LeitoGM,
Above Ground Piping - Any piping you can see, maintain or replace with out using a shovel to gain access. Piping in an open Trench is considered Above Ground.
Below Ground Piping - Any piping you need a shovel to gain access for maintenance or modification.
Submerged Piping - Any piping laying on the bottom of the ocean, a river, a lake or other body of water.
Note - Many cross country Pipelines may have one or all of the above, sometimes repeated many times over.
prognosis: Lead or Lag