11 – 1914 Completing the Main Basin

 
To bring the main basin into use, the sea wall had to be completed, and the basin excavated.

The east wall was constructed behind the main basin temporary clay dam after the main basin had been excavated. Trenched were dug from the excavated base of the basin and lined with timber to hold the poured-concrete foundations. At one point the bottom of this foundations trench was 70ft (21m) below Ordnance datum. The same technique was used to build the north wall and graving docks, with trenched being dug down from the original sea-bed level.

The west and south walls were nearing complete on on top of their concrete monolith foundations
But before the basin could be flooded, the entrance lock and emergency exits had to be completed.