Canadian Dam Association Bulletin - Fall 2016 - 13

BACKGROUND Lake Major Dam was originally built for a private milling operation in the 1940s. The former City of Dartmouth took over ownership in 1960 as part of overall improvements to the Dartmouth water supply system. Improvements included construction of East Lake Dam, located upstream of Lake Major, as a storage structure to facilitate demand during periods of low inflow. Halifax Water assumed ownership of the dam as part of amalgamation in 1996 and constructed the Lake Major Water Supply Plant in 1999. The current utilization and capacity of the Lake Major system is summarized in Table 1. The current demand is based on recorded withdrawal rates at the treatment plant. The current approved withdrawal is the licensed withdrawal rate (Approval #2006-055292, expires 2018). Demand capacity is the 30-year "Future High Growth Scenario Flow / Demand" outlined in the Halifax Water Integrated Resource Plan - Recommended IRP and Analysis, revision 2012-10-29. Plant capacity is the design capacity of the Lake Major Water Treatment Plant. TABLE 1 TREATMENT PLANT WITHDRAWAL RATES Commonly Reported Value Metric Imperial (m³/s) (MGD) Plant Capacity 1.05 20.0 Average Day Corresponding to Plant Capacity 0.87 16.5 Current Approved Withdrawal 0.76 14.5 Current Average Day Demand 0.50 9.5 The Lake Major Dam is comprised of rock-filled timber crib overflow abutments and central overflow spillway with a pool and weir fish ladder at the right abutment. East Lake Dam is a concrete gravity overflow spillway with five (5) intermittent piers, low level sluice gate, stoplog structure and Canadian Dam Association * Fall 2016 Lake Major Dam Sept 2011 left and right abutment wing walls. The catchment areas for Lake Major and East Lake are 47.7 km2 and 20.9 km2, respectively. FLOOD INFLOWS The Lake Major watershed is not gauged so inflow hydrology is established by transposing flow data from nearby Water Survey of Canada (WSC) gauged basins. Results of the extreme value analysis for WSC# 01DG003 are presented in Table 2. All analysis is completed using the three parameter log normal (3PLN) distribution using the maximum likelihood method. Due to the relative small size of the watersheds, the peak instantaneous value is used for extreme value assessment. The ratio of peak daily to mean daily flow is 1.14 when using measured data. Transposing the expected value for critical period's results in the following inflow peaks for East Lake, Lake Major and a combined system. The probable maximum flood (PMF) inflow for the Lake Major system was developed in 2005 and again in 2011 using different studies of probable maximum precipitation (PMP), as presented in Table 3. In both TABLE 2 PEAK INFLOWS (M³/S) AT LAKE MAJOR SYSTEM Period (Years) Peak Inflow (m³/s) Lake Major East Lake 2 15.2 6.8 22.0 10 25.7 11.6 37.3 100 41.4 18.6 60.0 1,000 59.8 26.8 86.6 10,000 81.3 36.5 117.8 Combined cases, attenuation from operation of gates at East Lake is assumed to be efficient. Lake Major dam is a High consequence dam with an inflow design flood (IDF) one third between a flood with an annual exceedance probability of 1,000 years and a PMF, i.e., IDF = 1:1000 year + 1/3 (PMF - 1:1000 year). For the current system, with East Lake 13

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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