Royal Seaforth Dock

In this post, we’ll take a detailed look at Royal Seaforth Dock, a container port built in the late 1960s.

History

In the 1960s, work began on one of the largest civil engineering projects in the UK at that time, the Royal Seaforth Dock.

It was commissioned by the Mersey Dock and Harbour Company in the late 1960s, however the dock had been earmarked for development for at least 50 years before that.

The Royal Seaforth Dock was one of the biggest impounded dock systems in the world at the time of its construction, and has recently been expanded with the addition of the Liverpool2 deep-water container terminal, which can handle 95% of the container vessels afloat today.

Originally, the dock was proposed to stretch to as far as South Road in Waterloo, however the MDHC decided against this, and settled with a much smaller design to begin, with the view to expand in future if needed.

The initial proposal of the Royal Seaforth Dock Estate
The initial proposal of the Royal Seaforth Dock. Note how it extends past Cambridge Road to South Road in the north.

It was initially designed as a traditional “branch” dock with finger piers, however the this decision was changed.

The rapid development in container traffic called for a radical reappraisal in the proposed design.

Seaforth Dock Original Dock Design
The original branch dock design. Note the potential new entrance lock on the bottom right, and the extension north.

Container handling and packing required considerably more land space and, in order to provide this, idea of branch docks were abandoned. The dock eventually ended up being developed with one large dock for container operations, with the view to expand further in the future if needed.

Seaforth Dock Plan As Developed
Seaforth Dock as Developed

The aim of the design was to have the first of the berths ready for commissioning within 4 years of construction. The grain berth was given high priority because of its extensive superstructure, so a temporary bund was constructed between “Area A” (the present day dock) and “Area B” (present day nature reserve), to facilitate rapid completion of Area A.

Sea Wall Construction – Royal Seaforth Dock

To build the basins, a massive sea wall had to be constructed. One of the main problems with the sea wall was locating a source of 2 million tons of hard, dense rock, then transporting and placing it accurately along the sea wall. All the the rock had to meet a specific density, and as Liverpool is situated in an area of Triassic sandstone which did not meet the requirements, the designers had a real issue finding a source of rock for the Seawall.

Seaforth Sea Wall Construction Sequence
Seaforth Sea Wall Construction Sequence

Luckily, a quarry at Dinmor on the north coast of Anglesey met the criteria, and the easiest method of transport was via barge, with a sea route of 45 nautical miles, making it relatively local, and minimising disruption to locals.

Bottom dump barges were used to transport the smaller rock (the “core” and “secondary” armour) to Seaforth and dump the rock on the sea floor to be raised by a dragline excavator.

The biggest rocks (the “primary armour”) were transported by flat top barges, where the rocks were lifted off by a crane grabber and placed along the wall.

Sea Wall Construction at Seaforth Dock
Construction of the Sea Wall Core and Secondary Armor by a Howard’s NCK 1405 Dragline

To begin with, smaller toe armour was dumped by barge on the sea floor, and a dragline excavator raised it to the full height. After this, a larger crane with a grapple placed the secondary armour, and then the primary armour on top of that. Difficulties obtaining the primary armour at a sufficient rate frequently left the smaller secondary and core exposed, but fortunately there was not a large loss of material.

Eventually, the northern wall required more primary armour and no secondary or core armour, and it became uneconomical to continue to mine at Dinmor Quarry. Limestone rock was brought in via road from Mold and Carnforth, and these were tipped and grappled to finish the sea wall.

Construction of the Sea Wall, using the Lima 1850 with a grapple.
Construction of the Sea Wall, using a Howard’s Lima 1850 with a grapple.

As the construction of the sea wall progressed, the dock was excavated and dewatered, requiring an immense amount of earthworks to remove material from the basin, allowing the construction of the quay walls to begin.

Seaforth Dock Aerial Progress
Seaforth Dock Earthworks Progress Picture. The grain terminal can be seen at the top under construction.

Seaforth Passage

Work begun on creating a passage from Gladstone dock through to the new dock. A massive Cofferdam was constructed in arch shape, with protective barges in place in front. The risk from the movement from shipping in the Gladstone dock threatened the entire project.

Seaforth Passage
Seaforth Passage / Gladstone Passage. Note the massive arched cofferdam.

After the demolition of the existing northern wall of Gladstone dock took place, dewatering could take place.

Seaforth Passage
Seaforth Passage showing the dewatering of the cofferdam

The dewatering of Seaforth passage allowed for the installation of massive sector gates, to protect against the possibility of a disaster at Gladstone Lock, which could threaten the whole 87 acres of water area of the new Seaforth dock. Unfortunately, erratic running of the east gate caused the gates to be withdrawn from service in 1972, and they were never used again. One was removed when the passage was widened in 2015.

Seaforth Sector Gates
Sector Gate Installation

The first ship entered the dock in 1971, the same year as the erection of the new container cranes from Paceco and the port officially opened in 1972.

Today the port handles the majority of container traffic in the North-West.

In 2016, Liverpool2, a massive addition to the dock, was completed. Liverpool2 is situated on the Riverside, in the location of what was the proposed new Seaforth Lock.

The construction process of Liverpool2.

Photos of Royal Seaforth Dock

Location of Royal Seaforth Dock

Additional Resources

Passage gates for Seaforth Dock, Liverpool – ICE Virtual Library

Seaforth Dock, Liverpool – ICE Virtual Library


Contributions

  • 21/04/2020 – Initial Post – Sefton Digital Team

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Credits

Images of Seaforth Dock Construction / Design Documents – Institute of Civil Engineers


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