History and background of Sungai Selangor Water Supply Scheme Phase 3 (SSP3)
The Sungai Selangor Water Supply Scheme Phase 3 (SSP3) is a project initiated by the Selangor State Government in the wake of the 1998 water crisis which affected people from all walks of life in Selangor and the Federal Territory.
Water demand in the State of Selangor and Federal Territory is continually increasing as a result of population growth, immigration from other states and increasing industrial, business and commercial activities.
In 1990, the total water demand in Selangor and the Federal Territory was 1,600 million litres per day (Mld). In 2000, the increase was almost two fold with demand up to 3050 MLD and the demand is expected to increase to 6205 MLD in 2010 and to 7642 MLD in 2020. Sg. Selangor is the last water resource in the state which can be feasibly developed to meet the increasing demand. Beyond this, raw water has to be imported via interstate water transfer from Pahang.
The rapid growth increase in industrial and residential development in Selangor and the Federal Territory gave reasons for Jabatan Bekalan Air Selangor (currently known as Perbadanan Urus Air Selangor Berhad) to undertake a study on water and supply. In the 1960s a study had already identified Sungai Selangor as a potential source for water supply and was regarded the ultimate and largest undeveloped source of water supply available in Selangor.
Subsequent studies in the 1980s recommended the development of the Sungai Selangor to fully utilise the available water resources. The Selangor State Government then proceeded to implement the development of the Sungai Selangor Water Supply Scheme Phase 1 & 2 in the early 1990s.
The water crisis in 1998 spurred for an urgent detailed technical and feasibility study on the water situation in the state of Selangor. The study, which was completed in December 1998, confirmed that the demand for water would once again exceed supply by 2003.
The major findings of the 1998 study were:
- The current supply situation is critical as existing treatment plants are operating at full capacity
- Although SSP2 will provide an additional 475 millions of water per day (MLD) by 2000, this increased supply will be matched by demand by 2003.
- Klang Valley and Northern Selangor will be the major areas of demand growth
- The State has one remaining source of water supply - Sungai Selangor from which an additional 1,050 Mld may be obtained
- The cost of water from Sungai Selangor is cheaper than other possible sources
The study revealed a need to urgently implement a new water supply scheme. This scheme, the Sungai Selangor Water Supply Phase 3 (SSP3) will meet the future needs of 2 million residents and new industries in the state of Selangor and the Federal Territory.
A proposal to study water supply via inter-state transfer from Pahang was considered. Because of high capital cost and long construction period, the project will only be completed by 2006, at the earliest. Therefore it was decided that SSP3 should be implemented first, to meet water demands by 2003.
The reduction of water wastage has been planned into future demand forecasts. Non-revenue water (NRW) which is currently at 39% of water supplied in 1998 (of which actual pipe leakage is only 16%) will be reduced to 20% by 2015. This is a long-term program involving the rehabilitation of more than 10,000 kilometres of pipes in the state, the amount of water saved through reducing leakages is less than 1% per year, much less than the 6% annual growth in demand forecasted. Therefore a new supply source is still needed.
As the implementation of SSP3 was already delayed (it was originally planned to start in 1998), the study recommended that SSP3 should be implemented on a fast-tracked and urgent basis to avoid a repeat of the 1998 water crisis.
A detailed Environmental Impact Assessment (EIA) study was conducted for the dam site. The EIA report concluded that the project could be implemented in an environmentally sustainable manner with efficient planning and management
SSP3 Components
The Sungai Selangor Water Supply Scheme Phase 3 project, the last major water resource in the state of Selangor, is targeted for full completion in 2005.
SSP3 has various components as below:
- A regulating dam
- Two water treatment plants, each located in Rasa (250 Mld) and Bukit Badong (800Mld)
- The realignment of Kuala Kubu Bharu-Bukit Fraser Road
- Relocation of Institut Kemahiran Belia Negara (IKBN)
- Relocation of 2 Orang Asli villages comprising 84 families
Fast Facts
| Concession | Build, Operate and Transfer Scheme (BOT) | |
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| Construction Period | Regulating Dam |
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| Project Consultants (SPLASH Appointed) |
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| Project Consultants (Government Appointed) |
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SSP3 Layout
Highlights
- The Sungai Selangor Regulating Dam is a 110m high rockfill dam founded on solid granite bedrock. The rockfill type of dam is similar to the Kenyir Dam in Terengganu (155 m), Temenggor Dam in Perak (127m), Ahning Dam in Kedah (74m,), Batang Ai Dam in Sarawak (85m) and Pedu Dam in Kedah (61m).
- It is situated at the narrow gorge on massive granite bedrock just downstream of the confluence of Sungai Selangor and Sungai Gerachi.
- The dam embankment comprises an impervious earth core covered with an external rockfill. In between, there is a layer filter material consisting of 0.62 million cubic metres of granular material. The dam, 400m wide at the base, 800m long and 110m high, is built up of 1.2 million cubic metres of clay core and 6.4 million cubic metres of granite. At full supply level, the inundated areas is just 600 ha, making it the dam with the largest storage capacity relative to the area inundated.
- Dam impoundment commenced on April 25, 2003 and reached its full supply level which is 220 m (above sea leave) with a total storage capacity of 230 million cubic metres on 13 April 2004.
- The dam is designed as a regulating dam. During heavy rains, excess water from the catchment upstream is stored in the reservoir within the dam. On dry days when water level at the intakes is low, water is released into the river. The volume of release is dependent on the amount of the raw water to be abstracted downstream at Rasa and Batang Berjuntai.
The dam has several key components which enable the dam to function effectively:
The Draw-off Tower
The draw-off tower is a crucial and prominent structure of the dam, standing at a height of 110m with a diameter of 9m. This is the structure through which water is drawn from the reservoir for release into the river whenever discharges from the dam are required to augment low flows in the river, ensuring that sufficient water is available at the raw water intakes downstream. The twin discharge pipes leading from the draw-off tower have flow measuring devices and flow regulating valves installed to control and measure the volume of water released into the river. The draw-off tower has four service gates at various levels (RL131m, RL160m, RL190m and RL210m. Two emergency gates located at the beginning of the twin discharge pipes ensure that water discharges can be shut down whenever required for pipe maintenance.Spillway
The chute spillway with a flip bucket has a width of 30m and a length of 230.54m which are provided for overflow during the wet season. It is designed as an open chute, discharging excess water over the crest of the dam. When water overflows into the spillway, it creates a waterfall like scene at the downstream face of the dam. Visitors may experience scenario during the wet season. The spillway has a discharge capacity of 3000m³/sec (260,000 Mld), more than sufficient to route excess water during extreme floods.Plungepool
The plunge pool, located at the lower end of the spillway functions as an energy dissipator to dissipate the energy of any overflowing water from the spillway before the water is allowed to rejoin the river. This is to prevent turbulence and erosion of the riverbed and its banks. The plunge pool is 196m long and is 4m deep.Diversion Tunnel
The 480m long diversion tunnel which was blasted through solid granite at the start of the construction to divert the river to facilitate construction of the dam, is now used to house the twin 2200mm diameter discharge pipes coming out of the draw-off tower. The water drawn from the dam for release flows through these twin discharge pipes before being released into the river. The tunnel is 7m in diameter and has a horseshoe shape. It was constructed using the controlled drilling and blasting method.Coffer Dam
The coffer dam is a temporary water-tight enclosure that was built to divert the river to enable work to be carried out in the dry for the construction of the main dam. The coffer dam is required during the construction of the main dam. The coffer dam is required during the construction phase but has no specific function after the completion of the dam.
Panel of Consultants Supervise Design, Construction and Operations of SSP3
The construction, operations and maintenance of the SSP3 regulating dam follows a series of guideline and procedures which also incorporate the environmental, ecological and social aspects imposed on by the dam project.
Significant advances in the design and construction of dams have been achieved nowadays. The construction material quality, construction techniques combined with new and improved construction equipment, better understanding of the science of soil mechanics and soil characteristics, and better quality control have also improved considerably.
Apart from this, independent dam safety reviewers are also being engaged by both SPLASH and the Government for SSP3. The qualified independent dam safety reviewers will conduct reviews throughout the design, construction and operational stages of the project.
Angkasa GHD, a joint venture between local consulting company and Australian company has been appointed by SPLASH and Mr. Douglas Galager (a dam expert from UK) has been appointed by Selangor State Government.
The panel of Consultants:
Design and Supervision:
- Setia Sepakat Perunding (SSP)
- SMHB Sdn Bhd
- Universiti Kebangsaan Malaysia (UKM)
- Garis Architect
- Gunung Ganang (State appointed EIA Consultant)
Independent Engineering Consultants:
- Angkasa GHD
- KLIAB Berhad (State appointed Ssupervising Engineers for design and construction)
The best site in the State
Comparison of potential sites :
| DAM SITE | DESCRIPTION | REMARKS |
|---|---|---|
Rening |
Extensive inundation of private land, 1600ha with active storage of 92 MCM, Sg Selangor dam is still needed | Not necessary if Sungai Selangor Dam is constructed |
Beletak |
Will flood North-South Expressway and Lembah Beringin | Not feasible |
Rawang |
Will inundate the entire amenity area of Templer's Park and North-South Expressway | Not feasible |
Batang Kali |
High social impacts and flood many developments | Not feasible |
Sungai Selangor |
Small inundated area, high storage capacity and good bedrock foundation | RECOMMENDED |
River Basin
Sungai Selangor Regulating Dam site is most appropriate:
- Biggest catchment and last major water resource available in the state
- Least area inundated with highest storage
- Least area of private land affected
- Low impact on environment
- Good bedrock foundation
- Affected private land area is small. Only 113ha private land is affected out of 600ha of inundated area for Sungai Selangor Regulating Dam.
Sungai Selangor Regulating Dam catchment area
- The Sungai Selangor will only flood 3% (600ha) out of 19,700ha of the dam catchment area, compared with 7% for the other 5 dams in the State.
- The dam catchment area forms only 13% of the total Sg. Selangor river basin
- To protect the dam and the quality of reservoir water, the entire catchment of 19,700 ha is gazetted as a protected watershed
Comparison of storage capacity with other dams
Sungai Selangor Regulating Dam only floods one-third the area with same storage compared with other dams combined in the state
| DAM | CATCHMENT AREA (ha) | WATER STORAGE (MCM) | LAKE AREA (ha) | |||
|---|---|---|---|---|---|---|
| Sg. Selangor | 19,000 | 235 | 600 | |||
| Sg. Batu | 5,000 | 26,400 | 32 | 258 | 220 | 1,840 |
| Klang Gates | 7,700 | 22 | 230 | |||
| Langat | 4,100 | 39 | 230 | |||
| Semenyih | 5,600 | 62 | 360 | |||
| Sg. Tinggi | 4,000 | 103 | 800 | |||
Potential