MODFLOW help

[GATV]

Hi everybody!

I hope someone can help me out. I'm trying to model a leaking sewer pipe and sheet pile wall in modflow and it looks like the choices I've got are either to model the them as drains, or model them as a material with a different permeability. Does anybody know what is the best option, or if there is a better one? It seems that the wall model in modflow is only for barriers and does not allow for leakage through.

any help is appreciated!

Thanks!

 

[Focht3]

Wow, I haven't fooled with MODFLOW in 14 or 15 years! And painful memories, to boot...

Anyhow, you will probably have to create an impermeable curtain within the model space to simulate the bulkhead. The space away from the bulkhead will have to be a high permeability soil (at least 100 times more permeable than the soil around the pipe.) The MODFLOW boundary conditions won't do you any good with that problem. The sewer pipe is similar, although the geometry makes it a bit more problematic.

Let us know how you (eventually) solve the problem -



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[agsgeophysics]

You can model the sheet pile wall using the Wall Package - it allows for input of the wall thickness and K. You will need to modify layer(s) to simulate the depth of the wall.

The leaky pipe can be simulated in a number of ways. The drain package may work. Or perhaps you can collapse the grid around the leaking portion and simply use a constant head cell (or variable head). I'll think more about that one for you.