Retaining Wall and Lawn Plumbing

[localhost]

I have an older home with a series of retaining walls. The house was recently re-plumbed with pex. I'd like to run a 3/4" line to the lower side of the property. How should this be properly done when there are retaining walls?

Currently there is one 3/4" line which runs over the retaining walls and terminates in a spigot. The pipe is insulated with foam wrap, which is unsightly. How do the pros put the lines in the ground behind the wall when the wall is pre-existing construction?

[DanG]

They would be dug down under the retaining walls. This may be a good project to discuss with a local company that does directional boring. There would be minimum disruption of lawn and other property.