The Vall d’en Joan waste deposit was since 1974 the final destination for most of the urban residues of Barcelona and its metropolitan area. Prior to its restoration it was a vast expanse of land with deep slopes. A 20-centimeter layer of soil covered the residues, and this did not guarantee total waterproofing.

The project sets out to make three basic aspects compatible in one single operation: to address a technical problem, to define a new public space, and to build a new landscape. The problems derived from the waterproofing process determined a strategy based on rationalization, which marks the geometry of the landfill site by organizing it in retaining terraces and side slopes. An ascending itinerary, inspired by the terraced Italian gardens on hillsides, structures the site, reflecting the purpose of transforming it into a public space. Following this aim, the project takes cues from the harvested valleys in the area, and applies agricultural systems that are able to provide guidelines for planning, maintenance, and durability. The transformation of the waste site into an agricultural landscape is based on three key concepts: topography, hydraulics, and vegetation.