Report on some major geotechical disasters in Malaysia.

Ooi, T.A. ; Ting, W.H.

Flooding, Landslides, Debris Flow and Tsunami are some of the disasters experienced in Malaysia. The flooding of Kuala Lumpur in the 1970s caused serious damages to lives and properties and called for the flood mitigation scheme in Kuala Lumpur. Over the years despite the repeated dredging and canalization of floodwater in Kuala Lumpur, there were repeated incidences of severe flooding of the city centre. As part of the overall solution to the frequent flooding problem, the diversion tunnel known as the SMART tunnel was constructed and will be completed in 2006. The SMART tunnel is a dual-purpose tunnel designed to cater to flow of water and ease traffic congestion in the Kuala Lumpur city. The Landslide that caused the collapse of Block 1 of the Highland Tower in December 1993 claimed 48 lives. The landslide occurred during 10 days of incessant rainfall. In November 2002, another landslide occurred and buried the bungalow at the foothill within the vicinity of the Highland Tower site. The incidence also occurred during the period of incessant rainfall and 8 people were killed. Debris flow occurred at the Genting Highlands area emerging from the mountain side flanking the access road and causing debris to flow onto the highway on 30th June 1995 and caused temporary closure of Kuala Lumpur- Karak highway. In the incidence 20 people were killed and 23 people were injured. Debris flow also occurred in the Gunong Tempurong area along the North-South highway, causing debris comprising boulders, timber logs and mud to impact on the beams of a bridge, necessitating closure of a stretch of the highway. Though not as common as conventional landslides, the unexpected nature of debris flow has cause problems, when the flow traversed facilities such as roadways and settlements. The Tsunami that struck Pulau Langkawi, Kuala Muda and Penang on 26 December 2004 took Malaysia by surprise and caused great concern to the public as to the safety of the buildings to withstand the tremors and the need to design for such forces generated, particularly for the high-rise buildings in Malaysia. This paper reports the incidences and look into the need of mitigation measures such as the design aspect of buildings for seismicity in Malaysia and other rehabilitation works.

INTRODUCTION

The Institution of Engineers, Malaysia (IEM), in its September 2005 bulletin devoted the entire issue to report on Disasters (IEM, 2005). Registered Engineers for Disaster Relief (REDR) was founded by Peter Guthrie, a Civil Engineer in 1979 whilst serving his stint at the Vietnamese refugee camps in Malaysia. It is a voluntary register of engineers who can be seconded to the front line relief agencies on notice (Wong, 2005). Marlinda (2005) gave an outlined description of the Disasters Management System in Malaysia. These are essentially a governmental effort in dealing with the occurrence of disasters in general. What is of concern to the geotechnical engineer is the prevention and mitigation of disasters as well as rehabilitations in geotechnical engineering. In Malaysia, major disasters arising out of geotechnical failures are: the flooding of Kuala Lumpur due to uncontrolled Earthworks, the collapse of Highland Towers Condominium in 1993, the Genting Highlands access road debris flow in 1995, landslide buried the bungalow at the foothill within the vicinity of the Highland Tower site in 2002, debris flow in the Genting Highlands area along the Kuala Lumpur highway and the tsunami that struck Pulau Langkawi, Kuala Muda and Penang on 26 December 2004. Malaysia has been considered as a non-seismic risk country until this tsunami incidence. In 1982, the Public Works Department, Malaysia stated in the Keynote address to the Conference on Tall Buildings held in Kuala Lumpur that "Malaysia is actually located in the 'ring of fire' that marked the areas affected or likely to be affected by earthquakes and cautioned that Malaysia will experience in the future severe earthquake arising from the Sumatra and Andaman fault that runs the length of Sumatra and the Andaman Sea to the north of the Straits of Malacca" (Yunus, 1982). The interest in earthquake design amongst Malaysian engineers in fact already started at that time. The Komtar Towers in Penang and the Penang Bridge built in the 1980s in fact were designed for seismic forces. This paper describes some of the incidence of the disasters and gives examples of some of the mitigation and rehabilitation works.

THE FLOODED CONFLUENCE OF KUALA LUMPUR

Kuala Lumpur (KL) was founded in the late 19th century as a tin mining settlement at the river confluence of the Klang and Gombak Rivers. KL is situated in the mid upper reaches of 120km long Klang river that drains a catchment of some 1288 sq. km. Situated in a flood plain, KL has experienced a number of major flood events with the worst recorded being the 1926 flood. The 1971 disastrous flood in the Business District at the centre of Kuala Lumpur then initiated the action by the government to look into the long term solution to the flooding problem in Kuala Lumpur City. By mid 1970s, a flood mitigation Master Plan had been developed that incorporated a number of engineering options including upstream storage; ponding and pumped drainage; and improving the drainage capacity of the Klang River and its major tributaries. A decade later, this plan had been enlarged to cover the whole of Klang Valley and modified to take into consideration to cancel the proposed Gombak Dam. During the 1990s, the pace of development increased with more green areas being urbanized and this resulted in a threefold increase in the annual discharge of the Klang River at the city centre. Entering the millennium, the flooding of the city has become an annual event. The ongoing works under the Kuala Lumpur Flood Mitigation Project is designed to reduce the occurrence of floods in the city. The Storm Water Management and Road Transport System (SMART) tunnel is a dual-purpose tunnel designed to cater for flow of water and ease traffic congestion in the Kuala Lumpur city. Fig. 1 shows the alignment of the SMART Tunnel. The alignment is notorious as it passes through the treacherous Kuala Lumpur Limestone Formation. The complex subsurface formation is as shown in Fig. 2.

[FIGURES 1-2 OMITTED]

The lowering of ground water table for the assembly of the TBM machine at about 18m below ground was known to have caused extensive sinkhole formations to the roads and cracks on buildings within the vicinity of the site. Some aspects of the tunnelling methods and ground conditions were presented by Ting, et al. (2005a). The use of slurry shield type of TBM boring through the limestone bedrock and the overlain problematic alluvial deposits and mine tailings comprising of loose sands/soft slimes was successfully done by the use of pressurized slurry composed of bentonite and air pressure. This is an illustration of how a notorious site condition has been successful managed and overcome with forward planning and the use of the correct and innovative technology. The total storm water tunnel length is 9.7km with 3km of motorway having two levels of traffic deck within the storm water tunnel. Pre-cast concrete linings were used for the tunnel and the voids between the excavated ground and the linings were immediately filled with cement mortar grout under pressurized conditions to ensure that all voids are properly and fully filled. The project is currently ahead of schedule and expected to be completed by end of 2005.

THE COLLAPSE OF THE HIGHLAND TOWERS

In December 1993, during a period of 10 days of incessant rain, Block 1 of Highland Towers Condominium collapsed resulting in loss of 48 lives and the loss of use of the remaining 2 Blocks that were still standing. Fig. 3 shows the collapsed Block 1 of the Condominium Tower. The Ampang Municipal Council (MPAJ, 1994) set up a Technical Committee of Enquiries and the findings were as follows:

1. The Highland Towers Condominium was sited mainly on fill ground over granitic formation. The maximum depth from the ground surface to bedrock is about 19m. Granitic rocks found in and around the areas were not highly soluble minerals to adversely affect the stability of the foundations.

2. Soils overlying the granitic bedrock were very loose to loose silty sand and highly permeable.

3. All 3 Blocks were on rail piles designed to take only vertical loads.

4. Surface drainage system provided was not in accordance to approved plan. Situations worsen when earthwork activities changed the drainage pattern on hill-slope behind the Condominium Blocks and available drainage system not maintained.

5. Clearing of trees on upper catchments resulted in increased runoff that flowed down the terraced hill-slope immediately behind the towers

6. Retrogressive slides progressively moved uphill starting from loss of toe mass at the back of the Condominium Block 1 (see Fig. 4).

7. The fallen debris accumulated behind the back terrace of Condominium Block 1 caused the slip to occur beneath the entire rail pile foundation that brought down the Condominium Towers within minutes of the landslide occurrence.

[FIGURES 3-4 OMITTED]

The case has several important implications for Developers, Building Professionals, Local Authorities, absentee landlords and developers of neighbouring properties in Malaysia. The Resident Association took the case to Court (Steve Phoa Chen Loon & Ors v Highland Properties Sdn Bhd & Ors, 2000) and the Court found that the landslide that brought down Block 1 of the Highland Towers Condominium was due to a rotational retrogressive slide emanating from a high retaining wall behind the 2nd tier of the 3 tiered car parks. Water was found to be the principal factors that caused this high wall to fail. Lessons learned from the decision of the High Court for an engineer are as follows:

The Engineer was liable in negligence for (i) not having taken into account the hill or slope behind the Towers, (ii) not having designed and constructed a foundation to accommodate the lateral loads of a landslide or alternatively to have ensured that the adjacent hill-slope was stable, (iii) for not having implemented that approved drainage scheme, (iv) for colluding with the First (Developer) and Second (Architectural Draughtsman) Defendants to obtain CF without fulfilling the conditions imposed by the Fourth Defendant (Local Authorities) and also in nuisance as he was an unreasonable user of land.

Ooi (2004) in his Special Lecture on Earthworks Practice in Malaysia at the MGC2004 in Kuala Lumpur presented many case histories of earthwork failures and their rehabilitations. Table 1 shows some of the landslide incidences. In general, water has been the principal cause of many geotechnical failures. The design should take in account of suitable surface and subsurface drainage of slopes and embankments. The use of tipped fill on slope and embankment should not be allowed under any circumstances.

DEBRIS FLOW

Debris flow is a natural Hydraulic-Geotechnical phenomenon that has been reported in various parts of the world. In Malaysia, debris flows do not occur as frequently as landslides; as a result of which there is no clear recognition of the problem. The impact of the flow becomes apparent when it traverses or is obstructed by a roadway or some human settlements. The immediate mechanism that distinguishes one from the other is that debris flow emerges from a streambed of a hill/mountain site, whilst a landslide is a slip of the flank of a hill or bank.

It can be said that debris flow results from the dam break of a barrier across the stream that has been "naturally" built up; releasing significant amount of water at high velocity and carrying along with it the debris upstream and downstream of the natural barrier. The "debris" besides comprising materials ranging between boulders and mud also contains significant amount of timber logs and other vegetable matters. Although of natural occurrence, certain hydraulic and geotechnical factors that may have contributed to the debris flow phenomenon could be identified. From the factors, certain mitigating measures may be recommended. Hydraulic factors dominate the impact of the debris flow, whilst geotechnical factors determine the formation of the natural barrier and the materials of the debris.

TSUNAMI ON 26 DECEMBER 2004--A MALAYSIAN EXPERIENCE

The tsunami that struck the Indian Ocean on 26 December was a global catastrophe that caught many in the world by surprise. There were no tsunami early warning systems established in the countries in and around the Indian Ocean. Malaysia was not spared the destruction caused by tsunami in places like Langkawi, Penang and Kuala Muda in Kedah. The actual death toll caused by the tsunami must necessarily exceed that reported figure of about 280,000 people. In Kuala Muda, the last time that tsunami struck was in 1880s according to record passed down by words of mouth. The December 2004 tsunami damaged about 1000 houses with about 4000 people directly affected. Fig.5a-5c shows the scenes of damage to properties.

[FIGURE 5 OMITTED]

The victims were housed in longhouse type temporary accommodations some few kilometers from the site. According to the Chief Resident Engineer of the Muda Dam Project, Ir. Ooi Choon Aun, who felt the tremor in Sungei Petani at about 9.00am local time but did not expect anything unusual had happened until he was in Balik Pulau in Penang later that day at about 1.30pm to witnessed the horror that had happened in the streets of Balik Pulau. People were dashing about in panic and there police with dead bodies laid by the roadside. Most of the tragedy occurred at Pasir Pangjang beach in Balik Pulau where people were there for picnic. The site faces the Straits of Malacca and when the seawater receded very far from the shorelines a lot of picnickers were excited and went after the fish that were left behind by the receding seawater. When the seawater rose again many were swept away with serious injuries resulting in numerous casualties. Tibballs (2005) in his book on the chapter on ' What is a Tsunami' stated that ' Often the only warning of an impending tsunami is the sight of the tide suddenly going out as exposed on the dry seabed but the eager fishermen or curious tourists who seek to far as the horizon ........ Experts say that a receding ocean may give people as much as five minutes' warning to escape to high ground. As the water is suck out to sea, fish are investigate this freak nature invariably pay with their lives when the water suddenly comes rushing back in as giant waves.'. This seemed to be the case that had happened at the Pasir Pangjang Beach.

On the other hand, there were very few casualties at the Batu Ferringhi site since they were able to clear most of the people on the beach in time. This according to informed sources was due to the early warning that they received from the hotel operators who has the experience of Tsunami in Langkawi earlier on 26 December 2004. The Batu Ferringhi site faces the Andaman Sea and therefore has the most direct effect from the Tsunami that destroyed Bandar Acheh. Interestingly, the floating Mosque at the adjacent Tanjung Bungah Beach was virtually untouched while the buildings on the beach suffered severe damages from the effect of Tsunami (see Figs. 6 and 7). Professor Shuto in his Lecture Tour of Southeast Asia on Tsunami, told his audiences in Penang in April 2005 that 'it is important to educate the people and provide timely information so that they know how to deal with the arrival of Tsunami'.

[FIGURES 6-7 OMITTED]

SEISMICITY DESIGN IN MALAYSIA

Traditionally, Malaysia has been considered as a non-seismic risk country. In 1982, the Public Works Department, Malaysia stated in the Keynote address to the Conference on Tall Buildings held in Kuala Lumpur that Malaysia is actually located in the 'ring of fire' that marked the areas affected or likely to be affected by earthquakes and cautioned that Malaysia will experience in the future severe earthquake arising from the Sumatra and Andaman fault that runs the length of Sumatra and the Andaman Sea to the north of the Straits of Malacca (Yunus, 1982). The tsunami that occurred on 26 December 2004 could be said to be the prediction that came true.

The interest in earthquake design amongst the Malaysian engineers in fact already started at that time. The Komtar Towers in Penang and the Penang Bridge built in 1980s were already designed for seismic forces. This is despite the fact that there is no requirements in the Uniform Building Bye-law for seismic forces for buildings. Ting et al (2005b) discussed some aspects of seismic design for slope stability of dams in Malaysia. Table 2 shows the different g values used for various dams. The designed g value applied in each dam site is dependent on the iso-seismal maps from Malaysian Meteorological Service (MMS) that are used as an indicator for zones that received different level of recorded intensity on Modified Mercalli (MM) scale (Mohd Rosaidi Bin Che Abas, 2001). Figure 8 shows the iso-seismal map for Peninsular Malaysia. The trend to use higher design g value in dam depended on the better information received and the increase in the intensity of seismic activities in the region. Of foremost importance, dam is a live threatening structure and needs to be fail proof. Judging from the increased frequency and intensity of tremors being felt in Malaysia in recent years, it may be prudent to allow for design of seismic forces for structures of higher level of public risks such as that of long span bridges, public and private buildings of higher than five storeys.

[FIGURE 8 OMITTED]

CONCLUSIONS

An attempt is made to highlight some of the major geotechnical disasters in Malaysia. Mitigation, Prevention and Rehabilitation of disasters are important considerations for any geotechnical disasters. The SMART tunnel project was born out of the disastrous flooding of Kuala Lumpur and is believed to be the first of its kind in the world where the tunnel will be used as a dual purpose tunnel for both flood control and to ease the traffic congestion of the Kuala Lumpur City Centre. The Highland Tower Condominium collapse shows that it is important for the designer to consider all aspect of foreseeable possible danger to the buildings in relation to the environment including future maintenance. The need to get rid of surface and subsurface water from site is clear from this tragedy. The stability of slope and the structural foundation of the building are integral in the design analysis process. Debris flow failures will increase with more development in the Highlands and mitigating measures recommended must consider hydraulic factors that dominate the impact of the debris flow, whilst geotechinical factors determine the formation of the natural barrier and the materials of the debris. The tsunami catastrophe that struck the Indian Ocean on 26 December 2004 brought about the urgent need from the geotechnical community in the region and Malaysia in particular to look at the mitigation by way of design provision and consideration. The programme of public education in awareness and training in the handling of such disaster must also be implemented.

REFERENCES

IEM (2005). "Bulletin, Institution of Engineers, Malaysia", No. 9.

Marlinda, B. A.M. (2005). "Disasters Management System in Malaysia", Bulletin IEM, No. 9, 10-12.

Mohd Rosaidi bin Che Abas. (2001). "Earthquake Monitoring in Malaysia", Seismic Risk Seminar 2001, Malaysia.

MPAJ (1994). "Report of the inquiry committee into the collapse of Block 1 and the stability of Block 2 and 3 Highland Towers Condominium, Hulu Klang, Selangor Darul Ehsan." Majlis Perbandaran Ampang Jaya.

Ooi, T.A. (1971). "Report on landslides at government quarters nos 1276 and 1280 at Section 5, Petaling Jaya, Selangor" PWD internal report.

Ooi, T. A.(2004) "Earthworks Practice in Malaysia", Proc. Conf. MGC2004, Kuala Lumpur, 45-58

Steven Phoa Cheng Loon & Ors v Highland Properties Sdn Bhd & Ors (2000) Current Law Journal, Vol 4, p.508-602.

Tibballs, G. (2005). "Tsunami The World's Most Terrifying Natural Disaster", Carlton Books Ltd., London

Ting, W.H., Ooi, T. A., Ahmad, A. and Tan, B. K. (2005a) " Comparison of Tunnelling Methods in Granitic and Karstic Limestone Bedrock in Kuala Lumpur.", Journal Engng Geology,Geomechanics and Tunnelling, Felsbau 23,No.2, 32-37.

Ting, W.H., Ooi, T. A., Ahmad, A. and Tan, B. K. (2005b) " Seismicity in Slope Stability Practice in Malaysia." Proc. Int. Conf. Geotech. Engng. For Disaster Mitigation & Rehabilitation,Chu, Phoon & Yong (eds) [C] 2005, World Scientific Publishing Company.

Wong, G. (2005). "Disaster Relief Engineers", Bulletin IEM, No. 9, 6.

Yunus, M. M. Y. (1982). "Keynote Address- Building High", Proceedings Asian Regional Conf. on Tall Buildings and Urban Habitat, Kuala Lumpur, Institution of Engineers, Malaysia., K-1 to K-8.

T.A. OOI

TAO Consult Sdn Bhd, 17A, Jln Awan Hijau,Taman Overseas Union Batu5, Off Jln Klang Lama, 58200 Kuala Lumpur, Malaysia

W. H. TING

Zaidun Leeng Sdn Bhd , Tingkat 5, Jalan Bukit Nanas, 50250 Kuala Lumpur, Malaysia

Table 1. Case histories of earthworks failures due to water

Date Location Landslide Details

A. Bukit * Gasing Height Development
January Gasing, * Flow slide of tipped fill damaged two
1971 Petaling Jaya Government Quarters completely
 during one week of incessant rain
 * The Quarters were subsequently
 rebuilt
 * Case settlement out of court
 * PWD internal report (Ooi, 1971)

B. Ulu Kelang, * Slope failure due to toe erosion at
September Ampang river bank and excavation on
1988 Jaya neighbouring land during raining
 season
 * Damaged to Bungalow and
 Swimming Pool
 * Court decided Engineer has a duty of
 care that he owed to the house owner
 * House owner awarded economic loss
 amounting to about RM360,000.00

C. Ulu Kelang, * Collapse of Block I of Highland
December Ampang Towers on 11 December 1993 during
1993 Jaya the raining season
 * 48 people were killed
 * Technical committee report of
 investigation by MPAJ (MPAJ,
 1994
 * Engineer failed in his duty of care he
 owed to the plaintiff

D. Genting, * Debris flow, Genting Highlands on
June Selangor 30 June 1995 caused closure of
1995 Kuala Lumpur--Karak Highway
 * 20 people were killed
 * 23 people injured
 * Economic losses, deconstruction of
 several vehicles, deconstruction and
 disruption of roadway
 * No inquiries

E. Ulu Kelang, * Bukit Antarabangsa fill slope failures
May Ampang during raining season
1999 Jaya * Access road to Bukit Antarabangsa
 cutoff
 * Residents of the area were evacuated
 * Economic loss and anxieties

F. Ulu Kelang, * Landslide buried the bungalow at the
November Ampang foothill during raining season. 8
2002 Jaya people were killed.

G. Bukit * Rockslide caused closure of NKVE
November Lanjan, Highway at Bukit Lanjan
2003 NKVE * Continuous heavy rainfall in the
 month of October and November
 before the rockslide

Table 2. Different g valuues used in dam slope stability designs
in Malaysia

 Dam Location Design value

1. Gemencheh, Negeri Sembilan (1980s) 0.10g

2. Sungai Selangor, Selangor 1990s) 0.10g

3. Sg. Kinta, Perak (2000s) 0.15g

4. Bakun, Sarawak (2000s) 0.20g

5. Kelalong, Sarawak (2000s) 0.30g