Background Although abandoned several decades ago, mining activities in the Murcia Region of Spain have left environmental scars that persist to the present day. The extensive mining of iron, lead, and zinc has left behind 85 mining ponds containing industrial mine tailings - the material remaining after removing the desired fraction from mined ores. The presence of these materials in the ponds creates unfavourable conditions for plant growth. Problems include residual heavy metals, macronutrient deficiencies, high acidity, reduced water retention, and poor physical characteristics. Over time, mine residues have also leached and been transported into surface and ground water. The most common techniques for the remediation of acid mine soils and tailing ponds involve encapsulation, topsoil addition and liming. However, in-situ treatment - immobilisation - of heavy metals is gaining increased acceptance by the scientific and regulatory communities. An additional waste management problem in the region is presented by organic wastes coming from the pig industry. Objectives The main objective of the MIPOLARE project is to evaluate, demonstrate and disseminate an alternative sustainable solution for the reclamation of mining sites based on soil amendment using two waste products - pig slurry and marble mud - and phytostabilisation. The project aims to demonstrate in-situ soil amendment using waste materials from the pig and marble industries - which present alkaline and organic characteristics, respectively. This will neutralise surface and subsurface soil acidity, immobilise toxic elements and thereby stop their translocation from the site, and allow sustainable habitat development through the creation of a healthy soil ecosystem. Following soil amendment, MIPOLARE will plant species tolerant to extreme soil conditions, including a high concentration of heavy metals. This will enable a process of phytostabilisation, which will decrease metal transportation by runoff, reduce the potential leaching of metals and establish physical stability to reduce erosion risks. Expected results: The re-establishment of stable ecological conditions at two abandoned mining sites; An improvement in the condition of soil affected by mine tailings. In particular, an increases in pH from around 2.5 to around 7.0, an increase of about 300% in organic carbon and phosphorous, a 100% increase in soil microbial biomass, and a 100% to 400% increase in enzyme activity, as well as a decrease of around 80% in soluble metals and 70% in available metals; A 70% increase in plant cover; Demonstration of a good environmental use for 160m3 of pig slurry and 160 tonnes of marble mud per 2 ha of abandoned mining land.