Stoppani: the history, the legacy, the cleanup that hasn't ended

If you come to Cogoleto for the sea and walk the coastal road east toward Arenzano, where the Lerone stream meets the shore you’ll see a construction site that doesn’t seem to end. Fencing, excavators, covered piles of waste, signs with ministry acronyms. That’s what’s left of the Stoppani plant: the chromium factory that was our main industry for over a century, and that today is one of Italy’s largest environmental cleanup sites.

This piece tries to tell it straight, without hiding the weight of it and without turning it into the monster newspaper headlines sometimes conjure. This is our industrial history. It’s the legacy we have to manage. And it’s a worksite that hasn’t closed yet.

A chromium plant, 1900 to 2003

In 1900, Milanese industrialist Luigi Stoppani obtained municipal authorisation to build the Fabbrica del Cromo, the Chrome Factory, at the bottom of the Arrestra valley, where the Lerone stream reaches the sea. Production proper started in the years that followed. The site wasn’t chosen by accident: fresh water from the stream, sea access for discharge, the railway line for goods, and a local workforce that until then had lived mostly off fishing and farming (Wikipedia).

What Stoppani made were hexavalent chromium compounds, Cr(VI): sodium and potassium chromates and dichromates, chromic acid, and sodium sulfate as a by-product. These went into the tanning industry, electroplating, pigments, metal treatment. For most of the twentieth century, Cogoleto was one of Europe’s main hubs for this kind of chemistry.

Inside the plant, two types of furnace ran: the flat furnace (operating until the 1980s) and the rotary-hearth furnace (commissioned in 1958). The first was the original heart of the works; the second was the post-war upgrade. In the 1970s and 1980s the company peaked at over 400 employees: a population of workers and technicians spread across Cogoleto, Arenzano and the wider western Genoese coast (Era Superba).

Then the long decline. Markets shifted, European environmental rules tightened, costs climbed. Production ceased in 2003 (not 1996, as some sources still report), with 140 employees still on the books at closure. By 2006 the successor company (Immobiliare Val Lerone) was in environmental emergency status; in 2007 it went bankrupt.

At that point, Cogoleto inherited everything: the sheds, the furnaces, the process tanks, and a century of chromium.

What was left behind

The European legal limit for hexavalent chromium in groundwater is 5 micrograms per litre. It’s a strict limit because Cr(VI) is classified as a known carcinogen by inhalation and a strong suspected carcinogen by ingestion.

Groundwater analysis under and downstream of the plant, before the cleanup began, measured an average of 250,000 micrograms per litre. Fifty thousand times the limit. After the first phases of work, today the groundwater sits at roughly 15,000 µg/L: a huge reduction in absolute terms, but still three thousand times above the legal limit (Era Superba).

The contaminated area, by SIN perimeter, is roughly 2 square kilometres: 0.4 km² on land (the plant, surrounding areas, part of the Lerone watercourse) and 1.6 km² at sea (the stretch of seabed offshore of the river mouth, where decades of discharge accumulated). MASE’s official perimeter, after a recent revision, covers about 45 hectares onshore and 167 hectares offshore, across two municipalities: Cogoleto and Arenzano (MASE — Cogoleto-Stoppani SIN).

In 2010, the then head of Italian Civil Protection Guido Bertolaso visited the site. In front of the press he summed it up with one image, which has since become the journalistic label for the place:

“A post-Chernobyl scenario.”

It was a line that hurt locally, and that also sharpened the focus. From that point on, the site was firmly on the national agenda.

One thing the Bertolaso quote, effective as it is, doesn’t convey: there was no single catastrophic event, there’s no radioactive cloud, there’s no exclusion zone. What there is, and this is something different but serious, is a century of stratified industrial residue in soil, groundwater and marine sediments, in a precisely delimited area, that the State is now removing through an expensive, long-running worksite.

The cleanup: who, when, how much

Stoppani is one of Italy’s Siti di Interesse Nazionale (SIN): Sites of National Interest, the category the Ministry uses for contaminated areas whose risk profile demands state-level intervention. The perimeter was set by ministerial decree on 8 July 2002, and the site is managed directly by the Ministry of the Environment and Energy Security (MASE).

The current governance, after years of stop-start work, is this:

Extraordinary Commissioner: Cecilia Brescianini, mandate through 31 December 2026.
Technical contracting authority: Sogesid SpA, the in-house engineering company of the Ministry.
Contractors on the ground: Riccoboni SpA and Furia Srl.

Funding has been set on a multi-year basis: €7.015 million per year across 2024, 2025 and 2026, a total of €21.045 million for this phase (Liguria Region press release).

The most recent update, April 2026, closed the operational phase of a €12.4 million tranche with these results (Genova24):

11,000 tonnes of hazardous waste removed in this single tranche: 9,500 tonnes of debris from the 2016 northern-area demolitions, plus 1,500 tonnes from tank decontamination and dismantling.
Cumulative total since the State took over: more than 34,000 tonnes of hazardous waste plus 16,000 tonnes of non-hazardous material removed and sent to authorised disposal facilities.
Lab analysis on the removed material confirms the two expected contaminants: hexavalent chromium and chrysotile asbestos (from old fibre-cement roofing).

If you like rough ratios, that’s about one tonne of hazardous waste for every three tonnes of material moved since work began. If you don’t, it means the physical plant (sheds, furnaces, pipework, tanks) is finally leaving Cogoleto, one truck at a time.

What this means if you’re visiting today

A fair question, one people ask: can you swim?

The answer is yes, with one detail worth taking the time to get right.

The beaches of Cogoleto town (Lungomare, Beata, the small coves along the old centre) are outside the SIN perimeter. The contaminated site is inland, up the Arrestra/Lerone valley, plus the stretch of sea offshore of the Lerone mouth at the boundary with Arenzano. Cogoleto’s bathing waters are monitored twice a month during the season by ARPAL (Liguria’s regional environmental agency) and have been classified excellent for years: the top category under European bathing-water rules.

So: yes, you can swim; yes, the SIN exists; no, the two don’t overlap. The beaches people use are not the beaches inside the SIN, and ARPAL publishes the analysis results on its portal for anyone who wants to check.

The perimeter is there for a reason, though. The worksite areas are fenced, access is restricted, and the Lerone beach plus the immediate stretch east of the river mouth are closed to bathing: not a place for an afternoon stroll. That’s the honest price to pay until the cleanup is finished.

What’s still missing

The Commissioner’s mandate ends 31 December 2026. After that, a political decision will be needed: extend the commissioner’s office, hand the site back to ordinary regional management, or open a new phase under a fresh decree.

The work still to be done, as of this writing, is well identified:

Groundwater: bringing the current 15,000 µg/L below the 5 µg/L legal limit requires a pump-and-treat system running on the scale of decades, not months.
Marine sediments: the offshore part of the contamination (the seabed off the Lerone mouth) is the technically hardest piece. It needs targeted dredging, separate handling of contaminated sediments, and a careful cost/benefit assessment.
Reuse of the land: once the industrial structures are gone, the future of the site has to be decided. Restored natural area? Light industry? Something in between? That’s a choice Cogoleto and the Liguria region need to make on a timeline that matches the end of cleanup work.

There’s also a subtler point, one you only get by knowing the SIN’s history. For about fifteen years after closure, the cleanup was a story of money allocated and never spent, tenders contested and frozen, executing bodies that kept changing. The 2024-2026 tranche reversed that pattern with committed funding and a single chain of accountability. The real test is after 2026: that same continuity will have to be rebuilt for the next phase, because groundwater doesn’t clean up in three years, and neither do marine sediments.

Stoppani is our industrial history and our open wound, and it is also, today finally, a worksite producing results measurable in tonnes and in micrograms per litre. Walking toward Arenzano and seeing those cranes at work isn’t a postcard view, but it’s the sign that someone is fixing it.