Storm and Sanitary Analysis question...

[jbarnesSKRZK]

All my nodes in SSA have rim elevations associated with them, but only a few are actually manholes or inlets. The others are mostly bends, wyes, etc., which have no rim elevations. Is there a structure for these type of nodes? How does one make the program understand a node has no rim elevation?

[MMcCall402]

A Null structure has no rim elevation.  It connects pipe to pipe.

[jbarnesSKRZK]

I understand that a null structure has no rim elevation... in Civil 3D. When imported into SSA, they all have rim elevations. They appear to be manholes, which, of course, they are not. My question is, how does one change the null structure to be just, say, a wye or a bend? Something without a rim elevation in SSA?

[fcernst]

No there isn’t..all nodes are Junctions …where you specify a Junction cross section area, Rim Elevation…and an optional Surcharge depth used for for modeling pressurization. 

[jbarnesSKRZK]

Pardon my ignorance vis-a-vis SSA... I'm just learning it. I'm still confused on how to import a storm system from Civil 3D without bringing in null structures as manholes. Bends, wyes, etc., shouldn't be modeled as having any storage capacity as a manhole would, right? Storm Sewers, as clunky as it is, allows for these kinds of junctions. 

[fcernst]

They will always come in as Junctions from Civil 3D.. those are minor losses and typically modeled in SWMM (SSA’s engine) by tabulating the avg minor loss along the length of the conduit and entering in the Avg. Loss Coeff. parameter in the Conduit.. 

[gbalajadiaV28JN]

Did you get an answer. Connecting open channels also require a junction and the junction behaves as a manhole, which modeling the open channel incorrectly.

[MattAndersonGauge]

In SSA, bends and other Wyes should have REALLY high Rim and Surcharge Elevation so that water can NEVER escape.

[gbalajadiaV28JN]

I got it. Removing the entrance losses on my channel segments makes it behave like a continuous channel rather than having a manhole between segments even though there are junctions.