The Geological Survey of India (GSI) had warned the Brihanmumbai Municipal Corporation (BMC) eight years ago that the Kurla hillside which collapsed on Wednesday, killing eight people, was likely to give way, and listed protective works that were never carried out, government records show.Documents reviewed by The Indian Express show the GSI had sought “immediate attention” to Hill No. 3 at Saki Naka, where three landslides between 2005 and 2008 killed 16 people and damaged at least 26 houses.The GSI, the Centre’s nodal agency for landslide studies, prepared a 435-page risk assessment in 2018 after two years of field visits and technical studies across 74 landslide-prone pockets of Mumbai, and asked the BMC to frame a land-use policy for the city’s vulnerable areas.The report named Kurla among Mumbai’s five primary landslide-risk zones, along with Bhandup, Ghatkopar, Vikhroli and Chembur. Hill No. 3 was on that list. It is a steep slope of jointed rock and loose soil, the kind that fails in heavy rain, with houses packed against its base and edge. After assessing Netaji Nagar and Milind Nagar, the two settlements on the slope, the GSI concluded that the risk to life and property there was “manifold” that of other parts of Maharashtra. Heavy rain triggers landslides in Ghatkopar; eight killed, including three children, while seven others sustain injuries as hillside debris crashes onto houses. Express photo by Deepak JoshiWednesday’s landslide began when a peepal tree on the slope was uprooted in heavy rain, sending rocks and boulders down on to the shanties below.The 2018 report had flagged that mechanism, warning that water percolation and root penetration along joint planes, the natural fractures in a rock body, aggravate the risk.“Considering the steep slope, the presence of jointed rock mass and root penetration along joint planes, there is a possibility of rock fall, which may pose a threat to life and cause damage to the settlements located on the edge and at the base of the hill slope. Immediate attention is needed,” the report stated.Story continues below this adClassifying Hill No. 3 as a Class II, or highly vulnerable, zone, the GSI recommended a halt to further cutting of the slope and to construction towards it, regular cutting of tree roots, removal of small trees, retaining walls with weep holes and toe drains along the full exposed slope behind the settlements, and drainage for surface and sanitary water. No major drain passed through the area, it noted.A GSI official said the cutting of hill slopes to make room for housing, and changes to the natural drainage system, are known to aggravate landslide risk. Once a deformed slope is saturated by a spell of heavy rain, it gives way.“We can firmly say that landslides don’t happen all of a sudden but change in slope geometry and land use pattern aggravate it,” the official said.“To avert these situations, a land-use policy needs to be adopted and the drainage system should be made secure. We had mentioned these recommendations in the risk assessment report submitted to BMC and the state disaster cell back in 2018,” the official added.Story continues below this adEight years on, none of it has been done. BMC records show Hill No. 3 was placed in 2023 on the civic body’s list of landslide-prone zones where a retaining wall was a priority.A civic official said the land under the settlements and the slope belongs to the collector’s office, leaving the BMC as the planning authority but without the power to build there. The wall was to be constructed by the Maharashtra Housing and Area Development Authority (MHADA) and the Public Works Department (PWD).“We had forwarded the GSI recommendation to the collector’s office and state government, following which they had chalked out a plan to construct retaining walls. However, the plan slowed down due to funding issues,” the official said.Shiv Sena corporator from Kurla Vijayendra Shinde said he had flagged the danger in the BMC House three months ago. “In May this year, I had taken notice of motion in BMC House and urged the administration to instal metal net wiring along the cliff of hills. These nets would prevent the rocks from falling… However, the administration didn’t pay heed, and now this incident happened,” he said.Story continues below this adBetween 2020 and 2023, the state government allotted more than Rs 400 crore for pre-emptive measures against landslides across Maharashtra. Government sources said the release of funds slowed after 2023, stalling the works.The measures drawn up included high-tensile wire mesh on the rock face, more vegetation to bind the soil and slope stabilisation work, an official said. The proposal, based on a consultation with IIT-Bombay, went to the state government.“Since too many agencies such as the BMC, SRA, Collector and PWD are involved in the process, securing funds is not easy as it needs multiple approvals. Also, every year, the BMC carries its own risk assessments when new vulnerable spots emerge, making the list never ending,” the official said.Even where walls have been built, the official said, they have not always held. “In many cases, we have seen that encroachers seal the weep-holes in the walls due to which the percolated water can’t run out and the wall loses its strength and eventually collapses,” the official said.