How to make a vertical refinement

Hi Everyone.
I'm focus in a rescent project that represent the dewatering process for a mine, but i built a mesh starting from a layered mesh, using nodal distribution for a each pit stage with 3D configurator, the final mesh has large  number of elements and nodes, aproximately >4000000 elements, considering that fact, i was looking for a solution and i saw that the best way is to use a vertical refinement like the image on this post. how to do this workflow to accomplish this due, i will appreciate some ideas, thanks.

You might want to have a look at https://www.youtube.com/watch?v=7VcGqRPvxdo for an introduction to unstructured meshes in FEFLOW. Note that handling models with unstructured meshes in general is more complicated than using the layered option.