Newbie Help - Error 700: Unable to Extend Routing Tables

[APG817]

Hi guys, new to HydroCAD, but trying to model a relatively simple system and it's giving me a huge headache.

We have a Collection Area -> Reach -> Detention System (Storage Pipe w/ Culvert outlet) -> Detention System (Catch Basin w/ Pump)

Everything was working fine, until I tried increasing my storm depth from 2.34 to 5.38 inches. Suddenly I get an Error 700: Unable to extend routing tables above 45.36'.
I added the pump curve data. My pump elevation is 38.91', the float/on is 39.41', and the outlet of my pump is 45.36'. Since it's a bubbler outfall any water will just bubble up and flow away, but the software obviously doesn't know this.
How do I properly model this situation?? I don't want to increase the outlet elevation because then it will affect my pump discharge rates. Really unsure what to do.

Any help will be appreciated!

 

[psmart]

Clicking the error message provides this advice:

Error 700: Unable to extend routing tables above xx'

While performing a pond routing, the water surface elevation has exceeded the expected range. HydroCAD attempted to extend the routing tables above the initial range, but failed because the storage and/or discharge curves are no longer increasing past the specified elevation.

This typically occurs because there is no additional storage or discharge capacity available. This makes it impossible to complete the routing operation.

To correct the problem, you must provide additional storage and/or discharge information for higher elevations.
To get a better view of your existing data, disconnect all inflows to this node and open the report window. This will let you verify the current stage-discharge and stage-storage data.

Assuming that the error is associated with the pump node, and that you expect any excess to "bubble up and flow away", you probably need to add an overflow outlet, such as a horizontal orifice. Otherwise the software has insufficient information to handle the excess (when the pond is completely full).

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[psmart]

Also, make sure you've defined the storage volume for the pump chamber. There has to be a volume to pump from so you shouldn't use the zero-storage option, even if it's just a catch basin.

In you have further questions please post the HydroCAD project file.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[APG817]

psmart thank you for the quick response. I understand what you mean regarding the overflow outlet, but how do I properly implement one? Is it considered a Secondary pump outlet, or a separate entity altogether?

Also thank you for the suggestion about the storage volume in the catch basin, I hadn't factored that in.

 

[psmart]

It depends how the overflow is routed in relation to the pump outflow. If they're routed to the same point you could set them both to primary, or set one to primary and one to secondary for separate reporting and routing.

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[APG817]

Awesome! I got it to work today. Your answer helped me out. Essentially my pump is only able to output 0.08 cfs, meanwhile the peak incoming is upwards of 0.5 cfs. At a certain point the detention fills, and since I had no designated overflow, there was nowhere for the water to go, hence the Error 700.

Adding a proper overflow remedied this.
Thanks psmart,