Design as Experiment: The Handan Wastewater Cleansing Terraces

A former municipal landfill has been transformed into an experimental, nature-based water restoration landscape at the 4th Hebei Provincial Garden Expo in Handan. For decades, heavy industry in the form of steel and coal mining left the city chronically water-scarce and polluted, and the 325-hectare brownfield was littered with coal ash, household refuse and solid waste. Turenscape, led by chief designer Yu Kongjian, won the invited competition to reimagine this derelict ground. The 10.4-hectare terraced wetland known as "Clear Channels Flowing Like This" stands as one of the expo's flagship works, demonstrating how nature-based solutions can purify wastewater and recycle solid waste while delivering ecological services, scientific research and aesthetic education. The site was originally a twenty-metre hill of urban garbage adjacent to a twenty-hectare degraded wetland; pre-design surveys confirmed the absence of hazardous substances, so the team could design without health safeguards for visitors. Three wetland typologies were deployed in sequence - free-water-surface terraces, subsurface-flow terraces, and sedimentation and oxidation basins - arranged into five observable purification combinations. The polished water then spills into the neighbouring wetland, helping to restore a degraded ecosystem. A timber boardwalk network links observation points, purification platforms and structures so that data can be collected and an immersive landscape experience created. Every day, 15,000 tonnes of pre-treated wastewater from the local treatment plant flows through the system, restoring more than twenty hectares of wetland and saving an estimated one million kWh of electricity each year compared with conventional treatment. Visitors can watch pollutants - chloride ions and uniquely coloured minerals among them - reveal themselves visually as the water clarifies. What was once a dumping ground has become a living laboratory and a place of leisurely contemplation, proving that a brownfield can heal itself when given the right ecological instrument.