ENCI

ENCI ("Eerste Nederlandse Cement Industrie" - First Dutch Cement Industry) is a Dutch company based in Maastricht, Rotterdam and IJmuiden. Their core business activity consists of the digging of marl out of St Pietersberg, which they use to make cement. The company uses the dug-up earth to make a new hill, called d'n Observant. Furthermore, there are plans to fill parts of the quarry holes with water for the creation of a water recreation area. 
Despite its name, ENCI was founded by a Belgian-Swiss consortium in 1925 with the first factory starting production in 1928. With the founding of ENCI, the Netherlands were no longer fully dependent on foreign cement. At the turn of the 21st century, ENCI produced 1.6 million tonnes of cement yearly, supplying roughly a quarter of all cement used in the Netherlands from its Maastricht plant.
In 1998, ENCI was owned by the Belgian CBR-Group (itself part of HeidelbergCement) and Holcim. Currently, HeidelbergCement is the sole owner. In 2019, HeidelbergCement announced that ENCI's Maastricht plant would be closed.
A pair of Eurasian eagle-owls have been nesting at the ENCI quarry since 2001, making the quarry one of the most well-known nesting sites for the bird in Western Europe.