Canadian Dam Association Bulletin - Summer 2017 - 14

1. INTRODUCTION
The Peace River hydroelectric system in British Columbia consists of
two existing projects, G.M. Shrum
Generating Station at the W.A.C.
Bennett Dam and Peace Canyon
Generating Station, and one project
which is currently under construction known, the Site C Clean Energy
Project. The Peace River hydroelectric
system is presented in Figure 1.
The Site C Clean Energy Project's
60 m high dam is located 83 km downstream of the Peace Canyon Dam. It
is 7 km southwest of Fort St. John,
just downstream of the confluence
of the Moberly River and the Peace
River, and 62 km upstream from the
British Columbia/Alberta border.
The reservoir, with a surface area of
approximately 9,310 hectares, will
extend back to the tailrace of the Peace
Canyon Dam.
The Site C Clean Energy Project will
consist of six generating units with a
total capacity of 1,100 MW, producing
an average of 5,100 GWh of electricity
annually. Site C will take advantage
of regulation of the Peace River that
is provided by the W.A.C. Bennett
Dam, generating electricity from
water discharged by the G.M. Shrum
Generating Station and the Peace
Canyon Generating Station. Most of
the inflow into the Site C reservoir will
come from the Peace Canyon Dam,
however, the Halfway River, and to a
lesser extent, the Moberly River and
smaller tributaries, will also contribute some inflows.
Studies for the development of the
third hydroelectric generating station
on the Peace River first commenced
during the late 1970's and early
1980's. Conceptual arrangements
of the project were developed and

Figure 1: The Peace River Hydroelectric System
14

extensive field and laboratory investigations were undertaken. Work on
the development stopped in the mid
1980's and was briefly re-started in
the period from 1989 to 1991. Studies
re-commenced in 2006 and the configuration design was completed in
2010. This was followed by the definition design and finally the implementation design which is currently
on-going.
Construction of the project started
in the summer of 2015 with the preliminary works (site clearing, access
roads, worker accommodation, construction power and other construction facilities). The Main Civil Works
construction, which includes the
construction of the earthfill dam,
the diversion works, the approach
channel, the roller compacted concrete (RCC) buttress and excavation
work started in the summer of 2016.
The implementation design of the
generating station and spillway is
currently on-going with the scheduled awarding of this work to be in
the summer of 2017. Commissioning
of the generating station is planned
for 2023-2024.

2. THE GEOLOGY AT THE SITE
2.1 Regional Geology
The project dam site and reservoir
area are located at the western edge
of the Interior Plains. This region,
from the Peace Canyon Dam to the
B.C./Alberta border, is a flat to slightly
rolling plain in which the Peace River
has eroded a broad, U shaped valley
on average a few kilometres wide and
180 to 230 m deep.
The modern Peace River began to
evolve after the retreat of the last ice
sheet and the subsequent drainage of
the glacial Peace Lake. In the expanse
between the Peace Canyon Dam and
Site C, the Peace River has cut down
through a thick cover of overburden,
which was deposited during and
after glaciation, and into flat-lying
Cretaceous silty shales, shales and
sandstones. The valley generally
follows the ancestral pre-glacial
or inter-glacial drainage pattern;

however, at the dam site the present
day river is on the North side of its
former valley.
The river has, for the most part,
rapidly eroded its valley into unconsolidated glacial deposits, leaving
steep overburden slopes that have
been prone to sloughing and sliding.
In the location where the river departs
from the overburden-filled ancestral
valley, it has cut down steep shale
slopes. Subsequently, large and small
bedrock slides have occurred along
the banks.
Marine and non-marine- sedimentation in North-Eastern British Columbia
and North-Western Alberta lasted from
Jurassic to Upper Cretaceous period
(190 to 65 Ma). In the Site C dam and
reservoir areas, only lower and upper
Cretaceous rocks are exposed in the
river valley. The rocks belong to the
Fort St. John Group of sedimentary
rocks which are subdivided into four
formations: Dunvegan, Shaftesbury,
Gates and Moosebar. Only the shales,
silty shales and sandstones belonging to the Shaftesbury formation, are
present at and near the surface at the
dam site.
2.2 Structural Geology at Site C
Site C is underlain by Lower
Cretaceous rocks of the Shaftesbury
formation. These rocks consist of
dark grey, moderately weak, flaky to
fissile, silty shale, interbedded with
thin beds of siltstone, sandstone and
shale. These rocks are of marine origin, and are in an intermediate stage
of diagenesis. Fourteen lithologic units
have been delineated in the bedrock
at the dam site. The predominant rock
type is a silty shale; weaker shale units
comprise a small portion of the rock.
The unconfined compression strength
of the rock units at the site vary from
5 MPa to 15 MPa.
The stratigraphic section remains
almost constant in thickness throughout the site, although rock units on
the left (North) bank are often slightly
coarser grained than their equivalent
on the right (South) bank. A stratigraphic column identifying the geology at Site C is presented in Figure 2.

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Table of Contents for the Digital Edition of Canadian Dam Association Bulletin - Summer 2017

Board of Directors
President's Message
Roller Compacted Concrete Buttress at the Site C Clean Energy Project
Hurricane Igor's Impact on Newfoundland Power's Small Hydro
CDA Conference Heads to Kelowna!
CDA Directors & Officers - Call for Nominations
2017 CDA Awards - Call for Nominations
CDA Developing New Ways to Distribute Guidelines
Notice of Annual General Meeting
Time to Renew Your Membership
Buyers' Guide and Trade List
Canadian Dam Association Bulletin - Summer 2017 - intro
Canadian Dam Association Bulletin - Summer 2017 - 1
Canadian Dam Association Bulletin - Summer 2017 - 2
Canadian Dam Association Bulletin - Summer 2017 - 3
Canadian Dam Association Bulletin - Summer 2017 - 4
Canadian Dam Association Bulletin - Summer 2017 - 5
Canadian Dam Association Bulletin - Summer 2017 - 6
Canadian Dam Association Bulletin - Summer 2017 - Board of Directors
Canadian Dam Association Bulletin - Summer 2017 - 8
Canadian Dam Association Bulletin - Summer 2017 - President's Message
Canadian Dam Association Bulletin - Summer 2017 - 10
Canadian Dam Association Bulletin - Summer 2017 - 11
Canadian Dam Association Bulletin - Summer 2017 - Roller Compacted Concrete Buttress at the Site C Clean Energy Project
Canadian Dam Association Bulletin - Summer 2017 - 13
Canadian Dam Association Bulletin - Summer 2017 - 14
Canadian Dam Association Bulletin - Summer 2017 - 15
Canadian Dam Association Bulletin - Summer 2017 - 16
Canadian Dam Association Bulletin - Summer 2017 - 17
Canadian Dam Association Bulletin - Summer 2017 - 18
Canadian Dam Association Bulletin - Summer 2017 - 19
Canadian Dam Association Bulletin - Summer 2017 - 20
Canadian Dam Association Bulletin - Summer 2017 - 21
Canadian Dam Association Bulletin - Summer 2017 - 22
Canadian Dam Association Bulletin - Summer 2017 - 23
Canadian Dam Association Bulletin - Summer 2017 - Hurricane Igor's Impact on Newfoundland Power's Small Hydro
Canadian Dam Association Bulletin - Summer 2017 - 25
Canadian Dam Association Bulletin - Summer 2017 - 26
Canadian Dam Association Bulletin - Summer 2017 - 27
Canadian Dam Association Bulletin - Summer 2017 - 28
Canadian Dam Association Bulletin - Summer 2017 - 29
Canadian Dam Association Bulletin - Summer 2017 - 30
Canadian Dam Association Bulletin - Summer 2017 - 31
Canadian Dam Association Bulletin - Summer 2017 - 32
Canadian Dam Association Bulletin - Summer 2017 - 33
Canadian Dam Association Bulletin - Summer 2017 - 34
Canadian Dam Association Bulletin - Summer 2017 - 35
Canadian Dam Association Bulletin - Summer 2017 - CDA Conference Heads to Kelowna!
Canadian Dam Association Bulletin - Summer 2017 - 37
Canadian Dam Association Bulletin - Summer 2017 - 38
Canadian Dam Association Bulletin - Summer 2017 - 39
Canadian Dam Association Bulletin - Summer 2017 - 40
Canadian Dam Association Bulletin - Summer 2017 - 41
Canadian Dam Association Bulletin - Summer 2017 - 42
Canadian Dam Association Bulletin - Summer 2017 - 43
Canadian Dam Association Bulletin - Summer 2017 - 44
Canadian Dam Association Bulletin - Summer 2017 - 45
Canadian Dam Association Bulletin - Summer 2017 - CDA Directors & Officers - Call for Nominations
Canadian Dam Association Bulletin - Summer 2017 - 47
Canadian Dam Association Bulletin - Summer 2017 - 2017 CDA Awards - Call for Nominations
Canadian Dam Association Bulletin - Summer 2017 - 49
Canadian Dam Association Bulletin - Summer 2017 - CDA Developing New Ways to Distribute Guidelines
Canadian Dam Association Bulletin - Summer 2017 - 51
Canadian Dam Association Bulletin - Summer 2017 - 52
Canadian Dam Association Bulletin - Summer 2017 - Notice of Annual General Meeting
Canadian Dam Association Bulletin - Summer 2017 - Time to Renew Your Membership
Canadian Dam Association Bulletin - Summer 2017 - Buyers' Guide and Trade List
Canadian Dam Association Bulletin - Summer 2017 - 56
Canadian Dam Association Bulletin - Summer 2017 - 57
Canadian Dam Association Bulletin - Summer 2017 - 58
Canadian Dam Association Bulletin - Summer 2017 - 59
Canadian Dam Association Bulletin - Summer 2017 - 60
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