In Singapore, all land or property owners (whether private or government) have the responsibility to maintain their slope and slope protection structure in a good and safe condition. They can take the necessary steps to ensure slope stability and prevent landslide which could otherwise damage properties and endanger lives.

Under intense prolonged rainfall, water seeps into the soil and are retained if it is not properly drained away. Over a period of time, the water will accumulate and cause water pressure that is high enough to trigger the failure of a slope and its earth retaining structure. This can be prevented by regular inspection and maintenance to ensure that surface protection, earth retaining structure, drainage, etc are maintained in a good and functional condition.

(a) Slope with vertical and horizontal drain	(b) Slope with horizontal drain
Fig (a) & (b) A well maintained slopes

What are the tell-tale signs of slope failure?

Usually, there are tell-tale signs before a slope fails or an earth protection structure collapses, for example, cracks or tilt on the earth retaining wall/ structures, blocked weep hole/drain, soil erosion etc.

More tell-tale signs are shown in the slope protection leaflet: http://www.bca.gov.sg/others/slope_protection.pdf

What should owners do if they detect tell-tale signs?

• engage a professional engineer to carry out structural inspection/assessment and recommend rectification measures.
• submit plan to the Building and Construction Authority (BCA) for approval and permit to carry out rectification works that involve stabilisation and strengthening to slope and/or slope protection structure.
• engage a contractor to carry out rectification works according to approved plan.

What will Professional Engineers engaged by owners do?

They will:

• carry out visual inspection and assessment;
• submit visual inspection report including recommendation of rectification measures and advise on any need to carry out detailed structural investigation;
• advise owner to put in place immediate measures to remove danger where necessary;
• carry out detailed structural investigation as recommended from visual inspection and propose appropriate rectification measures;
• submit plan to BCA for approval if rectification involves stabilisation and/or strengthening to slope and earth retaining structure
• supervise rectification works carried out by contractor;
• submit certification of supervision upon completion of rectification work.