Multiple Outlet Structures in VTPSUHM

[migotis]

Working on a project where the 2 year storm is supposed to discharge from the stormwater management pond to a bioretenion facility. All other storms are to discharge to an existing 30" Road Culvert. Was planning on using two separate structures, one to discharge the 2 year event to the bioretention area and the other to discharge all other storms to the 30" culvert.

Is there a way to model two outlet structures in the same pond in VTPSUHM?

 

[RWF7437]

There are ways to model multiple outlets in some programs. I do not know what the abreviation "VTPSUHM" stands for. You are much more likely to get an answer if you spell out all abreviations the first time you use them in a post....or any other writing.

good luck

 

[LHA]

I have used VTPSUHM (The Virginia Tech version of the Penn State Urban Hydrology Model) for years. It is a decent program, although much more clunky with data entry and limiting with design manipulation than some others.

I do not think you can accurately do this using VTPSUHM. There is only one tailwater setting, and your outfalls will have different tailwater characteristics. You can conservatively route the pond twice, use both Discharge Pipes and all other outlets each time though, or the routing will not be valid. During the 2-year inflow with no tailwater, to verify all that volume gets to the bioretention (I assume you are trying to meet Phase II WQ), and doesn't go out the 30" pipe. During the higher storms, set a conservative tailwater...at least enough to submerge the smaller Discharge Pipe, and I would want to see the entire depth of the biofacility...to show the design storm is depeaked and verify the 100-year flood is safely routed.

The reviewer should buy this; I believe I would. Fax or email him this scenario first though, before driving up your client's billings.

If you have a grated (horizontal) outlet in the controls, you will have to reduce the headwater, or VTPSUHM will not run the routing...one of the big drawbacks of this program, and one of the things that made me seek alternatives.