Stonecutters Island sewage culvert: stop-gate bulkhead
A diver-installed steel stop-gate built up in sections inside a live sewage culvert, after a CCTV and measurement survey.
- Year
- 2013
- Location
- Stonecutters Island, Kowloon
- Status
- Completed
- Category
- Hydraulic
Closing off a sewage culvert that is still in use is confined-space diving in its hardest form: fully sealed suits and helmets, surface-supplied air, and nothing visible without lights.
The job started with a survey. Divers entered through a man-cage lowered by a 50-tonne crane and recorded silt depth, water depth, the tide line on the walls, the wall lining, the outlet and, at the gate position, the smallest clear width and height, all on CCTV.
The gate was then built up from pieces a diver can handle, in four steps:
1. Clear the sediment and fix the inner angle frame.
2. Fit the bottom panel with its access manhole and drainage gate box.
3. Fit the middle and top panels.
4. Fix the outer angle frame and close the manhole.
Drawings
