Problem

In a SewerCAD model, the flow coming into a wet well is the same as that found downstream of the pressure system, rather than the flow seen from the pump.

Problem Number: 33543

Solution

This will occur if the SewerCAD calculation option field "Use Pumped Flows" is set to "False". If set to False, the discharging load will be recreated as a combination of dry, wet, and known flows in accordance with the loads entering the pressure subnetwork. If set to "True", the flows discharging from a pressure subnetwork into a gravity subnetwork will be based on the pump flow and the pressure equations. 

In a steady state run, in pressure subnetworks, the flow from the network is calculated using pressure equations, the characteristics of the system, and number of pumps running. For that flow rate to be passed to the downstream gravity system, the user should set this property to "True". In general, setting "Use Pumped Flows" to "True" is used when the user wants to look at the peak flows when the pumps are running.

Setting "Use Pumped Flows" to "False" will use the loading data into the pressure system (into the upstream wetwell), and give more of a true picture as one moves far downstream from the pressure system and the effects of pump cycling become diminished. In this use case, the user will not want to use the pumped flow. Instead, they would pass loading to the downstream system based on upstream loads and appropriate extreme flow factors similar to the way flows are handled in the gravity system.

NOTE : With  "Use Pumped Flows" set to "False", there was an issue in reported population count not correctly populated, which has been resolved with the help of a patch in SewerCAD 10.03.04.53 version. You can contact Technical Support to receive the latest patch or upgrade to the next higher version.

See Also

Using Extreme Flow Factors

Why do my pump results look different depending on the reporting time step and hydraulic/hydrologic time step?