Technical visit to the DSD Stanley Sewage Treatment Works in caverns
By Mr Timothy LAM
The captioned visit was organised by the CV Division on 23 July 2016. A total of 15 participants attended. The Stanley Sewage Treatment Works (STW) was commissioned in 1995, and was the first sewage treatment works in Hong Kong built in caverns. It is a secondary STW with a daily capacity of 11,600 cu m.
In addition to seeing the site, the participants also learned how the STW integrated with the surrounding community and environment, and the benefits of locating a STW inside a cavern.
Mr Brian Chan and Ms Angela Tong, engineers of the Drainage Services Department (DSD), gave a presentation on the background of the Stanley STW as well as the latest information on the relocation of the Shatin STW (STSTW) to caverns. This gave participants an overview of the benefits of the relocation project, the potential impact and the corresponding solutions.
A physical model and an animation of the relocated STSTW were shown to the participants. The proposed Shatin cavern site was carefully selected, with due consideration to various aspects including environmental impact, logistics, constructability and sustainability. Upon completion, only the top of the ventilation shaft will be visible, while the surrounding rural area will be green.
During the visit, Ms Vicky Yuen, representative of the DSD, explained the treatment process including the screening and de-gritting, biological treatment, final sedimentation, disinfection and sludge dewatering. In particular, she introduced the compact technologies adopted in this plant, namely the integrated fixed-film activated sludge process in the bioreactors and the lamella settlers in the final sedimentation tanks. The ventilation system, the air monitoring system and the vertical greening system inside the caverns were also demonstrated.
We would like to thank the DSD for their support and effort in making this visit a success.
Ir William Luk (left 2nd) presenting souvenir to the representatives of the Drainage Services Department