We have a handle-type shut off in the ground (dug out hole with cover over it) outside our barn. Even when fully shut off water is dribbling out of the interior faucet. Handle is on PVC pipe. Is there a gasket or something in there or does the entire thing have to be replaced?

Try shutting it on/off a few more times. It could just be some sediment got caught up and is interferring with full shut down.

If that fails to resolve the issue then you will need to replace the entire shutoff... no orings, etc... ;)

Mark