Canadian Dam Association Bulletin - Fall 2016 - 21

can be avoided by removing excavated rock from site to be disposed at an approved disposal site. Regional geology patterns indicate the Halifax Slate is more resistant to erosion than the Goldenville metasandstone. The geotechnical investigation indicated that bedrock surface is relatively deep at upstream locations with a deep pervious foundation that will require a complex and more elaborate foundation design. ABUTMENTS The left and right abutments consist of cantilevered retaining walls extending upstream and downstream flanked to natural grade by a zoned embankment dam. The main stem of the cantilevers section will be 0.5 metres thick (+/-) while the base width will vary as per stability needs, generally assumed to be 80% of the wall height. The embankment will slope 2.5:1 on the upstream and 2.2:1 on the downstream, and have a combined blanket and chimney filter. The upstream slope will be protected by riprap. SPILLWAY energy dissipation zone downstream of the spillway. The structure should blend into the existing environment as a linear landform with a local relief of about three (3) metres. The structure is orthogonal in nature, with flow at ninety (90) degrees to the centerline of the dam, which is parallel to the main axis on Lake Major. Three (3) spillway options are developed in concept for Location F; a free overflow ogee spillway, a six (6) gate structure, and a hybrid solution of a gated spillway for flow up to a 100 year flood and free overflow for lower frequency flood events. All structures, including the fishway, spillway and sluiceway, directly discharge square to the main dam axis. The fishway structure flow is either perpendicular or parallel to the structure, but never oblique. The structure Canadian Dam Association * Fall 2016 is compact with neat lines and will fit with the existing landscape. SUBSURFACE GEOLOGY The geotechnical investigation of the site concluded that the existing foundation conditions are semi-impervious to pervious and bedrock is near surface. The likely dam foundation system for an embankment dam will include a cut-off trench to bedrock. For a concrete structure, the likely foundation system will include excavation and removal of soil to competent bedrock. Both structures will require a cofferdam. Consolidation grouting and line grouting are also required to manage seepage. Bedrock is of the Halifax Slate formation and there is potential for acid rock drainage during construction if excavated rock is stockpiled on site. The risk Three (3) spillway crest design options are considered. An initial concept for an inflatable gate system was rejected due to the reliance on mechanical controls and added complexity of operations. Of the three concepts developed, the first concept is an overflow weir with the crest at the same elevation as the current structure, el. 19.0m. The weir length is increased to thirty five (35) metres and the crest was shaped as an efficient ogee. The second concept is a six (6) bay gated spillway with each gate 4.6 metres wide by 2.2 metres high and a sill elevation of 17.3 metres. The objective of the revised spillway design is to allow for a normal operating level of 19.5m, 0.5m higher than current, while still passing the IDF. A third concept developed is a hybrid alternative with a two (2) bay gated spillway with each gate 3.1 metres wide by 2.2 metres high and a sill elevation of 17.3 metres. The gated spillway is flanked on either side by an ogee shaped weir to pass 21

Table of Contents for the Digital Edition of Canadian Dam Association Bulletin - Fall 2016

Board of Directors
Board of Directors Nominations
Remedial Work at Lake Major Dam
CDA Conference Report: Otto Holden Generating Station Alkali-Aggregate Reaction Investigation
DSR Bulletin
Icold Corner
Notice of Annual General Meeting
Call for Papers, 2017 Conference
Young Professional Activities
Buyers’ Guide and Trade List
Canadian Dam Association Bulletin - Fall 2016 - cover1
Canadian Dam Association Bulletin - Fall 2016 - cover2
Canadian Dam Association Bulletin - Fall 2016 - 3
Canadian Dam Association Bulletin - Fall 2016 - 4
Canadian Dam Association Bulletin - Fall 2016 - 5
Canadian Dam Association Bulletin - Fall 2016 - 6
Canadian Dam Association Bulletin - Fall 2016 - Board of Directors
Canadian Dam Association Bulletin - Fall 2016 - 8
Canadian Dam Association Bulletin - Fall 2016 - Board of Directors Nominations
Canadian Dam Association Bulletin - Fall 2016 - Remedial Work at Lake Major Dam
Canadian Dam Association Bulletin - Fall 2016 - 11
Canadian Dam Association Bulletin - Fall 2016 - 12
Canadian Dam Association Bulletin - Fall 2016 - 13
Canadian Dam Association Bulletin - Fall 2016 - 14
Canadian Dam Association Bulletin - Fall 2016 - 15
Canadian Dam Association Bulletin - Fall 2016 - 16
Canadian Dam Association Bulletin - Fall 2016 - 17
Canadian Dam Association Bulletin - Fall 2016 - 18
Canadian Dam Association Bulletin - Fall 2016 - 19
Canadian Dam Association Bulletin - Fall 2016 - 20
Canadian Dam Association Bulletin - Fall 2016 - 21
Canadian Dam Association Bulletin - Fall 2016 - 22
Canadian Dam Association Bulletin - Fall 2016 - 23
Canadian Dam Association Bulletin - Fall 2016 - 24
Canadian Dam Association Bulletin - Fall 2016 - 25
Canadian Dam Association Bulletin - Fall 2016 - CDA Conference Report: Otto Holden Generating Station Alkali-Aggregate Reaction Investigation
Canadian Dam Association Bulletin - Fall 2016 - 27
Canadian Dam Association Bulletin - Fall 2016 - 28
Canadian Dam Association Bulletin - Fall 2016 - 29
Canadian Dam Association Bulletin - Fall 2016 - 30
Canadian Dam Association Bulletin - Fall 2016 - 31
Canadian Dam Association Bulletin - Fall 2016 - 32
Canadian Dam Association Bulletin - Fall 2016 - 33
Canadian Dam Association Bulletin - Fall 2016 - 34
Canadian Dam Association Bulletin - Fall 2016 - 35
Canadian Dam Association Bulletin - Fall 2016 - 36
Canadian Dam Association Bulletin - Fall 2016 - 37
Canadian Dam Association Bulletin - Fall 2016 - DSR Bulletin
Canadian Dam Association Bulletin - Fall 2016 - Icold Corner
Canadian Dam Association Bulletin - Fall 2016 - 40
Canadian Dam Association Bulletin - Fall 2016 - Notice of Annual General Meeting
Canadian Dam Association Bulletin - Fall 2016 - Call for Papers, 2017 Conference
Canadian Dam Association Bulletin - Fall 2016 - 43
Canadian Dam Association Bulletin - Fall 2016 - Young Professional Activities
Canadian Dam Association Bulletin - Fall 2016 - Buyers’ Guide and Trade List
Canadian Dam Association Bulletin - Fall 2016 - 46
Canadian Dam Association Bulletin - Fall 2016 - cover3
Canadian Dam Association Bulletin - Fall 2016 - cover4
Canadian Dam Association Bulletin - Fall 2016 - outsert1
Canadian Dam Association Bulletin - Fall 2016 - outsert2
Canadian Dam Association Bulletin - Fall 2016 - outsert3
Canadian Dam Association Bulletin - Fall 2016 - outsert4
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