Re: [MODFLOW] modeling a PIT

[rbwi...@mindspring.com]

If the pit is being kept dry by being pumped, you could use the drain package. If the pit is allowed to fill with water, the lake package might work.


-----Original Message-----
>From: Karen Martinez <mar...@gmail.com>
>Sent: Dec 6, 2013 3:09 PM
>To: mod...@googlegroups.com
>Subject: [MODFLOW] modeling a PIT
>
>Hi all.
>
>I'm relative new in MODFLOW, i would like to know how MODFLOW understand an
>open pit, or what package I may use.
>
>Thanks
>
>--
>You received this message because you are subscribed to the Google Groups "MODFLOW Users Group" group.
>To unsubscribe from this group and stop receiving emails from it, send an email to modflow+u...@googlegroups.com.
>To post to this group, send email to mod...@googlegroups.com.
>Visit this group at http://groups.google.com/group/modflow.
>For more options, visit https://groups.google.com/groups/opt_out.

[Julio Verdejo]

Hello i think this is  avery interesting question and i would like to join

What about if you wished to represent the existing dewatering system using pumping wells?. If you use drains, you must use drains representing the whole pit?

Thx

2013/12/7 <rbwi...@mindspring.com>

[None]

Here is my advice on modeling pits with MF:

Assuming you are trying to run some simple dewatering predictions, use the drain package.  You don't need simulate the physical excavation of material during dewatering, as it will be above the water table.  Intersect the final pit shell with the model grid, extract the elevations.  Assign the elevations to the corresponding model cells and interpolate these to your model time steps in the drain package.  Be careful with the conductance term as it is often the source of numerical instability.
If you have multiple pit shells through time, you can use these too, depending on the level of detail desired. 

If you need to estimate the number of wells required for dewatering, simply divide the discharge by well yield.  The actual number of wells needed will end up being a trial and error process anyway, no need to be too precise at this point.
It is best to have pilot dewatering well(s) in order to get the estimate of yield.

For pit lake recovery, you can use the lake package.  For recovery you will need to alter your model properties to represent the physical excavation of the pit.

Lastly, you may find it useful or necessary to use the MODFLOW-SURFACT code for numerical stability in such simulations.  I understand that MODFLOW-USG is supposed to address this issue, but have had limited success with it thus far. 

It would be nice if someone taught a short-course to transition from SURFACT>USG...    

Milos