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Express steps taken to mitigate landslides on Highway: NBRO
Immediate preventive measures have been taken to mitigate the problem of landslides on the Southern Expressway, a senior official of the National Building Research Organisation (NBRO) said.
The landslide on the Southern Highway. Pic by Sugathapala Deeyagahage
NBRO landslide Research and Risk Management division Head R.M.S Bandara said an Early Alarm System (EAS) has already been installed on one side of the Expressway and an EAS would be installed on the other side soon.
“First we have to dry out the area to minimise the damage caused by the recent landslide, following that, we will take steps to find long term solutions to prevent and mitigate the risk of landslides,” he said
“Landslide risk areas have been identified on the Kokmaduwa-Imaduwa section of the Expressway and this is why we have installed the EAS, to detect possible landslides in the future on rainy days.
This system will make the residents, public and respective authorities vigilant to any movement of land on or near the Expressway,” Mr. Bandara elaborated.
Authorities repeatedly closed the seven kilometre section between Kokmaduwa-Imaduwa on the Matara- Galle stretch of the Southern Expressway over the past few days, after the NBRO issued a landslide warning near the 114km post. Vehicles were diverted on alternative routes which caused delays.
Meanwhile, dewatering (the removal of water from solid material or soil) has been identified as the most cost effective mitigation option. “We have planned to instal horizontal drains to reduce the sub surface of the water.
Horizontal drains are generally used in establishing unsaturated enduring soil slopes. This measure will reduce the level of groundwater and the movement of slides,” Mr Bandara said.
The NBRO has also approved the blasting of large rocks using chemical explosions in the mountainous area along the Expressway to minimise the risk of landslide. He said the chemicals will not have an adverse effect on the people.
Mr. Bandara said the NBRO will issue a report on the recent landslides and recommendations for a permanent solution, in two weeks.
RDA Expressway, Operation, Maintenance and Management Division Director Saman Opanayake said earlier two possible landslide areas had been identified and one got activated due to the bad weather.
He said in the aftermath of the landslide, Southern Expressway contractors followed the instructions of geotechnical experts from the Moratuwa University and reinforced the area using the soil nailing method.
He said the affected area is stable now, pointing out that it is the foremost gradients balance measures used worldwide.
Meanwhile Disaster Management Center (DMC), Director General L.B.R Mark said an expert team comprising officials from the RDA, NBRO, Police and DMC has been formed to monitor the area.
Meanwhile the NBRO conducted several workshops in the districts of Ratnapura, Badulla, Nuwara Eliya and Hambantota to train skilled masons on disaster resilient housing construction technology. About 100 participants attended each workshop.
Mr. Opanayake, on Friday said they had a meeting with officials from the NBRO, DMC, Government Agents and other relevant authorities regarding the problem of landslides in these districts.
A spokesman for the Upcountry New Villages and Development Community Ministry said, houses were being built for the 19 families affected by the recent Kotmale landslide that claimed seven lives.
“The houses, each costing Rs. 1.2 million is being built on seven perches of land each and we hope to complete them in three months,” the spokesman said.
Matara Government Agent E.A.C Vidanagamachi said several houses in low lying areas in the district went underwater due to the torrential rains early this week.
Badulla District Acting Divisional Secretary Malani Lokubothagama said a landslide was reported in the section between Demodara and the third mile post along the Spring Valley.
“No lives were lost. Measures are being taken to remove the mound of earth as vehicular movement has been heavily hampered,” she said.
The NBRO also conducted workshops for Grama Niladharis in Badulla district on disaster risk reduction measures for human settlements in landslide prone areas.
The Badulla district was chosen for these workshops because it is prone to landslides and had several major incidents in the recent past.
The main objective of these workshops was to strengthen the landslide risk assessment process and create awareness on landslide hazards, Ms Lokubothagama said.
DMC Jaffna district Assistant Director S. Ravi said that the district experienced light showers during the past three days, while the Jaffna Teaching Hospital Director Dr. Sivapathan Moorthy said one person died of lightning.
Meanwhile the Met Department has warned that thundershowers will occur in the Western, Sabaragamuwa and Central Provinces and in the Galle and Matara districts after 2 p.m. today.
Met Dept. Deputy director Anusha Warnasuriya said that, the sea extending from Puttalam to Trincomalee via Mannar and Kankesanthurai and the sea extending from Hambantota to Batticaloa via Pothuvil will be fairly rough with winds of 50 kmph at times.