On Sat, 12 Mar 2005 10:04:11 +0800, OldNick
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

Bum! More like 35m3. sorry.

10 m * 10 m , starting at one corner at 150mm and having a max fall of
0.5 metres is mmmmm.... 20 m^3 with 45 degree fall on the batters? You
may get away with "local dirt" for a bottom layer or two, but be
careful, and check first if you are every going to concrete the floor,
or the authorities are ever going to delve around.