Landslide Emergency Services and Slope Maintenance Teams (Civil Engineering and Development Department)
"My grandpa and uncle are engineers. As a kid, they nurtured my interest in this area. Back then, whenever I saw tunnels, I found them so remarkable. I was always wondering why a tunnel would not collapse." Geotechnical Engineer, Civil Engineering and Development Department, Fung Ka-wing told us.
"Hong Kong has lots of mountains and little flat land, and the population density is high. Every year, the Geotechnical Engineering Office receives about 300 reports on landslides."
"Once, I arrived at a landslide site and I received a message at the same time that Super Typhoon Mangkhut would approach Hong Kong soon. I urged the villagers to move out temporarily as it was very dangerous. At first, the villagers did not listen to my recommendation. But I explained the situation to them patiently. Finally, they accepted it."
He said, "Our top priority is to ensure the safety of the general public. We believe that they can feel it too."
Hong Kong has a land area of about 1,100 km2. Around 60% of the land area consists of relatively steep natural terrain. During the rainy season, landslides occur frequently, with an average of 300 reported landslides in Hong Kong each year.
The Geotechnical Engineering Office (GEO) of the Civil Engineering and Development Department (CEDD) has a slope safety management system in place to protect the general public from landslide hazards.
When the Hong Kong Observatory issues a Landslide Warning or typhoon signal no. 8 or above, the Emergency Control Centre of the Geotechnical Engineering Office will be in operation.
Over ten geotechnical engineers and technical officers will be on duty to provide geotechnical advice to government departments on handling landslide emergencies.
Upon receiving landslide reports, geotechnical engineers will carry out site inspections and give advice to government departments to restore services and facilities disrupted by landslides.
Geotechnical Engineer, Civil Engineering and Development Department, Ting Sui-man said, "Our top priority is to ensure the safety of the general public. If rescue work is required, we will collaborate with the Fire Services Department and provide advice to the Police on the areas to be cordoned off. We will also contact responsible works departments to carry out emergency slope works. It includes promptly covering the slopes with tarpaulin to prevent rainwater infiltration which may cause further landslides."
When more serious landslides occur, the work of the geotechnical engineers will be even more hectic.
In the evening of 29 August 2018, a massive landslide hit a road section of Fan Kam Road near Ta Shek Wu Tsuen. Both lanes of Fan Kam Road were closed due to inundation of debris and muddy water on the road.
Geotechnical Engineer, Civil Engineering and Development Department, Fung Ka-wing said, "When I arrived at the site, the landslide debris from the hillside covered the entire road. The debris was up to knee level. I urged the villagers to move out temporarily."
Resident, Angelina Yeung said, "I heard a “boom” and all of a sudden the debris rushed to near my house, and a van was bumped in. The Geotechnical Engineering Office used concrete blocks to build a barrier around the slope, covered the slope surface with tarpaulin and shotcrete the landslide scar."
Angelina Yeung continued, "A lot of elderly people live here. They (CEDD) did a lot of works, some beyond their scope. They have been really helpful. And we are so grateful to them."
The day after the landslide, staff of the Geotechnical Engineering Office and Survey Division visited the site again.
They used drones and handheld laser scanners to quickly conduct landslide risk assessment. Detailed geographical data of the nearby natural terrain were collected, providing useful information for the design of emergency works.
Geotechnical Engineer, Civil Engineering and Development Department, Choi Wai-kwok, Michael explained, "The data collected on site, i.e. the three-dimensional image, enabled our engineers to carry out landslide hazard study and to assess whether there is any immediate or long term landslide risk. Based on the estimated size and volume of potential further landslides, suitable engineering works would be carried out accordingly, such as the installation of soil nails and flexible barrier to protect Fan Kam Road at slope toe."
Fan Kam Road is the main road connecting Fanling and Kam Tin. The landslide took place just before the school re-opening in September. To restore the road service as quickly as possible and to minimise disruption to the residents, the Geotechnical Engineering Office worked closely with the Highways Department. Immediate action was taken to mobilise the contractors to carry out emergency repair work at the critical location.
Geotechnical Engineer, Civil Engineering and Development Department, Lo Ho-pong said, "Most of the landslide debris was accumulated at the mid-level of the hillside, posing subsequent landslide danger. The biggest challenge was how to deal with these debris. Our target was to re-open at least one lane of the road to cope with the traffic on the first day of school."
He continued, "We discussed with our contractors and engineers on how to optimise the design to ensure that the construction works could be completed by 10 p.m. that night."
Immediately after completion of Stage 1 emergency works, Stage 2 works was also successfully completed within the next two weeks. All these emergency works were essential for preventing more severe landslides from happening when Super Typhoon Mangkhut hit Hong Kong.
Actually, there are some other works of the Geotechnical Engineering Office that are closely related to the daily life of the general public.
Geotechnical Engineer, Civil Engineering and Development Department, Chu Kei-hong said, "CEDD operates 90 raingauges in Hong Kong, which account for the majority amongst all government departments. The rainfall data collected by these raingauges enable us to have a clear picture of the rainfall condition of Hong Kong. This facilitates our joint decision with the Hong Kong Observatory on the issue or cancellation of a Landslide Warning."
Chief Geotechnical Engineer, Civil Engineering and Development Department, Yeung Fei, Jenny said, "We are now facing the challenge of extreme rainfall events caused by global warming. We must stay alert, and cannot slack off. We will keep striving our best to serve the public, and to protect their lives and properties from the threats of landslides."
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