July-August_2021 - 31

PFAS
The result is that as CAC is injected, it
moves through the soil pores but also
coats them with a thin carbon layer that
encapsulates the individual soil grains, in
effect " painting " them with activated
carbon.
In Situ CAC Treatments
for PFAS at Aviation Facilities
- Current Status
In situ CAC treatments have been
used for the treatment of organic
groundwater contaminants since 2014.
These treatments have been applied
at numerous PFAS-contaminated
groundwater sites,
including three
ongoing pilot tests at aviation facilities
- a former Army airfield and two
commercial airports.
Camp Grayling Army Airfield,
Scanning electron microscope image of clean
sand particles without CAC.
REGENESIS
Scanning electron microscope image of sand
particles coated with CAC.
REGENESIS
Currently, there are limited
opportunities to dispose of PFAS
waste as landfills are turning it away
and the EPA is now scrutinizing
the incineration of the material as
commercial incinerators may be
generating unwanted toxic by-products.
More
recently,
groundwater
remediation scientists and engineers
have adopted an in situ PFAS treatment
method. This approach uses a colloidal
form of activated carbon applied directly
into the groundwater. The colloidal
activated carbon (CAC)
treatment
works by intercepting contaminants
that move naturally through established
groundwater pathways. To accomplish
this, CAC is injected along a line of
delivery points (i.e. wells or boreholes)
into the affected aquifer zone to form
a permeable reactive barrier (PRB). As
groundwater migrates across the PRB,
PFAS sorbs onto the carbon, resulting
in a clean water discharge from the
barrier's downgradient edge. The
treatment, therefore, eliminates risk
by eradicating the potential exposure
to these chemicals through drinking
water ingestion.
Material scientists developed CAC
to overcome the challenge of evenly
dispersing a solid injected material
(i.e. activated carbon) through aquifer
soils. This required carbon particles
to be ground to one to two microns,
equivalent in size to a red blood cell
and small enough to fit
through
soil pore throats. However, due to
hydrostatic forces that result in particle
agglomeration, merely shrinking their
particle size will not allow carbon to
pass through these openings readily.
Overcoming the clumping tendency of
particles required forming the carbon
as a colloidal suspension, made possible
through a proprietary, drinking-water
safe, anti-clumping treatment
that
cloaks the particles' surface charge.
Michigan - In 2016, PFAS was found
commingled with a chlorinated solvent
plume that was migrating towards
the property boundary. In reviewing
remedial options, the Michigan
Department of Military and Veteran
Affairs chose to conduct an in-situ
CAC PRB pilot test to halt the PFAS
plume. PFAS were reduced from more
than 100 nanograms per liter or (ng/L
or ppt) to below detection limits in the
first sampling event, approximately one
month after installing the CAC PRB.
PFAS have remained non-detect in all four
downgradient well-pairs after nearly two years
of post-application monitoring completed thus
far. Tetrachloroethene (PCE) was also
reduced and maintained below detection
limits by the treatment.
Fairbanks International Airport
(FAI), Alaska - In late Oct. 2017, PFAS
were discovered in the groundwater at
the Aircraft Rescue and Firefighting
(ARFF) training areas. PFOA and
PFOS were detected above the EPA's
Health Advisory Level of 70 ng/L. An
in situ CAC proof-of-concept pilot
test application was completed in
2019 near MW-1903. The treatment
has maintained PFOA and PFOS
below detection levels from a starting
concentration of 500 ng/L and
reduced all PFAS by 97 percent (i.e.,
includes short-chain compounds) after
approximately 1 year of monitoring
completed.
A pilot test has also just commenced
at Southampton International Airport in
JULY/AUGUST 2021 \ AVIATIONPROS.COM / 31
http://www.AVIATIONPROS.COM

July-August_2021

Table of Contents for the Digital Edition of July-August_2021

Inside the Fence
Industry Update
FBOs Make a Strong Case for Increasing Charter, Flightschool Business, Other Service Offerings
Legal Matters
New Technology Takes Control of Baggage Systems
Innovating Airport Operations
TAC Air Expands and Improves in Amarillo
PFAS-Contaminated Drinking Water: A Growing Concern for Airports
Airports by the Thousands
Satellites Have the Power to Transform the Aviation Industry
Product Focus
July-August_2021 - 1
July-August_2021 - 2
July-August_2021 - 3
July-August_2021 - 4
July-August_2021 - Inside the Fence
July-August_2021 - Industry Update
July-August_2021 - 7
July-August_2021 - 8
July-August_2021 - 9
July-August_2021 - FBOs Make a Strong Case for Increasing Charter, Flightschool Business, Other Service Offerings
July-August_2021 - 11
July-August_2021 - Legal Matters
July-August_2021 - 13
July-August_2021 - New Technology Takes Control of Baggage Systems
July-August_2021 - 15
July-August_2021 - 16
July-August_2021 - 17
July-August_2021 - 18
July-August_2021 - 19
July-August_2021 - Innovating Airport Operations
July-August_2021 - 21
July-August_2021 - 22
July-August_2021 - 23
July-August_2021 - 24
July-August_2021 - 25
July-August_2021 - TAC Air Expands and Improves in Amarillo
July-August_2021 - 27
July-August_2021 - 28
July-August_2021 - 29
July-August_2021 - PFAS-Contaminated Drinking Water: A Growing Concern for Airports
July-August_2021 - 31
July-August_2021 - 32
July-August_2021 - Airports by the Thousands
July-August_2021 - 34
July-August_2021 - 35
July-August_2021 - Satellites Have the Power to Transform the Aviation Industry
July-August_2021 - 37
July-August_2021 - 38
July-August_2021 - 39
July-August_2021 - Product Focus
July-August_2021 - 41
July-August_2021 - 42
July-August_2021 - 43
July-August_2021 - 44
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