Design of Wastewater Storage Ponds at Land Treatment Sites. II: Equilibrium Storage Performance Functions

Abstract

A new reliability‐based method is presented to size a storage pond at a land treatment site operated for the disposal of municipal wastewater. Reliability is defined as the probability that wastewater levels remain below the pond freeboard zone. Starting with the mass conservation principle and the theorem of total probability, an integral equation representing the cumulative distribution function of wastewater storage levels is developed. This equation is solved with Monte Carlo simulation, a technique often used in stochastic reservoir analysis. Results are presented on dimensionless design charts called equilibrium storage performance functions which show the steady‐state cumulative distribution function of wastewater levels in a storage facility of specified capacity. An example illustrates how the equilibrium storage performance function can be used to design a wastewater storage pond that meets a specified annual reliability.