Most of us known about Megatron, a Victorian-engineered labyrinth of storm drains with cathedral-like brick archways and interconnected dark tunnels to contain the overflow of water. (Although officially, the Megatron is one huge chamber further up the network).
Seemingly forgotten for years, this complex system of underground waterways, gained worldwide attention when it was “rediscovered,” becoming a favourite for urban explorers, and even attracting guided tours.
The misconception is that these subterranean drainage channels were built in the mid-1800s, an effort to channel the huge flow of water from Sheffield’s three main rivers – the Don, Sheaf and Porter, but the real story is very different.
Let’s start with the Porter Brook, with its source on Burbage Moor, descending into Sheffield before disappearing into culverts in the city centre. During the late 19th century, sections of the Porter were covered over, partly because the water supply was so poor and had become a sewer, but also to allow for the construction of factories above.
The Porter Brook joins the River Sheaf, the river that gave Sheffield its name, in the Sheaf Valley at a location that becomes evident later.
The Sheaf Valley had historically been prone to severe flooding, the areas around Pond Street and Ponds Forge, particularly susceptible when the River Sheaf burst its banks, and rendering much of the land unusable.
The River Sheaf flows through Sheffield, joining the mighty River Don at Blonk Street Bridge, near to where old Castle Markets stood, and the site of long-lost Sheffield Castle.
Our story really begins with the arrival of the Midland Railway Company, connecting Sheffield with London, which had blundered on its original route, inconveniencing passengers to change at Rotherham Masborough Station and take a branch line to The Wicker.
By the late 1850s, the company made proposals to rectify the matter, bringing the direct line into Sheffield. The site chosen for the new railway station caused disbelief as it was in the valley through which the River Sheaf flowed.
In the 1860s, after gaining Parliamentary consent, land was cleared on a site that was bounded east by Granville Street, on the west by Pond Lane, at north by Harmer Lane, and south by Turner Street.
The platforms were to be built where the River Sheaf flowed, and so the whole distance of the river between Harmer Lane and Turner Street was spanned by three arches and then covered over. The Porter Brook was spanned with two arches, also enclosed, and a portion of the nearby Bamforth Dam (now Sheaf Square) was filled in.
“For months and months past, seeming chaos has reigned in Granville Street and the region adjoining. Thick-booted, muddy-smocked navvies have laboured along in dust and mud, fine weather and wet, pulling down houses and the foundations on which they stood, tearing up banks, blasting rocks, making huge caverns which they said were to serve for tunnels, heaping up and then carting away great mounds of earth. The lines of the rails will run over the bed of the River Sheaf, which is degraded to the condition of a sewer. The work is being undertaken by Messrs. Chadwick and Thurwall for £20,000.”
The Midland Station, now Sheffield Station, opened in 1870, its passengers forgetting that the River Sheaf flowed under their feet (now Platforms 5-8), before emerging again after Harmer Lane.
It was a huge success and by the late 1890s the Midland Railway Company was planning the expansion of the station, and the widening of the tracks.
In 1899, the land in front of the station was cleared and between 1900-1903 its facade was built further forward and surrounding land used for railway business.
The River Sheaf, between Suffolk Road and the Midland Station was arched over and covered, as was a section running underneath Sheaf Street towards Commercial Street. A little-known stream, Pond Brook, between Station Road and Harmer Lane was also diverted through another large culvert.
More importantly, the confluence of the Porter Brook and Sheaf was also covered and is now underneath the south end of Platform 5, close to where Platform 2A is. Thank you to Phil Jones, who volunteers for the Sheaf and Porter Rivers Trust, for explaining that today there is a large square wooden access cover, exactly over the confluence.
As to who funded what, is a matter of debate, but it is likely that the “sewer” system, as the River Sheaf was ingloriously relegated to, was funded and built by Sheffield Corporation.
And so, the first parts of the underground maze were completed, and hereon becomes something of mystery.
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