Yair . . .
I found these pics on a historical site.
The tank is larger than normal station/farm tanks but style and batters are identical with all the water stored below ground level in "the hole", a flat apron or table and then, what in effect are spoil banks . . . just a place to stack the spoil.
The banks were battered off smooth and level and the old tanksinkers took a great deal of pride in the finish of their work . . . legend has it that one bloke used to do a final clean up with a wheelbarrow and shovel.
The point I was making is that in the "old days" this was how it was done and in these days of motor scrapers the "deep and steep" design philosophy has been compromised some what . . . those batters were no problem to a crawler tractor and scoop/scraper.
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Trust this old stuff I dig up continues to be of interest.
Notice those tractors (TD24's?) are scoop and ripper rigs only, they are not set up for blades.
Cheers.