Thiruvananthapuram: Eight months ago, the Kerala State Disaster Management Authority (KSDMA) received a report stating that the unscientific construction of National Highway 66 in the state could lead to a disaster. The preliminary report was prepared by a panel of experts appointed by the authority following landslips at the highway construction sites in Bevinje, Thekkil, Veeramalakkunnu and Mattalayi in Kasaragod district.

The report, which pointed out that unscientific demolition of hills for building the road had increased the risk of disasters, also suggested follow-up studies and precautionary measures to avert tragedies. 

The recommendations of the report included improvement of the slopes adjacent to the highway by building benches depending on the nature of the soil and providing sufficient width for each bench.  The report also said that a single solution could not be suggested for all locations, as the type of soil and its thickness would differ in each area. It wanted identification of spots where there is a risk of landslips and implementation of specific engineering solutions.

Major findings of the report

• Areas with red laterite stone have been sliced up to a depth of more than six metres, without strengthening the soil or constructing retaining walls.
• Ancient, broken rocks seen in areas where the earth was removed to build the road could collapse, causing landslips.
• Landslips are caused by steep slopes, loose soil, mounds of earth which are weak or in contact with groundwater and alterations to nature by humans.
• Landslips and mudslides have occurred several times on the road built by slicing the hills. In these areas, the upper layer of earth comprises silt and clay, below which red laterite rock is present. Granite rock is seen only at the bottom. Earth collapses because the red laterite layer cannot withstand the weight of the soil above it.

Crucial recommendations of the panel

• Build a proper drainage system for the road. Water from the slopes should be directed to drains and culverts.
• Install drainage pipes to drain groundwater, as natural water channels have been blocked following the construction work.
• Build benches at the slopes, instead of excessive and steep slicing of the hills.
• Apply concrete mixture (shotcrete) on the slopes of the hills and retaining walls. Provide holes on them to allow water to flow out (weep holes).