1 April 2013
Recent structural work on the Netherton Tunnel and information released from the War Office records have unearthed details about the existence of a hitherto unknown link between the Netherton and Dudley Tunnels on the Birmingham Canal Navigations.
Whilst undertaking the £1.5m repairs to the Netherton Tunnel, engineers were surprised to discover the entrance to a further north south tunnel. They report that differential settlement between the two excavations is the likely cause of recent helical cracking seen in the roof the 1858 bore, rather than the unstable sub strata which was previously thought to be the issue. It appears that the 1940’s extension, constructed amidst intense secrecy, was a hurried affair with insufficient resources devoted to the structural integrity of the subterranean junction.
This new linking tunnel exited the Netherton about half way along and progressed due north to join the smaller 1785 Dudley Tunnel via the abandoned limestone caverns. The northern entrance remains visible within the modern tunnel complex and is seen by thousands of visitors each year as the sealed entrance to Dark Cavern, a tunnel which was found to be unstable and was blocked off by the construction of a newer navigation channel in the 1980’s.
The records indicate that this linking tunnel was dug in the early days of World War 2 to gain access to a reserve of high grade oil contained within an anticline hydrocarbon trap approx 300 metres below Dudley Castle. The unusual mix of rich mineral oil and the adjacent limestone resulted in an oil which was particularly well suited to hydraulic applications in the aerospace industry.
Workers accessed to the terminal was via a shaft descending from the grounds of Dudley castle but the oils themselves were shipped out by Claytons of Oldbury under direct contract to the War Office. Claytons initially used the tanker motors Soar and Taff for this trade till they were sold and replaced by Ribble and Spey towards the end of the war. These craft accessed the underground oil terminal, operated by the Government owned Aprilla Fuels, during the hours of darkness and transporting the unrefined oils to Midland Tar Distillers works at Oldbury. An uninterrupted power supply was provided via a micro hydro electric generating station sited at the foot of the Tividale Aqueduct, powered by water drawn from the higher Wolverhampton Level.
After processing, the high grade hydraulic oil was transported by Claytons in barrels to Bromford Wharf on the Birmingham and Fazeley Canal for use in the manufacture of Spitfires, a site now occupied by Jaguar.
This source of British mineral oil was so important to the war effort that steps were taken to protect the portals of the Netherton Tunnel from the Luftwaffe’s version of the bouncing bomb. A close inspection of the portal walls has revealed fixing brackets for a disguised metal mesh screen which could be dropped in the event of an air attack. It is unclear if this defensive counter measure was ever actually deployed. The oil reserves were exhausted just before the end of the war and the tunnel was bricked up to minimise the risk of explosion.
This new discovery potentially provides a huge boost to Dudley’s tourist industry, linking the Dudley Castle and Zoo, Dudley Canal Trust Trust and the Black Country Living Museum into an integrated whole and is likely to attract an additional 100,000 visitors each year. A new Aprilla Fuels Restoration Trust has been constituted as a Community Interest Company and Messrs WS Atkins have been appointed to undertake feasibility report to restore the semi circular tunnel to full navigable standards.
Mr C Lion, spokesman for Dudley Castle and Zoo, expressed delight in this find which will be accessed via their hilltop site. “This added attraction will really put Dudley on the map. The Aprilla Fuels Tunnel, as it will be known, will do much to oil the wheels of a local economy which has been struggling to keep its head above water for several years”.
Limited public access is expected in the spring 2014 with full boating access expected in very early April 2015.