The results display for a modified rational results has a column for outflow volume target (which displays as N/A) and then shows the outflow volume value and then the next column shows FAIL, as there is no target to compare to. Has anyone any advice as to how to deal with this superficially negative FAIL message?
Sorry, I forgot that things are a bit different when you're using the modified rational method in Pondmaker. In this case, the "target outflow volume" field in the Design worksheet will always be user-editable and N/A by default. This is because with the modified rational method, the predevelopment conditions do not have a hydrograph to coompute volume from - it is just one peak flow value.
However, the rest of what I explained before remains - you can either ignore the "fail" message for the volume comparison, or overwrite the "N/A" values with real volumes in the "target outflow volume" field of the worksheet Design tab.
Jesse
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Hello Jak,
It looks like you're talking about Pondpack V8i. The "N/A" for Target Outflow Volume in the Pondmaker Routing worksheet can appear when you set the "target flow/volume source" to "user defined" in step 1. In this case, the user must manually enter the target flow for each return event. So, the "target peak outflow" and "target outflow volume" fields in the Design worksheet become editable. They are both "N/A" by default, so it sounds like you only entered target peak flows.
With that being said, you may not always need to design a pond to keep the total volume below the predevelopment conditions. Typically this only happens with significant infiltration, otherwise there would be no reduction in postdevelopment volume. So, that means that the "fail" message for "Computed outflow volume vs. target" is not necessarily a problem. If you're not designing the pond to keep the total volume below the predevelopment conditions, you could either ignore this or enter some values for the "Target Outflow volume" in the Design tab of the Pondmaker worksheet and adjust the "volume allowed below" and "volume allowed above" fields in the Options tab.
If you have any other questions about this, please contact technical support .
Jesse Dringoli
Bentley Technical Support