The history of the Mine
In Olgiate Molgora, in the area between via Fabbricone and Via San Primo, there was a large factory which occupied generations of workers and miners, “el Fabbricon” that produced Portland cement. The factory remained in operation until the middle of the last century, until June 3, 1967, when there was an explosion and fire in the factory, with the death of six workers of Olgiate, facts that led to the transformation of area usage to building area for residence.
The Fabbricone was born in 1906 when the brothers Gnecchi (former owners of quarries in Maggianico, just below the Resegone) had the idea to exploit the deposits of marl placed under the floor of San Zeno and Santa Maria Hoè. The area where Fabbricone was born had considerable logistical advantages: it was close to the train station of Olgiate Molgora, close to the main road to Como and to Bergamo.
The factory, since 1908, was equipped with installations to produce Portland cement; competition in the cement industry, however, grew from year to year, and Gnecchi did not know how to react to the crisis and gave the entire complex to the Pesenti, major shareholders of the Italian Cements Limited Company of Bergamo. They embarked on a substantial expansion of the factory and marl pits and as a result, between 1914 and 1925, new production plants were implemented. At the top of his power the Fabbricone produced 50,000 tons of cement per year, starting from 70,000 tons of rough stone. In subsequent years the yield decreased slowly over time, especially due to the exhaustion of old mines of marl and to strong competition from new cement plants, more efficient from the point of view of production efficiency.
The mining of marl began to be excavated since 1906. In search of new material to be extracted were dug several different levels formed a labyrinth below the territory of Olgiate.
The main mining complex is referred to as “Pelucchi” and consists of five levels of tunnels dug into the marl, overlapping and almost parallel to each other, of which the four lower levels are constantly inundated by water from the groundwater and percolation. The five levels are in communication by means of a well in reinforced concrete, used for the ascent and the descent of the bins for the transport material.
The dry part of the mine
The first level is almost completely dry (a few centimeters of water in some areas), with a length of 130 meters, a width variable between 15 and 10 meters and a height of about 12. This level ends with a junction that gives rise to two additional longs tunnels: one to the left for the other 136 meters with a height of 12 meters and a width of 15, the other to the right, much narrower than the other, that develops for about 360 meters.
This second passage, wide and about 2 meters high, it is called “Galleria Piave”, allowing the passage of the mine train and wagons and connects the first level of the galleries “Pelucchi” with the first level of so-called galleries “Buttero”.
The whole complex ends with the galleries “Cepera”, named from the homonymous village Cepera, a short distance from the Church of Monticello, but now in the Municipality of Santa Maria Hoè. The excavation continues in the direction of the hill above the church of Santa Maria Hoè and Rovagnate.
Environmental preservation and promotion
This mine represents a unique system flooded by both rainwater and resurgences. Unique stone and calcite concretions can be found there. The extraordinary discovery of what the geologists technically call “pisolites”, calcareous formations that are usually created in hundreds of years by rolling of material around an initial grain of sand up to create a sort of ping pong ball.
This mine also represents a unique testimonial of the industrial history of the city.
Endangered protected species
Bats here are a unique feature in Europe. At about 3-400 meters from the entrance, you can find hanging specimens of Myotis Capaccini and Myotis Nattereri: the singularity of the colony present in the Pelucchi tunnels is in the fact that these are two species at serious risk of extinction and that they are on the list of the Annex of the IV Directive 92/43 / EEC concerning the conservation of natural and semi-natural habitats of wild flora and fauna.