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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 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:

 

Fast Facts

Concession Build, Operate and Transfer Scheme (BOT)
  Component
  • Regulating dam over Sungai Selangor at 66.5 Km of KKB - Bukit Fraser Road
  • Water treatment plants
    • 250 Mld intake and treatment works (125 Mld x 2) at Rasa to serve Northern Selangor
    • 800 Mld intake and treatment works (400 Mld x 2) at Bukit Badong to serve the Federal Territory
  • Realignment of a 7.7 Km section of KKB-Bukit Fraser Road
Dam Storage Capacity
  • 235 million cubic metres
  Location
  • 5 Km east of Kuala Kubu Bharu, along Km 66.5 of Jalan KKB-Bukit Fraser
  Height
  • 110 meters
  Type
  • Rock filled
  Width
  • 800 meters
  Catchment Area
  • 197 sq km mainly secondary jungle
  Impoundment
  • 600 hectares/ 6 sq km (3% of catchment area)
Construction Period Regulating Dam
  • 3 years
  Water Treatment Plant
  • In stages over 66 months
Project Consultants
(SPLASH Appointed)
  • SMHB Sdn Bhd
  • Angkasa GHD
  • Universiti Kebangsaan Malaysia (UKM)
  • Setia Sepakat Perunding (SSP)
  • Garis Architects
Project Consultants
(Government Appointed)
  • KLIAB
  • Gunung Ganang

 

 

SSP3 LayoutSSP3 Layout
SSP3 Layout

Highlights

 

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 3000m/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:


Independent Engineering Consultants:


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 BasinRiver Basin
River Basin

Sungai Selangor Regulating Dam site is most appropriate:


Sungai Selangor Regulating Dam catchment area

 

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

 

PotentialPotential
Potential