Phase II Environmental
Site Assessment
ESA - Environmental Site Assessment
Phase I
•
Records review
•
Site reconnaissance
•
Inter views
•
Report
•
No invasive sampling!
The objective of a Phase II ESA
is to determine the exact nature
of contamination at a site and to
characterize the sources, extent,
and movement of contaminant
plumes in the subsurface.
Phase II
•
Triggered by findings of Phase I
•
Delineation of type and extent of site
contamination
•
Invasive sampling and testing
Phase III
•
Remediation and site monitoring
Brownfield Action
Phase II BA Tools
Invasive:
Drilling / Push
Excavation
Non-Invasive:
Ground Penetrating
Radar (GPR)
Magnetometry / Metal
Detection (MMD)
Seismic Reflection and
Refraction (SRR)
Topographic Survey (TS)
Drilling / Direct Push
Direct sampling of
groundwater at
multiple levels.
Elevation of the water
table.
Elevation of the
bedrock surface.
Groundwater samples
can be analyzed for
hydrocarbons or for
tritium.
Push is cheaper than
drilling, but limited to
a depth of 100 ft
below the surface.
Ground Penetrating
Radar (GPR)
Detects disturbances
and objects in the
subsurface along a 100
ft transect.
Useful for detecting
USTs, buried drums,
dry wells (disturbed
soil), fill areas.
Magnetometry and
Metal Detection (MMR)
Detects metal objects
in the subsurface
within a 10 square ft
area.
Useful for locating
buried drums, USTs,
and buried pipelines.
Excavation
Excavation of a 10 ft
by 10 ft square hole.
Description of soil and
any objects
encountered.
Useful for confirming
the identify of objects
detected using GPR or
MMR.
Soil Gas Sampling and
Analysis (SGSA)
Sampling of soil gas to
a depth of 10 ft in the
zone of aeration
(vadose zone).
Detects hexane - a
major component of
gasoline.
Gasoline floats on
groundwater and pools
in the vadose zone,
emitting vapors.
Seismic Reflection and
Refraction (SRR)
Provides the elevation
of bedrock at points
every 10 ft along a
transect.
DNAPLE contaminants
(more dense than
water) sink and pool in
bedrock lows.
Each transect is a
maximum of 230 ft.
Useful for creating a
map of the bedrock
surface (base of the
aquifer).
Topographic Survey Tool
(SRR)
Provides the elevation
of the land surface at
a point.
Useful for estimating
the shape of the
water table.
Depth of the water
table below surface
can be confirmed by
drill / push.
Testing is expensive. Plan ahead. Choose your
testing locations carefully based on the map grid
and Phase I intelligence.
Use non-invasive tests first - they are cheaper.
Locate potential sources of contamination (product).
Start groundwater sampling at potential source
points for contaminant. Once detected, fan out in
the direction of groundwater flow.
Take careful notes and tabulate all results as they
come in.
Plot results on map grid. Use separate sheets for
different types of data.