M. Benedikt, F. Zimmermann, B. Auchmann, Wolfgang Bartmann, Jean-Paul Burnet, C. Carli, Antoine Chancé, P. Craievich, M. Giovannozzi, C. Grojean, J. Gutleber, K. Hanke, A. Henriques, P. Janot, C. Lourenço, M. Mangano, Thomas Otto, J. Poole, S. Rajagopalan, T. Raubenheimer, E. Todesco, L. Ulrici, T.L. Watson, G. Wilkinson, Asmâa Abada, M. Abbrescia, H. Abdolmaleki, S. H. Abidi, A. Abramov, Christophe Adam, Marton Ady, P. R. Adz̆ić, I. Agapov, D. Aguglia, I. Ahmed, M. Aiba, G. Aielli, Tamer Akan, N. Akchurin, D. Akturk, M. Al-Thakeel, G. L. Alberghi, J. Alcaraz Maestre, M. Aleksa, R. Aleksan, F. Alharthi, J. Alimena, Andrea Alimenti, Simone Alioli, L. Alix, B. C. Allanach, Lukas Allwicher, A. Altintas, M. Altınlı, M. Alviggi, G. Ambrosio, Y. Amhis, Amirpiran Amiri, G. Ammirabile, T. Andeen, K. D. J. André, J. Andrea, A. Andreazza, M. Andreini, Tito Andriollo, Luis F. Angel, M. Angelucci, Stefan Antusch, Muhammad Naeem Anwar, Liliana Apolinário, G. Apollinari, R. B. Appleby, A. Apresyan, A. Apyan, Armen Apyan, A. Arbey, B. Argiento, V. Arı, Silvia Arias, B. Arias Alonso, O. Arnaez, R. Arnaldi, F. Arneodo, H. Arnold, P. Arrutia Sota, Maria Elena Ascioti, K. A. Assamagan, S. Aumiller, G. Aydın, Kobra Azizi, P. Azzi, N. Bacchetta, A. Bacci, Bin Bai, Y. Bai, Lorenzo Balconi, Giorgio Baldinelli, B. Balhan, A. H. Ball, A. Ballarino
Abstract Volume 3 of the FCC Feasibility Report presents studies related to civil engineering, the development of a project implementation scenario, and environmental and sustainability aspects. The report details the iterative improvements made to the civil engineering concepts since 2018, taking into account subsurface conditions, accelerator and experiment requirements, and territorial considerations. It outlines a technically feasible and economically viable civil engineering configuration that serves as the baseline for detailed subsurface investigations, construction design, cost estimation, and project implementation planning. Additionally, the report highlights ongoing subsurface investigations in key areas to support the development of an improved 3D subsurface model of the region. The report describes the development of the project scenario based on the ‘avoid-reduce-compensate’ iterative optimisation approach. The reference scenario balances optimal physics performance with territorial compatibility, implementation risks, and costs. Environmental field investigations covering almost 600 hectares of terrain—including numerous urban, economic, social, and technical aspects—confirmed the project’s technical feasibility and contributed to the preparation of essential input documents for the formal project authorisation phase. The summary also highlights the initiation of public dialogue as part of the authorisation process. The results of a comprehensive socio-economic impact assessment, which included significant environmental effects, are presented. Even under the most conservative and stringent conditions, a positive benefit-cost ratio for the FCC-ee is obtained. Finally, the report provides a summary of the studies conducted to document the current state of the environment.