Expert: Hillslope development guidelines need fine-tuning

PETALING JAYA: The current rainy spell has raised fears of landslides for especially those living on elevated grounds. A section of the old trunk road near Templer’s Park in Selangor had to be closed recently due to a landslide. There was also a report of soil erosion said to be threatening the safety of medium-cost flats nearby.

Landslides and hill slope development are not new in Malaysia. The federal government recently unveiled the Guidelines for Hillside and Highland Areas Development Planning with provisions to managing hill slope developments. Among other things, the guidelines ban building activities on slopes of more than 35 degrees. Also not allowed are projects on slopes of between 15 and 35 degrees and which display signs of erosion, land instability or laden with sensitive geological material. All development applications must be accompanied by a technical report by a registered engineer.

Slopes have been classified into four classes and four levels of height. Class 1 is for slopes of less than 15 degrees; Class 2 for slopes of between 15 and 25 degrees; Class 3 for slopes of 25 to 35 degrees; and Class 4 where slopes are more than 35 degrees.

Meanwhile, low land is classified as those below 150m high; hill land -- between 150m and 300m; highland -- from 300m to 1,000m; and mountain -- more than 1,000m.

The guidelines, however, do not sit well with Dr Gue See Sew, CEO of G&P Professionals Group, an engineering consultancy. The group provides engineering services in the various areas such as geotechnical, infrastructure, flood mitigation and environmental. Gue feels that the guidelines are complicated and open to interpretation. He told that it should be straight forward as the guidelines will be implemented by non-technical personnel.

Gue explains, for example, that there is no clear definition about the amount of erosion, which plays a crucial part in the classification process of a slope. “In all slopes, even Class 1 and 2, one is bound to see erosion features,” he explains. Gue says the guidelines should go by the gradient of the slope, which is simple and conservative, and already ascertained awhile back. As for the height aspect in the guidelines, he says the evaluation of a slope is not dependent on elevation but its geometry.

Overall, Gue sees a need for simpler guidelines on policy and stringent controls on managing a development from the engineering, construction and maintenance aspects.

To hear more of Gue’s comments on the hillside development guidelines, go to’s podcast audio in the multimedia segment.

The massive landslide that hit Bukit Antarabangsa, Hulu Klang, after heavy rains
on Dec 6, 2008, caused deaths and untold damage

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