Cheesy title? Indeed. The cheesier the better. You remember it that way.
So there are a few options for showing these types of pressure pipes and cover driven conduits in Civil 3D. The original workflow I proposed a few years ago had you using regular pipes- but tweaking your styles, making invisible structures, and using the pipe style cleanup. There are a few other ideas out there- like using projected feature lines, but a few months ago I found one that I really liked.
I had been playing around with the notion of using alignments and profiles as pipes in the past, especially for conceptual work. Sometimes, its just tough to get all of your rules to stack up and do what you want with pipe networks, and they aren't always as super flexible as you might like when you are sketching things out.
When working on a sanitary sewer retrofit project a few years ago, I came up with a alignment styles that looked like this:
Note that you can get true horizontal and vertical curves this way. You can add arrows to act as flow arrows. PI locations can be made to look like manholes, values, hydrants... And you can do the same thing with your profile styles (realizing that they aren't going to have the same BIM smarts as true pipes.)
Now, this is all great, but it's a bit cumbersome. What if there was a way to get that profile to follow (and with any luck respond to) the existing ground?
1. Create an assembly that is just a marked point placed at your cover (or desired invert), say 3 feet deep.
2. Create a corridor with your pipe alignment and the appropriate ground profile.
3. Extract a profile from that one marked point feature line in the corridor (Corridor>Utilities).
Note the profile is not dynamic to changes in the corridor (but the corridor can be rebuilt to reflect changes in the alignment and existing ground, which is key)- but it might get you thinking about some possibilities for other options for some of your design needs- like some of the dynamic feature line/alignment relationships, etc.
Consider what else you can do- pipe trenching corridors for preliminary volume calculations that help you decide which route is best, cover checks for when you run true pipe networks, and other applications that you need to edit in an easy, breezy way.
While I did use the idea of alignments and profiles as concept pipes for iterations on that forcemain project, I was not clever enough to come up with the marked point corridor idea. Credit there goes to my friends at Hazen and Sawyer.