The client challenge
The VINCI / Spie Batignolles consortium was awarded Lot 1 of Grand Paris Express Line 18, an €800M project comprising 12 km of tunnel, 3 stations and 13 ancillary structures crossing the southern suburbs of Paris.
On each of the construction areas, earthworks, drilling and mechanical activities generate platform water — runoff from impervious zones, plant and equipment washwater, road cleaning effluents — that cannot be discharged directly into stormwater networks or the natural environment.
The requirements of the site's prefectoral order imposed compliant treatment of platform water across the first 6 work sites dispersed along the route of the future metro line, with specific operational constraints:
- Multiple dispersed sites, each requiring independent, mobile units
- Water loaded with suspended solids (TSS), hydrocarbons and high pH from concrete activities
- Significant space constraints on constrained urban construction sites
- Variable flow rate requirements depending on the area (10 to 20 m³/h)
VINCI – Spie Batignolles entrusted Nomado with the design and deployment of 6 containerised treatment units, adapted to the specific constraints of each area.
The Nomado solution
Nomado designed and deployed a range of containerised platform water treatment units, incorporating a complete physico-chemical process adapted to two flow rate levels depending on the construction area.
Physico-chemical treatment process
Each unit integrates a 5-stage treatment process enabling discharge limit values set by the prefectoral order to be met:
Suspended solids and turbidity treatment
- Coagulation: destabilisation of fine suspended particles by injection of coagulant reagents
- Flocculation: agglomeration of destabilised particles into large flocs to facilitate separation
- Lamellar settling with automatic sludge withdrawal: separation of flocs by accelerated gravity, with automatic sludge extraction from the base of the settler
- Sand filtration: polishing step to remove residual fine particles and meet TSS targets
pH correction
- pH correction by CO₂ injection: neutralisation of alkaline effluents from concrete washwater or site activities, in a controlled manner with no risk of overdosing
- Automatic outlet flow regulation: control of discharged flow to ensure continuous compliance
6 containerised units on 6 construction areas
To cover the varying requirements of the different construction areas, Nomado deployed two unit formats:
- 3 × 20 m³/h containerised units: for higher-flow areas or those with significant impervious surfaces
- 3 × 10 m³/h containerised units: for more compact areas or those with limited runoff activity
Each unit is delivered plug-and-play, with all measurement, automation and reagent injection equipment integrated within the container.
Design phase and support
- Preliminary design file: unit sizing adapted to each construction area
- Workshop design and integration of units
- Delivery and installation on site
- Commissioning and training of site teams
- Operational support throughout the works
Results achieved
- Compliance with prefectoral order requirements across all 6 areas from commissioning
- Deployment of 6 independent units on constrained urban sites with no pre-existing treatment infrastructure
- Complete physico-chemical process (coagulation, flocculation, settling, filtration, pH correction) integrated in a compact container format
- Treatment capacity matched to each area's requirements: 10 or 20 m³/h depending on configuration
- Turnkey approach enabling VINCI – Spie Batignolles to focus on advancing the tunnelling works
