On 29 Jul 2006 12:48:56 -0700, TrailRat wrote:
A friend of mine is having a huge underground bunker style room put
into his garden. It will be the length + width of his garden and will
be buried under 2' of soil.
... stuff deleted
lawn so he is raising the domes 8' and having long sunlight pipes. The
company has assured him that the pipes will still work over the 11'
distance.

Not quite answering your question, but I don't think a 2 foot depth
of soil is sufficient to dig a hole that'll keep a 10 foot pole
upright (even if it's hollowed out).
Plus, where the sunpipe enters the bunker, 2 feet isn't enough to
stop water ingress: the joint will leak.
Also, have you or your friend thought about how many sunpipes/poles
will be needed to illuminate the bunker? I have looked into these
for a project of my own: a 12-inch pipe will only light about 150 sq.ft.
and an 8-incher considerably less. You can get 21 inch pipes, these
may be easier to disguise as something else - and you'll need fewer of them.

It may be a good move to buy one sunpipe first and experiment with
ways of mounting it, before committing to a full-scale implementation.
You never know, when he sees it, he may like the look of the dome!

Pete
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.................................................. .........................
.. never trust a man who, when left alone ...... Pete Lynch .
.. in a room with a tea cosy ...... Marlow, England .
.. doesn't try it on (Billy Connolly) .....................................