Our environmental interventions in Assemini

Environmental recovery, requalification and soil valorisation are the drivers of our strategy for the site.

Assemini, an example of remediation, productive requalification and valorisation

The former Assemini petrochemical hub is characterised by a complex industrial history, its coexistence with the Conti Vecchi salt pans, a site of natural and environmental importance, and remediation interventions aimed at valorising its resources. Production activities began in the 1960s with eight integrated companies operating in inorganic and organic chemistry, which merged first into Rumianca Sud and then into SIR. In this context, the adjacent salt pans, dating back to the 1920s, provided salt for the production of chlorodichloroethane, necessary for the vinyl chloride and polyvinyl chloride (VCM-PVC) supply chain. In the early 1980s, following the chemical industry crisis, the site with the salt pans was conferred by law to Eni that, over time, launched an industrial redevelopment and remediation project. In the site, which has been included in the Sulcis Iglesiente Guspinese Site of National Priority (SIN) since 2001, are currently operating Società Chimica Assemini, to which have been trasferred the chlorine-alkali assets as well as the water treatment and recovery facilities, and Italkali, which took over management of the Conti Vecchi salt pans. As Eni Rewind, we continue to carry out environmental interventions on the groundwater and soil of the disused owned areas, through the implementation of a mix of technologies primarily in situ and on site, which are identified based on the contaminants detected and their distribution. As of 31 December 2024, we have incurred environmental costs amounting to €524 million for our areas. In line with the site's historical development goals, in 2018, a photovoltaic system was built by Plenitude within the decommissioned Coastal Deposit area, covering approximately 49 hectares.

Assemini: key elements

From historical petrochemical hub to a cutting-edge example of sustainable remediation and resource valorisation.
Sustainable and tailored remediation
Sustainable and tailored remediation

In Assemini we implement a mix of in-situ and on-site remediation techniques selected on the basis of contaminants type and distribution.

Area valorisation
Area valorisation

Within a decommissioned area, a 23 MW photovoltaic system has been installed.

A complex industrial history
A complex industrial history

The Conti Vecchi salt pans, an area of historical, naturalistic and environmental importance for the territory, are located in the proximity of the industrial site.

Assemini at a glance

Icona tagLocation: Italy, Sardinia
Icona tagStart of the environmental interventions: 2003

Assemini past and present

Site history

Transfer of the caustic soda assets

In 2021, Eni Rewind transferred to Società Chimica Assemini the caustic soda assets, as well as the water treatment and recovery plants in 2023.

Italkali takes over the the Conti Vecchi salt pans management

Italkali, as operator in the salt industry, acquired the shares of ILCV in 2022, taking over the management of the Conti Vecchi salt pans.

Production requalification of the salt and caustic soda cycle

The dichloroethane production plant was definitively halted and a requalification plan related to salt and caustic soda was launched through the controlled Ing. Luigi Conti Vecchi company.

Scaling down of the soda and dichloroethane production

Following the exit from the Italian market of Ineos (Vinyls Italia) which managed the CVM-PVC production plants, the Assemini site was downsized to include caustic soda and dichlorethane production.

The environmental recovery interventions begin

Enichem launched the first environmental interventions at the Assemini site, identified in 2001 as part of the Sulcis Iglesiente Guspinese Site of National Priority (SIN).

A plan for the industrial regeneration of the site

The industrial regeneration programme launched by Eni peaked in 1986 with the introduction in the caustic soda plant of a more sustainable membrane technology which replaced the mercury-based one.

The plant is conferred by law to Eni (through Enichem)

With the chemical industry crisis, the SIR Group's sites were transferred to Eni by Law No. 784/80. The assets included the Ing. Luigi Conti Vecchi company, owner of the salt pan concession.

Our history

Establishment of the Assemini site

The Assemini site is included in the Sardinian Revival Plan. Operations began with eight chemical companies, which later merged into Rumianca Sud and then into SIR.

Our activities in Assemini

Our environmental revovery activities in Assemini include projects already approved and currently completed or underway in the areas known as Plants Area, Island 5, External Areas, the external area of the former Rumianca landfill, and the Coastal Deposit, as well as interventions carried out at Is Campus, owned by the CACIP Consortium. We also carry out remediation activities in the Radice Pontile area, which is under municipal jurisdiction and outside the SIN (Site of National Priority). With the exception of Island 5, where the excavation and disposal of the waste present is completed, the interventions include treating soil and groundwater contamination sources using in-situ and on-site remediation techniques based on the type and distribution of pollutants. Therefore, also for groundwater, different procedures are envisaged for the individual areas, according to the specific nature of contaminants. Furthermore, the site features various hydraulic barriers and pumping systems, both internally and externally, and a groundwater treatment plant with a capacity of 180 m³/h.

Status of the environmental process

We are committed to the remediation of the internal and external areas of the plant in accordance with the ministerial decrees issued.

Sustainable and tailored remediation interventions

At the Assemini site, we carry out area remediation primarily by implementing various in-situ techniques, which are identified based on the type and distribution of contaminants:

  • Enhanced Natural Attenuation (ENA) - technology selected for a total of approximately 55 ha distributed among the Plants and External Areas as well as the Coastal Deposit, which involves the anaerobic biodegradation of chlorinated hydrocarbons in the aquifer through the injection of easily biodegradable substrates.
  • Air Sparging (AS) e Soil Vapor Extraction (SVE) - the intervention launched in 2024 includes the injection of air underneath the groundwater with the use of 161 dedicated wells, generating the stripping of volatile compounds and their transfer into the gaseous phase. This technology is combined with SVE, which is the recovery of the AS-generated vapours, extracted through a separate set of 125 windowed wells positioned in the unsaturated soil. Subsequently, the vapours are treated on active carbon filters. The AS/SVE plants’ arrangement in modules will enable their reuse in other sites at the end of the intervention.
  • Multi Phase Extraction (MPE) - the technology, applied on approximately 30 ha in the Is Campus Area, consists in the simultaneous extraction in liquid (submersible pump) and vapour (vacuum pump) phase, removing contamination from groundwater, as well as from the unsaturated and capillary zones. Here too, the plant can be moved and used in other sites at the end of the intervention.

Renewables in Assemini

At Eni Rewind, we make our decommissioned and no longer productive areas available to host plants for the production of energy from renewable sources, that is employed for the necessities of the group's industrial assets at the sites and, in part, fed into the grid. This commitment towards the redevelopment and valorisation of territories has already been implemented at the Assemini site since 2018, thanks also to the synergy with Plenitude. Within the Coastal Deposit area, which covers approximately 49 hectares, a photovoltaic plant with a capacity of 23 MW has been built, producing around 42 GWh per year.

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