A THEORY OF STORAGE-TREATMENT SYSTEMS

A simple expression is presented on the capability of storage-treatment systems to reduce non-point pollutant runoff load. The effectiveness depends on capacities of the facilities and probabilistic properties of the runoff, such as the interval, duration, volume and concentration of the runoff events. Assuming the compound Poisson process for the runoff time series, the exact expressions of the ratio of treated load in terms of storage and treatment capacities are theoretically derived on the neibourhoods of all boundaries of the domain on which the problem is defined. Then, an approximate expression over the whole domain is presented of which the value and the first order derivative coincide with those of the exact ones near the boundaries. The accuracy is checked by means of Monte Carlo simulations.