Standing 60-metre steel extraction tower of the Pozo Santiago at Caborana, the last operative coal mine in the concejo of Aller, closed in 2018 and now awaiting repurposing.
The Pozo Santiago is a closed underground coal mine at Valdefarrucos, Caborana, in the concejo of Aller, Asturias. It was one of three shaft collieries operated by the Sociedad Hullera Española in the lower Aller valley, together with the Pozo San Jorge and the Pozo San Antonio. The Sociedad Hullera Española was founded in 1892 and dominated coal mining in the lower Aller valley until its integration into HUNOSA in 1967.
The Santiago shaft was sunk around 1951 and entered service in that same period, reaching 581 metres depth across eleven levels. Together with the Pozo San Jorge and Pozo San Antonio, it formed the Área Aller group within HUNOSA and exploited the María Luisa, Sotón, Generalas, and San Antonio coal packages. In 1988–89, the original 38-metre headframe — installed in the early 1950s — was replaced by a modern 60-metre steel extraction tower, erected around the old structure while the shaft remained in service.
The shaft was deepened at the same time from the ninth to the eleventh level. Coal extraction ceased at the end of 2018, making the Pozo Santiago the last mine to operate in Aller. The 60-metre extraction tower stands on the site, with multiple proposals for future use under discussion but none confirmed at the time of research.
The Sociedad Hullera Española, founded in 1892, exercised sole control over the coal mining territory of the lower Aller valley through three shaft collieries: San Jorge, Santiago, and San Antonio. The Pozo Santiago was sunk around 1951 at Valdefarrucos in Caborana, reaching 581 metres depth with a shaft diameter of six metres at the collar and eleven underground working levels. An initial headframe — of the type associated with Duro Felguera construction from the early 1950s — was installed at the start of operations and stood 38 metres high.
The Sociedad Hullera Española was integrated into HUNOSA in 1967, and the Santiago shaft became one of the constituent collieries of HUNOSA's Área Aller group, alongside the Pozo San Jorge and the Pozo San Antonio. The shaft exploited the María Luisa, Sotón, Generalas, and San Antonio coal packages. The Pozo San Jorge, situated nearby and connected underground to the Santiago at the third level, closed its active production in 1995, after which all activity in Caborana was concentrated at the Pozo Santiago.
In 1988 HUNOSA commissioned the construction of a new 60-metre extraction tower to replace the original 38-metre headframe and to modernise the shaft's output capacity. The tower was erected by Duro Felguera without dismantling the old headframe and without interrupting shaft production. In November 1988, once the new tower was fully assembled, the original headframe was dismantled.
Simultaneously, the shaft was deepened from the ninth to the eleventh level and its caldera, reaching a final depth of minus 306 metres on the deepest level. These works were completed in early February 1989. The Pozo San Antonio at Moreda, underground-connected to the Santiago, ceased productive extraction in October 1994 but remained in use for mine services; its 200 miners transferred to the Santiago upon its final closure in October 2003.
From that point the Pozo Santiago was the only operative extraction colliery in the concejo of Aller, with a workforce of around 850. Coal extraction at the Pozo Santiago ceased at the end of 2018, simultaneously with the Pozo Carrio, after which the only operating pit in Asturias was the Pozo San Nicolás. The closure of the Santiago ended mining in Aller.
Following closure, activities at the shaft were confined to recovery of underground materials. The Aller Turismo website describes the shaft as currently operative for innovative and strategic purposes, though multiple proposals for future use — including geothermal energy, a data centre, a cider cellar, and a vaccine storage facility — had been raised without resolution as of 2022.