Courtesy of the New Straits Times archives

        Proposed dam may cause
        soil erosion

                            Tuesday, March 2, 1999

                             By Esther Tan
                             KUALA LUMPUR, Mon. - The proposed Sungai Selangor dam
                      project in Hulu Selangor will cause significant soil erosion if
                      land-clearing is not strictly controlled.

                      According to the Detailed Environmental Impact Assessment for
                      the proposed project, the catchment area for the dam has been
                      categorised a "High Erosion Risk" area in a recent study.

                      SMHB Sdn Bhd, the consultant who carried out the EIA, did not
                      state which study was involved. However, the Agriculture Ministry
                      had drawn up a map of high-risk erosion areas for Peninsular

                      The consultant warned that the duration and size of land left
                      exposed should be minimised.

                      This is because land-clearing will increase surface run-off rate
                      which can result in flash floods and even landslides during rainy

                      The EIA report has been put up for public viewing in the
                      Department of Environment offices from today.

                      The EIA was commissioned by Consortium TSWA-Gamuda-KDEB
                      after it was given the rights by the Selangor Government to carry
                      out a technical feasibility study for the development of the
                      Sungai Selangor Water Supply Scheme Phase Three project.

                      The State Government is seeking new water resources because it
                      has been projected that by the year 2003, there would be an
                      acute shortage of water supply in Selangor and the Federal

                      When asked about the EIA findings, Science, Technology and
                      Environment Minister Datuk Law Hieng Ding said the Department
                      of Environment would ask for more details from the consultant
                      before making any decision.

                      On the signature campaigns being organised to protest the
                      proposed dam, Law said it would be better if the people were to
                      provide their views and state their reasons after looking at the

                      Asked if environmental consultants could be biased since they are
                      engaged by project proponents to carry out EIAs, Law said the
                      EIA approval was given by the DOE and not the consultant.

                      He said a technical committee set up by the DOE would review
                      the EIA taking into considerations public views.

                      "That is why we ask developers to only engage consultants
                      registered with the DOE," he added.

                      The proposed dam involves the construction of a dam in the
                      headwaters of Sungai Selangor to harness water for use in the
                      State's northern region and the Federal Territory.

                      It will comprise a reservoir of 600 hectares in surface area and
                  will be located about five kilometres from Kuala Kubu Baru town. 

                      A stretch of the existing Federal route 55 from Kuala Kubu Baru to
                      Fraser's Hill will be flooded.

                      The proposed project will displace two Orang Asli communities and
                      affect downstream activities besides bringing about environmental

                      Soil erosion and siltation of the watercourses are among the main
                      environmental impacts since the dam and road construction
                      involve significant land-clearing and earthworks.

                      Under the existing condition, the average annual rate of soil
                  erosion is estimated at between 100 and 150 tonnes per hectare
                  per year.

                      Using Universal Soil Loss Equation based on the worst case
                  scenario, the consultant believes the removal of vegetation cover
                  at steeper slopes during the construction of the dam may result
                  in soil loss of about 1,300 tonnes per hectare per year.

                      "Therefore, it is important to minimise the extent of areas cleared
                      at any one time," states the EIA.

                      All unnecessary land-clearing should also be avoided and selective
                      clearance should be adopted to prevent soil erosion.

                      The EIA states that all exposed areas must be covered
                      immediately either with geotextile or turfing and that a temporary
                      storm water diversion should be constructed to divert storm
                      water from exposed areas.

                      Since a stretch of the KKB-Fraser's Hill route will be inundated,
                  the project proponent has to build a realignment road.

                  The new road will pass through undulating terrain, therefore,
                  construction will involve rock-blasting works and hill-cutting.
                  These can result in soil erosion and slope failures too.

                      Soil erosion will increase silt loading and affect the water quality
                      of the nearby Sungai Luit, a tributary of Sungai Selangor.

                      The EIA warns that sediment load from the construction work can
                  settle within the reservoir which can reduce its storage volume.
                  This means the useful life of the reservoir will be affected.

                      Rock-blasting will cause vibration and air and noise pollution but
                      these will be temporary and localised.

                      The EIA states that most of the forested areas proposed for the
                      project are logged over or secondary forests or plantation sites.
                      There are no rare endemic or endangered plant species or
                      biodiversity attributes in the area.

                      As for dam safety, the consultant states that the dam is
                      designed not to fail and that the spillway is designed to pass the
                      Probable Maximum Flood.