The prime contractor's proposal to consider stormwater management on site was a trigger for the project. However, the fact that work had already begun on the other areas of the site's requalification was a difficulty, given that the rainwater to be collected came from these areas. Many meetings were necessary to determine the possible interfaces in the water garden and other sites.
The slope of the site represented a technical difficulty because it was not suitable for rainwater infiltration. The solution proposed by the project manager was the use of a system of successive basins in "Asian terraces" format.