Ontario Power Generation
WAWAITIN GENERATING STATION
PLANT GROUP: Northeast Plant Group
DRAINAGE BASIN: Hudson/James Bay
RIVER: Mattagami
NEAREST POPULATION CENTRE: Timmins (26 KM (16 Miles) Northeast)
ORIGINAL IN SERVICE DATE:
UNIT 1-2 - 1912
UNIT 3 - 1913
UNIT 4 – 1918
RE-DEVELOPMENT IN SERVICE DATE: UNIT 1-2 – November 2010
NUMBER OF UNITS: 2 – vertical, single regulated “Francis” turbines directly coupled to air cooled generators operating at 4.16Kv. Water to Wire equipment was supplied by Litostroj Hydro (Slovenia)
ACQUIRED BY HYDRO-ELECTRIC POWER COMMISSION OF ONTARIO: November 1, 1944
FROM: Northern Ontario Power Company
Asset Transferred to Ontario Power Generation: April 1, 1999
CONTROL: Remote from North East Control Centre
POWERHOUSE: The powerhouse is approximately 33M by 17M by 11 m (109 by 57 by 36 ft) high of pre-engineered structural steel construction. The service bay floor and perimeter walls were elevated 0.5M above the historical high tail-water level as a precaution against flooding which has occurred in the past.
INTAKE: A new concrete intake structure equipped with trashracks, headgate vents and individual headgates operated by cable hoists enclosed in a headgate house was constructed 60M north of the original intake.
The original intake has been plugged with a reinforced concrete block and backfilled to ensure stability.
PENSTOCK: There are two “Weholite” HDPE penstocks 3.3 m (11 ft) in diameter leading 430M from the intake structure to a concrete thrust block # 1. At this point, the penstock transitions to 3M diameter steel and is equipped with an expansion joint and access manholes. The 3M steel penstocks continue for 370M to the powerhouse and are equipped with a second expansion joint and thrust block 150M from the powerhouse. All penstock joints, steel and Weholite are welded, the entire penstock is fully buried and equipped with a dedicated drainage system to ensure the ground water level surrounding the penstock does not rise.
CANAL: The canal which feeds the station is 366 m (1,200 ft) long by 14 m (45 ft) wide and has an average depth of 5.5 m (18 ft). The total distance from the canal to the powerhouse is 790 m (2,600 ft). The new intake structure is tied into the existing canal with a short section of new canal.
DAM(S): The dams are about 1.6 km (1 mile) from the station. The east dam has seven sluice ways and the west dam five. There are about 91 m (300 ft) of rock fill between the two dams. The dams hold back about 4 m (13 ft) of water at the deepest sluice. As part of the site re-development, both control dams were rehabilitated to meet current dam safety standards.
SITE: The storage of water for the generating stations on the Mattagami River is controlled by a number of dams on the river and its tributaries. The Wawaitin station, which is located on the river above the other stations, has a drainage area of 3500 km2 (1,350 miles2).
HISTORICAL NOTE: The original Wawaitin generating station was initially placed in service in 1912 to supply mining and domestic customers in the Porcupine area. However by the end of the 20th century there was no demand for 25 cycle power and the Wawaitin Generating Station was deemed to be at the end of life. A decision was made to re-develop Wawaitin, Sandy Falls and Lower Sturgeon on the Upper Mattagami River and Hound Chute on the Montreal River.
CONSTRUCTION: The station was designed by KGS Inc, consulting engineers from Winnipeg and constructed by KAP (Kiewit Alarie Partnership) via a Design Build Contract. Work began in February 2008 with mobilization and clearing of land for the new facility.
The existing generating station remained in-service for 22 months of the new facility construction. The 25 cycle Wawaitin Generating Station was shut down for the last time March 01, 2010. De-commissioning and demolition continued throughout the summer of 2010. The powerhouse was demolished down to the generator floor with all equipment and buried penstocks removed for re-cycling and the cavities filled with rock or concrete.
The site at Wawaitin was large enough to permit construction to proceed at 3 locations simultaneously. The intake excavation and concrete structure, the penstock excavation and pipe welding, and the 3rd site was the powerhouse and tailrace construction.
Construction continued without any major delays. The penstock excavation proved to be challenging due to high ground water levels. KAP employed a well point system to dewater this excavation before actual penstock installation began in the summer of 2009.
Commissioning of auxiliary systems and test operation of the water to wire equipment continued throughout the fall of 2010 with commercial operation beginning November 22, 2010.