Tank farm for Exxon in SC(14 tanks for)
Two for Coast Guard on Hatteras Island
Smaller tank farm for Port of NC Morehaed City (5)
Two in Winston Salem NC (for different owners)
Both of the tank farms we used a PC 400 w/ Labounty UP70 to bring the tanks down and torches for sizing. All but one of the others were cut and pick (no room to drop). One of the tanks on Hatteras I weakened and pulled over with the cable from a roll-off container truck. I have pix of that one, I'll have to dig em out and scan em in.

I did a 1.4 million gallon elevated water tank (205' tall). It was the worlds largest until 1998. I dropped the roof in first. I then walked around the platfrom and cut 2' at a time around the tank. It dropped 2' at a time. This is a tried and true method that lends to minimal liability.
I learned this technique from a few mexicans doing a big tank at a Texas refinery. I couldn't believe it until I saw it done. When I tried it, every bystander thought I was crazy. It works though!

One year I did 23 tanks in eight months using all different methods. Tanks are some of the more fun things to demo for me.

Good luck with that one!

You should be able to cut a wedge at the base leaving a central piece to act as a column, then cut around the base leaving holds at the bases of your wedge (to act as a pivot)and at 180* from the column, then attach a cable between the column piece and your excavator,next cut the rear hold and then pull the column allowing the tank to lower to the ground. Your wedge should be one third of the circumference of the tank and aligned in the direction of fall. Judging from the pics I would try to make the wedge column about 8ft high and at least 4ft wide. Watch out for weak welds or rivets on those panels though, they can cause premature failure.
If tripping is not an option, then you can always just cut and drop the panels in as large or small a size as you are comfortable with.
Good luck and work safe!

Digdug, you may get a little smoking from the paint (all coatings will have some volatile output) just make sure your burners are wearing some sort of respiratory protection. Tnemec is a fairly standard type of coating; it's a super durable paint. It's good that it is on the inside as well, because the coatings Nukeworker was talking about is a hard tar like coating that will ignite and burn and is hard to put out. I would suggest either cutting an inspection hole near the base (making sure you have some fire suppression close by) or opening an existing inspection cover just to make sure. I once demoed a 180' x 75' surge tank that we were assured was clean. I accessed it to find 5 feet thick of sludge in the bottom and a flammable coating all over. It's worth the extra time just to check.
Like Nuke said if there is room, tripping is the way to go. Get it on the ground and the do your scrap sizing.
Good Luck!