DENGKIL: Unscheduled water disruptions in Kuala Lumpur, Selangor and Putrajaya could soon become a thing of the past with the enhancement of interconnectivity or water grids in districts under the purview of Pengurusan Air Selangor Sdn Bhd (Air Selangor).

Its head of operations and director, Abas Abdullah, said this was made possible through the Off-River Storage (ORS) system utilising nearby ponds, mainly ex-mining sites, to ensure sufficient water supply even during incidences of river pollution.

"This will reduce occurrences of unscheduled water cuts in areas where Air Selangor is operating.

"For example, whenever there is pollution in Sungai Semenyih, consumers who usually get water supply from the Semenyih Water Treatment Plant (WTP) would instead get water from the Semenyih 2 WTP that has ORS as an alternative source," he told reporters during a site visit at the Semenyih 2 WTP today.  

The operations at Semenyih WTP, which gets raw water through direct intake from the Semenyih river, had this year alone experienced three pollution-related incidents.

Operations at the second Semenyih WTP were unaffected as it has its own water reserves, he said.

He said the Semenyih 2 WTP started operations in March 2018 and was the first automated WTP in Malaysia with the capacity to produce an average of 100 million litres per day (MLD).

It requires only 10 personnel to operate, compared to usual manpower strength of about 20 people at any WTP.

Treated water from the plant, covering an area of 28.76 acres (11.6ha), mainly supplies parts of Hulu Langat, Bangi, Semenyih and Beranang.

"The other WTPs that are currently in operation with the ORS system are Labohan Dagang (average capacity 200MLD) and Sungai Labu (105MLD), while a similar project at Rasau WTP is ongoing and is expected to complete in 2025.

"We are looking at the whole pipe network, covering almost 30,000km, as part of efforts to develop interconnectivity.

"Meaning, when river pollution is reported, the water supply (in the respective district) will not be disrupted as we can source treated water from other WTPs," he said.

He said improvements to the whole water supply network under Air Selangor is expected to be fully developed by 2030.

He said the Rasau project, which costs about RM3.3 billion, will see an average 700 MLD capacity in the first phase and double that by the time of completion in 2025.

He said Air Selangor was among the first to adopt the ORS system, which also promotes sustainability as the amount of residual waste produced at the plants were less than those with direct intake from the rivers.

He said the water operator was continuously identifying areas that could be improved, although the ORS system has its own limitations as it needed huge land areas to operate the ponds.

"It will not be easy to find such space, especially in densely-populated urban areas. In this instance, the idea of interconnectivity will help to ensure minimal water disruptions as supplies could be sourced from WTPs located in other districts."

Abas said the Selangor state government has also introduced the Raw Water Guarantee Scheme or SeJAM (Skim Jaminan Air Mentah) to repurpose unused ponds to function as both water storage and flood mitigation initiatives.

He said in supporting the authorities' role in curbing river pollution, Air Selangor has also set up its own Pasukan Khas Lembangan dan Alur Air or Pakar (basin and streams task force) team to take pre-emptive measures including sampling of waters from the rivers.

Meanwhile, Air Selangor head of southern region, Mohd Yunus Othman, said the ORS system made use of gravity, allows water quality to improve as it transfers from pond C to pond B and A and eventually to the plant.

"For example, the concentration of ammonia in water from Sungai Langat is at 0.40mg per litre, 0.32mg per litre in pond A, and later further reduced to 0.08mg per litre when it reaches pond C.

"This will effectively reduce operational costs in the long-run and improve water experience for some 8.4 million consumers. We aim to improve our reserve margin to 15 per cent by 2030," he said.

He said the usual soil odour at conventional WTPs was not present at the ones with the ORS system, allowing them to be built near residential schemes.

The daily consumption in Kuala Lumpur, Selangor and Putrajaya hovers around 5,100 to 5,200 MLD (5.1 to 5.2 billion MLD).

Air Selangor operates 34 WTPs in 11 districts, namely, Petaling, Klang/Shah Alam, Kuala Langat, Sepang, Gombak, Hulu Langat, Hulu Selangor, Sabak Bernam, Kuala Selangor; and federal territories of Kuala Lumpur and Putrajaya.