Domestic water well separation from UG utility primary?

[fastline]

Working in a tight area and need to get a UG primary extended for another transformer. There is a domestic water well right smack in the way. Can curve around it, but curious what typical separation is? The well case is plastic.

 

[qcroanoke]

Working in a tight area and need to get a UG primary extended for another transformer. There is a domestic water well right smack in the way. Can curve around it, but curious what typical separation is? The well case is plastic.

Is this a poco primary? Is It a service lateral? or feeding the poco xfmr?
What's the voltage?