KARACHI: Chief Minister Syed Murad Ali Shah on Saturday directed the Karachi Water and Sewerage Corporation to conduct a master-plan study within six months to control urban flooding mainly caused by clogging of drains with solid waste, lack of outfall infrastructures and growing squatter settlements and encroachments in the city.

Presiding over a meeting at CM House, he emphasised the need for establishing an urban flooding control system in the city and identifying low-lying vulnerable hotspots so that the design of sewer tunnels leading to the main interceptor tunnels at Lyari and Malir Rivers could be made.

According to a press statement, the meeting was attended among others by Local Government Minister Saeed Ghani, Mayor Barrister Murtaza Wahab, Chief Secretary Asif Hyder Shah, Principal Secretary to CM Agha Wasif, LG Secretary Khalid Hyder Shah, KWSC Chief Executive Officer Syed Salahuddin Ahmed and Karachi Metropolitan Corporation Municipal Commissioner Afzal Zaidi.

The CM said that there was a need for a master plan study to control urban flooding in Karachi. He added that the study should include a tunnelling option and be completed within six months.

Asks KWSC to conduct master-plan study on different options, including tunnelling, to establish urban flooding control system in Karachi

“Once the study is conducted, a financial model would be developed,” he said.

He said that first, hotspots of low-lying prone to urban flooding areas needed to be identified. “The sewer tunnels will be designed including their alignment and outfall points so that the tunnels bring water to the main interceptor tunnels at Lyari and Malir River,” he said and added that to achieve the objective, rejuvenation of Lyari and Malir Rivers by making them free from all sewer outfall structures might also be undertaken.

During the discussion, it was observed that some of the leading causes of urban flooding were clogging of drains with solid waste, obstruction of flow in drains, lack of outfall infrastructures, growing squatter settlements and encroachments.

The CM said that efforts were made to tackle this problem by removing unauthorised settlements or cleaning drains and developing watershed plans, but these actions remained ineffective in the long run.

“We can construct new sewage tunnels in flood-prone areas which would carry a load of sewage from internal trunk sewers in the city and bring wastewater to treatment plants,” the CM said.

He said that the provincial government was building treatment plants according to the wastewater generated in the city and its by-products might be used for agriculture and horticulture.

Earth pressure balance machines

Mr Shah said that there was some proposal for a rapid large urban tunnelling system through most modern earth pressure balance machines which “do not cause problems for surface settlement”.

He added that the tunnelling system with pipe jacking would collect urban floods and in return, all natural streams of the Lyari River and Malir River would be restored.

Murad Shah directed the KWSC to propose that Karachi should have a combined sewerage system or otherwise.

“It is also pertinent that effluent discharge from the industry is accommodated for treatment at the treatment plants making it a combined effluent treatment, including that of domestic or municipal wastewater.”

The KWSC suggested that a pilot study should be done in terms of wastewater generated till 2047 as the water utility was already undertaking its master plan of water and sewerage services and infrastructure till 2047.

The mayor proposed that old areas of the city might be taken as pilot projects for urban flooding control systems.

Published in Dawn, July 21st, 2024