SEPA
United States
Environmental Protection
Agency
Office of Solid Waste and
Emergency Response (5102G)
EPA 542-F-12-028
September 2012
Green Remediation Best Management Practices:
Mining Sites
Office of Superfund Remediation and Technology Innovation
Quick Reference Fact Sheet
The U.S. Environmental Protection Agency (EPA) Principles for
Greener Cleanups outline the Agency's policy for evaluating
and minimizing the environmental "footprint" of activities
undertaken when cleaning up a contaminated site.1 Use of
the best management practices (BMPs) recommended in
EPA's series of green remediation fact sheets can help project
managers and other stakeholders apply the principles on a
routine basis while maintaining the cleanup objectives,
ensuring protectiveness of a remedy, and improving its
environmental outcome.
Federal agencies estimate that approximately 500,000
abandoned mines and associated ore processing facilities
exist across the United States.2 Of these, approximately
130 National Priorities List (NPL) or NPL-caliber sites
covering more than a million acres are contaminated
from past hard rock mining activities and are now
undergoing cleanup led by the lead federal agencies or
potentially responsible parties. Much of the work to
remediate and reclaim abandoned mine land (AMI) at
other sites is conducted or overseen by state agencies,
often with voluntary assistance from non-profit groups.
Cleanup and restoration of sites with areas formerly used
to mine coal or hard rock ore (containing metals such as
gold or copper or other resources such as phosphorous)
present unique challenges. Past activities typically included
onsite extraction, crushing, and separation of extracted
mineral ore into useable material (beneficiation) and
onsite or offsite processes such as smelting. Environmental
contamination and degradation at mining sites commonly
resulted from:
Waste rock and beneficiation waste such as mill tailing
piles often scattered in numerous surface
impoundments
Mining influenced water (MIW), including contaminated
surface water, groundwater, and seepage from former
mine adits (openings)
Waste in the form of slurry that was injected into
abandoned coal mines
Waste sludge (often containing surfactants and
flocculants) that was discharged into unlined lagoons,
or
Aerial deposition of heavy metals and other
contaminants from ore processing activities.
Steps to remediate these conditions can pose their own
environmental footprint, which can be reduced by
adhering to EPA's Principles for Greener Cleanups.
The core elements of a greener cleanup involve:
Reducing total energy use and increasing the
percentage of renewable energy
Reducing air pollutants and greenhouse gas (GHG)
emissions
Reducing water use and
negative impacts on
water resources
Improving materials
management and waste
reduction efforts, and
Protecting ecosystem
services.
Materials
& Waste
Energy
Lai
Ecosystems Atmosphere
Water
EPA's suite of green remediation BMPs describes
specific techniques or tools to address the core elements.
The availability of liquid fuels and electric power, for
example, poses a major challenge at many mining sites
due to their remote and often high-altitude locations.
Green remediation BMPs focusing on fuel and energy
conservation techniques or renewable sources of energy
can help minimize the environmental footprint of
particular activities (and improve the project's
environmental outcome) while addressing this challenge.
Three documents in EPA's "BMP fact sheet" series3
provide detail about BMPs relating to fuel or energy use
or optimization of energy-intensive ex situ technologies
often deployed in MIW treatment plants:
Green Remediofion Besf A/lonogemenf Practices: Clean
Fuel & Emission Technologies for Cleanup30
Green Remediation Best Management Practices:
Integrating Renewable Energy into Site Cleanup,3b and
Green Remediation Best Management Practices: Pump
& Treat Technologies.3^
Other significant opportunities to reduce the
environmental footprint correspond with common
components of mining site cleanup projects:
> Characterizing MIW in order to better understand
the nature and extent of contamination
^ Using passive treatment systems for acid mine
drainage
> Integrating onsite renewable energy to power
cleanup operations
^Installing soil covers to stabilize soil and waste piles
and reduce their exposure
> Reclaiming residual natural resources such as
economically valuable metals from waste piles, and
> Integrating cleanup with restoration and
reuse of sites.
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Characterizing MIW
Green remediation BMPs for MIW characterization prior
to remedial system design and construction include:
Use field test kits for screening whenever possible, to
reduce the number of samples requiring offsite
laboratory analysis
Deploy low-flow sampling equipment whenever
possible, to minimize purge volumes and energy use
while producing little investigation-derived waste
Deploy remote sensing techniques for identifying and
surgically removing any subsurface obstructions or
potentially dangerous materials (such as residual
explosives), to avoid excavating excess soil or material
Use noninvasive, less energy-intensive investigative
techniques such as borehole and surface geophysical
methods for identifying fracture zones and groundwater
flow/direction, to optimize contaminant mapping, well
placement, and treatment system design
Maximize reuse of existing boreholes for capturing and
hydraulically controlling seeps, to avoid additional land
and subsurface disruption caused by creation of new
boreholes
Choose sonic instead of conventional rotary drilling or
hammer techniques whenever possible, to minimize
discharged waste, avoid the need for drilling fluid, and
reduce noise
Use phosphate-free detergents instead of organic
solvents or acids to decontaminate sampling
equipment, and dispose of used washwater in contained
vessels or designated onsite areas, and
Use environmentally friendly drilling fluid or water in a
closed-loop system when rotary drilling is needed.4
Additional BMPs are described in Green Remediation Besf
A/I an ag em en f Practices: Site Investigation .3d
Voluntary cleanup by a non-profit environmental group at the
DeSa/e Restoration Area in western Pennsylvania involves
a passive treatment system for acid mine drainage
exiting abandoned surface and underground coal mines. The
system contains agricultural waste (spent mushroom compost)
and limestone from a nearby quarry. It effectively neutralizes
about 180 pounds of acidity per day. Over eight years of
operation, the system recovered about two tons of manganese
oxide; proceeds from sale of the recovered material were used
to maintain the treatment system and construct additional
systems in other portions of the Slippery Rock Watershed.5
Using Passive Treatment Systems
Highly acidic water rich in metals (acid mine drainage
[AMD]) can be produced indefinitely after mining activities
cease and continue to pose significant risks to aquatic life
and to humans through fish or water consumption or
direct contact. AMD and other MIW could be remediated
by a passive treatment system comprising one or more
ground-surface "cells" that take advantage of a site's
naturally occurring chemical and biological processes.
For example, a passive treatment system could consist of
an oxidation pond, a biochemical reactor to transform
contaminants into immobile forms and increase pH, and
remediation polishing technologies such as aerobic
wetlands or limestone beds. The site's natural hydraulic
gradients or a pumping system can be used to transport
the MIW to these treatment cells from adits or seeps. A
passive treatment system also can be used as a polishing
step following ex situ treatment of MIW in an onsite water
treatment plant.
Through EPA funding, the University of Oklahoma constructed
a passive treatment system for seepage from abandoned
underground lead and zinc mines at the Tar Creek
Superfund Site in Oklahoma. The system encompassed
oxidation/re-aeration ponds, surface flow wetlands, vertical-
flow/sulfate-reducing biochemical reactors, and horizontal
flow limestone beds. Approximately 90% of each biochemical
reactor consisted of agricultural and forestry waste
products.
To accelerate oxidation in the ponds, off-grid renewable
energy systems were integrated into the system's design:
* A 20-foot windmill provides mechanical energy to power a
vertical displacement pump operating in one pond, and
* A photovoltaic array generates electricity to directly operate
a compressor in an adjacent pond.
10%
manufactured
limestone sand
Green remediation BMPs for constructing a passive
treatment system include:
Design extensive stormwater controls prior to use of
heavy machinery, to avoid additional runoff and
watershed sedimentation or contamination; controls
may involve existing rock-lined channels or other
topographic features as well as engineered structures
such as berms and grassy swales
Maximize reuse of remnant service roads or cleared
areas, and use surgical techniques to remove any
vegetation during construction of new transportation
corridors or work areas
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Explore the use of check dams and other structures to
capture any rainwater or snow melt for application in
onsite activities such as controlling excavation dust,
rinsing hand-held equipment after field use, or irrigating
newly planted vegetation
Preserve existing corridors or create new ones if needed
to assure safe passage of migratory animals, and
Schedule startup of major land-disturbing activities
during non-nesting or non-birthing periods of local
ground-dwelling birds or wildlife, and install grates in
mine adits to allow bat passage.
A biochemical reactor is typically lined and contains
organic-rich material along with buffering material such
as crushed limestone. Lumber, agricultural, or greenhouse
byproducts (such as hardwood chips, mulch, hay,
livestock manure, or spent mushroom compost) or
municipal biosolids often provide the organic matter.
BMPs for constructing and monitoring a biochemical
reactor within a passive treatment system include:
Choose a geomembrane (liner) manufactured through
processes involving a low environmental impact, such
as those described in ISO 14001 (Environmental
Management Systems)
Procure organic materials from producers closest to the
site, to minimize fuel consumption and related air
emissions from heavy trucks
Explore other industrial byproducts that may be more
available on a local basis, such as chitin or cocoa shells
Consider use of novel protein-containing food waste
such as banana peels to bind metals existing at trace
concentrations in water; research has shown that such
waste may improve metal detection during monitoring
and potentially serve as a sorbent to remove metals at
higher concentrations,6 and
Install remote monitoring equipment such as sonde
units to continuously collect water quality data while
significantly reducing frequency of site visits.
Integrating Onsite Renewable Energy
As an alternative to using and transporting liquid fuel or
attempting to extend connection to the local utility grid,
onsite renewable energy systems may be installed during
remedy construction or added as needed during system
operation to:
Supplement gradient-driven transfer of MIW to or
among treatment cells
Improve treatment efficacy of certain cells such as those
used for aeration, and
Generate electricity or mechanical energy for routine
field equipment or small devices.
Mobile units now available in the commercial market offer
significant potential for generating renewable energy at
remote locations such as mining sites. Depending on a
site's accessibility and terrain, mobile systems could
provide collapsible photovoltaic (PV) arrays or small wind
turbines mounted on trailers designed to supply over 20
kilowatts (kW) of electricity. Smaller arrays or mini turbines
(generating less than 1 kW) can be packaged on simple
frames or skids to be hauled by a pick-up truck or all-
terrain vehicle.
In addition, surface waters on or adjacent to many mining
sites offer the potential of hydropower at various scales. A
2 kW micro-hydropower submersible turbine, for example,
can be deployed to operate with a hydraulic head as little
as 1.5 meters to provide mechanical energy or drive an
electricity generator. In contrast, a 36 kW microturbine at
the Summitville Mine in Del Norte, Colorado, generates
hydropower that offsets grid electricity consumed by an
onsite water treatment plant.
Solar energy is used at the Leviathan Mine Superfund
site in the Sierra Nevada Mountains of California for four
remote monitoring stations at key seeps and creeks and for an
onsite emergency shower unit. Each monitoring station was
custom built by EPA Region 9 staff to include a PV array for
battery charging; multiprobe sonde to measure water quality
parameters of streams impacted by AMD; and satellite
telemetry for hourly data collection and transmission to EPA
offices.
The Atlantic Richfield Company operates a PV-powered
meteorological station and a solar thermal unit at adjacent
portions of the site. The solar thermal unit maintains warmth
throughout the year for an electrical system used to control
propane-fueled generators powering a semi-passive treatment
system. In cooperation with the National Renewable Energy
Laboratory, EPA Region 9 is investigating larger renewable
energy applications to power the treatment system pumps,
which currently rely on summer-only fuel delivery to this
remote site.
Installing Soil Covers
Waste rock and ore process tailings found in surface
impoundments at mining sites typically settle over time.
Impoundment stabilization often involves constructing one
or more soil covers (caps) for waste left in place or
consolidated in one or more selected areas. Green
remediation BMPs for designing a cover include:
Mimic rather than alter the site's natural setting, to
improve the cover's long-term performance and protect
local ecosystem services
Account for potential effects of climate change, such as
increased vulnerability to flooding or sudden shifts in
temperature
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Explore industrial waste products as a partial substitute
for productive soil to be imported for a cover's
compacted clay layer or the liner of a new landfill for
waste consolidation, if product testing shows no
contaminant leaching, and
Consider anticipated site reuse options during design of
a cover; for example, industrial redevelopment of the
site may reduce the volumes of materials to be imported
for a vegetative cover.
Biosolids, limestone, potash, and fly ash were blended to form
a soil amendment that was spread on ground surfaces
through a single pass at the Palmerton Zinc Pile Superfund
site in Carbon County, Pennsylvania. A seed mix of native
plants unlikely to accumulate metals (such as big and little
bluestem, deerfongue, Indiangrass, and switchgrass) was
applied with the ground amendment and aerially distributed.
Onsite studies conducted 10 years later indicated significant
re-growth of vegetation in formerly denuded areas across the
estimated 2,500 acres previously amended and little
accumulation of metals such as cadmium, lead, and zinc in
resident mammals.7 Current efforts by EPA, the Pennsylvania
Game Commission, and the National Park Service focus on
developing a remediation and reuse plan for remaining
denuded public land covering about 1,200 acres along the
Appalachian Trail.
Consider onsite generation of compost made of forest
waste resulting from logging activities or disease-
infested trees, to reduce import of soil amendments; for
example, "beetle kill" trees could provide a significant
source of biomass
Explore use of biochar (a charcoal-like substance
produced by heating biomasss in the absence of
oxygen) as a soil amendment, to better retain moisture
and nutrients, and
Blend amendments into a single mixture that can be
applied above the cover through a one-step process
rather than a series of applications, to minimize
operation of front loaders and other heavy machinery.
Additional BMPs regarding ET or other alternative designs
as well as conventional covers are described in Green
Remediation Best Management Practices: Landfill Cover
Systems & Energy Production.3"1
Research is underway in test plots at the Hope Mine near
Aspen, Colorado, to evaluate efficacy of biochar
amendment in restoring soil affected by mine waste rock
piles. Along with biochar, the applied amendment contained a
seed mix, compost, hydromulch, and naturally occurring
mycorrhizal fungi to help plant roots take in nutrients. In each
plot, biodegradable netting was placed on ground surfaces to
hold the amendment in place. No irrigation was needed for
plant re-establishment, which occurred within one year.
Soil covers at some mining sites involve use of an evapo-
transpiration (ET) system, which relies on a thick layer of
soil with vegetative cover capable of storing water until it
is transpired or evaporated (and consequently minimizing
percolation into underlying waste). Soil in the upper layer
is often amended to restore quality of the soil and provide
nutrition to the vegetation. Amendments containing
organic-rich material such as biosolids can also bind
metal in soil, thereby reducing the metal bioavailability.
Green remediation BMPs for an ET cover include:
Select drought-resistant plants for the upper vegetative
layer, to reduce maintenance needs; in some cases,
non-native species may offer higher viability potential
and water storage capacity than native plants
Preserve biodiversity and related ecosystem services by
installing a suitable mix of non-invasive grasses, forbs,
and shrubs
Choose nonsynthetic nutritional soil amendments such
as compost instead of chemical fertilizers
Reclaiming Residual Natural Resources
Historic landfills, waste piles, and components of passive
treatment systems at many mining sites offer the
opportunity to reclaim rather than dispose of valuable
metals or other natural resources. The reclaimed material
often can be sold to industrial businesses for recycling.
Depending on the type of materials formerly mined onsite,
green remediation BMPs include:
Use water treatment systems that recover metals from
AMD; for example, a system at the French Gulch site
near Breckenridge, Colorado, produces zinc sludge that
is used directly by a nearby zinc smelter
Recover metals such as copper or nickel from oxides
settling in limestone beds
Recover gold or copper from former mine tailings, if
control of associated cyanide- or sulfuric acid-
containing solution or leachate is feasible
Recover metals such as copper in slag remaining from
past smelting
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Explore options for excavating and recycling landfill
wastes from past coal mining and processing into
synthetic fuel (synfuel) that can be converted to useable
energy, rather than installing a new cover system, and
Explore potential to use methane from a co-located
landfill, ongoing coal extraction processes, or an
abandoned coal mine with methane recovery potential;8
at the abandoned Cambria Slope 33 Mine in
Pennsylvania, for example, recovered waste methane
powers a 0.7 megawatt (MW) off-grid electricity
generation facility for onsite natural gas extraction.
During cleanup at the 97-acre Fairmont Coke Works-
Sharon Steel Site in West Virginia, reclamation of historic
landfill material for use as synfuel feedstock resulted in:
Reduced burdens on the hazardous waste-permitted facility
otherwise receiving nearly 241,000 tons of waste
Avoided CHC emissions and heavy road use associated
with transport of waste to the permitted facility
Substitution of raw coal otherwise mined and processed to
produce electricity for about 37,000 homes over one year
Averted use of water otherwise needed to produce an
equivalent amount of fuel from raw coal by an offsite coal
processing plant. .
Re-establishment of
vegetative and soil
conditions that ex-
isted before mining
activities occurred
often is a critical
cleanup step and accelerates site restoration and
productive reuse. Re-established vegetation can help:
Stop physical dispersal of the waste through erosion,
wind, or human or animal direct contact
Minimize infiltration to and through mass below a
landfill/waste cover and control associated leachate
production and release
Provide elements of an ET cover that could develop
naturally over time
Apply phytotechnologies to treat soil or water
contaminated by non-heavy metals or chemical
compounds used in past processing activities
Capture and sequester atmospheric carbon, and
Restore ecological services to the community.
Ecosystem services are the benefits that people,
communities, and economies receive from nature. At mining
sites, healthy soil and vegetation provide significant
ecosystem services such as:
Purifying shallow groundwater and surface waters
Retaining water otherwise lost to runoff or evaporation,
and
Controlling erosion and minimizing associated loss of
valuable topsail during flooding.
EPA's National Risk Management Research Laboratory
recommends a three-step process to select plants most
effective for a vegetative landfill cover and complementary to
site reuse plans:
1) Obtain lists of suitable plants from:
The pertinent state highway department
Relevant and concerned non-government organizations
such as the Nature Conservancy
Researchers or contractors knowledgeable about the role
of vegetation in remediation and the site's conditions
2) Cross-reference the lists to identify plants recommended by
multiple organizations or experts
3) Consult with the local U.S. Department of Agriculture or
U.S. Forest Service office to determine which of those
plants are likely most viable in the target microclimate.
Integrating Cleanup with Restoration/Reuse
Green remediation BMPs can be implemented during
cleanup design or construction phases to ultimately help
restore mining-impacted ecological systems; for example:
Install trees that complement forestry plans on adjacent
properties owned by government agencies such as the
U.S. Forest Service, if the installation area excludes
constructed soil covers and suggests tree survival under
likely acidic conditions
Promote surface water corridors that replicate original
riparian conditions and complement regional watershed
plans
Incorporate re-use preferences of organizations wishing
to expand local recreational or environmental
education services for the community
Design cleanup infrastructures that complement
municipal or industrial plans to use the land for
regional waste-to-energy facilities; for example, timber
and agricultural businesses could supply biomass for
electricity generation, or food producers/retailers could
provide waste serving as feedstock for a biodigester
(which converts waste heat to useable energy), and
Coordinate with prospective renewable energy
developers to combine cleanup efforts with site reuse
for producing energy from onsite renewable resources;
EPA's RE-Powering America's Land initiative can provide
assistance in pursuing renewable energy development.9
At the Chevron Questa Mine site in Taos County, New
Mexico, a 1 MW concentrated solar photovoltaic (CPV)
facility currently operates above 20 acres of covered mine
tailings as remediation work in other areas begins; since
early 201 1 startup, the facility has sold generated electricity
to a local utility under a power purchase agreement.
At the New Rifle Mill site in Colorado, portions of the site
were converted to an energy innovation center without
disturbing continued cleanup efforts to address uranium and
vanadium contamination; the first installation of clean
energy technology on this site is a 12-acre, 1.7 MW zero-
emission solar energy system that powers a co-located
regional wastewater reclamation facility.
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Remedy construction and operation as well as site restoration
at the Elizabeth Mine Superfund site near South Stratford,
Vermont, involves a range of BMPs to: reduce air
contaminants associated with onsite or offsite fuel
consumption; use onsite rather than imported natural
resources wherever possible; establish processes for maximum
recycling or reuse of waste materials; and initiate a
procurement process for environmentally preferred products.
The greener cleanup strategy includes methods for preserving
the site's historic aspects and ecosystem services.10
Mining Sites:
Recommended Checklist
Characterizing MIW
Use field test kits, remote sensing techniques, and
geophysical methods wherever possible
Deploy low-flow sampling devices
Choose sonic drilling techniques and environmentally
friendly drilling fluids wherever possible
Using Passive Treatment Systems
Choose quickly renewable agricultural products or
industrial byproducts rather than raw natural
resources as organic-rich materials wherever possible
Integrate stormwater controls and capture rainwater
and snowmelt for onsite use
Minimize site disturbance by reusing remnant roads
and other infrastructure components
Integrating Onsite Renewable Energy
Maximize use of renewable energy systems to power
cleanup equipment
Deploy mobile units to generate power from solar or
wind resources as needed
Installing Soil Covers
Design with the intent of maintaining natural settings
and addressing potential effects of climate change
Maximize control of soil erosion caused by rain, wind,
or construction activities
Explore use of industrial waste products rather than
imported soil
Reclaiming Residual Natural Resources
Reclaim valuable metals from tailings or leachate
Explore production of useable energy from onsite
waste left by coal extraction/processing
Investigate potential to convert methane from a co-
located landfill into useable energy
Integrating Cleanup with Restoration/Reuse
Complement regional forestry and watershed plans
Deign cleanup infrastructures that complement reuse
options such as recreation
Coordinate with prospective utility-scale renewable
energy developers
Since 2001, a public-private partnership among the
Pennsylvania Department of Environmental Protection, Trout
Unlimited, other government agencies, local stakeholders, and
private industry has worked to address coal AMD at the
abandoned Fran Contracting, Inc. Camp Run No. 2
surface mine near Renovo, Pennsylvania. Preliminary
remediation work included constructing a pilot-scale passive
treatment system to treat AMD affecting three Susquehanna
River tributaries with high or exceptional values for water
quality and cold-water fisheries.
The system's sulfate-reducing bioreactor consisted of 50%
wood chips, 30% limestone, 10% manure, and 10% hay in a
lined cell three feet below ground surface and capped with
soil. Performance monitoring indicated the bioreactor
achieved significant increases in pH and reductions in acidity
and iron, aluminum, and sulfate concentrations within one
year of startup. Costs to construct the system, which treated
about one gallon of AMD per minute, totaled $42,000.
References [Web accessed: September 2012]
1 U.S. EPA; Principles for Greener Cleanups; August 27, 2009;
http://www.epa.gov/oswer/greenercleanups
2 Abandoned Mine Lands Portal;
http://www.abandonedmines.gov/ep.html
3 U.S. EPA; Green Remediation Best Management Practices:
" Clean Fuel & Emission Technologies for Site Cleanup; EPA 542-F-
10-008; August 2010
b Integrating Renewable Energy into Site Cleanup; EPA 542-F-l 1 -006;
April 201 1
c Pump and Treat Technologies; EPA542-F-009-005; December
2009
dS/fe Investigation; EPA542-F-09-004; December 2009
e Landfill Cover Systems & Energy Production; EPA 542-F-l 1-024;
December 201 1
4 U.S. Department of Energy; Environmentally Friendly Drilling System
Program: Balancing Environmental Tradeoffs; June 201 1
5 U.S. EPA; CLU-IN Green Remediation Focus; DeSale Restoration
Area; http://www.cluin.org/greenremediation/subtab_d20.cfm
6 "Banana Peel Applied to the Solid Phase Extraction of Copper and
Lead from River Water: Preconcentration of Metal Ions with a Fruit
Waste;" Renata S.D. Castro et al.; Industrial & Engineering Chemistry
Research; 201 1, 50 (6), 3446-3451
7 U.S. EPA; Palmerton Zinc Pile, Superfund Case Study; February 201 1;
EPA 542-F-l 1-005
8 U.S. EPA; U.S. Abandoned Coal Mine Methane Recovery Project
Opportunities; EPA 430-R-08-002; July 2008;
http://www.epa.gov/coa I bed/docs/cmm_recovery_opps.pdf
9 U.S. EPA; RE-Powering America's Land;
http://www.epa.gov/oswercpa/index.htm
10 U.S. EPA; CLU-IN Green Remediation Focus; Elizabeth Mine;
http://www.cl uin.org/greenremediation/subtab_d36.cfm
EPA/OSWER appreciates the many contributions to this fact sheet, as
provided by EPA's National Mining Team, regional offices, and
laboratories or by private industry.
The Agency is publishing this fact sheet as a means of disseminating
information regarding the BMPs of green remediation; mention of specific
products or vendors does not constitute EPA endorsement.
Visit Green Remediation Focus online:
http://www.cluin.org/greenremediation
For more information, contact:
Carlos Pachon, OSWER/OSRTI (pachon.carlos@epa.gov)
U.S. Environmental Protection Agency
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