On the specific character of wastewater system reliability indicators

Summary

Authors of technical literature related to various aspects of municipal wastewater disposal systems sometimes introduce notions and definitions that concede varying interpretations which is inaccurate, particularly when using mathematical tools. Therefore, the severity and definiteness of terminology under the circumstances are of special importance. The necessity, possibility and specific character of sewer reliability indicators are discussed. One of such indicators based on the hypothesis of the steady state of «failure-rehabilitation» processes is analyzed. The calculation of the introduced integrated municipal sewer reliability indicators essentially amounts to the estimation of the predictable volume of raw wastewater discharged from the system in some period because of the failure of some elements. One of the possible approaches to the solution of this problem in the context of the hypothesis of the steady origin of the sewer elements and facilities failure and rehabilitation flow is the method of segmentation and equivalenting. The ways of extending the suggested approach to an unsteady case when the failure flow rate shows seasonal periodicity or the network elements show tendency to «ageing» are designated.

Key words

sewerage network , reliability indicator , relative discharge volume , rate of failure , method of segmentation and equivalenting