Chung Hom Kok: landing a new submarine cable
The shore end of a new cable at Chung Hom Kok: a 3 m trench through armour rock, an HDPE duct set in concrete, and a sea earth jetted into the seabed.
- Year
- 2012
- Client
- NEC
- Location
- Chung Hom Kok, Hong Kong Island
- Status
- Completed
- Category
- Underwater & marine
A submarine cable is most at risk where it comes ashore. At Chung Hom Kok the new cable landed beside two existing cables, so every anchor point was first searched by divers over a 20 m circle.
- A landing craft beached at high tide put a backhoe ashore.
- The 4–5 t armour rock was lifted aside and a trench about 3 m deep was dug by backhoe on land and by grab barge offshore.
- An HDPE duct was laid by derrick lighter and by hand, and steel formwork set around it.
- Concrete was pumped in from a floating platform.
- Divers cut the formwork off underwater and the cable was pulled in.
For the sea earth, a 3.5 m patch of concrete was broken out, a Ø400 × 5 m steel casing was jetted down with a high-pressure pump, and the earth unit and Ø300 conductor were installed. The area was then reinstated with sandbags and concrete.
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