| Abstrakt: |
Combined sewer systems in low lying areas, such as those in the Western part of the Netherlands, have very specific characteristics. Due to a lack of available head gravity driven flow is possible only over short distances, so pumps are needed throughout the system. Lack of available gradient also means fairly large diameter pipes are needed to transport the maximum design flow, so storage volume is usually available. Systems tend to respond quickly and prevention of combined sewer overflows is strongly dependent on available pump capacity and storage volume. For a simplified system model a mathematical proof is given that for a system, designed by Dutch rules of thumb under spatially homogeneous load, local control is nearly as effective as central control when it concerns the prevention of CSO events. |
