Drafting - Stationing a manhole on the inside of a tangent-tangent intersection 2

[ShafeW]

I've been drafting and engineering a long time, so I feel like I should know this, but for the life of me I can't remember how to handle this situation. (I did try to search Google and these fora.)

I have an offroad sanitary sewer running in an easement that follows a sidelot property line. The PL takes a roughly 90° bend at one point. I've set a baseline along the PL, which creates a tan-tan PI at that bend. The sanitary sewer runs parallel to the baseline, offset from it, and the sewer includes a manhole to make the turn. Because it's on the inside of the bend, the manhole could be stationed from the approaching leg of the intersection 12+42.50 or the departing leg at 12+77.50. In plan view, no big deal, I can station off the approaching limb, end of story. But in my profile, stationed per the baseline, it's a different story. The manhole would appear in the profile at both 12+42.50 and 12+77.50 (and all points in between?) So how should this be drawn?
[ul]
[li]One thought was to move the baseline to follow the sewer line itself, eliminating any offsets so the manhole is exactly at the PI, but I'm not a fan of that method.[/li]
[li]Another is to leave the baseline as-is, show the manhole in the profile at 12+42.50 with the outgoing pipe only shown in end-view, then show the same manhole again at 12+77.50 with an end view of the incoming pipe. There would appear to be two manholes with a 35' gap between them, but in reality, it would be two views of the same manhole.[/li]
[li]Perhaps the best is to place the manhole in the profile at 12+42.50, and the outgoing pipe would stretch all the way to the next manhole, appearing 35' longer than it actually is.[/li]
[li]Lastly, I could split this into two separate baselines with two separate profiles, in which case the manhole is shown on each.[/li]
[/ul]
Any other thoughts or ways you've seen it done? I can sketch it out if that helps.

 

[Pinwards]

If the sewer is the primary focus of the plan then I would move your alignment to follow the sewer, like your first suggestion and just include ties or offsets to the property line for helping locate the sewer.

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[FacEngrPE]

I like the elevation following the centerline of the sewer, and where bends and turns in the sewer exist treating the turn as a "fold". In the sheetmetal world this is called a strechout view (Shape before bending). These are style choices, all of them could be OK depending on the audience. Which one are the contractors in your area most likely to understand as you intend?

 

[ShafeW]

I appreciate the answers and I agree with you two that using the centerline of the sewer is simplest for representing the sewer. I have a couple hang ups owing to preference, such as I prefer my baseline to follow existing features in the field like roadway centerlines or property corners (as opposed to what will be an open trench, though I know offsets work both ways), or that I'm still left with stationing ambiguity for a waterline I'm running parallel to the sewer (though stationing is less of a concern for the waterline.) I'm still left wanting a good answer for the best way to station the manhole if I will not or cannot move the baseline to suit my convenience.

The question of what will the contractor understand is paramount, so my 2nd option above is likely most confusing, as it appears to include an extra manhole. I feel the 3rd option is suitable, since the manhole is locatable off the approaching leg of the baseline, and while the outgoing pipe would scale 35' too long in profile, the label would call the correct length and slope. (It's a whole other issue to figure out how to get Civil 3D to show it how I want it.)

I may be fussing too much over this, since I'm well aware the contractor will end up pulling the manhole location from the courtesy copy of our CAD file and locate the manhole however he prefers, no matter how I warn that the CAD file is not a contract document. Still, I want my sealed drawings to be complete, accurate and clear.

 

[fel3]

You could use two baselines, one (sewer) offset from the other (property line). You could then station both the property line and the sewer. I would station them differently to avoid confusion.

If you want to use just the property line as the baseline, then you could station the offset sewer using the property line stations, but with a station equation at the manhole at the 90°bend.

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