Background Toxic residues from the former production of the pesticide, Lindane, present a pollution risk at the Bailín landfill, in Spain’s Aragon region. A pollution plume is now emerging which is contaminating soil, water and aquifers. Significant levels of diffuse pollution are also present in the surrounding soil and water. New methods for mitigating such pollution problems are sought that could not only tackle the Bailín hazard, but also be replicated elsewhere, where similar problems exist. Objectives The main aim of the project is to design, install and operate a prototype pollution mitigation system that will use is In-Situ Chemical Oxidation (ISCO) with alkaline activation to restore water quality in aquifers that have been contaminated by lindane from landfill sites. Once the pilot test is completed, and all information and results have been collected and interpreted, the project will assess the technical and economic feasibility of a full scale programme of aquifer remediation in the polluted area. Project actions will focus on: demonstrating the feasibility of ISCO techniques in lab and field conditions; carrying out risk reduction assessments according to specific environmental quality indicators; preparing innovative approaches for adapting ISCO technologies to the existing pollutant mixture; assessing the full-scale applicability and effectiveness of these techniques (via evaluation of ratios such as cost/effectiveness/times, cost/treatment times/energy consumption, and feasibility/efficiency of the pollution reduction); and analysing the applicability and transferability of these techniques to the decontamination of similar sites. Expected results: In relation to the ISCO pilot test with alkaline activation, it is expected that the results will reduce pollutant concentrations in the target site. Positive effects will be observed in the form of oxidised/reduced pollutants, the volume of treated water, and the amounts of waste extracted. An assessment will be made available that details the pilot test’s effectiveness as a method for treating the specific mix of target pollutants. A dosage evaluation and quantification will also be conducted during this pilot stage of the project. In relation to the project’s full scale implementation study, the key result will be an assessment of the technical and economic feasibility of scaling up the pilot system. This will include assessment and reference tables on cost, effectiveness, treatment time and tested techniques viability for DNAPL treatment and pollutant plume, as well as cost/benefit ratios and a socio-economic impact assessment. This knowledge will inform a set of associated methodological guidelines. It is expected that the project will also help to increase awareness among stakeholders on the relevance of addressing environmental issues at Bailín. The project will also foster collaboration between the different agencies involved in tackling pollution.