The Terengganu Hydro-Electric Project is located in the State of Terengganu, Malaysia and comprises twin diversion tunnels, a main dam, a free overflow spillway, an inlet structure leading to 4 steel-lined tunnels, a conventional surface power station housing 4 generating units of 100 MW each, and 8 saddle dams. The main dam is a rockfill structure with a height of about 150m. All the saddle dams are of earthfill construction. The total volume of fill for these dams is 25.7 million m3.
From a catchment area of 260,000 ha the dam impounds 13,600,000,000 cu. metres of water at normal full supply level, of which 7,400,000,000 cu. metres are utilzed as live storage. The surface area at full supply level is 36,900 ha.
Twin tunnels 14m in diameter diverted the river flow during construction of the dam. One 1.75 m hollow cone valve and a butterfly valve provided in one of the diversion tunnels discharged riparian flows during the filling of the reservoir. The generating facilities consist of four machines with a total installed capacity of 400 MW and produce an average energy output of 1,600 million units per annum.
The power station has four generating units made up of Francis type turbines vertically coupled to air-cooled generators. The units are housed in a conventional building which includes repair bay, control room, workshops, office and storage facilities.
The four turbines have an output of 100 MW each at a rated head of 120m and the generators are rated 112 MW/0.9 pf 50 Hz.
The generators´ output is connected to three-phase 13.8/275 kV/112 MVA oil-cooled transformers, through the substation and then by 275 kV transmission lines to the system network.
A total volume of 17,000,000 m3 of fill material was used for the construction of the Kenyir Dam over a period of two and a half years.
The core material of weathered granitic clay was obtained from borrow areas located 1 to 2 km upstream of the site. It was placed in the central zone of the dam to act as the impervious layer.
The rockfill for the dam, obtained from the borrow area located 2 km upstream of the site is granite which also extends throughout the entire foundation area. Rock from the borrow area was placed on the outermost zones of the dam. Filter material consisting of fine crushed rock and river sand was placed in between the rockfill and core zones to serve as transition material.
The upstream cofferdam was built to a height of some 60m to pass flood flows through the diversion works during the construction period. The cofferdam was subsequently incorporated into the main dam.
There are 8 saddles along the catchment boundary of the Terengganu River Basin which are below the proposed maximum water level of the reservoir.
To prevent overflow or leakage through these saddles, an embankment with the same crest elevation as the main dam is constructed in each of these saddles. They vary in height from 10m to 45m. All of the saddle dams are homogeneous earthfill embankments and have a similar cross-section which provides for a cut-off to groutable rock and a vertical chimney drain.
The spillway is located on the right bank of the dam abutment. The spillway is an ungated, ogee-type structure with a 140m wide crest, leading to a 50m wide chute which terminates in the river channel. The spillway is capable of attenuating the incoming proable maximum flood to a maximum discharge of 7,000 m3/s with a corresponding rise of the reservoir level of 8m.
The history of construction of the dam spanned for 15 years, which is from the planning stage to the completion of the dam. Actually it was first identified in 1961 but it proved uneconomic due to the small demand and the high cost of production. Early 1970’s the government revived the study and further site investigations was proceeded.
Even though the original survey for the project was in1972 the construction was started in 1978 and was completed in 1985. In 1987 the whole project was officially opened by his Royal Highness The Sultan of Terengganu Darul Iman and was named after the baginda Sultan “Sultan Mahmud Hydro Electric Power Station”.
The main project site is located at Kuala Kenyir (about 55km from Kuala Terengganu). The main features of Kenyir Hydro Electric Project are a rock fill dam with 400 megawatts of generating plant. During the construction period, two temporary diversion tunnels were built for the purpose of diverting the rivers.
The normal capacity of the lake store is 13.6 billion cubic metres of water. Whereas the deepest point is 145 metres deep. This power station complex building can produce 100 MW (megawatts) power units which can be supplied through out Malaysia. Normally the daily operation operates at a continuous power output of 165 MW and its average annual output is 1600 GWh (Giga watt hours).
A total volume of 17,000,000 cubic meters of fill material was used for the construction of the Kenyir Dam over a period of two and a half years.
The core material of weathered granitic clay was obtained from burrow areas located 1 to 2km upstream of the site. It was placed in the central zone of the dam to act as the impervious zone.
The rockfill for the dam, obtained from a borrow area located 2km upstream of the site is granite which also extends throughout the entire foundation area. Rock from the borrow area was placed on the outermost zones of the dam. Filter material consisting of fine crushed rock and river sand was placed in between the rockfill and core zones to serve as transition material.
The upsteam cofferdam was built to a height of some 60m to pass flood flows through the diversion works during the construction period. This cofferdam was subsequently incorporated into the main dam.