Aluminum tank gauge thickness

Greetings,

I live in an area where new construction requires some kind of water tank for fire truck access, I will also be using it for an exercise tank, 7 feet deep, (In order to kill 2 birds with one stone), it needs to be at least 3,000 gallons, I will figure out the diameter later. I would like o build it out of 6061 Aluminum. The head of water pressure is around 3 psi. for static water. I saw that dynamic was different. Given the exercise activity in the tank what gauge of Aluminum sheet should I use?

Thanks for any and all responses.

Might want to do an internet search "swimming pool." :)
Building a pool out of 6061 aluminum would be quite expensive compared to a swimming pool? You'll also need to be careful about what you sit an aluminum tank on. Concrete will rot it. not sure about how well aluminum would hold up sitting on dirt / clay or sand?
If you're set on 7 foot deep then you'll need to be a little over 15 foot diameter for a round tank... Go 16-17 foot to allow for evaporation and not filling it to the very top? Adding vertical members around the tank and a brim or lip of some sort around the top would make a huge difference on how thick you'll need to go as well. (Like a swimming pool...)

Good Luck.
Bob