what do i do need some opinions

Hi there, I am building a new home, unfortunatly its on really bad ground :doh: rocks rocks and more rocks mixed in with alot of clay..... I have just had a 13 tonne excavator in digging my backyard up for hours to get down an extra 200mm below footing height. Reason why is because we had alot of rain and it just sat there, so i dug it all up put in a few drains etc. Now i want to fill it back up.... Ive been told a few different thing but i want to know whats a good option for the future.

Yard will be filled 250mm sloped down hill to 50mm which equals about 80-100 cubic metres.
1. Do i put sand as a base? if so what kind? (Beach sands cheap here but naturally will have salt in it so probably no good)
2. Do i truck in alot of good top soil? :no: $28/cu-m
3. Scoria is $12m nice cheap base and add 80-100mm of topsoil on that?
4. ???????

I have rang all bobcat drivers in the area and they havent came across any good dirt to be trucked away.

Well see what you think i really have not much of an idea and it sorta needs to be done very soon before more rains come threw
Keep in mind its a backyard of my house and will need it to grow grass.

cheers
Tim

I don't know what scoria is but my dictionary says "The scum formed by oxidation at the surface of molten metals", dross,
slag.
If this is the case water will drain through it very quickly, so if it is any depth any soil spread on top will dry out very quickly especially on a slope thus making it very difficult to grow grass. The salt in the sand will leach out eventually but you will still have the same problem with the soil drying out.
Hope this helps, not much I know.

scoria down here is a fine "crushed rock" or "crusher dust" very good packing compound for under slabs of concrete etc.
fair point about making the top soild dry to quickly.

any other opinions?

Crusher dust will be fine covered with soil, it also contains many natural minerals so is good for growing plants.

came across 50cu/m of quality dirt for delivery price only today.... so only need 20cu/m of sandy loom and its all done. thanks anyway guys