The Brihanmumbai Municipal Corporation (BMC) has received approval from the Maharashtra Coastal Zone Management Authority (MCZMA) to construct twin underground tunnels to transport treated wastewater from the proposed Dharavi wastewater treatment facility to Mahim Creek in Mumbai.
The approval, granted at an MCZMA meeting held last month, is restricted to construction within the Coastal Regulation Zone (CRZ) II. Construction is prohibited in CRZ IA, CRZ IB and CRZ IV areas under the clearance conditions.
Project Details
The project involves the construction of two underground tunnels, each measuring 2.6 metres in diameter and 501.6 metres in length. The tunnels will carry treated wastewater from the proposed treatment facility near Sion railway station to the marine outfall system at Mahim Creek.
The underground alignment is intended to minimise disruption to existing utility networks, reduce traffic congestion and limit tree removal in the ecologically sensitive Mahim Nature Park area. As the proposed tunnels will pass beneath the protected forest, the BMC must obtain the necessary No Objection Certificates (NOCs) before proceeding with the work.
Environmental Conditions
The MCZMA has imposed several environmental safeguards as part of its approval. The BMC must submit a separate, detailed application for the final discharge of treated wastewater into Mahim Creek, incorporating recommendations from the National Institute of Oceanography.
The civic body has also been prohibited from disposing of solid or liquid waste within the coastal zone. All construction debris must be processed and managed using scientifically approved methods.
Project Significance
The tunnel system is an important component of Mumbai’s wastewater management infrastructure. It is intended to provide a safe and efficient conveyance route for treated effluent while reducing the impact of construction on the surrounding urban area and sensitive coastal ecosystems.
However, the coastal clearance covers only the specified tunnel construction within CRZ II. The BMC must fulfil the stipulated environmental conditions, secure the required NOCs and obtain separate approval for the final wastewater discharge before proceeding with the relevant activities.
