Rehabilitation of the sanitation networks on Esplanade Saint-Gervais in Rouen
SADE and SAT working well together!
The Rouen Normandie Metropolitan Authority has appointed a SADE (agent)-SOGEA consortium to rehabilitate the wastewater and stormwater networks on Esplanade Saint-Gervais in Rouen. This area on the banks of the Seine – used regularly for major events, such as trade fairs, funfairs, exhibitions, etc. – is now a huge construction site working to a tight timescale.
The main objective is to be able to collect and pre-treat – by means of temporary connection points, a new network and associated works – all the wastewater generated during the events held on this site, for sending to the treatment plant. Stormwater collection will also be optimised.
Ad hoc design
A total of 49 units, each with 4 temporary connections, to give a total of 196 junction points, will be available for funfair operators and exhibitors. These will supply a ∅ 20 GRP network, comprising 2,840 linear metres (640 m of branch connections and 2,200 m of mains), the offshoots from which will lead towards a backflow station. Work on the site’s new sanitation system will also include the installation of fat separators, inspection holes and a water-gate chamber.
A backflow to behold
The backflow station is a GRP construction (∅ 1,600) buried 4.5 m down and fitted with two 40 m3/h pumps functioning on a 1+1 basis. It will send wastewater via a ∅ 125 HDPE pipe to a gravitational collector, located 600 m further on, right next to the magnificent Flaubert bridge.
In order to pre-treat wastewater full of substances used to cook chips, pancakes, waffles, churros, etc. 5 fat separators will be installed in the collection network. Made of stainless steel, these will be placed in a buried concrete construction (L 2.8 m x W 1.8 m x D 3.65 m) and will be accessible for maintenance via a cast-iron hatch.
The Rouen Regional Division and SAT teams are working together on this site and sharing the same quarters. The former are responsible for all the civil engineering work, while our subsidiary is in charge of the entire stormwater network (625 m of three-layer polypropylene ∅ 400 tubes and 270 m of ∅ 315 tubes) and half of the wastewater network (1,390 m of ∅ 200 GRP and 600 m of ∅ 125 HDPE). It is a joint effort that began well in advance of the construction work, with SAT engineers having played an active role in the costing exercise required to respond to the call for tender.
A very tight timescale
It was the time allowed for the assessment and execution of the work that brought SADE, SAT and SOGEA together to respond to the call for tender. Having commenced on 15 March, all works must be accepted and signed off before 31 August, to allow for the resumption of festive events on the esplanade. The companies themselves are aiming for 14 July, so as to avoid having to stop work over the national holiday and then come back to finish up.
It is a collaborative effort that benefits all parties involved and an excellent demonstration of the adage that we are “stronger together”!