Geotech - Ottawa Confederation Line

Light Rail Transit
OLRT Tunnel Geotechnical Update
Technical Briefing
December 21, 2010
John Jensen
Rail Implementation Office
Presentation Overview
• Background
• Preliminary Engineering Overview
• OLRT Project Review
• Geotechnical Investigations Rationale
• Geotechnical Investigations Update
• Questions
Project Review
Functional Design
The functional design of the OLRT project (approved by
Council January 2010) described a downtown tunnel
• Is approximately 3.2km in length with 4 underground
• Has a western portal located just east of Lebreton
Station, near Brick Hill Street
• Has an eastern portal located just south of Campus
Station, near Mann Avenue
Council directed staff to continue to refine the OLRT
project design and seek cost savings where possible
Project Review
• The Rail Implementation Office (RIO) last provided its
quarterly update to Transit Committee in September
• At that time, RIO advised Committee that Phase 1
geotechnical fieldwork had been completed and that
Phases 2 and 3 were scheduled for fall 2010 and spring
2011, respectively
• RIO’s intent was to provide a geotechnical report with
data and analysis once Phase 3 investigations were
• Due to expressed interest, RIO will provide the
preliminary data set as provided by the firm chosen to
conduct the geotechnical investigations, Golder
• This presentation is to review the Phase 1 geotechnical
data set
Preliminary Engineering
• The City selected Capital Transit Partners, a joint venture
involving four firms with international expertise, to conduct
OLRT preliminary engineering
Jacobs Associates
Morrison Hershfield Limited
STV Canada Consulting Inc.
URS Canada Inc.
• The Preliminary Engineering work will advance the OLRT design
and generate specifications for final design and construction and
will be complete in Q1 2012
• Golder Associates has provided the Phase 1 geotechnical data to
the preliminary engineering team and will continue as the
selected firm to conduct Phase 2 and 3 investigations
Preliminary Engineering
Advancing Design
• As a result of data gathering and advancing the OLRT project design,
preliminary engineering staff are exploring several design
modifications including:
• Locating tunnel’s east portal on the existing transitway south of Laurier Avenue,
and situating Campus station on the surface in its current location instead of in
the tunnel
• Shifting the ORLT alignment at Train station slightly northward outside of the
Train station frontage area to allow for planned development and Highway 417
pedestrian bridge
• Remaining on the transitway alignment at Bayview station and simplifying the
station and phasing its’ construction
• Once design modifications have been fully explored staff will present
them to Council.
Project Review
January 2010
May – August 2010
September 2010
Approved Functional Design
Phase 1 geotechnical investigation fieldwork
Preliminary Engineering Commences
October – December 2010 Phase 2 geotechnical investigation fieldwork
April - July 2011
Q1 2012
2012 - 2013
Phase 3 geotechnical investigation fieldwork
Preliminary Engineering completed
Procurement process underway
Construction Contract Award
Construction Begins
System in Service
Geotechnical Investigations
• The purpose of geotechnical investigations is to
obtain information necessary to understand
engineering characteristics of the ground
• For a tunnel designer and builder, the ground
conditions set the construction environment
• Understanding the ground’s engineering
characteristics are as important as the concrete and
steel used to construct stations
Geotechnical Investigations
• In keeping with industry best practices, more
thoroughly investigated tunnels have better cost and
schedule certainty
• The geotechnical investigations for the LRT project
are being undertaken in phases with each phase
building on what was learned in the previous phase
Geotechnical Investigations
Geotechnical Investigation Schedule
# of Boreholes
Phase 1
May to August
December 2010
Phase 2
October to
December 2010
April 2011
Phase 3
(≈ 100)
April to July
November 2011
Geotechnical Investigations
• Phase 1 of the Geotechnical and Hydrogeological Field
Investigation was completed in August 2010 and was
confined to the tunnel alignment
• Preliminary data indicates that nothing has been
encountered that would affect the technical feasibility
of the project
Geotechnical Investigation
• West tunnel portal (west of Bronson) to Laurier Ave –
fill, glacial till and bedrock
• Laurier Ave to East tunnel portal (near Campus
station) – fill, silty clay, sand, glacial till and bedrock
• Bedrock consists mostly of limestone although some
eastern sections are mostly shale
• As anticipated, a number of seismically inactive faults
have been inferred from the boreholes
Geotechnical Investigation
• The results of this investigation are generally consistent
with the ground conditions indicated in the functional
• Some variations were encountered along the alignment
south of Laurier Avenue, where the bedrock was generally
deeper than assumed in functional design
• The specific locations where the ground conditions differ
are subject to further investigation in Phases 2 and 3 of the
geotechnical work
• Data from Phases 2 and 3 of the geotechnical fieldwork will
be provided on the OLRT website when available in April
2011 and November 2011
Key Messages
 The results of this investigation are generally
consistent with the ground conditions indicated in
the functional design
 Preliminary data indicates that nothing has been
encountered that would affect the technical
feasibility of the project or the project cost estimate
 All ground conditions noted to date can be
accommodated using standard engineering practices
and contracting strategies
 The preliminary engineering team continues to adapt
and refine the project design to match our
knowledge of the ground conditions