Ontario Power Generation
SANDY FALLS GENERATING STATION
PLANT GROUP: Northeast Plant Group
DRAINAGE BASIN: Hudson/James Bay
RIVER: Mattagami
NEAREST POPULATION CENTRE: Timmins (11 KM (7 Miles) Southeast)
ORIGINAL IN SERVICE DATE: UNIT - June 1, 1911
RE-DEVELOPMENT IN SERVICE DATE: October 2010
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
NUMBER OF UNITS: 1: Vertical, 3.1M.double regulated Kaplan type, axial flow turbine supplied by Litostroj Hydro (Slovenia).
CONTROL: Remote from North East Control Centre
POWERHOUSE: The powerhouse is situated approximately 30 m (100 ft) west of the weir. The building is of pre-engineered structural steel framework, 25m x 17m steel clad, insulated walls and sloped roof and equipped with a 3 axis, 50tonne overhead crane.
FOREBAY AND HEADWORKS: Adjacent to the south end of the weir, a short concrete intake canal leads to the intake deck. The concrete intake is equipped with trash racks and a headgate. The headgate are 2 piece steel construction and are equipped with an enclosed AC powered cable hoist..
INTAKE: The original unit 2 & 3 intakes were demolished, sealed with concrete and backfilled. Unit 1 intake was demolished and enlarged to suit the new station single unit capacity of 68CMS. The headworks and powerhouse are an integral part of the concrete dam. the turbine/generator unit is equipped with dedicated trashracks and a cable hoist operated 2 piece headgate. Sectional headgates are supplied and fit into the trashrack opening.
DAM(S): The dam at Sandy Falls is a concrete overflow weir structure extending across the river. The crest elevation of the weir is at 269.15m.a.s.l. There are two de-commissioned log chutes. The dam or weir leaves the north shore, running in a southerly direction for a distance of 72 m (238 ft), where it is anchored by a cement pier. From here the weir curves down the centre of the river in a westerly direction for 128 m (421 ft). The dam then swings to the south shore, having an overall length of 216 m (710 ft). The overflow weir will be rehabilitated to current dam safety standards to conclude the re-development.
Wawaitin and Lower Sturgeon plants belong Ontario Power Generation while Smooth Rock Falls and Smoky Falls were privately owned. The water available from these sources during the time of low natural run off warranted the building of four storage dams.
The first dam is at the end of the Kenogamissi Lake, about 40 km (25 miles) above Wawaitin Falls. This is a concrete dam 85.3 m (280 ft) long and 6.1 m (20 ft) high with six sluices, each 4.3 m (14 ft) of water.
The second dam is at the foot of Minisinakwa Lake on the Mattagami River, about 43 km (27 miles) above Kenogamissi. It is 75 m (250 ft) long and 2 m (6 ft) high with five sluices and will hold about 25 000 000 m3 (900,000,000 ft3) of water. The third dam is located about 32 km (20 miles) farther up the river at the outlet of Mesomikenda Lake and about 21 km (13 miles) from the C.N.R. The dam is about 122 m (400 ft) long and 3 m (10 ft) high, with three sluices, each 4.3 m (14 ft) wide. It will hold about 57 000 000 m3 (2,000,000,000 ft3) of water.
The Grassy dam (destroyed in 1949 and rebuilt again) was at the foot of Peter Long Lake on the Grassy River, about 29 km (18 miles) from its mouth at the Mattagami River below Wawaitin. It is 76.2 m (250 ft) long, 3.6 m (10 ft) high, with two sluices each 3 m (12 ft) wide, and holding approximately 56 634 000 m3 (4,000,000,000 ft3) of water.
SITE: The Mattagami River drains an area of 4000 km2 (2,500 miles2) above Sandy Falls. The Mattagami drainage area starts at the height of land at Westree. This area is headed by Mesomikenda Lake which flows through a network of lakes and rivers (Makami Lake, Wizard Lake, Minisinakwa Lake and Minisinakwa River) and finally empties into the Mattagami River headwater. There are also other tributaries flowing into it, such as the Nabakwasi River, Grassy River and Chestnut Creek.
CONSTRUCTION: The station was designed by RSW Inc, consulting engineering of Montreal and constructed by KAP (Kiewit Alarie Partnership) via a Design Build Contract. Alternate locations for the new powerhouse were explored with the decision to locate adjacent to the south end of the weir using a tailrace canal blasted into the bedrock.
The original Sandy Falls G.S. was shutdown and decommissioned in June 2008. All buried penstocks were excavated and materials (metals) recycled or disposed in a landfill (wood stave penstock). An un-expected project cost was hidden walls entirely clad with asbestos material which required a specialized sub-contractor.
Construction of the Sandy Falls station commenced at the same time as de-commissioning and demolition in June 2008. An upstream cofferdam was used throughout to ensure upstream dewatering, on the downstream end of the works a “rock plug” remained in place acting as a cofferdam. All 5,000 Mcu of concrete used on the site was supplied by a local (Timmins) contractor and batched off-site.
Commissioning of auxiliary systems and test operation of the water to wire equipment was completed in the fall of 2010 with the station commercial service beginning Oct 27, 2010.
HISTORICAL NOTE: In 1910 the Hollinger Syndicate, later incorporated as Porcupine Power Company, acquired the lease of Sandy Falls, which is situated 11.3 km (7 miles) below Timmins on the Mattagami River. In the year 1911 two of this plant's machines were delivering power to the Hollinger Mine. In June 1912, the Northern Ontario Power Company, Cobalt, under its new name, the Northern Canada Power Company acquired Sandy Falls from Hollinger. In 1916, the third unit was installed. In March 1945, the Commission became Sandy's new and final owners.
The colony abandoned in May 1949. The permanent staff were moved to Timmins. The abandoned site was situated on a hill 244 m (800 ft) from the south side of the powerhouse. There were no sewers on basements and the houses were added as required by the tenants.