Impound Station
Built in 1912, the Impound Station draws water from the Thames to maintain safe water levels across the Royal Docks, quietly keeping the whole system operational.
The pump station behind the docks
The Impound Station is a key infrastructure facility serving to pump water from the River Thames for two reasons:
- To maintain the water level within the docks between its upper and lower limits. Water is lost within the docks through seepage, evaporation and lock movements.
- To allow water level adjustments to be made to enable inspection of the dock walls and the false quays.
The station was built in 1912 and originally housed 3 steam driven pumps. Four electrically powered pumps replaced these in 1954. The pumps were changed again in 2003 for the electrically powered pumps we see today. All four pumps were removed, refurbished and reinstalled between 2019 – 2022 at an average cost of £192k per pump. This was the first time they had been refurbished since installation.
From the Thames to the docks
The station pumps water from the River Thames at Gallions Reach, where a screening, intake structure and cover flap are situated. This is owned by the Environment Agency as part of the flood prevention scheme. This is connected via a 4m x 5.5m intake culvert to the huge wet well below the station. The building sits above this well and houses the 4 pump sets, electrical intake switchgear, a motor control centre, low voltage switchboard and a control room. Outside the building, located on the east side, there are three transformers in a fenced compound and to the west are the four pump discharge pipes with gantry access incorporated over the top.
Interesting Facts
Behind the machinery, there’s more to this station than meets the eye.
When the latest pumps were installed in 2003, the roof was removed in order to lift them in one piece. To save the roof being removed for refurbishment in 2019, the pumps were lifted, chocked and broken into parts using the gantry crane and additional mobile lifting equipment. This saved the considerable cost, disruption and impact on residents.
The pumps can only be switched on when the height of the tide in the River Thames reaches 5.40m chart datum. Then pumps 2,3 & 4 are started 5 minutes after the preceding pump. They are then turned off when the tide reduces to 5.5/5.4m. This makes it challenging to impound during neap tides (lowest highs and highest lows).
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