Former site of the northern shafts of Důl Doubrava, the deepest colliery in the Karviná coalfield, now fully liquidated with no surface structures remaining.
Důl Doubrava sever identifies the northern sector of the former Důl Doubrava colliery in the village of Doubrava near Orlová, comprising the intake shaft Doubrava III (Sever) and the ventilation shaft Do-IV. Důl Doubrava as a whole was the deepest mine in the Karviná coalfield, with its main hoisting shaft reaching the tenth working level at a depth of 930 metres and the shaft itself extending to over 1,000 metres. The northern shaft area reached a maximum absolute depth of 1,176 metres (jáma Doubrava III).
The mine originated in 1822 with early prospecting activity by baron Anton Mattencloit, passed to Salomon Mayer Rothschild in 1845, and after nationalisation in 1945 was constituted as Důl Doubrava through the merger of the Bettina and Eleonora shafts. Coal production continued until 27 April 2007. The northern shaft sector suffered a catastrophic shaft-lining failure at jáma Do-IV on 28 July 1998, which caused the collapse of the shaft building and headframe into a crater approximately 62 by 49 metres.
Progressive surface liquidation of the entire Důl Doubrava complex began in 2004 and was completed by 2011, leaving no standing structures.
The earliest recorded mining activity in the Doubrava cadastral area dates from 1822, when baron Anton Mattencloit had an exploratory shaft — known as Versuch (Pokus) — sunk on the hill known as "U havírny" (near Vidrholec). In a shallow depth coal was encountered. Over the following decades further shallow shafts were sunk, most of which later fell into disuse. In 1845 Salomon Mayer Rothschild acquired the mining rights across the Orlová and Doubrava area. In 1854 an exploratory shaft was deepened to 152 metres and named Eleonora; in 1855 the sinking of the Versuch shaft was resumed, deepened to 120.8 metres and renamed Bettina — after Rothschild's daughter. In 1845 the first ventilator, a wooden-wheeled device of 80 cm diameter and 15 cm width, was placed over the Bettina shaft. The first mechanisation came in 1864 in the form of steam pumps for drainage and the first steam winding engine on the Eleonora shaft. The Doubrava mine was the first in the coalfield to introduce electric power on a significant scale, from 1896 onwards, applied to pumps, the coal-preparation plant, the chain conveyor, and the hoists.
Connection to the Košicko-bohumínská dráha railway in February 1869 provided a first rail outlet, but the decisive transport link was the Báňská dráha section from Michálkovice to jáma Bettina with a spur to Eleonora, brought into service on 12 September 1870. By 1914 both shafts had been deepened to 578.2 metres and ownership had passed to the Vítkovické kamenouhelné doly. In 1942, during the German occupation, jáma Eleonora was converted to a materials transport shaft.
Following the end of the Second World War, mining was formally resumed on 29 May 1945 under the merged Důl Doubrava, created by the combination of the Bettina and Eleonora shafts. The mine was absorbed into the state enterprise Ostravsko-karvinské kamenouhelné doly, later OKD. From 1 July 1995 Důl Doubrava was incorporated into Důl ČSA as a shaft enterprise. By this reorganisation jáma Eleonora served as a ventilation and media-transport shaft (degas gas, process water, compressed air, fly ash, and nitrogen) rather than a production shaft.
The northern sector of the mine field was served by jáma Doubrava III (Sever), which in its final configuration reached an absolute depth of 1,176 metres with a surface elevation of 281 metres, placing its bottom 895 metres below sea level — the greatest absolute depth recorded in the Důl ČSA complex. The intake shaft Do-IV lay immediately adjacent and reached a depth of 1,176.5 metres. By 1985, following a major reconstruction that brought the mine's tenth level into service, the mine field of 9.54 km² was divided into nine working panels. The operational mine field was served by jáma Doubrava I (skip, primary winding), jáma Doubrava II (intake), jáma Eleonora (ventilation), a pair of Orlová ventilation shafts, and the two northern shafts: jáma Doubrava III and jáma Do-IV.
On 28 July 1998 a catastrophic failure occurred at jáma Do-IV: at approximately 04:08 hrs, the shaft lining on the south-west side failed at a depth of approximately 86 to 90 metres below the shaft collar (an opening of approximately 3 by 3 metres). Progressive failure of the shaft lining above and below the breach followed rapidly, and the upper portion of the shaft, the shaft building, and the headframe collapsed into a crater measuring approximately 62 by 49 metres on the surface and 36 metres deep, with a volume of approximately 65,200 m³. Two miners in the vicinity of the ventilation shaft were struck by the pressure wave from the collapse but sustained only minor injuries; no fatalities resulted. The crater was subsequently backfilled with approximately 60,000 m³ of mine spoil. Work at the Doubrava sector, which employed approximately 1,500 underground workers at the time, was suspended during the emergency and resumed after stabilisation measures were completed.
Throughout its operational life Důl Doubrava was classified as a methane-hazard mine of the second degree of danger (class II), with high propensity for spontaneous combustion and risks of water inrush and rock outbursts. A methane explosion on 12 February 1949 in the Hubert seam above the eighth level killed 19 miners; a rescue team of five mine rescue workers also perished. The subsequent attempt to extinguish the underground fire led to the first application in world mining history of nitrogen inertisation, pumped from the surface: between 8 August 1949 and 12 September 1950, a total of 5,056,644 cubic metres of nitrogen at 99.5% purity were introduced into the sealed mine. A further methane explosion on 7 May 1985 killed 25 people, including 6 mine rescue workers of the Důl Doubrava colliery rescue station.
Coal winding at Důl Doubrava ended on 27 April 2007, timed to allow the reserve panel within the mine's protective perimeter to be extracted by the adjacent Důl Jan-Karel. The second headframe — over jáma Doubrava II — was demolished by explosive demolition on 2 November 2007 as the fifty-first headframe to be liquidated in the OKD rationalisation programme. The skip headframe over jáma Doubrava I (Bettina) had been demolished by controlled explosive on 23 October 2006. The 18.5-metre headframe over jáma Eleonora was demolished by collapse on 26 February 2010 following shaft backfilling. Progressive demolition of surface structures at the Doubrava complex began in 2004 and by 2011 the shaft buildings, headframes, and shaft collars had all been liquidated. Total coal extraction over the mine's history amounted to approximately 112 million tonnes.