Background There are around 3 000 active foundry operations in Europe that annually generate over 9 million tonnes of waste sand, with ferrous industries the major generators. Only 25% of this Spent Foundry Sand (SFS) is recycled for a few applications, mainly by the cement industry, but these sectors are unable to absorb the total amount of sand generated so the remaining 75% is landfilled. The global warning potential of sand extraction (quarrying and dredging) and processing is between 92-120 g CO2 eq. per 1 kg of dry silica sand obtained. Air pollutants are emitted by the extracting equipment (usually diesel), and noise is a common occurrence due to extraction and transportation. Sand extraction involves considerable land take and loss of soil (estimated at 0.4 ha per tonne of sand extracted), with associated loss of wildlife habitat. The re-use of foundry sand would minimise these impacts. Objectives The LIFE ECO-SANDFILL project aims to demonstrate the technical and economic feasibility of using Spent Foundry Sand (SFS) as an eco-friendly fine aggregate in construction applications. The goal is to reduce the large volume of foundry sand annually sent to landfills. The mechanical process, demonstrated for the first time in Europe, will treat up to 1 500 tonnes of SFS in a pilot plant integrated into a foundry in the Spanish Basque Country. The new product will be used as fine aggregate for three different construction applications: embankments, mortars and as Controlled Low Strength Material (CLSM). The proposed technology performs better than existing technologies in terms of sand impurity removal, and from an economic perspective it is expected to reduce foundry sand management costs by 40% and construction industry raw material costs by 30%, while establishing a green economic activity with potential for job creation. The ECO-SANDFILL technique is suitable for all type of sands and moulding systems, and it has high replicability potential. The project’s objective of reusing a waste stream to divert it from landfill is in line with the Roadmap to a Resource Efficient Europe and the 7th Environment Action Programme (EAP). The specific objectives are to: Demonstrate that SFS correctly pre-processed can be re-used in construction applications with a high demand for fine aggregates; Obtain non-hazardous sand as a safe by-product from waste; Contribute to ‘close to zero’ main solid waste from foundries being sent to landfill and to reverse the trend of new sand excavation from virgin land; and Stimulate industrial activity and increase competitiveness in several sectors (e.g. casting, construction and waste management). Expected results: Valorisation of around 1 500 tonnes of Spent Foundry Sand (SFS) in the Basque Country during the project, with a scenario report for the potential recycling of 3 000 000 tonnes of reclaimed sand per year in Europe, and its associated CO2 reduction; Reduction of the volume of the annual foundry sand disposal in landfills by up to 1 500 tonnes; with an estimated CO2 reduction of around 15 tonnes/year; Reduction in consumption of natural aggregates by up to 1 500 tonnes, with an estimated CO2 reduction of over 100 tonnes/year; Reduction of energy consumption by 600 000 KWh/year; Production and demonstration of high performance embankments and Controlled Low Strength Material (CLSM), substituting the virgin fine aggregates with 100% SFS; Sand impurities removal (e.g. metal scrap, organic matter) with an efficiency of more than 95% (loss on ignition Environmental safety of sand (leaching procedure: phenol Production of good practice guidelines and policy recommendations for a future standardisation of reused sand exploitation; and Detailed financial cost-benefit analysis of the technology and a LCA of the new applications, including data on carbon footprints and resource consumption comparing ECO-SANDFILL with conventional solutions.