‘Malabar Hill tank crash could cut off water to 1m’ | Mumbai News – Times of India

MUMBAI : Amidst the ongoing battle between civic authorities and activists over the reconstruction plan for the Malabar Hill reservoir, the BMC has presented citizens with a scenario that charts out the potential collapse of the structure’s arch roof. Activists and locals are opposed to reconstruction because it would require the closing of Hanging Gardens, which lies above the reservoir, for about seven years.
Officials say if reconstruction does not go ahead and if the reservoir’s roof collapses, water supply to south Mumbai’s population of 10 lakh would be disrupted indefinitely since there is no alternative supply arrangement in place. The reservoir was constructed in 1887 and supplies water to four wards, A-D, through 19 distribution pipes.
The structural audit that was done in 2017 reported de- terioration in the reservoir’s floor, recommending “refurbishing”. It also pointed out that flowing water had increased porosity in the reservoir’s walls, leading to leaching in places.
Tank worn out, say experts; locals sceptical of collapse
A 2017 structural audit of the Malabar Hill reservoir had warned of structural damage and recommended its refurbishing. “Lateral load analysis may add tension in the masonry and may make the structure vulnerable.
The vertical masonry columns which take up unbalanced lateral loads of the arch barrel may induce tension in the masonry,” the report said. “In our opinion the retrofitting of this structure is not possible at all.”
Tardeo resident Dr Nilesh Baxi, a frequent visitor to Hanging Gardens, expressed doubts over the numerous reports presented by the BMC. “If there are five compartments within the reservoir, they must be interconnected in some way. It is difficult to believe that the structure can come crashing down. Moreover, a slab lies over the arch roof supporting Hanging Gardens,” he said, reflecting a prevailing sentiment among locals.
The audit stated that flowing water had increased porosity in the reservoir’s walls, leading to leaching in places, indicating chemical reaction of the minerals in masonry with chemicals available in flowing water. “The columns/piers of the structure are inadequate to bear the load from the superstructure and shows distress in many locations,” the report said. Observations on the structural audit were made by IIT-Bombay, which mentioned that it is difficult to certify the safety and stability of such a structure after the expiry of its service life, which is 70-100 years. The Malabar Hill reservoir is 136 years old.
The BMC has said expert divers assessed the reservoir’s condition for possible phased demolition, but it was deemed unfeasible. The BMC also sought opinion from VJTI and an empanelled consultant. VJTI said the stability of the structure cannot be ensured if portions (one or more compartments) are demolished, rather than the entire structure. The consultant said about structural stability that the partition walls may fail as they were likely not designed as independent retaining walls. “It is thus strongly recommended to construct a new reservoir at a suitable location, after which one can take up the reconstruction of the entire Malabar Hill reservoir at one go.”
On the BMC seeking suggestions for site alternatives, Malabar Hill resident Sanjay Shirke said that since the BMC has the entire map of the city, it would be best placed to finalise a place.