Building underground safe rooms

[Highwhistler]

Hello Friends,

I will be building a green home, above ground,
but I want a few rooms in it to be underground
or backed up against a natural rock formation
into which rooms can be "bored."

Do any of you know the suggested specs for
building underground rooms that protect
from the type of solar activity and pole
shifts as discussed on Project Camelot?

For instance: Is adequate protection gained
from significant solar mass ejection in rooms
with 1 foot of rock overhead? Or is it 3 feet?
10 feet? Or is it much more than that?

I have found websites that discuss underground
homes and that have photos as well, but I've not
found a site that discusses the engineering of
rooms and homes that are designed with
solar mass ejections in mind.

In advance: thank you for your response, links,
information and advice.