Looking at a residence with several hundred feet between the 12 wells and the building. I'm an EE not the HVAC person, but was asked anyhow. [Client thinks engineers know everything...] It seems to me that either the inlet and outlet to the field manifolds should be as isolated as possible. The pipe installers were talking vertical separation, i.e. inbound at 5ft depth, backfill to 3ft and lay outbound. I wondered about using say 8-10 thick sheets of styrofoam from wall to wall of the trench atop the lower for better separation. We could use separate ditches instead, with ~5 ft. separation between them. Any writeups on either approach I should read?