ngneer,
I incorrectly assumed when you referenced the contractor your query was primarily premised on field work. However in reading the Bobpe's post, I understand your query to be more fundamental. As I understand it, you are referencing the profile drawings and the stationing and a method through which the contractor will understand.
Your stationing will involve two considerations:
1) Real Ground Distances (chainage)
2) Sewer Pipe Length (Profile Distances)
The real ground is important because that is how your legal evidence is posted. All the reference locations, centrelines, offsets and Fd.I's will be premised on this evidence. This will also be the reference for the contractor and the surveyors.
The sewer profiles drawings will show the actual (laid) pipe length (in profile). These lengths are important for the estimates and quantity takeoffs. It is also important to note that these lengths will never, ever match the surface profile distances, and should never be used as the reference for stationing.
Your plan/profile design drawings should show the surface stationing of the sewer pipe and appurtenance locations, in whatever stationing methodology you wish to choose. The profiles will either show the pipe referenced to the surface stationing (manhole tie-ins, etc.) or will be plotted as an actual length. In most cases, due to the different vertical and horizontal scaling, the pipe will be plotted and shown as being longer than the surface stationing.
In my experience, most contractors prefer the cleaner plan/profiles where the pipe is plotted in prfile to coincide with the surface stationing and are knowledgable to know that they cannot "scale" the profile pipe for quantities. In this instance, the calculated pipe lengths and proposed grade should be shown on the drawing.
I hope this clarifies this for you.
KRS Services