Sustainable Infiltrated Drainage System with Porous Sublayer Modules

The main problem in the current urban drainage system is the inefficiency of the drainage system to accommodate high stormwater discharge in the system. This experimental study was aimed to investigate the effectiveness of porous sublayer modules in an infiltrated drainage system. Primarily, this chapter focused on the influence of different lengths of porous sublayer module on the infiltration, flow depth and velocity distributions in the drainage system. Laboratory experiments were carried out for three porous sublayer module lengths to drain diameter ratio ( \(Ls/d\) ) of 0.7, 1.0 and 1.4 for two drain bed slopes and four drain section spacing. The study found that the optimum ( \(Ls/d\) ) for 0.7 and 1.4 which allowed more than 75% of surface runoff to infiltrate into underground storage, as stated in MSMA for On-Site Detention. The flow velocity in the drain reduced by more than 80% with the application of porous sublayer modules. It was also found that the spacing between drain sections was a significant factor to lower the drain velocity. Its velocity increased as the water travelled further downstream and reduced as the drain spacing became larger.