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Inchindoun Fuel Tanks

Invergordon, Inchindoun, Ross and Cromarty.

The Inchindown Fuel Oil storage tanks are part of a disused underground oil depot in Invergordon, Ross-shire, Scotland. Two Access tunnels and six storage tanks (five very large 237 m x 9 m x 13.5m, one smaller, the same width and height but 2/3 the length) originally connected by pipes to the Royal Navy's docks at Invergordon. Two entrances 250 m apart lead to separate access tunnels. Tunnel one leads to the a series of ladder shafts rising 13.5m to inspection chambers at the top of the tanks. Entrance from tunnel two to the bottom of one of the tanks can be achieved by mounting a sliding tray which is pulled through one of the (now disconnected) pipe connections. Ladders (probably unsafe) run from the inspection chambers to (flooded) sump pits at the ends of each of the tanks.

Work began in 1938 and was completed in 1941. They were supply of Furnace to the base at Invergordon.

In 2009, guided tours of the tanks were offered by Forestry Commission Scotland. After these were mentioned on The One Show (BBC television), Trevor Cox, professor of acoustic engineering at the University of Salford, was inspired by the unsubstantiated reports of its amazing acoustics to carry out reverberation tests in the tanks. In 2014, Allan Kilpatrick from the Royal Commission on the Ancient and Historical Monuments of Scotland fired a pistol blank inside one of the tanks. The sound was recorded by Cox, and is reported to have reverberated for 112 seconds at 125 hertz, 30 seconds at mid frequency, and 75 seconds broadband.

In February, 2019, Simon Riddell and David Allen recorded a documentary in the Inchindown Oil Tanks. The documentary includes Preston White's guided tour of the facility. In the documentary, the photographers used a large format camera to a negative of the first tank. Then, staying overnight in tunnel 2, the next day they turned it into a darkroom. They printed of their negative without leaving the tunnel. The film won 'best documentary with the UK Monthly Film Festival.

The remains of the pipeline from the tanks to the Invergordon base can still be traced to Tomich (NH67SE 53), and to the oil tanks at Invergordon.

From the Forest Heritage Scotland website (www.forestheritagescotland.com).

On the edge of Kinrive Forest, hidden in the side of Kinrive Hill, are two bolted doorways. Today they stand forgotten and unheeded, but during World War II they formed the entrance to a vital part of the British government's defence plan against the Germans and their allies. The doorways lead to the bombproof fuel tanks beneath Kinrive Hill. Inchindown was one of three secret fuel stores constructed near the main naval anchorages in Britain, in this case Invergordon naval base. The tanks held a specific kind of fuel called Furnace Fuel Oil (FFO). The Royal Navy used this type of fuel for their ships until the late 1960's. The government needed to keep stores of fuel, in case the German Navy managed to block the ports or destroy shipping convoys and stop fuel supplies reaching Britain from overseas. These supplies of fuel had to be hidden from view and protected or German planes would have targeted and tried to destroy them. The fuel would make sure the Royal Navy could continue to protect Britain, no matter what happened. In 1941 the Germans did successfully destroy one of the above-ground oil tanks immediately beside Invergordon naval base. Four miles of pipes connected Inchindown to the naval base, keeping it supplied with fuel and ready for action. The fuel flowed downhill from the stores to Invergordon, but restocking the tanks from the base was more problematic. To get the fuel back up hill they built three pumping stations, the largest located at Tomich.

The construction of the six fuel tanks inside Kinrive Hill was a major feat of engineering. The tanks are enormous and held almost 32 million gallons of fuel. There were five main tanks and one smaller reserve one. The larger tanks were 9m wide by 237m long and 13.5m high; you could fit 16 double decker-buses end to end into one of these tanks. The government contracted engineering firm William Arrol to build the depot, who in turn sub-contracted the work out, probably to the construction firm Yemen, Bald, and Hutchison [Baldry, Yerborough & Hutchison]. It was not an easy task to hollow out the hill. Nor could it have been much of a secret. The hill was selected for its hard rock, and was deep enough to protect the tanks from bombing. They quarried over half a million tonnes of rock and dumped it on the hillside. This was visible from the air and the Germans probably knew about the construction. The hill provided protection rather than a secret location. Locals still remember the quarrying of the hill. As well as a local workforce, gangs of labourers from Ireland were hired. Malcolm MacLeod recalls his father cycling the 5 miles and back from Adross to work a fourteen hour shift drilling the tunnels and tanks. The tanks had no doors only four circular pipes, through which men had to pass to reach the tanks. The staff lay flat on a gurney, a wheeled board, and slid down the pipes. Today the tanks are clean but it must have been a rather dirty and smelly job.

From Invergordininfo.

Huge squads of workmen were engaged on the project. A camp for travelling workmen was built at nearby Castle Dobie. The workmen from local towns and villages cycled to the site, not a pleasant journey in the severe winters of that time. Their pay was about one shilling (5p) per hour. There are still men in the area [c. 2000] who worked there and are now in their eighties.

The trench from Inchindown to Invergordon was dug by hand - there were no JCBs at that time. Inside the Tunnel the work was dangerous and unhealthy. There were no safety helmets in those days but paper masks were issued. Some of the workers contracted lung and chest problems and were unable to work in later years. It is believed that there were some fatalities, and other men injured by rock falls. There was little in the way of health and safety measures in those days. The rock excavated from the Tunnel was taken to a tip at the foot of the hill by a small railway. Some of it was used for construction purposes at the smelter years later.

The service tunnels are also partially lined with concrete and contain the pipelines below floor level. The pipelines fed into the pump house at the crossroads at Tomich Farm and thence to Seabank Oil Depot and to the pier head, where the oil tankers loaded and discharged. Many tankers were lost in the war taking oil to Invergordon, some in the Moray Firth.

The above-ground tanks at Seabank were bombed in February 1941 by a low-flying German aircraft. Fortunately only one tank, no. 13, was hit, causing the thick black oil to flood the railway station and temporarily disrupt railway services. A bomb was also dropped at a farm near the pipeline to Inchindown, killing a sheep. Following this the fuel tanks were protected by thick blast-proof brick walls, with large numbers of bricklayers being engaged on this task.

After the war, fewer naval ships used the Cromarty Firth and not so much fuel oil was required, although oil continued to be stored at Inchindown until 1982. By then the Tunnel had served its purpose and was sold off. This little known site, together with the Seabank and Cromlet oil tanks, played no small part in the war at sea by providing the fighting ships of the fleet with the fuel they needed to perform their duties during the difficult years of World War 2.

Alternative Names: Inchindown, Royal Navy Fuel Tank, Royal Navy Fuel Tanks (Inchindown), Invergordon Oil Fuel Depot, Inchindown Admiralty Underground Oil Storage Depot, The Tunnel

Notes: As long as the area is geologically stable the actual geology is largely irrelevant as the tanks were built to be bomb-proof and are lined in mass concrete.

The tanks were designated as a Category A listed building in 2014, although the footprint of the area listed only covers the surface buildings does not apparently include the underground areas (the tanks themselves).

Inchindown was featured in the "Swamp of Despair" episode of the Science Channel's TV series Mysteries of the Abandoned (season 6, episode 2), on April 2, 2020.

Places on the first public tours in 2009 were booked out within 90 minutes.

Plans in 1988 to upgrade the depot for use by Nato were later abandoned and the site was closed by 2002.

Hydrographic Feeds: None

Hydrographic Resurgences: None