not sure on if they are very dependent upon their powerplant since lynette wants it to be permanently shut down :/ There is a possibility that they have their own reactor or something inside the vault, giving them power.
They have a reactor covering their basic supply.
Yet still, they also draw power from Gecko, as far as i know from Fallout 2. What reason would they have to keep the ghouls at Gecko and not eradicating them as possible threat/nasty inconvenience? (apart from being humane)
If you modify the plant with Gordon's holodisc, the ending for Gecko is being a slave town for VC.
The plant is really handy for them.
Anyway, i guess it's only logical that NCR will build the railway there, between raiders and mutants, to get a safe quick gold delivery. At last, New Reno don't trade Jet to NCR, but gold. Tandi don't get her wrinkled arms dirty. All the jet is being sold in northwest, where the workfolk needs to be controlled by chemical means, slaves included.
NCR gets the clean gold and can trade it to the Hoover Dam and whoever lives beyond the radioactive storms for ammo, technology and such stuff. Everyone in Wasteland is glad and happy.
But it's all empty talk, since miners are paid in Jet for hammering caps in FOnline. There's no gold in Redding and even if, it's a rare throwing and HtH item, nothing else. But then it should be called in the description "Redding, the main source for CAPS in the wasteland"