ABSTRACT
This chapter discusses the hydraulic design of storage and tanks at any point in the urban drainage system. It explains level pool routing and discusses alternative routing procedures. Storage can be provided by construction of below-ground detention tanks and chambers, or may exist within the system without being deliberately provided, especially in pipes with spare capacity. Storage for stormwater can also be created above ground and is an integral element in stormwater management. In an urban drainage system, storage tanks can have the functions of: limiting flooding; reducing the amount of polluted storm flow discharged to a watercourse; controlling flow to treatment; and providing a resource for reuse. Online detention tanks are constructed in series with the urban drainage network and are controlled by a flow control at their outlet. A more accurate assessment of the effect of the storage can be obtained by routing an inflow hydrograph through the tank/pond. This can be done using the level-pool routing technique.
