ELMINA RIDGE LANDSLIDE

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Quote : 

SHAH ALAM: Two Bangladeshi construction workers died after being buried in a landslide in an incident at a concrete drain construction site in Elmina Ridge, Section U15 here today.

In the incident at about 10 am, the victims were working on the construction of a 0.3 m deep drain in the housing area.

Upon inspection, firemen found that the victims were buried by earth and concrete of the U box culvert while they were doing drainage construction work.

Meanwhile, Shah Alam district police chief ACP Mohd Iqbal Ibrahim said his investigation found that at the time of the incident, there were three workers who were installing concrete drains at the location involved.

He said the ground at the side of the drain suddenly collapsed causing the concrete wall of the drain to break and fall on one of the workers and the other was buried by the falling earth.

Photo Source : Bernama

MY PERSONAL OPINION

Let's first look into the typical construction methodology (excerpt from a method statement)

TYPICAL RISK, DANGERS AND HAZARDS DURING U-BOX CULVER INSTALLATION

1) Trench Collapse

The sides of the trench may collapse, especially if the soil is unstable or the trench is deep.

1.1  Preventive Measures

Use trench shoring, trench boxes, or sloping to prevent collapse. Workers should avoid working in trenches without proper protective systems.

2) Heavy Equipment Hazards

Risks associated with the operation of heavy machinery like cranes, excavators, and trucks. These include crushing, falling objects, and equipment malfunction.

Note : Please be aware that limited working space between heavy equipment, such as a crane, and the excavation area can impact the soil load and potentially lead to a collapse.

2.1 Preventive Measures

Ensure proper training and certification of operators, maintain equipment, and establish clear communication and signaling protocols.

Ensure the placement of heavy equipment such as cranes are placed at the appropriate position during excavation. The working space between the crane and the excavation area must be adequate.

3) Falls

Workers can fall into the trench or off equipment.

3.1 Preventive Measures

Install guardrails, barriers, or fencing around open trenches, and ensure workers use harnesses or fall protection gear when necessary.

4) Water Accumulation

Water can accumulate in the trench, leading to slippery conditions or creating a drowning hazard.

4.1 Preventive Measures

Ensure proper drainage and dewatering systems are in place before excavation begins.

5) Exposure to Hazardous Materials

Workers may be exposed to hazardous materials such as contaminated soil or underground utilities.

5.1 Preventive Measures

Conduct a site survey for potential hazards and use appropriate personal protective equipment (PPE).

6) Utility Interference

Risk of damaging underground utilities (like gas, water, or electrical lines) during excavation.

6.2 Preventive Measures

Conduct a utility survey and mark utility locations before excavation. Follow local regulations for safe digging.

INCLEMENT WEATHER

During the rainy season, the ground becomes saturated with water, which can reduce soil stability. This makes the soil more prone to collapsing, especially if the trench walls are not properly supported or shored. Saturated soil can be heavier and less cohesive, increasing the risk of a trench collapse, which poses a safety hazard and can delay the installation process.

Water Accumulation in Trenches

Rainwater can accumulate in the open trenches, creating additional challenges for the installation of the culvert. Waterlogged trenches may require dewatering before installation can proceed, which can add time, effort, and cost to the project.

Difficulties in Compaction and Backfilling

Proper compaction of the backfill material is essential for ensuring the structural stability and longevity of the culvert. However, wet conditions make it difficult to achieve the required compaction levels. Wet or muddy soil may not compact well, potentially leading to settlement issues in the future.

Logistical Challenges

Heavy rain can disrupt transportation of materials and equipment, affect worker safety, and make the construction site more challenging to navigate.

Damage to Installed Structures

Rain can cause erosion around the newly installed culvert if drainage and runoff are not adequately managed, potentially undermining the structure before it is fully set.

DO IT DURING DRY SEASON

Benefits

Reduced Water Interference During the dry season, there is minimal or no water flow in the drainage channel, making it easier to excavate, place, and align the culvert without the risk of flooding or waterlogging.

Improved Safety

Lower water levels reduce the risk of trench collapse and other water-related hazards, such as slippery conditions or equipment getting stuck in mud.

Better Soil Conditions

Dry soil is generally more stable, making excavation and backfilling easier and more effective. It also reduces the risk of soil erosion or settling, which could compromise the culvert's installation.

Efficient Construction

Work can proceed faster in dry conditions since there are fewer weather-related delays, allowing for a more efficient and timely installation.

Typical Safety Slope for Trench Walls

To prevent trench collapse, especially in deeper trenches or in unstable soil conditions, the trench walls should be sloped or benched according to safety standards. The appropriate angle of the slope depends on soil type:

Stable soil

A slope of 1:1 (45 degrees) is typically used.

Less stable soil: A slope of 1.5:1 or even 2:1 (about 33 to 27 degrees) may be necessary.

WHEN SINKHOLES HAPPEN IN URBAN AREAS

Photo Source : Sinar Harian

Sinkholes are sudden depressions or holes in the ground caused by the collapse of a surface layer. When they occur in urban areas, they can cause significant damage and pose serious safety risks.

Here's what typically causes sinkholes in cities and how they can be prevented.

COMMON CAUSES OF URBAN SINKHOLES

1) Underground Water Erosion

• Water Main Breaks - Leaking or broken water mains can erode the soil beneath the surface over time, leading to sinkhole formation.
  
  
• Sewage Leaks - Similar to water mains, leaking sewage pipes can erode the ground, weakening the surface above.
  
  
• Stormwater Infiltration - Heavy rainfall or poor drainage systems can cause water to infiltrate the ground, washing away the soil and creating voids.

2) Construction and Infrastructure Issues

• Excavation Work - Construction activities like digging or tunneling can disturb the ground and create weak spots that may collapse into a sinkhole.
  
  
• Old or Abandoned Infrastructure - Forgotten underground tunnels, mines, or other infrastructure can weaken over time, eventually collapsing.
  
  
• Poorly Compacted Soil - During construction, if the soil is not properly compacted, it may settle over time, leading to a sinkhole.

3) Geological Factors

• Karst Topography - In areas with limestone or other soluble rocks, natural processes can dissolve the rock, creating cavities that may eventually collapse.

• Underground Caverns - Natural caverns or voids can exist beneath the city, which might collapse under certain conditions.

PREVENTION OF SINKHOLES IN URBAN AREAS

1) Regular Inspection and Maintenance

• Infrastructure Monitoring - Regularly inspect water, sewage, and drainage systems to detect leaks or weaknesses early
  
  
• Ground Surveys - Conduct geotechnical surveys in vulnerable areas to identify potential risks before construction begins.

2) Improved Drainage Systems

• Stormwater Management - Implement effective drainage systems to prevent water accumulation and infiltration into the ground.
  
  
• Surface Water Diversion - Ensure that surface water is diverted away from buildings and infrastructure to reduce the risk of erosion.

3) Better Construction Practices

• Proper Soil Compaction - Ensure that soil is properly compacted during construction to prevent future settling.
  
  
• Use of Modern Technologies - Employ advanced techniques like ground-penetrating radar (GPR) to detect underground voids before construction.

• Reinforcement - Reinforce underground structures with materials that can prevent collapse.

3) Public Awareness and Reporting

• Education - Educate the public on the signs of potential sinkholes (e.g., cracks in the ground or building foundations) and encourage prompt reporting.
  
  
• Quick Response- Develop a rapid response system to address potential sinkholes before they become severe.

By combining regular maintenance, improved infrastructure, and public awareness, cities can significantly reduce the risk of sinkholes and mitigate their impact.

FLOOD MITIGATION - WHAT'S THE CONCLUSION? - NIK ZAFRI

Personally and professionally speaking, I still do not fully “understand” the never ending problem of flood especially in the East Coast of Malaysia.

(Source : http://d.ibtimes.co.uk) 

As a person who is also having a minor 'stake' in flood mitigation program (which I consider a great honour) I've witnessed the superb knowledge, skills and experience of my fellow professionals and experts in the fields supported fully by the Department of Irrigation and Drainage (DID) and the team of consulting engineers appointed by them. 

The Terms of Reference (TOR or Design Specifications/Briefs) provided by DID is very clear even 'dare' to take a step forward by introducing the need of a comprehensive Flood Risk Management Plan (FRMP) which I am personally involved in including the introduction of Flood Risk Map. (read my lips carefully...not "Flood Hazard Map" but "Flood RISK Map") - any sample Mr. Nik? Sorry...Confidential!

The comprehensive FRMP is the FIRST in Malaysia despite the country has yet a specific Flood Risk Act (also which I have proposed to the Government – hopefully to be passed in Parliament soon)

The proposed Act for Malaysia should be something like this sample :

Introductory Text

Part 1 Flood and Coastal Erosion Risk Management

1. Key concepts and definitions

1.“Flood” and “coastal erosion”

2.“Risk”

3.“Risk management”

4.“Flood risk management function”

5.“Coastal erosion risk management function”

6.Other definitions

2. Strategies, co-operation and funding

7.National flood and coastal erosion risk management strategy: (Malaysia)

8.National flood and coastal erosion risk management strategy:(States)

9.Local flood risk management strategies: East

10.Local flood risk management strategies: West

11.Effect of national and local strategies: North

12.Effect of national and local strategies: South

13.Co-operation and arrangements

14.Power to request information

15.Civil sanctions

16.Funding

17.Levies

3. Supplemental powers and duties

18.DOE: reports

19.Local authorities: investigations

20.Ministerial directions

21.Lead local authorities: duty to maintain a register

4. Regional Flood and Coastal Committees

22.Establishment

23.Consultation and consent

24.Membership

25.Money

26.“The Minister”

5. General

27.Sustainable development

28.Power to make further amendments

29.Restructuring

30.Designation of features

31.Amendment of other Acts

Part 2 Miscellaneous

32.Sustainable drainage

33.Reservoirs

34.Special administration

35.Provision of infrastructure

36.Water use: temporary bans

37.Civil sanctions

38.Incidental flooding or coastal erosion: DOE

39.Incidental flooding or coastal erosion: local authorities

40.Building regulations: flood resistance

41.Compulsory works orders

42.Agreements on new drainage systems

43.Drainage: concessionary charges for community groups

44.Social tariffs

45.Water and sewerage charges: non-owner occupiers

46.Abolition of Overlapping Committees

Part 3 General

47.Pre-consolidation amendments

48.Subordinate legislation

49.Technical provision

SCHEDULES

SCHEDULE 1 Risk Management: Designation of Features

SCHEDULE 2 Risk Management: Amendment of Other Acts

SCHEDULE 3 Sustainable Drainage

SCHEDULE 4 Reservoirs

SCHEDULE 5 Special Administration

And yet, some parties keep emerging and simply pointing their fingers towards DID when it comes to flood problems. (Remember, there are still other stakeholders as well – check your facts) With all due respect, sometimes I wonder if these finger pointers have any experience involving themselves in DID flood mitigation projects.

First a disclaimer, I am neither working nor instructed by DID or any party to write this article – just to make "a wake up call" and not some "rude awakening"

Let's talk a bit about what I am involved in - been assigned to prepare the Risk Management Plan in 4 parters

Part 1 – Preliminary (mainly about Flood – with all the complete datum – among others, causes of flood, rainfall data and IDF Curves, Mann-Kendall, Hydraulics, risk of flood on people – residential, assets and offices/businesses, roads, riparian issues etc., Climate Change and many others. All these are mostly based on the Site Visit, Survey and Investigation around the catchment area. Both Consultants and DID have been very generous to cooperate by providing me all the datum that I require and at the same time, proposed new ideas to ensure proper mitigation is happening.

Part 2 – Conceptual Design – risks involving design and also future construction activity – focus on the proposed mitigation – such as Bunds, Rubberdams, Bridges, Floodgate and Pumps, Detention Ponds etc. and what are the risks associated with them especially during construction, post construction and once it is handed over to DID.

(Source : http://huachenrubber.en.ecplaza.net)

(Source : http://www.gobizkorea.com)

Part 3 – Interim Report - basically the progress and effectiveness of Part 1 & 2 and how Part 3 is going to be..

Part 4 – Final – integration of both Part 1 and 2. Findings – to include numbers of those at risks, match them with the numbers shown on (a) Socio-Economic Report (prepared by another team member to include survey with the experienced residents) and match them with the (b) Flood Hazard Map, Statistics from many stakeholders and Land Use Map (Current and Future). Then I need to do a projection by marking them in Red, Yellow/Orange, and Green at different bandings – Below and above 0.5m and 1m (extracted from Flood Hazard Map prepared by the Consultants). I then build a flood risk map (still being proposed) with proper scales vs properties at risks. 

(Source : http://i.dailymail.co.uk)

On the other hand the Design and Construction risks are mostly proactively identified based on my experience in the construction industry especially my experience in construction of hydro electric dam has proven very useful.

Using the hazard and risk management method, I have identified the risks and effectiveness of the proposed mitigation from the detailed design – both reports and drawings. Also giving points on each mitigation and mark them with 3 colors as well.

Both flood risks and proposed mitigation design are identified on the likelihood, severity, risk matrix and priority in order to to project – high, medium and low a.k.a. Red, Yellow/Orange and Green.

The Risk Management Plan is aimed at providing a high level and proactive findings of flood risk from local flood sources specifically in consequent to the flooding events which may have commenced from the catchment areas determined/identified by DID. It is also to identify design and construction activity risks as far as is practicable resulting from during and where applicable the possible post-construction activities of the proposed mitigation.

I am also most impressed and proud with DID upon seeing the locally customized calculation dubbed as Hydrological Procedure No1- Estimation of Design Rainstorm in Peninsular Malaysia (HP 1). The report had outlined the new procedure to estimate design storm using a new IDF relationship and developed new temporal pattern for various rainfall duration. I've seen the final projected results and it's really a WOW factor.So, what are the typical causes of flood? While many has given their views, I too have my own views as well.

a) Loss of flood storage as a result of development extending into and taking over flood plains and drainage corridors

b) Increased runoff rates due to urbanisation

c) Inadequate drainage systems or failure of localised drainage improvement works, extended insufficiently downstream.

d) Constriction at bridges and culverts that are either undersized or partially blocked by debris build-up or from other causes

e) Siltation in waterway channels from indiscriminate land clearing operations

f) Localised continuous heavy rainfall

g) Tidal backwater effect

h) Inadequate river capacity

(Source : http://static.euronews.com)

(Source : http://floodlist.com)

Some also blamed sand mining activity but so far I've seen no evidence of that except such activity; if any; are being controlled and monitored properly by the authorities.

(Source : http://www.ejolt.org)

I also see other issues need to be addressed :

a) it appears that many people reported experiencing interaction of sea level rise with other climate extremes – a potential rise could be coupled with risk of river floods and high population density. Example, the sea rise at almost the same time of the river/drainage floods. (this was reported in the East Coast)

b) Risk for coastal ecosystem (wetlands, mangroves, coral reefs); increased coral bleaching leading to widespread coral mortality for temperature increases

c) Considerations before any mitigation process – that it will not increase flood risk but to minimize risk to people, property, economy and the environment, ensure residual risk are manageable, mitigation compatibility with the town/urban planning program and other relevant factors,

d) Proper channel management – agree and define success criteria, challenge the need of intervention, act to the risk proportion, Recognize that channel form part of dynamic system

Deal with the course - not Symptom, work with natural processes and deliver multiple objectives, Learn and Adapt,

e) Sediment and Debris control especially during proposed mitigation construction phase, (BIG ISSUE)

f) River Diversion during Construction : to determine the right construction time either high or low flow period. This is because the construction during high flow may increase the velocity of flow from outside the work area due to the constriction of the channel, but, the construction during low flow will decrease the flow velocity and hence, potential erosion and movement of sediments/debris mudflow in the stream channel.

g) future appointed flood mitigation main contractors or sub-contractors; as part of the contractual terms and conditions; to submit proper documentation (not limited to the examples quoted) that takes into account periodical risk assessment, PQP, OSHEMP, Construction Work Method Statement that takes into account JSA/JHA, Sediment Control Plan etc. for all Civil and Structural, Mechanical and Electrical works related to the proposed mitigation

There are other concerns that are not highlighted. Despite they are not within the scope of work, failure to address such issues may also affect the project to a certain extend as well. This require cooperation with all the stakeholders, civil and structural consultants, architects, engineers etc. that may be working in the same area to ensure that the surroundings redevelopment/resettlement to be as consistent as possible with the mitigation works.

According to one random Malaysian Institute of Architects (PAM) report, after a large-scale disaster occurs – for example the recent 2014 flood, it is common to witness the influx of relief efforts from all sectors into the affected areas. This can be seen in the recent flooding where many parties such as NGOs come to the aid of the flood victims. When this aid begins to encroach into construction, in particular new homes, the end result is often confusion and efforts that oppose one another. As aid parties and locals alike rush into the rebuild efforts, it will be obvious that these constructions:

i. may be built in zones not gazetted in any local plan as residential,

ii. may not be built with connectivity to any predesigned or pre-laid infrastructure – example – houses built in the surrounding may have no proper or improper drainage or waste management that is not related/linked directly or indirectly to the mitigation structures

iii. may not comply with any state or federal Uniform Building By-Laws,

iv. may not follow any council guidelines on building construction,

v. may not be approved by council for construction,

vi. may not be inspected by a qualified building professional, and

viii. may not have any certification

The issue here is the people living in the surrounding tend to relate their problems with the proposed mitigation which may lead to unnecessary disputes.

Although of little relevance, but should there be any issues raised, the Consultant, DID and the municipal councils should made it clear that it is not within their jurisdiction but in order to get future cooperation from the general public, meetings should be held with other infra and building developers; if any; working in the vicinity. Other infra and building developers also need to work together with the Consultant and all interested parties especially if the new housing or other infrastructures - example on drainage issues and point of final discharge that do not create a conflict with the proposed mitigation structures.

I always view the business of flood mitigation is always a business of “saving people's lives” and “reducing losses of assets” due to flood disaster.

Thus I would like to suggest that the flood mitigation programs everywhere in Malaysia should be expedited and I am pleading the Government to provide more budget for a better and safer mitigation. 

And whoever says Malaysia do not have the experts or expertise?

We also need to have all government and private sectors to prepare a Flood Disaster – Emergency, Evacuation and Recovery Plan. It should also include counselling sessions to the victims.

Don't wait for another flood to come..

A personal note : When I was co-training Lembaga Urusan Tabung Haji on Flood Disaster, Emergency, Evacuation and Recovery Plan, there was a moment silence during the simulation and drills of Flood Disaster...the sorrow and traumatic experience can still be refreshed clearly - but it was a good therapy. 

Let's stop finger pointing...OK? People are very impatient – some have been waiting for so many years to get a better life without having to fear the monsoon season with traumatic events everytime the coming of a new year. Let's also not depend too much on bright sunny day – we need to have some more concrete action and the time is NOW.

I have so many parties and people to thank especially Department of Irrigation and Drainage (DID), The National Hydraulic Research Institute of Malaysia (NAHRIM), my fellow team of Consulting Engineers, my fellow partner who recommended and introduced me to the project and so many others who have assisted me to make this FRMP a reality. The DID Guidelines, MASMA (Manual Saliran Mesra Alam), NAHRIM comprehensive researches on Climate Changes are excellent!!

I also have to thank National Security Council, Institution of Engineers Malaysia, Malaysian Institute of Architects, numerous researchers, DEFRA UK, Department of Meteorology Malaysia, Department of Environment Malaysia, Department of Occupational Safety and Health Malaysia, municipal councils, SIRIM and other foreign certification bodies and so many others for having excellent proposals, write-ups, case-studies, guides, standards and codes of practice, researchers etc – all published online for me to refer to.