Climate change and human mismanagement of water resources, such as river channels and floodplains, increase flooding and erosion problems. Poor urbanization restricts floodwater flow and eventually leads to destructive flooding. Detention and retention systems are commonly adopted in urbanization planning and development to prevent flooding.
This project site is located at Taman SPPK, Segambut, Malaysia. Insufficient drainage and sewerage capacity in the Taman residential area raised concerns of flood risk due to occasional thunderstorms. An underground stormwater detention system (StormTrap Double Trap) was then introduced to store water runoff in an underground chamber for some time before releasing it back to the drain. StormTrap is one of the global pioneer providers of stormwater management systems that provides cost-effective solutions to engineers, owners and municipalities.
A 23.0-foot (7.0-m) depth of soft soil was measured at the project area, with the groundwater table nearly at the same level. The soft soil comprised of 9.8 feet (3.0 m) soft clay at the top, followed by 13.1 feet (4.0 m) very soft sandy silt below and then firm ground. Due to the soft subgrade, a stable construction and load transferring platform are needed to support the underground stormwater detention system.
The construction began with installation of sheet piles over the entire project perimeter, followed by excavation to the designed depth for a load transferring platform.
Bakau pile from mangrove trees was installed at 19.7-inch (500-mm) c/c spacing throughout the project area. A thin soil layer was then backfilled on top for surface preparation to lay the geotextile. Next, Mirafi HP380a geotextile was laid and subsequently a 19.7 inch (500 mm) thick aggregate fill was placed and compacted to create the stabilized load-transferring platform.
Lastly, the construction was finished with the installation of the StormTrap system and backfilling of soil. The land above the underground system will be used for a playground and parking lots.
This article originally appeared on the TenCate Geosynthetics Asia case studies web page, https://www.tencategeo.asia/en-as/resources/case-studies.
Subgrade stabilization and load transfer platform for stormwater management system in Malaysia
Taman SPPK, Segambut, Malaysia
Fixus Construction Sdn. Bhd.
TenCate Mirafi HP380a geotextile
TenCate Geosynthetics Asia Sdn. Bhd.