News
Landslide mitigation measures in place as one lane opens for traffic at Pahala Kadugannawa
One lane of the Pahala-Kadugannawa Road that was temporarily closed due to landslide risk was reopened on Thursday, after mitigation measures were put in place by the authorities.
“We opened a single lane under the assurance given by the National Building Research Organisation (NBRO) that it was safe to do so,” Road Development Authority (RDA) Director General Sardha Weerakoon said.
“The risk was mainly to the escarpment area over the road and not the road itself,” he said adding that the closed lane will act as a barricade against any debris that may fall from above.
The water within the soil on the slope overlooking the road was being sucked out as a temporary solution and the NBRO is due to submit a report with long-term solutions to the RDA in two weeks.
This slope is made up of soil and rock boulder deposits which began to fall onto the area behind the shops along the side of the road. Due to the persistent rainfall the water had seeped into the cracks resulting in soil movement, NBRO Landslides Studies Division head R.M.S.Bandara said.
The excess water in the soil is being sucked out through eight horizontal drains. According to the NBRO, about 30-35 litres of water gushes out of the pipe every minute. However, the road itself and the railway line are built on a strong bedrock and face no threat.
“There will be no sudden movement of soil, so it is safe for the road to open under certain conditions,” Mr. Bandara said.
Officials will maintain constant vigilance for any changes in the seismic movements.
Bright lights have been installed with two men being posted round the clock.
If there is more than 75 millimeters of rain over a 24-hour period, the road will be completely closed again, he said.
An early warning system will be set up tomorrow where a siren will go off if any movement occurs uphill, Mr. Bandara said.
He said the recent movement was not entirely a natural phenomenon. “Drainage systems are blocked which hinders the natural flow of water,” he said.
Deforestation in the area was also causing soil erosion and creating unnatural waterways that could result in landslide risks. “Unauthorised constructions must stop because the consequences are far reaching and sometimes unseen until disaster strikes,” he warned.
Prof. Atula Senaratne, Senior Professor of Geology at the University of Perdeniya who initially warned of landslide risks said the horizontal drilling that was underway would remove excess water and mitigate the immediate danger.
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