Monaco’s planned waste treatment and recovery complex in Fontvieille is being framed as a once-in-a-generation opportunity to dig out a new underground cavern that the principality’s water utility, Société Monégasque des Eaux (SMEaux), could share with a future wastewater treatment plant, according to a report published on 19 August 2026 by Nice-Matin.
Key takeaways
- Monaco is preparing a call for tenders in 2026 covering the design, construction and operation of a new waste complex that includes a plastics sorting unit and an energy recovery unit (Nice-Matin).
- SMEaux wants to excavate additional underground space beneath the future complex and link it to its existing plant beneath the Triton with a connecting tunnel of around 10 metres (Nice-Matin).
- The current Triton facility covers 12,500 square metres across 10 levels, from 17 metres below street level to 25 metres above, and treats wastewater from Monaco, Beausoleil and parts of Cap-d’Ail and La Turbie (Nice-Matin).
- SMEaux general manager Manuel Nardi said the new space is needed because European Directive 2024/3019 tightens treatment requirements for micropollutants, PFAS and other substances (Nice-Matin).
- Uisce Éireann is running a parallel national plan for small wastewater treatment plants in Ireland serving communities under 1,000 population equivalent, with submissions open until 20 October 2026 (The Clare Herald).
What happened: a twin-track opportunity in Fontvieille
The waste project under preparation includes a new plastics sorting unit and a new energy recovery unit, both housed within a complex civil engineering structure, with a call for tenders scheduled for 2026 to cover the design, construction and operation of the facility, according to Nice-Matin. SMEaux, the principality’s water utility, sees the same construction site as a rare chance to extend the underground envelope it already occupies beneath the Triton building in Fontvieille, the report said.
The stakes for SMEaux are significant, because its current wastewater treatment plant already sits underground beneath the Triton and serves Monaco, Beausoleil and parts of Cap-d’Ail and La Turbie, with facilities covering 12,500 square metres across 10 levels running from 17 metres below street level to 25 metres above, Nice-Matin reported.
Why a new cavern, and what happens next
The driver, according to Nice-Matin, is European Directive 2024/3019 on urban wastewater treatment, which strengthens requirements for micropollutants, PFAS and substances that have historically been less tightly controlled. That means future treatment plants will need to push beyond today’s performance, raising the bar for tertiary and advanced polishing stages.
SMEaux general manager Manuel Nardi told Nice-Matin: “If the State goes ahead with this new facility, we absolutely must not miss the opportunity. We need to take advantage of the construction work to excavate a large underground space beneath the entire future facility and put the necessary civil engineering infrastructure in place. We could then install our own equipment there.” He added: “If we miss this opportunity, there will never again be a site like this right next to the Triton,” Nice-Matin reported.
According to Nice-Matin, a short connecting tunnel of around 10 metres could link the existing Triton facilities to the new underground space, allowing process streams to move between the two without a separate civil works contract. The article does not name a contract value, a tender ID or a construction start date for the cavern.
Separately, on a different site but in the same regulatory moment, Uisce Éireann has opened a public consultation on a national plan for wastewater treatment plants serving communities of less than 1,000 population equivalent, with submissions accepted until 20 October 2026, The Clare Herald reported. The Irish plan is not part of the Monaco project; it is included here only to show that the same Directive-driven pressure on small and constrained sites is being worked through on multiple networks at once.
Specification read
The reported footprint is large but compact for a coastal megacity utility: 12,500 m² over 10 levels, with the lowest floor 17 m below grade and the highest 25 m above it, serving Monaco plus parts of Beausoleil, Cap-d’Ail and La Turbie (Nice-Matin). The article does not quote a daily flow, a population-equivalent figure or a pollutant load, so the hydraulic capacity in m³/day cannot be derived from the report. For an underground municipal works of this scale in a dense European capital, daily throughput of tens of thousands of cubic metres per day across the screening → primary → biological (typically MBR or SBR given the headroom constraint) → tertiary / disinfection train is the typical class, and PFAS and micropollutant removal would now sit ahead of the UV or chlorination step (general industry range, not from the sources). The next procurement step is the 2026 call for tenders that will bundle the design, construction and operation of the waste complex together with the civil engineering for the SMEaux cavern (Nice-Matin). For a municipal plant engineer specifying compact biological reactors and tertiary polishing inside a 10 m tie-tunnel, the relevant process stages to focus on are biological (MBR/MBBR/SBR), followed by advanced oxidation or activated carbon for PFAS and micropollutants, then UV or chlorine disinfection; the cavern decision does not change the train, it just enlarges the room for it. If your plant is a Municipal coastal site of similar size running at high organic load with tightening PFAS and micropollutant limits, this is the moment to confirm civil works headroom and tertiary polishing space before tender documents are issued. Buyers comparing biological reactor footprints and tertiary skids will find the side-by-side selection logic in this DAF vs Clarifier for Transportation Equipment Wastewater in Jacksonville: 2026 Factory Selection Guide useful when sizing clarifier versus DAF for the new cavern, and the broader equipment context is mapped on our Industries We Serve page.
FAQ
What is the next milestone for the Monaco wastewater expansion?
The 2026 call for tenders for the design, construction and operation of the waste complex, which SMEaux wants to include the underground cavern and a 10 m link tunnel to the existing Triton plant, is the next procurement step on the public record, according to Nice-Matin. No start date or contract value is reported.
What new treatment requirements is SMEaux preparing for?
European Directive 2024/3019 on urban wastewater treatment tightens requirements for micropollutants and PFAS, which is the driver Nardi cites for needing the extra underground space, Nice-Matin reported. Buyers should expect tertiary and advanced polishing stages to be emphasised in any new tender.
How much underground space does the existing Triton plant already use?
The plant covers 12,500 m² across 10 levels, from 17 m below street level to 25 m above it, serving Monaco, Beausoleil and parts of Cap-d’Ail and La Turbie (Nice-Matin). Daily flow in m³/day is not disclosed in the article.
Is the Uisce Éireann small-plans consultation part of the Monaco project?
No. It is a separate national consultation on plants serving communities of less than 1,000 PE, with submissions open until 20 October 2026, The Clare Herald reported. It is mentioned only to show the wider European context of small, constrained sites adapting to the same directive pressure.
