Box culvert desilting, Hoi Fai Road to Olympian City
Diver-operated desilting of a flooded box culvert, with on-site settling and dewatering so only dry spoil leaves the site.
- Year
- 2020 – 2021
- Client
- Kei's Engineering Limited
- Location
- West Kowloon
- Status
- Completed
- Category
- Hydraulic
A long box culvert between Hoi Fai Road and Olympian City had silted up while still full of water. We compared three methods: a diver-operated sand pump feeding settlement tanks, a 0.3 m³ grab bucket, and jet-pump flushing. We costed each by the volume of solids removed per day.
Chosen method
- Settlement, percolation and storage tanks, a generator and diving equipment set up at the manhole.
- A diver, on surface-supplied air with a backup cylinder and constant voice communication, drags a 100 mm sand pump through the culvert.
- The pump stops when the tanks are full, while the water clears and drains off.
- Clean water is pumped away, and solids are moved to storage by grab and trucked off site.
Each team: a supervisor, a working diver, a standby diver, a tender and a communicator, working to the confined-space diving code.
Drawings
