The client challenge
Bouygues Travaux Publics was commissioned to build and install 71 gravity concrete bases weighing 5,000 tonnes each, designed to anchor the 7 MW turbines of the Fécamp offshore wind farm in Normandy.
The concrete bases were prefabricated on a 33-hectare platform within the Grand Port Maritime du Havre (Bougainville quay), with no connection to the public sewerage network. The site mobilised up to 960 people per day across 3 welfare facilities, and simultaneously generated several types of water requiring compliant management:
- Domestic wastewater from the 3 welfare facilities (960 PE/day) with no network connection
- Runoff water from the 33-hectare concrete platform, potentially loaded with suspended solids and hydrocarbons
- Concrete washwater from the manufacture of the gravity bases, highly alkaline (pH > 12), prohibited from direct discharge
Nomado was tasked with ensuring complete water management of the site, from the study phase through to 2-year operation, covering all these streams.
The Nomado solution
Nomado took full responsibility for all water-related aspects of the site, from regulatory design through to day-to-day operation, deploying 8 complementary treatment units covering the 3 types of effluents on site.
Our approach was structured around integrated engineering, complete regulatory management and continuous operation throughout the project.
Design and regulatory phase
- Full preliminary design file
- Water Act file (DLE) including submission to the Préfecture
- Design and integration of all treatment units
Wastewater treatment — 3 welfare facilities (960 PE/day)
Three containerised wastewater treatment plants, sized to cover the combined capacity of the site's welfare facilities:
- 310 PE containerised WWTP
- 120 PE containerised WWTP
- 100 PE containerised WWTP
- 3 associated wastewater lift stations
Platform runoff water treatment (33 hectares)
Stormwater treatment system for the concrete platform, sized for high runoff flows over an impervious surface:
- 2 above-ground lamellar settlers: removal of suspended solids (TSS) from runoff over the concrete platform
- 2 pumping stations (230 and 190 m³/h): collection and transfer of runoff water to treatment structures
- 2 hydrocarbon separators: treatment of oils and hydrocarbons associated with plant circulation on the platform
Concrete washwater treatment
- 1 containerised concrete washwater treatment unit: pH neutralisation and settlement of cementitious fines before discharge, compliant with natural environment discharge requirements
Full operation over 2 years
- Delivery and installation of all units on site
- Commissioning and team training
- Operation, maintenance and regulatory sampling throughout the project duration
Results achieved
- Full water management of a 33-hectare site hosting up to 960 people/day, with no public network connection
- Continuous regulatory compliance across all 3 streams (wastewater, runoff, washwater) over 2 years of operation
- Water Act file submitted and approved by the Préfecture, zero non-compliance incidents throughout the project
- Turnkey approach from design to operation, allowing Bouygues TP to focus on its core business: concrete base prefabrication
