The main sewer (GOK) solution as defined in the sewerage system optimization project (POKS) is presented. Some data about the present GOK condition, and the description of tasks to be accomplished in the scope of the POKS project, are provided. Possible scenarios, emergency measures, and the development plan, are described, and the list of problems to be solved through emergency measures is ... [Show full abstract] presented. The complexity of the GOK issue and methods for its solution are discussed. The GOK alternative that is considered to be an optimum solution for the defined POKS program, is presented and described in full detail. Main features of the proposed solution are presented in the final part of the paper.