We came to the competition knowing little about Basel and without much familiarity with the Schweizerhalle fire of 1986. The disaster, triggered by a warehouse fire at a chemical plant near the Rhine, sent toxic pollutants into the air and contaminated the river system far beyond the immediate site. Its effects moved quickly across borders, making clear that ecological damage does not recognise national territory or political jurisdiction. What it exposed was not only the scale of the event itself, but the extent to which Basel sits within a larger bioregional system, where contamination, water, air and ecological harm are shared across connected geographies.  We were also struck by the way Switzerland has since reckoned with the broader legacy of toxic waste, mapping thousands of polluted sites across the country that now require ongoing rehabilitation.

Our proposal reworked the car park and district basin from a passive piece of infrastructure into an active environmental system. Drawing in part on precedents such as the Energiebunker in Hamburg, the project combined ecological monitoring, filtration, remediation, energy generation and storage within a single site. Rooftop photovoltaic arrays generated power, which was stored within adapted water basins and used to support a network of analytical and filtration devices. Pollutants carried through urban runoff, including oil, tyre wear, cigarette butts, pesticides and microplastics, were collected, filtered, documented and archived, allowing the site to operate as both remediation infrastructure and a long-term environmental record.

Photovoltaic arrays installed along the southern façade and across rooftop parasols generate electricity during the day. Surplus electricity powers a gantry-based gravity battery, lifting rough-cut stone blocks to store energy as gravitational potential. At night, the blocks are gradually lowered to generate electricity when solar power is unavailable. The existing circular void is converted into a large thermal water battery, recovering and storing waste heat from nearby industrial buildings for later use, drawing on the precedent of Hamburg's Energiebunker. Within the former underground retention basins, modular saltwater batteries provide additional electrical storage, converting infrastructure originally intended to contain toxic water into a system for storing renewable energy.

The proposal also establishes a network of environmental monitoring and filtration systems to identify and process pollutants carried through urban runoff, including oil, tyre wear, cigarette butts, pesticides and microplastics. Existing basins are adapted to collect and filter contaminated water, while monitoring equipment records changes in water and air quality. Rooftop planting contributes to water filtration and supports the site's wider environmental functions. Together, these systems enable the collection, analysis, filtration and documentation of pollutants, establishing a long-term environmental record. A series of lightweight research and office spaces is suspended from the existing car park structure, accommodating facilities for environmental monitoring, water quality testing and the analysis of collected contaminants. These spaces support ongoing research into pollution, filtration and remediation, making the technical processes of the site accessible to researchers and the public. The project also employs interrelational systems diagrams to document the connections between its physical infrastructure, environmental inputs, energy flows, pollutants and outputs, extending architectural representation beyond the boundaries of the building itself.

The Reservoir becomes an active piece of civic and ecological infrastructure, generating and storing energy, supporting environmental research, and contributing to the ongoing monitoring and remediation of its surrounding environment.