I have an Engineering Math Puzzle

I'm trying to build a pool on the side of a mountain.
We dug down to bedrock and we've built a stone box on the hillside that is roughly 30' x 30' x 6' high that is reinforced with concrete and rebar. the base of the walls are 5' thick and the tops are 3'.
My plan was to fill it with crushed stone and a fiberglass pool (16X24 +-), which is about 70 tons of water.
How do I calculate what the outward pressure on the walls will be once i fill it with crushed stone and a 70 ton bowl of water?
signed:
Math is really haard.:banghead:

So you thought you could bit of free engineering on an online forum? Check the yellow pages for a licensed engineer familiar with your local codes.

Most engineers with the knowledge sets you need are quite busy and the time required to analyze your requirements is significant.

You are most likely to get an answer to a simpler, less effort question.

Weirdly enough, you just missed a pool designer.

It sounds like you've already built the pool enclosure which kind of makes the question irrelevant. outside of the basic physics, you'll need an engineer familiar with your local concrete codes and geotechnical conditions. Remedial works are always difficult (read: time consuming and expensive) so lets hope you've over egged it. You can easily search for ways to find pressure but I'm sure your local codes will call for factors of safety of different magnitudes or loading factors for ground conditions etc.

Good luck.

70 tons of water? you don't want design or engineering advice from an internet forum on this one..

Someone (a PE) needs to sign off on the design anyway.