CLOGGED drains, a silted retention pond within a private lot and extreme rainfall were among the factors that contributed to the flash floods that hit Jalan Sri Manja and the New Pantai Expressway (NPE) near Taman Dato’ Harun, Petaling Jaya, on Nov 17 and Dec 30 last year.
The Dec 30 incident led to the partial closure of the expressway.
In a statement to StarMetro, Petaling Jaya City Council (MBPJ) said an investigation into the Dec 30 incident found the Sri Manja retention pond to be shallow, with surrounding earth drains clogged with silt and rubbish, restricting water flow and worsening flooding.
The city council said the situation was further compounded by the area’s geographical conditions and a sudden surge in Sungai Klang.
“The flooding was caused by extreme rainfall, rising river levels, and the area’s low-lying terrain.
“A total of 182mm of rain fell within two hours, exceeding the capacity of most urban drainage systems.
“The situation was worsened at the confluence of Sungai Klang and Sungai Penchala, where water levels surged from 10.3m to 12.93m and triggered backflow, resulting in flood depths of up to 400mm.”
MBPJ said interim and long-term measures were being implemented to reduce the risk of future flooding at Jalan Sri Manja (junction of Taman Buana Perdana/Jalan PJS 3/25) and along the NPE.
The city council said recurring incidents had prompted it to deploy mobile pumps and plan permanent pumping systems, while reminding land owners to ensure drains within their premises were kept clean and properly maintained.
“Our engineering, drainage and slope unit has implemented several measures, including cleaning and desilting drains along the affected stretches and placing mobile pumps and lorries on standby at the Taman Sri Manja Community Hall.
“There are also plans to instal temporary CCTV cameras and a siren system for real-time water-level monitoring.
“Site visits are being conducted with developers and relevant agencies to ensure corrective actions are carried out promptly.”
On the shallow retention pond and clogged earth drains within a private lot, MBPJ said: “We have directed the developer to clean, widen and deepen the drain and to instal a trash trap at the inlet.”
It is closely monitoring the affected areas and ensuring that supporting systems are operating efficiently to speed up water discharge.
MBPJ said Jalan Sri Manja had been identified as a flash flood hotspot and had been under continuous monitoring.
Mitigation measures that have been implemented include the construction of two on-site detention ponds and a river overflow control structure (Skalis) in 2024.
“A developer has also proposed raising the level of Jalan Sri Manja by between 600mm and 900mm.
“However, the existing system can only handle rainfall intensity of about 60mm per hour, with an estimated effectiveness of 80%, without a permanent pump system.
“We have applied to the Housing and Local Government Ministry for RM2mil to instal permanent pumps at four key locations, complete with a fixed power supply, CCTV, sirens and floodlights.”
MBPJ added that so far, approval had only been granted for the Skalis project in Jalan Sri Manja costing about RM600,000.
“We hope landowners, developers and local communities can work together to maintain drainage systems within their lands and avoid illegal dumping, which can worsen flood risks.” – By BAVANI M
