Reliability of River‐Treatment Plant Systems

Abstract

The reliability of river‐treatment plant systems is determined by considering fluctuations in both the streamflow rate and waste loading rate. The method involves an application of the elementary theory of hydrologic statistics and waste assimilation models to the cumulative density functions of the flow rates and loading rates. The products of the method are the expected number of system failures per drought, the interval between failures and the annual return period of droughts containing at least one systems failure. It is shown that the usual methods based on rare drought flows (e.g., the seven‐day average flow with a 10‐yr return period) cannot provide this information. Also, designs based on rare drought flows are not conformable to stream standards, whereas designs based on the proposed method are intrinsically conformable to stream standards.