The former ACNA chemical plant was built at the end of the nineteenth century in Val Bormida, near Cengio, in the North-West of Italy.
Located in Alpine foothills at about 400m above sea level, the plant was located in a long sweeping curve of the Bormida River.
It’s location, close to a ready supply of water probably made great sense at the time, but more than a hundred years later, residual pollutants at the site and its potential to leak into the river is a great ecological and environmental threat.
Geologically, the area is characterized by surface alluvial deposits overlying marl at between 4m to 9m. Once through an upper weathered zone, the marl, which can be seen outcropping on some stretches of the nearby mountain slopes, generally has a low permeability and provides a suitable layer in which to create a cut-off and so contain the pollutants at the site.
The plant was originally established for the production of explosives but over its 120 year working life expanded its output to at least 374 known chemical compounds, most of them extremely polluting.
Unsurprisingly, given such a long history of chemical production at the site, significant heavy pollution occurred, largely as a result of leakage from on site waste lagoons. In particular these have affected surface alluvial deposits and the groundwater.