Underfall Yard - Underfall Sluices

Underfall Sluices

Jessop's original designs for the harbour included a dam with an 'overfall', with the level of the water determined by the height of the dam's crest. As a result of the accumulation of mud and silt in the harbour, ships entering the narrow harbour were frequently being grounded. In 1832 Brunel was called upon to provide the solution to this problem and designed the sluice system, still in use today, to remove excesses of foul-smelling silt and mud.

In place of the Overfall he constructed three shallow sluices and one deep scouring sluice, between the harbour and the New Cut, together with a dredging vessel, known as a drag boat, to scrape the silt away from the quay walls. Sluices 1 and 2 ('shallow') are used to control the water level, while sluices 3 and 4 ('deep') remove the silt. When the deep sluices are opened at low tide, a powerful undertow is created which sucks the silt out of the harbour and into the river. In March 1988, the sluice control was computerised and automated.