The FROG team working just below the Wapping entrance to the London Docks uncovered what appeared to be a brick culvert embedded in the foreshore, a few feet above present-day low-water level. It appeared to be constructed of two thicknesses of brick and have an internal diameter of about 600mm to 750mm. The alignment was along the river, not at right angles to it, so it seemed not to be part of a system of drainage directly into the river. None of us present knew what it had been.

My guess was that it had been part of the temporary drainage system installed to cope with rising ground water and leakage through the caissons or cofferdams built to hold back the river while the walls to the lock and river frontage were built. Smaller bore pipes in cast iron would have picked up water from the further parts of the excavations, coming together in progressively larger bore pipes until brick was needed to give a sufficiently large diameter. This final brick pipe would have brought water to a pit on the river front from which it could be pumped out into the river. Such an installation might have been in use throughout the construction of the dock.

I decided to see if there was any information available in London which would confirm this thesis, deny it, or suggest another one. I have looked to the resources of the Museum of London in Docklands, the Institution of Civil Engineers, the London Borough of Tower Hamlets, and the London Metropolitan Archives. I have reached no very firm conclusion.

An article in the Newcomen Society Transactions ¹ indicated that construction of a cofferdam across the Wapping entrance was begun in June 1802 and a drainage well was sunk beside the Wapping Basin but no plan was published to establish exactly where that was. Drawings from 1872 held at the Museum of London in Docklands show brick sewers of similar construction to the culvert but also, in the same series, drawings show outfall hatches of the kind associated with permanent drainage. No precise indication of location is given. ²

At LMA, a small bound volume of manuscript site reports gets a little closer to the answer. The report dated 15th October 1802 states “The East wing of the Entrance Lock has been founded below Low Water Mark firmly set on Piles and Framing, and is now built to a height of 121/2…….” and later, “The two Large Steam Engines for pumping Water have been at work since April – the Drainage Well and its apparatus together with the Drainage Pipes leading from thence to the River and placed at the Level of the Low Water Mark were completed at the same period. The Drain leading from the Well through the Bason to the Communication Lock is nearly got to its proper depth and a considerable portion of the Bason is Excavated as well as the foundation of the Lock, which will enable the foundation Piles soon to begin.” ³

A report in the following summer states:

The Cofferdam at Bell Dock Entrance is completed. Much exertion is making in Excavating the Entrance Lock and in about three weeks time it is expected to be ready to be piling the foundations. ⁴

The cumulative effect of this material, particularly the site reports, is to give some support to my theory but well short of a proof, and no stronger alternative is evident. The Unknown remains just that.

¹ A W Skempton: Engineering in the Port of London 1785 – 1808 in Newcomen Society Transactions Vol 50. 1978 – 79. Seen at the ICE.

² Ref 488 0028, 488 0029 1872: London – Wapping Entrance Pierhead Sewer Shaft; ref 488 0030 1872: London Dock Superintendents House: Sewer Flap.

³ Ref CLC/270/MS00538: General report on the state of the works of the London Docks 15th October 1802

⁴ Ref CLC/270/MS00538: Report on the general state of the works of the London Docks 10th June 1803