NH-85 mudslide at Adimali due to NHAI's unscientific excavation, area highly vulnerable, warns probe report, families in distress

The expert committee, which probed the devastating landslip at Koombanpara near Adimali in Idukki, has cautioned about the high probability of similar incidents during the rainy season in the future. The report, accessed by Onmanorama through RTI, lays bare yet another instance of glaring lapses in the NH construction in Kerala, leading to slope failures. Numerous slope failures on NH construction sites were reported in various districts of Kerala in the past few months.

On October 25, 2025, a massive volume of soil slid onto an under-construction stretch of the Kochi–Dhanushkodi National Highway (NH 85) and crashed into the M N Smaraka Laksham Veedu Colony, situated nearly 200 metres below the road. An early intervention by the Adimali panchayat, which evacuated 22 families after noticing cracks triggered by heavy rain, helped avert a larger tragedy. However, one person, 48-year-old Biju, was killed, and at least eight houses were completely destroyed in the incident. 

The committee, which comprised experts from the state departments of Geology, Groundwater, Disaster Management, Soil Conservation, and Public Works, warns that the area remains highly vulnerable to similar disasters, both at the site and in nearby locations. The report identifies the southwestern slope sector as particularly prone to secondary landslides, particularly during future monsoon seasons.

Although the study recommends several safety measures, experts warn that they cannot provide permanent solutions. Many of the safeguards, they point out, should have been incorporated during the early stages of road construction, limiting the scope for complete stabilisation at this stage.

According to the report, the landslip was primarily caused by unscientific slope excavation carried out as part of the widening of NH 85. This disrupted the slope's natural stability, significantly increasing the risk of failure. Heavy rainfall triggered soil oversaturation, reduced shear strength, and eventual collapse.

The probe panel recorded multiple cracks in the area, including a 15-cm-wide major tension crack just 15 metres from Biju’s house. The crack aligns with the bedrock fracture plane, signalling the possibility of further detachment. A nearby retaining wall also shows signs of creep deformation and cracking, indicating continuing instability, the report added.

The area has been classified as a landslide red zone, characterised by steep slopes of approximately 60 degrees and impermeable, saturated clay layers—conditions that significantly increase the risk of failure. While the landslip was initially localised, the panel warned that progressive movement along fracture planes could reactivate or extend the slide.

Measures proposed, but risk remains
The panel has outlined multiple levels of interventions to reduce risk. Immediate measures include constructing retaining and toe-support structures with proper weep holes and horizontal drains, improving drainage management, and excavating the tension-crack zone during summer, followed by gradual slope reshaping after retaining walls are built.

Medium-term steps involve regrading the slope during dry seasons, installing anchoring systems, and adopting vegetative stabilisation to curb surface erosion. Long-term recommendations include conducting regular geotechnical and hydrological surveys before and after monsoons, installing surface extensometers to monitor slope movement, and strictly controlling slope cutting based on scientific assessments and land-use planning, particularly in red and orange zones identified by the Geological Survey of India.

The report underscores the need for urgent stabilisation, continuous monitoring and strict curbs on unscientific excavation to prevent recurrence and protect lives, livelihoods and agriculture.

Meanwhile, experts say the risk remains. “The problem is structural. We cannot say that the situation is even temporarily under control,” said Ajeeb P A, District Geologist, Idukki. He stressed that the recommended measures should have been implemented before construction began.

“At this point, implementing the proposed safeguards is the only viable course of action. Proper drainage is critical, as any water accumulation can trigger fresh disasters,” he said, adding that similar precautions are needed in nearby areas. He also noted that no discussions have been held with the National Highway authorities following the study.

Echoing these concerns, Rajeev T R, Hazard Analyst at the District Emergency Operations Centre, said the region is inherently landslip-prone, though not entirely unfit for habitation. “Living in such areas demands extreme caution, especially during the monsoon. In this case, unscientific slope cutting was the key trigger, and similar actions could lead to new incidents,” he said, advising relocation from high-risk zones.

Onmanorama sought a comment from the NHAI authorities on the findings of the report, but the officials didn't respond.

Displaced families in prolonged distress
According to the district administration, 27 houses were either damaged or face relocation. While the initial evacuation brought relief, the situation for displaced families has since worsened. Eight families whose homes were destroyed were shifted to a nearby KSEB quarters, while others were asked to move into rented houses on the assurance that the monthly rent would be paid by the highway authorities. However, residents say no rent assistance has been received so far.

Noushad, a driver who lost his five cents of land and house worth around ₹30 lakh, said conditions at the KSEB quarters are unlivable. “Each unit has just one bedroom. Some families have six to eight members. The buildings are dilapidated, roofs leak, windows are broken, and plumbing facilities fail constantly,” he said. 

“Neither NHAI nor the Kerala government has helped us. Only the contractor gave ₹15,000 per family initially. That’s all we received,” Noushad said, adding that authorities cited the incident as a ‘man-made disaster’ to deny compensation.

Divya, another displaced resident, said life has come to a standstill. “We were living in a rented house in the colony. Everything we owned was inside that house, and we lost it all,” she says. Although the quarters allotted to her family are relatively better than those of some others, she says that many families are living in severely dilapidated units, including those with young children. “We lost everything. There is no clarity on how long we can stay here. There have been no discussions with us. We fear we may be asked to vacate at short notice,” she said.

Former Adimali district panchayat vice-president Anas Ibrahim also said repeated appeals by the local body to the government have failed. “Neither the government nor highway authorities seem concerned,” he said, adding that protests will be the only option left.