new well

I have a shallow well with a jetpump. If I want t have a new deep well drilled in the future can they drill it on the same spot or does it need to be drilled a certain footage away from the old well?
I live on an island and they told me that thy need to drill a minimum of 500 ft because of salt water intrusion.

Ron

The driller in that area that told you about having to drill 500', whould be the best one to tell you how far from the shallow well. Is that Woodrow Sapp Drilling you are using? If so they should know.