MUMBAI The Brihanmumbai Municipal Corporation (BMC) on Wednesday issued a show-cause notice to the contractor – Omkar Engineers and Contractors – who built the compound wall of the civic-owned reservoir in Malad, which collapsed on Tuesday.The wall, which was built in November 2017, is still in the defect liability period of three years, making it the responsibility of the contractor to show why an FIR should not be filed. Ronak Shah, son of the partner in the firm, Narendra Shah, said, “The firm has not received the show-cause notice yet. But we went to the site and spoke to locals. We found the reservoir was overflowing at night. All water and muck put pressure on the retaining wall. The water even flowed over the wall. This wall has collapsed because of the water pressure.” After the incident, municipal commissioner Praveen Pardeshi initiated an inquiry. A preliminary report of this probe submitted on Wednesday revealed that the wall collapsed owing to pressure from water that overflowed from the reservoir towards the wall. Ashok Tawadia, chief engineer of the hydraulics department, said, “The reservoir is about 300m from the wall. The water overflowed from the reservoir and took muck and soil with it. These accumulated against the wall, and flowed over its top. Meanwhile, the soil under and around the wall also got washed away. This landslide weakened the structure and it toppled.” The peepholes in the wall to flow out accumulated water were blocked by bamboo sticks inserted by locals to rest their shanties on. Praveen Darade, additional municipal commissioner incharge of the hydraulics department, said, “The preliminary report has not yet fixed the responsibility on any person. A detailed inquiry will be conducted within 15 days.” He also set up a committee of experts from the IIT-Bombay and VJTI.