. Based on the
design specifications and analysis of site
conditions, an area of higher elevation
along the southwestern boundary of
MMR property was identified as the
optimal location. Use of an existing cleared
area behind the treatment plant at this
location would avoid destruction of
vegetation and minimize ecosystem
disruption. Turbine siting near an
operating plant also allowed for
streamlined monitoring and maintenance.
A 2007 environmental assessment
completed under National Environmental
Policy Act requirements found that the
proposed project would pose no significant
impact on wildlife or other natural
resources. Clear visibility of the proposed
turbine from certain areas was predicted
within a 6.7-mile radius. Much of this
visibility was from Buzzards Bay or would
be blocked by terrain or seasonal forest cover.
Noise assessment predicted a level of 65
dBA at the turbine tower base, which is
below the 85 dBA eight-hour threshold set
by the National Institute for Occupational
Safety and Health. Estimated noise levels
decreased to less than 40 dBA on the
perimeter of the closest residences and to
less than 35 dBA at the edge of sensitive
ecological environments extending to the
bay. Other environmental factors included
potential disruption to aviation patterns
and radar equipment used by onsite and
nearby facilities operated by the U.S. Air
Force, Otis Air National Guard Base Airport,
U.S. Coast Guard, and Camp Edwards. The
Federal Aviation Administration and base
facilities determined the proposed wind
turbine would not significantly impact their
mission or activities, and the U. S. Air Force
Space Command found no problems
related to radar use.
Studies indicated that resident and
migratory birds tend to forage in nearby
pine forest habitats, rather than on bare
ground of the proposed turbine site, and
that the proposed site contains no unique
habitat features likely to funnel bids
through the turbine rotor-sweep zone. The
studies also considered results of a recent
literature review that found bird fatalities
caused by turbine collision across the
United States have been low, averaging
2.3 birds per turbine per year. Assessment
of effects on other wildlife concluded that
potential impacts on two species of
concern (the eastern box turtle and New
England cottontail) during construction
would be minimized by best management
practices such as installing silt fencing and
performing daily site inspections.
Field preparations for the wind turbine
began in late 2008, following nearly two
years of approval and planning activities.
In March 2009, approximately 600 yd3 of
5,000-psi concrete were laid to form a
foundation 57 feet wide and 3-8 feet high,
meeting specifications that included a
load-bearing capacity for the selected 37-
ton rotor and 73-ton generator. Detailed
coordination was needed to transport
turbine components from various
manufacturers as far away as Germany and
North Dakota.
By the end of October 2009, construction
was complete (Figure 1). Turbine
operations that began in early December
2009 are expected to produce 3,810 MWh
each year, based on a 29% capacity.
During the initial two months of
operation, the turbine produced
approximately 602 MWh of electricity,
which represents an electricity purchase
savings of $100,000.
Turbine installation did not impact
MMR remedial work. Operation and
maintenance (O&M) includes weekly
visual inspections by the turbine installer
and semiannual maintenance by the
turbine manufacturer to ensure proper
torque, lubrication, and working order of
[continued on page 3]
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[continued from page 2]
components. Onsite staff can access
continuous monitoring data, while
comprehensive monitoring and control is
provided remotely by the manufacturer's
control center in Germany.
The expected lifespan of the new turbine is
25 years, although groundwater remediation
in some areas of MMR may continue over
the next 50 years. As a result, AFCEE plans
to investigate potential installation of two
or three additional wind turbines to fully
offset power used by the treatment systems
and an ongoing Army Impact Area
Groundwater Study Program.
Contributed by Rose Forbes, AFCEE/
Otis Air National Guard Base
(rose.forbesfaus. af.mil or 508-968-4670)
Gas-to-Energy System at Former Landfill Generates Power for Gas and Leachate Treatment Systems
Since 2002, the U.S. Environmental
Protection Agency (EPA) Region 9 has
deployed a system for converting landfill
gas (LFG) to electricity at the Operating
Industries, Inc. Superfund site (Oil) in
Monterey Park, CA. The system relies on a
network of microturbines that generated
sufficient electricity upon startup to meet
70% of the site's remediation needs.
Substitution of conventionally-generated
electricity with the onsite renewable energy
saves an average of $250,000 per year in
energy costs for the project.
The Oil site served as a municipal landfill
from 1948 to 1984, amassing both residential
and commercial wastes in a former quarry
pit through cut-and-cover construction.
Approximately 38 million cubic yards of
municipal solid waste and up to 300 million
gallons of liquid waste including a wide
range of hazardous waste accumulated at
the 190-acre landfill. The Pomona Freeway
now splits the site into two parcels (Figure
2) with different terrain and waste
thicknesses, which are estimated at 200-325
feet in the south parcel and up to 55 feet in
the north parcel. Observation of leachate
seeping offsite in 1982 led to the
construction of a leachate collection system
and ultimate closure of the landfill in 1984.
Remedial investigations found that elevated
concentrations of hazardous substances in
both leachate and LFG at Oil were migrating
to surrounding soil, groundwater, surface
water, and ambient air. The selected remedy
involved construction of LFG and leachate
collection systems, stormwater collection
ponds, and cover systems. The LFG
collection system comprises 460 gas
extraction wells, including 185 dual-phase
extraction wells, and transmission lines to
prevent lateral and upward migration of LFG.
The landfill gas treatment system (LFGTS)
consists of two thermal oxidizers with a
continuous emission monitoring system. The
oxidizers operate at 1,800°F, achieving a
99.99% destruction rate efficiency for
contaminants (primarily volatile organic
compounds) prior to air release.
In 2001, when the retail rate for electricity
increased Oil's annual treatment costs to
$370,000, Region 9 determined that significant
savings could be achieved using some of the
LFG as a renewable energy source to directly
power the treatment systems rather than
treating it for air release. Microturbines were
selected for electricity generation to
accommodate the LFG methane content, which
was lower than typically needed to operate
internal combustion engines conventionally
used for gas-to-energy systems but high
enough to meet more than half of the energy
demand. Microturbine operations also were
expected to result in lower rates of nitrogen
oxides production and were more compatible
with the smaller LFGT S at Oil. The total energy
demand of the treatment systems was
estimated at 600 KWh.
Six 70-kW Ingersoll-Rand PowerWorks
microturbines (Figure 3) were installed at
the north parcel in 2002. The units are
equipped with onboard compressors that
pressurize the LFG to 15 psig to remove
moisture. Because the power output of
microturbines is greatest at cool ambient
temperatures, the compressed LFG is chilled
to 40°F with a refrigeration system and then
reheated to 65°F by a heat exchanger.
LFG from the south parcel is transferred to
the treatment system by way of a six-inch
dedicated transmission line running
through a bridge over the Pomona Freeway.
Extracted LFG from the combined parcels is
monitored for methane concentration,
temperature, gas flow, pressure, and oxygen
content through use of a continuous gas
quality analyzer. Since the microturbine
exhaust has an oxygen content and
temperature compatible with the LFGT S, the
exhaust stream is routed directly to the
LFGT S combustion air blowers for treatment
by thermal oxidizers to destroy remaining
offgases. The system currently extracts LFG
at an average rate of 4,200 scfm and with an
average methane content of 21%.
[continued on page 4]
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[continued from page 3]
Microturbine purchasing costs (including
equipment, installation, and warranty)
totaled $ 1.25 million, which was reimbursed
in part by a $450,000 energy grant from
Southern California Edison and a $105,000
energy rebate from the California Energy
Commission. Annual operating costs for the
microturbines averaged $ 10,000 during the
five-year warranty period and now average
$25,000 for labor, parts, and repairs. To date,
the system has generated more than 15,000
MWh of electricity, which is equivalent to
an energy cost savings of nearly $21,000
for the project each month or approximately
$1.75 million over seven years of operation.
Cumulative net project savings are
conservatively estimated at $647,000, based
on 2006/2007 energy production rates.
LFG methane content over the eight years
of microturbine operation has ranged from
29 to 3 9%-somewhat higher than the 25%
used in project design. Initial capacity of
the microturbines to meet 70% of the
treatment system's total energy demand has
decreased to 50% over time due to reduced
equipment efficiencies caused by aging
and frequent repairs. The capacity is
expected to decline further as LFG begins
to gradually diminish. As a result, EPA plans
to replace the six microturbines with next-
generation turbines having a combined
capacity of 500 kW and capability to generate
power from LFG with lower methane content.
In 2006, a 6-foot monocover (primarily clay)
and geosynthetic clay liner cap were
completed on the south parcel to minimize
percolation of liquids into the waste,
improve slope stability, and provide
erosion and gas migration controls. A
companion leachate collection system
and a leachate treatment plant (LTP)
collects the landfill liquids for treatment
through processes such as GAC
adsorption, chemical precipitation, air
stripping, and sand filtration. In addition,
construction of a perimeter liquids control
system (PLCS) to control offsite leachate
migration is nearly complete. The LTP has
treated approximately 4.5 million gallons
each year since 2000 and will annually
treat up to 10 million gallons when
the PLCS fully operates. EPA
anticipates future sale of the treated
liquids for irrigation of neighboring
agricultural and cemetery properties.
Construction of a similar cap began two
years agoon 10.5 acres west of the north
parcel. Upon capping completion, the
entire 45-acre north parcel (excluding the
LTP and LFGTS treatment facilities) will
be redeveloped as a retail marketplace.
Ongoing exploration of the site's
redevelopment potential and long-term
energy needs has prompted EPA to
explore other renewable energy sources
at OIL For example, the onsite thermal
plumes could provide up to 48 MBTU/hr
of energy for combined heat and power
available to the LFGTS building or future
businesses on the north parcel. Other
opportunities include leasing of 50 level
acres on the south parcel for development
of a solar energy farm.
Contributed by Shiann-Jang Chern,
Ph.D., EPA Region 9 (chem.shiann-
jang(a),epa.gov or 415-972-3268)
Figure 3. Oil's microturbines were
installed in a covered area
Solar-Powered Recirculation Accelerates Bioreactor Operations at Travis AFB
and Travis Air Force Base (AFB)
have partnered to demonstrate an in situ,
solar-powered bioreactor for treating residual
contamination at the base's Site DP039 near
Fairfield, CA. The system was installed in
2008, following seven years of dual-phase
extraction treatment that reduced TCE and
daughter product concentrations in
groundwater from 20,000 ppb to asymptotic
values of 300-400 ppb. Following 12 months
of bioreactor operation, performance
evaluations indicate that the new treatment
system has reduced TCE concentrations in
source area groundwater an additional 75%.
Until the late 1970s, vehicle and aircraft
maintenance at Site DP039 involved use
of a battery acid neutralization sump.
Investigations indicated that unauthorized
disposal of cleaning solvent in the sump
had created a TCE plume extending over
1,500 feet downgradient of the source. The
confirmed TCE source encompassed an area
approximately 20 by 20 feet and extending
40 feet below ground surface (bgs). Source
area and surrounding soil consists of layered
silts, clays, and sands with an average
hydraulic conductivity of 10"4 to 10"5 cm/s.
Depth to groundwater is 25 feet bgs.
Design of the bioreactor was based on a first-
generation system implemented in 2003 at
Altus AFB, OK. The second-generation
design used at Travis AFB includes a deeper
excavation and addition of iron pyrite to
stimulate chemical reduction of TCE and
daughter products. Construction of the
bioreactor began in early November 2008.
Field preparations included clearing a
concrete and steel vault used by the past
dual-phase extraction system, which
employed two extraction wells. One well
was targeted for use in bioreactor
recirculation, and the second was
preserved for performance monitoring.
Approximately 300 yd3 of soil were
excavated from the former sump area. Of
this, 20 yd3 required disposal at an offsite
hazardous waste disposal facility, and the
[continued on page 5]
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[continued from page 4]
remainder was deemed suitable for on-
base fill material.
A conventional excavator was used to dig
a trench 20 feet long, 20 feet wide, and 20
feet deep. As excavation progressed, a
square trench box was installed to prevent
sidewall collapse. A mixture of 45%
gravel, 50% mulch, and 5% iron pyrite was
poured into the bottom five feet of the
excavation. The gravel-and-mulch mixture
was added in five-foot lifts, and each lift
was sprayed with food-grade soybean oil.
The completed bioreactor contains 150 yd3
of tree mulch that provides a long-term
source of dissolved organic carbon (DOC)
to create anaerobic conditions that support
growth of contaminant-degrading bacteria.
The mulch contains shredded branches
gathered from fast-growing eucalyptus and
other trees located in other areas of the
base. Microbial growth and associated
biological reductive dechlorination is
enhanced by the 600 pounds of soybean
oil serving as an additional source of soluble
organic material.
A 12-inch gap was left between the top
layer of reactive material and the ground
surface to provide space for an infiltration
manifold consisting of perforated, one-
inch-diameter PVC pipe to distribute
pumped groundwater. The infiltration
manifold was connected to the recirculation
well and covered by a geotextile layer, and
the trench was backfilled with 30 inches
of clean soil (Figure 4). A 1/3-hp solar-
powered pump was installed inside the
former extraction well to capture
contaminated groundwater from the aquifer
Figure 5. The Site DP039
PV system was installed
approximately 30 feet from
the bioreactor "mound" to
maximize electricity
transmission efficiency
while retaining sufficient
space for recirculation well
and bioreactor O&M.
. r
Former Sump Source Area
iackfill
Figure 4. Recirculation
of contaminated
groundwater through
the bioreactor increases
contact time with the
reactive materials; after
percolating through the
bioreactor column, DOC
from the bioreactor
reenters the surrounding
aquifer to promote
additional reductive
dechlorination ofTCE.
and return it to the infiltration manifold
overlaying the bioreactor.
Based on data from the National Renewable
Energy Laboratory, the annual photovoltaic
(PV) solar resources at Travis AFB average
5.5 kWh/mVday. A 250-watt PV array
consisting of five 50-watt panels was used to
supply variable direct current to the solar
pump (Figure 5). The PV system has been
generating sufficient power to achieve an
average groundwater recirculation rate of 815
gallons per day.
Nine months after bioreactor startup,
performance evaluation determined that
addition of a soluble organic substrate was
needed to create sufficient anaerobic
conditions in the aquifer surrounding the
bioreactor. Consequently, 1,200 pounds of
fructose corn syrup were injected into the
bioreactor to increase aquifer DOC to
concentrations above the target of 20 ppm.
Six weeks after fructose injection, average
DOC levels in the surrounding aquifer
increased from 6 mg/L to 9 mg/L. The most
recent comparison of analytical results for
groundwater entering and exiting the
bioreactor indicates a 99% decrease in TCE
concentrations and a 77% total reduction
of TCE, dichloroethene, and vinyl
chloride. Low production of vinyl chloride
in the bioreactor, in the 1-4 ppb range,
suggests that both biotic and abiotic
reductions are occurring in the bioreactor.
To date, the solar-powered treatment
system has recirculated and treated
220,000 gallons of groundwater.
The total cost for design, regulatory
approval, construction, and initial 30-month
operation of the treatment system is
estimated at $320,000. This includes $10,000
in capital expenses for the P V array and solar-
powered pump. Return on investment for
the PV array is anticipated in approximately
10 years as a result of purchasing less
electricity. When no longer needed at Site
DP039, the array may be reused at other
locations. Project review also indicates that
shutdown of the dual-phase extraction
system when contaminant concentrations
reached asymptotic levels annually saved
approximately 30,000 kWh of electricity and
[continued on page 6]
In the December 2009 article
"Vegetable Oil Emulsion Promotes
Contaminant Degradation in Bedrock
Groundwater," concentrations of all
contaminants were erroneously
printed in unit measures of "mg/L"
rather than "|ig/L"
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Solid Waste and
Emergency Response
(5203P)
EPA 542-N-10-002
April 2010
Issue No. 47
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]
avoided the associated emission of
approximately 24 tons of CO equivalent.
Final evaluation of the demonstration, which
was funded by AFCEE's Broad Agency
Announcement Program, will be used to
prepare a final record of decision in 2011.
AFCEE also anticipates using the
demonstration results to help design and build
two additional solar-powered bioreactors
at sites in Kansas and Washington.
Contributed by Lonnie Duke
(lonnie.duke(a),travis.af.mil or 707-424-
7520) and Doug Downey, CH2M Hill
(doug.downey(a),ch2m.com or 303-674-
6547)
Program Expands for Upcoming Green Remediation Conference
"Renewable Energy and Site Reuse" is one of several program tracks at the Green
Remediation: Environment, Energy, and Economics international conference to be
held June 15-17 in Amherst, MA. Other program tracks offered at the conference, which
is co-sponsored by EPA and the Environmental Institute, include:
> Understanding the environmental footprint
> Policy and regulatory considerations
> Quantifying the environmental footprint
> Environmental footprint mitigation
> Innovative technologies for green remediation, and
> Economic considerations.
To obtain more details or to register, visit the University of Massachusetts Amherst
online at: www.umass.edu/tei/conferences/GreenRemediation/index.html.
Contact Us
Technology News and Trends
is on the NET! View, download,
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Contributions may be submitted to:
John Quander
Office of Superfund Remediation
and Technology Innovation
U.S. Environmental Protection Agency
Phone:703-603-7198
quander.iohn@.epa.qov
Partnering for LFG Energy
EPA's Landfill Methane Outreach
Program forms partnerships to help
communities, landfill owners, utilities, and
other stakeholders assess feasibility and
find financing for projects involving
recovery and use of LFG as an energy
source. Learn more about the opportunities
and access technical information and tools
at: www.epa.gov/landfill/basic-info/
index.html#03.
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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