Taman Wawasan landslide: Probe must consider various factors, not just rainfall, says IEM

THE Institution of Engineers, Malaysia (IEM) has emphasised the need for competent engineers in the field to lead the investigation and remedial works at Taman Wawasan in Puchong following a landslide that took place there last month.

Its president Prof Dr Norlida Buniyamin said that these engineers need to work with the assistance of relevant professionals and technologists such as surveyors, geologists, and remote sensing experts.

She cautioned that though it is easy to link the landslide to heavy rainfall, there are other factors that can influence slope stability.

In a statement today, she conveyed the institution’s regret for the affected residents around the landslide incident.

She noted that according to media reports nine terraced houses were affected and four cars were damaged in the incident.

Based on Google Earth and video footages from the media, the landslide spanned approximately 70 metres along Jalan Wawasan 3/9 with a slope height of about 13 metres, she noted.

“While it may be easy to associate the landslide (which occurred after a heavy rainfall) with rainfall as the triggering factor, IEM wishes to point out that the stability of a slope is influenced by various factors.

“These factors include, but (are) not limited to, slope geometry, soil properties, rainfall, groundwater level, slope surface protection, historical failure events, human activities (e.g. excavation and earth filling), et cetera," she said.

“It is imperative to conduct a thorough investigation to identify the root cause(s) of the landslide, backed by appropriate engineering assessments, for the subsequent remedial works.”

Four cars were buried in the landslide and nine terrace houses were affected in the incident that happened on the evening of December 16. The occupants of these buildings were advised to seek shelter elsewhere. 

Works to install 375 iron piles in the 150m area began at 4am the next day.

In addition to installing these, tarpaulins were placed in the area to prevent water from entering the ground as a precautionary measure, averting further soil aggravation.

Norlida noted that IEM had issued a position paper on hill-site development in 2002.

This was updated in 2009 and 2011 with a more comprehensive list of recommendations prepared to permit the identification and mitigation of circumstances that could lead to potential landslides hazard in the country.

The paper recommended that all existing completed developments located on or adjoining slope sites of Class 3 (gradient of 25 degrees to 35 degrees) and Class 4 (minimum gradient of 35 degrees) slopes be urgently assessed by qualified persons other than the submitting engineers to determine if upgrading to the safety of any slope at any such development is required to be implemented and to advise the local authority to order such works immediately, she said.

She added that the October 2023 issue of IEM Bulletin, which dealt with slope engineering, highlighted the crucial roles that various stakeholders can play in mitigating landslide risks and promoting slope safety.

Norlida stressed that IEM stands ready to provide technical assistance through its qualified and experienced members.

“As a learned society with over 50,000 members and affiliated to several international engineering organisations, IEM is recognised locally and internationally as the learned society and professional body representing engineering fraternity,” she said. – The Vibes, January 5, 2024