Problem wich Retention basin's surface

[bruperton]

Hello, my name is Bruno and I'm Brazilian. From now on, I'm sorry for my bad English...
I have a problem: I'm trying to create a surface of a retention basin (is it correct this name?), but I am unable to make the walls. 

I did a proposed model using 3dfaces, as follows:

Now by the Civil 3d like this (for the Object Viewer):

It seems that Civil 3D does not understand to make the triangulation on the Z axis. 
I've tried the "trick" to fend 0.001 'coplanar lines but did not work

The file is this, if someone help me. I thank you.

[Karsten.Saenger]

Hi Bruno,

looking at your sample data, I do not understand what you mean with "Civil 3D does not understand to make the triangulation on the Z axis". Could you please further explain what you expect from the triangulation?
Other than that, I am wondering if it does make more sense to build your basin with the grading tools of Civil 3D. Please see the tutorial files "Grading..." from the help folder for a quick impression how the results can look like.

Regards,
Karsten.

[ccoles]

There is not enough data from the perimeter contour ('PAREDE') to properly triangulate the TINN. Re-add it to your surface with a supplemental distance of 10m. That should add enough data to form the long walls.