SURCHARGE NETWORK

Question

HELLO, 
 IS IT POSSIBLE TO OPTIMIZE MY NETWORK BY MAKING MY CATCH BASINS AND MANHOLE WORKED AS SURCHARGE NETWORK USING STORMCAD?

Tom Walski · Accepted Answer

StormCAD can calculate depth or flow and surcharging in pipes, inlets and manholes. It can tell you gutter depth and spread. It does not calculate 2-D overland flow because that would require a huge amount of very precise data that most systems don't have. 
 
If you need to perform dynamic calculations such as the time it takes to fill or train a tank, you are better off using CivilStorm or SewerGEMS.

Jesse Dringoli · Answer

Hi Daniel, 
 
Just to confirm - are you referring to surcharging or flooding? As Tom and others pointed out, StormCAD can accurately calculate a *surcharged* pipe, where the HGL is above the top of the pipe (the pipe is flowing full). However, when the HGL rises above the rim/ground elevation of a structure such as a catchbasin and the structure *floods* , StormCAD does not calculate the overflow and resets the HGL to the rim elevation (see link in Scott Kampa's first reply). This means that water will not overflow into the street from a flooded catchbasin, and the inlet capture calculations will continue to assume no tailwater conditions (no influence from the flooded structure). 
 
So, I would agree with the suggestion of CivilStorm, which can handle flooding and overflow, including into the above-surface gutter system.

Scott Kampa · Answer

Hello, 
 
Surcharging is allowed in StormCAD, though if the hydraulic grade is above the ground elevation (i.e., if there is flooding), storage cannot be computed (see this link for information: communities.bentley.com/.../11166.why-is-the-hgl-reset-to-rim-elevation-for-flooded-structures ). 
 
We may need some additional information on the optimization that you are trying to do. If you can provide some additional information, that will be useful. 
 
Regards, 
Scott

Tom Walski · Answer

StormCAD can handle this. This isn't so much a modeling question as a design question. You are trading off some cost savings with the risk of street flooding. 
 
Whether you want to do it depends on your design standards. In many locations, the standard says you should not design a system to surcharge.

Sushma Choure · Answer

Hello Daniel, 
 
As mentioned by Dr. Tom already in his reply, you can use StormCAD for design of such surcharged network, but why would you do that? Why would you want your network to surcharge by using small diameter. 
 
When the elements are surcharged, you will see a notification about that, or you can see that in the pipe properties. 
Or you can color code the elements based on field - Is ever surcharged? using element symbology