This paper presents the first elements of a methodology for designing Participative Document Spaces (PDS), as well as the initial results produced by this methodology within an industrial project aiming at designing a radioactive waste disposal. We define PDS as networked digital settings (such as blogs, forums, wikis) which enable their users to build documents and converse at the same time. Designing a PDS in a given situation thus implies modeling the links between existing settings for building documents and conversing, as well as the costs generated by replacing all or parts of these settings with a PDS. The analysis of our model project shows (a) that numerous settings, both for building documents and conversing, are being used to discuss document content, (b) that improving tracking those discussions could improve the “memory” of the project evolution. In this context, a wiki seems an appropriate tool in the extent that it would allow to directly attach to the documents most of the conversations related to them, thus fostering readability of those conversations and the “memory” of the project. Further studies remain to be conducted to determine the proper functions of the wiki, the rules applying to its use and the diverse costs generated by its deployment within this particular project.