Transcript EGP Intervener Meetings June 2014

Eagle Mountain – Woodfibre Gas
Pipeline Project
Geotechnical and geophysical tests
James Lota, FortisBC
September 25, 2014
Welcome
Why are geotechnical & geophysical
tests needed?
• Common engineering
practice when planning
underground construction
method such as horizontal
directional drilling (HDD).
• Minimize environmental
impacts and construction
risk:
• Squamish Estuary
• Highway 99 at Industrial Way
Where are the tests being proposed?
2 boreholes
in the dike
3 boreholes
in the Estuary
1 borehole
outside the
Estuary
4 boreholes
along
Finch/Industrial
What is a borehole?
• Commonly used in engineering site assessments around
the province.
• Used to collect soil samples to determine subsurface
conditions of the area.
• Narrow vertical shaft bored into the ground to a depth of
20 to 70 metres (~ 10” diameter).
What is a borehole?
Heli-portable
drill eliminates
need for
clearing of
access trails
Core Sample
Non-Reactive
Bentonite “Plug”
Approx. 30m x 30m safe workspace is required
20m – 70m deep
10” diameter
Example of core samples
Typical borehole testing equipment
Heli-portable drill rig
Typical borehole testing equipment
Track mounted drill rig
Minimizing environmental impacts
• Boreholes in estuary were
handpicked to minimize
clearing requirements.
• No clearing – Dike or
Finch Drive – Industrial
Way.
• FortisBC will replant any
disturbed areas with
native vegetation.
What is geophysical testing?
• Three types of testing are proposed:
• Ground penetrating radar (GPR)
• Electric Resistance Tomography (ERT)
• Multi-channel analysis of surface waves (MASW)
• All the above technologies consist of portable
equipment that workers can easily carry in the field.
Ground Penetrating Radar (GPR)
environmental impacts
• Transmits radio waves into
the ground to detect
subsurface features.
• Non-invasive and
relatively quick
Electric Resistance Tomography (ERT)
• Images sub-surface areas
by measuring resistivity
with low-levels of either
AC or DC current.
• Helps determine the
geometry, lithology,
hydrology and/or petrology
of subsurface geologic
formations.
Multi-channel Analysis of Surface
Waves (MASW)
• Exploration method used
widely since the 1990s.
• Measures seismic surface
waves generated from a
seismic sources (such as
sledge hammer).
• Results characterize or
estimate
stiffness/hardness of
materials at depth.
Minimal environmental impact
• Hand clearing of brush and
deadfall, as necessary for
worker safety.
•
Required by Worksafe BC to
avoid injuries.
• Animal walking trail width is
sufficient.
• Doesn’t require cutting down
large timber (e.g. > 3” – 4”)
Environmental Management Plan (EMP)
• Although geotechnical / geophysical tests have minimal
environment impact, FortisBC has prepared extensive
EMP that includes:
• Environmental monitoring
• Archeological monitoring
• Environmental controls such as:
• Schedule – access
• Tree and vegetation
• Fire
• Drilling waste
• Hazardous materials
• Waste management and disposal
• Air
• Noise
• Environmental incidents and spills
• Restoration
Thank you
Proprietary and Confidential
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