Mactaquac Dam

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Mactaquac Dam
Mactaquac1.jpg
Mactaquac Dam in January 2005 seen from west bank of Saint John River on downstream side.
Mactaquac Dam is located in New Brunswick
Mactaquac Dam
Mactaquac Dam in New Brunswick.
Official name Mactaquac Generating Station
Country Canada
Location Bright Parish / Kingsclear Parish, York County, New Brunswick
Coordinates 45°57′15.2″N 66°52′5.8″W / 45.954222°N 66.868278°W / 45.954222; -66.868278Coordinates: 45°57′15.2″N 66°52′5.8″W / 45.954222°N 66.868278°W / 45.954222; -66.868278
Status Operational
Construction began 1965
Opening date 1968
Owner(s) NB Power
Dam and spillways
Type of dam Embankment dam
Impounds Saint John River
Height 55 m (180 ft)
Length 518 m (1,699 ft)
Spillways 2
Spillway type Concrete
Spillway capacity 16,282.18679 m3 (575,000.000 cu ft) per second
Reservoir
Creates Mactaquac Headpond
Total capacity 1,307,491,000 m3 (4.61736×1010 cu ft)
Surface area 83.85 km2 (20,720 acres)
Max. water depth 39.624 m (130.00 ft)
Power station
Type Run-of-the-river
Hydraulic head 31.7 m (104 ft) - 35.4 m (116 ft)
Turbines 6 x Kaplan
Installed capacity 653 MW

The Mactaquac Dam is an embankment dam used to generate hydroelectricity in Mactaquac, New Brunswick. It dams the waters of the Saint John River and is operated by NB Power with a capacity to generate 653 megawatts of electricity from 6 turbines; this represents 20 percent of New Brunswick's power demand.

Location[edit]

Formally called the Mactaquac Generating Station, the dam and power house are located approximately 15 km (9.3 mi) upstream from the city of Fredericton. The dam is an embankment dam consisting of a rock-fill structure sealed by clay. It combines with two concrete spill-ways to form an arch across a narrow section of the river between the communities of Kingsclear on the west bank, and Keswick Ridge on the east bank.

Construction[edit]

Rising 40 metres in height above the river level, the reservoir (referred to locally as the "head pond") covers 87 square kilometres and extends 96 kilometres upstream, near Woodstock. The dam and powerhouse are a "run of the river" design, meaning that the reservoir has no additional holding capacity in the event of unusually high water flows, such as during the spring freshet.

Kingsclear, NB is also the site of an Atlantic Salmon fish hatchery, located immediately downstream from the dam. The Mactaquac Dam also has a fishway to catch salmon and transport them upriver.

The dam also serves as a locally important public road bridge across the Saint John River, linking provincial highways 102 and 105 on the south and north sides of the river.

Mactaquac Dam in January 2005 from downstream side showing spillway

Lifespan[edit]

The concrete portions of the dam (namely the spill-ways) are currently experiencing a problem of expanding concrete. When built, locally quarried greywacke was used as the aggregate and is responsible for an alkali-aggregate reaction expansion. The dam is being monitored and extra maintenance work is being performed, although the original 100-year lifespan of the spillway has been reduced by almost 40 years.[1]

On October 1, 2014, NB Power officials presented 3 options for the facility to the provincial utility regulator, the New Brunswick Energy and Utilities Board. A decision will have to be made by 2030 to either restore or decommission as follows:

  • Re-power the dam by replacing the spillway and the powerhouse;
  • No continued power generation, maintain the headpond by replacing the spillway but not the powerhouse;
  • Remove the spillway, powerhouse and earthen dam and restore the river to its original state.

All 3 options have a minimum cost of $100 billion (as of 2014), however, the first option also has an additional cost of $1-3 billion and the third option has not had a complete cost estimate provided.

The reduced lifespan of the spillway and dam was first brought to the attention of the provincial government in 2000 when projections by NB Power at that time had placed the dam's end-of-life at 2028, instead of the original 100-year lifespan of 2068. NB Power officials would not say at that time how much it would cost, nor when those costs would show up on the utility's accounts.[2]

Flooding of the Mactaquac Headpond[edit]

Electrical generation began in 1968 after the reservoir, named the Mactaquac Headpond, had completely filled. The flooding of the valley resulted in the displacement of several thousand residents and land owners in areas such as Bear Island and other small communities, as well as the abandonment of a Canadian National Railway line and numerous local roads and small rural communities. A historic waterfall was also submerged as the reservoir filled.

Some new infrastructure was also built as part of the planned flooding of the Saint John River valley. The provincial government built Highway 2 (the Trans Canada Highway) along the southwestern shoreline of the flooded valley. Since 2002, this road has been bypassed and is now designated Highway 102. The Hawkshaw Bridge, a cable-stayed suspension bridge, was constructed across the valley from Hawkshaw to Southampton; at the time of construction in 1967, the bridge was high above the valley floor and the original river level. The planned town of Nackawic, New Brunswick and the nearby Ste-Anne-de-Nackawic pulp and paper mill were also built to accommodate the new reservoir and the new electrical power opportunities. Closer to the dam, the Mactaquac Provincial Park, including a marina and beach was also built.

Following the success of preserving historic buildings at Upper Canada Village when the upper St. Lawrence River valley was flooded by the Long Sault Dam, the government of New Brunswick created the King's Landing Historical Settlement to save several buildings which would otherwise have been flooded by the Mactaquac Headpond. The economic development created by dam-associated development was inspired by the Tennessee Valley Authority, which undertook several similar projects in the 1930s, during the Great Depression, in the southern United States.

Inspiration for arts and culture[edit]

The building of the dam was the inspiration for Riel Nason’s 2011 novel 'The Town that Drowned', published by Goose Lane Editions. The fictional book, winner of the 2012 Commonwealth Book Prize, is set in the 1960s near Pokiok Falls, where the characters learn their homes will soon be swallowed by the rising water.

References[edit]

  1. ^ "Mactaquac dam replacement cost could hit $5B, says NB Power". CBC.ca. October 1, 2014. Retrieved 1 October 2014. 
  2. ^ "Report says Mactaquac Power Station in trouble". CBC.ca. December 11, 2000. Retrieved 1 October 2010. 

External links[edit]