I found out that the gutter just right above the hole has full of leafs.... I guess that explains why water just pours down directly washing the sand off?....

What I am going to do is, get a few bags of concrete mix from Bunnings and mix it up with water, and then pour them into the hole, hopefully…

I don't know... cuz I don't live there, so it's very hard to find out what caused it. Any solution you can suggest?

Oh, don't even have to mix it up with water beforehand?
What else can I do to prevent it? Should I level up the side dirt so that it's higher?

I have this driveway which sunken over a year and I only just got it relayed last week. But with the crazy amount of rain fall we have these few…

Thank you Linda, that answered my question.... So builder should be able to start putting slab down right?.... Because i was worried if I had to wait another 2 weeks…

Thanks guy.
I had it out of contract... and I have done demolition, and site work. The land is flat now... but the builder called me yesterday and asked if I…

Might sound stupid, but is soil removal generally before any slab/footing work?