The project proposal provides for activities for the preparation of a regional pre-investment study (RPIP) for the territory of Sofia Municipality, preparation of conceptual projects for infrastructure, project documentation, assessments and assessments of compliance with environmental legislation, etc. analytical documents, preparation of institutional, financial and economic analyses and cost-benefit analyses (CBA), for the consolidated region, as well as preparation of documents for subsequent application under OPE 2014-2020 of measures identified in the RIPP, including an application form. The activities set for implementation in the project proposal are aimed at the population on the territory of the entire municipality. After its implementation, the conditions for increasing the share of the population included in the sewerage system in Sofia Municipality will be created. The measures will allow to meet the requirements of EU Directive 91/271/EEC on urban waste water treatment, improve waste water collection by increasing the number of households connected to the collecting system. The presence or not of engineering infrastructure, in particular — of sewerage, is an extremely important factor directly influencing the quality of the environment and its attractiveness to potential investors and respectively — for the implementation of municipal policies. Public investments in sewerage are one of the most efficient tools at the disposal of the municipality to guide urban development and achieve the objectives set out in its strategic documents.