The estimate has been submitted to the state government, which will be cleared once finance ministry gives its approval, Chief Conservator of Forest N Vasudevan told PTI today.
"The actual construction of fence will begin in January so that a continued stretch till June will be utilised. A sizeable stretch would be fenced before the beginning of the monsoon season. The maps and routes of the wall are already finalised. The cell is waiting for finance department's approval," Vasudevan said.
"Mumbai has total 5,469 hectares of mangrove land, which is notified as a reserved forest. Of this, 2-3 per cent is vulnerable to encroachments and in many pockets, it has been encroached," Vasudevan said.
The cell would also use other measures such as CCTV and satellite based monitoring to keep a check on encroachments.
Most of the encroachments have taken place in areas like Colaba, Trombay, Malvani and Charkop, the senior officer said.