If groundwater from a contaminated plume is pumped out using strategically placed wells to contain the contamination. What options do you have to dispose of the pumped groundwater?
Most often you do not "cart the water off" to dispose - it is treated (hence the name "above ground treatment")
How it is treated depends on what's in it. Volatiles (like hydrocarbons) can often be driven off with heat and/or low pressure ...
Discusses briefly, ex-situ treatment technologies for contaminated groundwater