Challenges to Management and Treatment of Stormwater Runoff from Newly Constructed Williams Landing Railway Station Car Park

The recently constructed Williams Landing railway station provides a new transport node for the rapidly developing western suburbs of Melbourne. It was designed based on providing state of the art safety and environmental benefits to the community. Management and treatment of stormwater runoff generated from the newly built car park is a major challenge due to the flat nature of the area, additional runoff from an air force base and increased flooding impacts on existing railway tracks, downstream properties and the existing railway culvert crossings. In addition to that, stormwater runoff should be treated to meet the Melbourne Water quality guidelines.

Initially, the Railway asset authority, VicTrack, agreed to provide land along the railway track which can be developed as a detention basin in order to address the stormwater management and flooding issues. The effect of storage on flood management has to be addressed in such a way that the defence facility or other properties should be safe for a 100 year ARI event. Therefore, the design of the detention basin was carried out using EPA-SWMM modelling to optimise the detention basin volume and to achieve the above objectives. Based on MUSIC model results, the detention basin, with a gross pollutant pit on the drainage line from the car park, can treat almost 100% of stormwater runoff from both the car park and the air force base to meet water quality targets.