Curb Inlet Rim

[b22smith]

Just purchased StormNET and setting up models. What elevation do you use for a curb inlet "rim"? The curb inlet lip at the pavement or the top of the curb inlet box?

[Chris Maeder]

The "Inlet Rim Elevation" corresponds to the top of pavement where the inlet grate is.

[Steve Garland]

What would be the proper way to model two curb inlets in a sag condition of a road. If the curb inlet is set to "sag" then the bypass option is grayed out and ponding occurs. The weir option from curb inlet to curb inlet doesn't seem to be the solution as the weir carries no flow.

If the curb inlets are set to on grade, then bypass outlets to simulate overland flow can be modeled but mass continuity is off from one inlet to the other as flow is "lost", the upstream curb inlet having more peak flow than the downstream curb inlet.

However, modeling the two curb inlets as flow diversions connected with a pipe and an bypass channel seems to work.

Any clarification on this?

[Chris Maeder]

There are different ways to model dual (two) inlets on sag:

1. If the dual inlets are relatively close together, simply place only one inlet in the Horizontal Plan View and then increase the number of inlets within the Inlet dialog using the "Number of Inlets" field.

2. If one of the inlets is actually "upstream" of the other inlet and there is some distance between the two inlets, then the "upstream" inlet should be defined as "on grade" and a bypass link defined for routing flow to the lower (downstream) inlet on sag.

Note that when you route a model where the link distances are relatively short, make certain you have a short enough time step to actually account for the water entering and leaving the routing links. For example, if the bypass link is only 10 feet between the inlets and the flow velocity of the bypass flow was 1 fps, then you would have to set the time step to 10 seconds or less. Otherwise, if the time step is defined too large, you can have problems with continuity errors or mass balance errors. Note that this is described in detail in the new StormNET User Manual. See the sections on Project Options, Analysis Options, and Inlets.