Groundwater Pollution
0420 – Site Investigation
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Will the material be tested in
the ground or removed for
testing?
- in the ground – using remote
sensing
- removed for testing – using
cores or pumping gas or
water.
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Remote sensing
technology is being
developed.
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Photograph of a fiber optic biosensor; the
functional tip with immobilized pH indicator and
cells is directly over the coin.
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005
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Fiber optic biosensor.
One end of the optical fiber is coated
by a pH-sensitive fluorophore which is
covered by cells or enzymes in Caalginate.
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005
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2-layer detection element of the CSU biosensor, illustrated for the
ethylene dichloride biosensor. The pH-sensitive fluorophore is excited
with 480-nm light and emits fluorescence at 520 nm, which is
transmitted along the optical fiber to a photomultiplier.
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005
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Down-hole profiling setup.
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005
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Down-hole profiling results
(biosensor readings vs. depth)
Final Report: Fiber Optic Biosensors for Contaminant Monitoring. US DoD 2005
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Downhole XSD (halogen specific detector),
uses oxidative chemistry.
Vapors pass through a reactor core of 800-1100
C, which breaks C-Cl bonds. A current forms as
the chlorine atoms pick up electrons.
Direct Push Chemical Sensors for DNAPL DoD 2007
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Experimental data from pushes of the halogen specific detector at a former dry
cleaning site.
Direct Push Chemical Sensors for DNAPL DoD 2007
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Direct push sensor systems
– Petroleum sensor: LaserInduced Fluorescence (LIF)
– Metal sensor: Laser-Induced
Breakdown Spectroscopy (LIBS)
– Solvents/soil characteristics:
Soil Video Imaging System
(GeoVIS)
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Problems with traditional
characterization methods
• Traditional methods depend on collection of
samples and laboratory analysis
– difficult to know where to collect samples
– delay in getting results from laboratory
• may require several trips back to the field
– limited sample coverage
• may miss sources of contamination
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Downhole video imaging system probe
Direct Push Chemical Sensors for DNAPL DoD 2007
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In situ image of soil showing NAPL micro-globules
Direct Push Chemical Sensors for DNAPL DoD 2007
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Fiber optic chemical sensors
(FOCS) operate by
transporting light by
wavelength or intensity to
provide information about
analytes in the environment
surrounding the sensor.
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The sensor is placed directly into
the media to be analyzed.
Interaction of the analyte with the
chemically selective layer creates a
change in absorbance, reflectance,
fluorescence, or light polarization.
The change is detected by
measuring changes in the light
characteristic carried by the optical
fiber.
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Intrinsic FOCS measure:
- volatile petroleum constituents,
such as benzene, toluene,
ethylbenzene, and xylenes (BTEX),
- chlorinated volatile organic
compounds (VOCs), such as TCE,
PCE, and carbon tetrachloride, in
water, air, or soil gas.
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Extrinsic FOCS can detect:
- fluorescing hydrocarbons in
the subsurface (often PAHs).
- elements in water, air, or soil.
- metals and organic chemicals
in solid, air, or liquid.
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Laser-Induced Fluorescence (LIF)
detects:
- hydrocarbons (gasoline, diesel
fuel, jet fuels, fuel oil, motor oil,
grease, and coal tar) in
undisturbed subsurface soils
and groundwater.
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Laser-Induced Fluorescence (LIF) tip
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Components of monitoring well
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Waste Containment and Remediation Technology
Well Logs
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Waste Containment and Remediation Technology
Well installation Diagram
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Waste Containment and Remediation Technology
Soil borings are often drilled to assess
the extent of contamination in the
vadose zone.
Samples are taken at every 2 or 3 m, and
analyzed for soil properties.
Some samples are analysed in laboratories for
contaminant concentrations.
From these data, a diagram is often developed
to show the spread of the contaminant plume.
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http://mn.water.usgs.gov/bemidji/results/fact-sheet.pdf
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A map can be
made of the
plume
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NAPL may float on top of the
water table and form a layer.
Estimate the volume or mass of
the floating contaminant.
The thickness of free pollutant
found in monitoring wells can be
used to calculate the volume of
the pollutant.
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http://mn.water.usgs.gov/bemidji/results/fact-sheet.pdf
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Example cross section
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Waste Containment and Remediation Technology
Laboratory Analysis
Full analysis - $1100
(volatiles, semivolatiles, hazardous waste, pesticides, herbicides)
Volatile organics - $185
Semivolatile organics - $360
RCRA Appendix 8 metals - $110
(As, Ba, Cd, Cr, Pb, Hg, Se, Ag)
TAL metals - $240
(Al, Sb, As, Ba, Be, Cd, Ca, Cr, Co, Cu, Fe, Pb, Mg, Mn, Hg, Ni, K, Se, Ag, Na, Tl, V, Zn)
Pesticides - $145
Herbicides - $250
Source: Alpha Analytical Labs, Westborough, MA. April 2001 price list
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Waste Containment and Remediation Technology
Groundwater can be sampled
Purging means take out old
water from a monitoring well
before sampling groundwater.
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Two rows of monitoring points
http://toxics.usgs.gov/sites/laurel_bay/images/LaurelBay4.jpg
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When you take a sample from a
monitoring well you must remove
the water which is in the well before
sampling the groundwater.
A few parameters are often
monitored, such as conductivity, pH,
and temperature, so they reach an
even level before sampling.
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Well purging before sampling
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Purge 3 to 5 well volumes
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He is collecting
a sample of
groundwater
from a well
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http://nevada.usgs.gov/adrs/images/photos/groundwater/GroundWaterSampling/gw3.html
Purging can create problems.
It takes time
It produces waste water which
needs to be treated.
Instead of purging the water it
might be possible to pull out
some water directly from the
bottom of the well.
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Passive diffusion sampler for
water phase
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The diffusion sampler stays in
the bottom of the well for some
time.
Then it is removed and the water
inside it is analyzed.
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Water samples must be analyzed.
This can be done in a laboratory
or at the site (in the field).
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Determine the number and type of microorganisms
carrying out biodegradation
http://toxics.usgs.gov/photo_gallery/photos/bimidji/bemidji_inoculating.jpg
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