Guest Post
by James L. Gordon, P. Eng. (Ret’d)
THE NORTH SPUR DESIGN
HAS NOT BEEN REVIEWED BY
MULTIPLE GEOSCIENCE
ENGINEERS!
The presence of quick clay and soft sensitive clay has been
known ever since the Spur was first investigated in 1965. Several consulting
engineering companies have looked at the Spur and issued reports on their
investigations. Many have proposed solutions to stabilize the Spur.
However, all this work can be regarded as preliminary since
the geotechnical investigations were incomplete. None of the proposed solutions
were “approved for construction”, nor intended to be. They were the first
attempts to find a suitable solution to the instability demonstrated by the
many landslides in the vicinity of the Spur, and on the Spur.
SNC have undertaken further geotechnical tests and have
developed a design which has been “approved for construction”, and has been
built.
However, the design has
not been reviewed by senior geotechnical engineers with experience in sensitive
and quick clay, contrary to the assertions of Natural Resources Minister
Siobhan Coady.
Also, the Canadian Dam Safety Guidelines are not applicable to
natural dams, and are intended for use on fully engineered and constructed
dams, such as those at Bay d’Espoir.
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| James L. Gordon, P. Eng. |
Also the statement “Engineering design was undertaken by
qualified geotechnical engineers," validated by MWH Canada, the project's
independent engineer, and consultant Hatch Ltd., Nalcor said, is not correct.
There has been no validation of the design, for the following reasons –
1.
MWH
was retained by the Federal Government to report on the construction progress,
and their mandate specifically excludes any design review. I asked Mr. D.
Penman, Project Manager at MWH to comment on this, and his emailed dated
9/12/2016 reply was – “MWH have never at
any stage been involved in the design of the North Spur. We act as
Lender’s Engineer to the Federal Government and have never at any point been
actively involved in the design of any of the project components. I
think you should correct this as I believe some of this ends up in the
Newfoundland Press.”
2.
I
asked an engineer at Hatch if they have reviewed the design of the North Spur,
and his verbal answer was all they have
contributed was a 3-dimensional computer program designed to simulate the
ground water levels in the spur during and after the reservoir is filled.
It is acknowledged that this statement needs corroboration by Hatch.
Other experts mentioned by Nalcor who have undertaken a
review are Dr. Lerouil and Professor Idriss. This is subject to interpretation
since –
3.
Dr.
Serge Leroueil, a professor at the University of Laval, Quebec City, in his
letter review of the SNC “Engineering Report – North Spur
Stabilization Works – Dynamic analysis study – Phase 2, dated May 2014”, sent
to Mr. Regis Bouchard, Lead Geotechnical Engineer for Muskrat dated August 24,
2014, Dr. Leroueil states in the opening paragraph - “my knowledge on the dynamic behaviour of soils and its analysis is
rather limited”. In other words, he acknowledges that he is not qualified
to review the report.
4. The other expert mentioned by Nalcor
is the retired Professor Emeritus I. M. Idriss of the University of California
Davis Campus. He is a recognised expert in earthquakes. He attended a few
meetings, but never issued any reports.
This has been the main reason for my concerns about the North
Spur: a natural dam containing sensitive and quick clays, normally avoided at
all costs by dam designers, and built with no detailed review of the design by
qualified geotechnical experts.
Jim Gordon. P. Eng. (Retired)
