I'm running 2 100 amp 110 lines 35 yards from my well house main to a sub panel in my garage. Do I need to run a ground wire and a neutral wire or can I just run one of them from the sub panel to a ground rod? If I run the ground to a grounding rod, do I disconnect the green screw in the sub panel?
You'll have to run four conductors, two ungrounded (hot) conductors, one grounded (neutral), and one grounding (earth) conductor.
At the garage you'll have to install a grounding electrode (ground rod, etc.), and bond the panel and grounding conductor from the feeder to it.
You'll then have to isolate the grounded (neutral) bus bar and conductors, from the grounding bus bar, conductors, and panel.