Economic Analyses In Sewage System Designing For Rural Settlement – Case Study

The paper presents application of multivariate economic analysis to decision making process of selection of the most economically suitable concept of sanitary sewage system for a selected rural settlement in Poland. Analysis covered Drelow, Lublin Voivodeship, settlement area with 121 households with 421 residents and several municipal services. Three variants of sewage removal and treatment were developed: unconventional gravity-pressure network, gravity-pressure network combined with local domestic wastewater treatment plants (WWTPs) and full pressure sewerage network. In all variants, the container wastewater treatment plant of daily capacity 450 m³ day^-1 was applied. Estimations of investment and exploitation costs for 30 years period operation were performed. Economic multivariate analysis was based on: Payback Period, Dynamic Generation Cost (DGC), Net Present Value (NPV) and Benefit-Cost Ratio (BCR). The obtained indicators were the input data for the weighted sum model allowing to select the most appropriate variant. Analysis showed that the most suitable was variant No 1. However, it was also noticed that all of the tested designs were ineffective economically.