This document consists of the analysis of the social and economic impacts produced by the activities and results of the LIFE GAIN project carried out by COMSA. The project tries to enhance the valorisation of an industrial waste product, such as the black slag derived from the steel production, using it in the railway foundations layers. As a result it will improve the mechanical properties of the track and clearly reduce the environmental impact of the track maintenance, renewal and construction. The LIFE GAIN is carried out in a context where the eco-friendly activities are promoted by the European Union since it is important to reduce the waste production and the social and environmental impact that it has. With this objective, this project has been presented to solve the problem of Steel Furnace Slag (SFS), which actually is an important waste product in the whole Europe. With this analysis we have tried to conclude which is the impact of the project on the society and to evaluate the social and economic impacts that the project actions will have in the influence zone of the activities. Likewise, we also try to gain knowledge about the social opinion of a project like that, since nowadays it’s important to include the population feedback in the companies’ actions and strategies to improve their results and turnover. In the first place, with the aim to make clear the objectives and the previous research and activities of the LIFE GAIN project, a brief introduction has been done. This introduction consists of the description of the context and objectives of the project and the state of the art of the SFS. Furthermore, the properties and the previous tests done in the investigation of the valorised product (SFS-RAIL) are detailed in this point to have an idea about the commercialized product. Secondly, it is presented the diagnosis of the studied area, which describes and characterizes different topics of the project’s influence zone. In this chapter we have analysed the territory and demography of the area since it is an important issue to quantify and evaluate the possible impact of the project in the society and the surrounding environment. A delimitation of the territory influenced by the project has been necessary to analyse the local impact. Moreover, the description of the structure, distribution and evolution of the population affected has been done to get a better characterization of the region inhabitants. In addition, we have analysed the active population that we could find in the area, which will be a priori the most affected group by the generation of economic activity because of the project actions. In addition, the local business network has been studied in order to quantify the contribution of each industrial sector in the economic activity of the region and bear out the importance of the siderurgy sector in the two areas of analysis. In the same way, the labour mobility patterns of the population in the influence zone are analysed to identify the main poles of attraction. It is important to characterize the situation of the industry, since the new industrial activity created by the project could modify this flow of daily trips or enhance the trends if it is in line with them. Furthermore, in this chapter we have carried out an anonymous survey to the population of the region to know their opinion about the project analysed since it is undeniable the relation between the activity of a company and the society. Nowadays, it’s important to establish a dynamic interaction with the different social agents, where its expectations and opinions are included in the company strategies. The information flows resulting from this new dynamics are very precious actives for the company since it will provide a higher sensitivity with the surrounding area, helping to anticipate risks and to get more profit from the opportunities that may arise. To complete this section, a more detailed analysis of the siderurgy industry of the project and field test influence zone has been carried out. During this analysis we have characterised and delimitated the siderurgy sector of Asturias and Catalonia and its economic contribution in the whole country concluding that both of them are two of the most important Spanish siderurgy areas. The waste production of the sector and the waste recycling techniques are also described since it will be necessary to quantify and evaluate the innovations introduced by the project and how it will affect to the amount of waste landfilled and to the different uses that black slag have in the present. Continuing with the scheme of the analysis, the different impacts of the project and its consequences in the topics explained above have been described in the next chapter. We have summarized the main impacts in different topics such as the impact of the foreseen investment, the impact of the increase of steel slag recycling, the impact of the decrease of industrial waste, the impact of the reduction of quarries activity and the impact of the increase of jobs. A relation and the consequences in the topics of the previous chapters have been established for the correct evaluation of the impacts. To finish with the analysis, all the conclusions extracted from the different chapters of the evaluation of the project have been presented summarized in a list. Some positive results derived from the implementation of the project have been identified, which allow us to conclude that this project is interesting in both social and economic terms.