Infiltration and exfiltration from sewer network with a focus on house connections in city of Prague

摘要

Sewer systems constitute a very significant patrimony in European cities. Their structural quality and functional efficiency are key parameters to guarantee the transfer of domestic and industrial wastewater to treatment plants without infiltration or exfiltration. House sewer connection (hereinafter referred to as HC) is standpipe which draining the house estate to the main sewer. In case of combined sewer system is one house connection per one house estate. House connections are the most sensitive parts of whole sewer system. Frequently are neglected during their construction and operational conditions. The paper shows analysis of several damages occurring on the house connections, their causes and influence on the amount of infiltration water to sewer system by HC or exfiltration of wastewater from HC to environment. Thereinafter, the paper focuses on a field experiments and evaluation of results. The measurements of the amount of water infiltrated to a HC or exfiltrated from HC comprises the identification of the defect and the measurement itself. Related Infiltration assessment, the methodology is based on the monitoring of minimal discharges during the night in a catchment with using of Parshall's flume. In the case of Exfiltration, the methodology is based on a watertightness test. Measurements are performed on a selected catchments in Prague city, in order to obtain a lot of results from different types of build-up area, age of pipes, geology and hydrology conditions. However, in this paper is presented two localities for Infiltration and Exfiltration assessment.