The allusion of the Caldwell zoo's savanna has tricked you David The elephants actually live in a small dusty paddock which is surrounded by a moat. Because of the clean sight lines it appears the elephants share the savanna with the Kudu and impala. Which unfortunately is not the case.
As for enrichment all I saw was a tire. And of course the pool and mud wallows are enrichment as well. In Dallas we have over head hay-bags, the strangler fig with different places to hide food, as well as direct contact with other species, a water fall, and dead fall/vertical logs (which I feel is an essential part of displaying African elephants).
