Life cycle impacts of soil construction, an innovative approach to reclaim brownfields and produce nonedible biomass

Abstract The objective of the LORVER project was the construction of fertile Technosols on an industrial brownfield using wastes and byproducts to produce biomass for industrial purposes (hemp as a fiber source and poplar for short rotation coppice). A Life Cycle Assessment (LCA) of the Technosol construction was conducted to highlight the most significant environmental contributions. Three scenarios were compared: a reference scenario (REF) without improvement of the brownfield, a Technosol scenario (LORVER) using industrial byproducts (treated excavated soil, dredging sediments, paper mill sludge, compost and green waste) and a scenario where the brownfield was covered by topsoil (TS). An LCA was performed using SimaPro 8.5, the Ecoinvent v3 database and the ILCD impact indicators. The main contributors to the LORVER scenario that affected air quality and had energy-related impacts were the indirect demand of quicklime due to the use of paper mill sludge, which would have otherwise been spread on fields to save calcic amendments, followed by the transportation of waste from its source to the brownfield site. For the REF and TS scenarios, transportation and organic material spreading caused the most significant impacts. The LORVER scenario was the best or one of the best options for the fertility, carbon and pollution regulation-related impact categories due to the high carbon storage capacity of Technosols and its potential as an alternative solution to waste landfilling. Sensitivity analyses have shown that the LORVER scenario was always the best scenario for the climate change and land-related impacts and that it outperformed alternative scenarios if their required transportation distances exceeded 200 km. This very first LCA of a constructed Technosol made of inert and organic wastes on a brownfield site has proven the merit of this new approach, provided that environmental impacts are evaluated on a case-by-case basis, with the main variability source being the used materials and their alternative management strategies. It has also been demonstrated that these unused soils and materials could provide provisioning, regulation and cultural ecosystem services.