I would dig a shallow hole and line it with lathe (wire mesh), and then concrete (a mix of mortor and portland cement). To get really elaborate, dig a trench and put in a drain (prior to cement). This might require a little bit of shovel work to bring the pool up a bit to allow for drainage. At the bottom of the pool have a female pipe adapter to screw a stand pipe into (unscrew to drain). Allow the cement to cure for a while before letting torts have it.
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Zoodude
1.1 Acrantophis dumerli
0.0.1 Morelia veridis
0.2 Bogertophis subocularis
1.0 Pogona henrylawsoni
0.1 Geochelone carbonaria
3.2.1 Phelsuma laticaudal laticauda
1.2.0 Morelia spilota mcdowelli