Best practice for creating survey drawings?

Short answer? The linework is almost always drawn using 2D figures rather than drawing 3D lines between the elevated points. (Or we use the FLATTEN command if we forget and draw the lines in 3D.)

Most drafting programs will dimension 3D linework correctly; I don't do it that often, but it is necessary from time to time, usually for some construction application, or sometimes if we do as-builts of pipes and need to show slope distance and grade.

But what if the 4 property corners (points) are different elevations.  Especially if drastic changes in elevations.

Boundary dimensions are expressed in the horizontal dimension only. Any inversing routine in your software will handle that. 

Using UTM zones, NAD83 or state planes

You are mixing apples and rutabagas thete.

UTM, state plane, and custom Low Distortion Projections are examples of projecting the ellipsoidal earth onto flat planes.

NAD83(with realization date) is a datum that locates points relative to a larger framework. 

A datum AND a projection are needed to locate points on a flat map.

But what if the 4 property corners (points) are different elevations.  Especially if drastic changes in elevations.

Boundary dimensions are expressed in the horizontal dimension only. Any inversing routine in your software will handle that. 

Understood.  Horizontal only.

So if for example the HORIZONTAL distance (dimension) states 100' between 2 property corners (points), but the ACTUAL "slope" distance is actually say 110', how is that typically shown to account for the actual slope distance?

Does a topo show this also in addition for the boundary lines?

I guess my point is when elevations and slopes need to be accounted for proper design when elements run along or follow the slope of the terrain?  May fall short when just relying on horizontal distances?

But, yes, I do follow you, plan drawings are shown as horizontal distances only using a standard projection and coordinate system such as UTM zone, NAD83 or state plane.

Does a topo show this also in addition for the boundary lines?

No, I've never seen a survey express boundary dimensions as slope distance.

Your mileage may vary...

So if for example the HORIZONTAL distance (dimension) states 100' between 2 property corners (points), but the ACTUAL "slope" distance is actually say 110', how is that typically shown to account for the actual slope distance?

Engineers aren't looking at the boundary in 3D. They (should) treat it as a "wall" polygon that occupies all elevations.

They're going to be looking at the TIN surface and improvement elevations to do their design, and because they are designing in a plane coordinate system (projection) they just need to make sure their design elements remain inside that "boundary wall".

It's also important to remember that this is possible because the projections we employ are conformal, meaning that shapes are preserved, and they are carefully chosen so that the element that is distorted by conformal projections - size - is affected as little as possible.

So what is typically provided and used when elevation data is needed for design work?  Topo 2D flat projection drawings with spot elevations? TIN files etc?

Thank you.

So what is typically provided and used when elevation data is needed for design work? 

Contours, generated by a surface model. Sometimes augmented with spot elevations at high points and depressions. 

In C3d the surface model is contained within the drawing file. With other software packages the surface model is a separate file. Frequently the surface model is delivered in the form of a LandXML file.     

Our surveys are always done on a plane surface, back in the day it was multiple planes created by each instrument set up. Every time the instrument was moved a new plane was surveyed on. 

These were such small discrepancies that they were ignored. Today we pick the plane we survey on and we project everything to it using GPS. We disregard the slope vs horizontal issue and do everything horizontally. Until we don't, but those are special cases. 

@dougie I agree that most distances for boundaries are reduced to A horizontal plane. State plane or ground etc.  However just in the last couple months I pulled a deed that was pre 1930’s. Done in poles.  It was slope distance or point to point along the surface. After doing a bit of research I found here the requirements to reduce distance to a hz plane was not adopted until later 1930’s. If I remember correctly many years ago doing some retracements of mine and mine shafts in Colorado some of that was slope especially the acreage. So never say never lol . But most states today usually require hz distance I assume.

plan drawings are shown as horizontal distances only using a standard projection and coordinate system such as UTM zone, NAD83 or state plane.

Frequently a local coordinate system is created with an arbitrary local origin and basis of bearings. Commonly such a system employs 5000,5000 (or similar) as the beginning coordinate and designates some tied boundary line as having a particular bearing, per some survey of record. Things are not always done on an agency datum.   

Using UTM zones, NAD83 or state planes.

NAD83 is a datum. UTM and State Plane are projections of that datum. A projection is a manner of expressing positions of the datum in cartesian coordinates rather than latitude and longitude.   

I will long remember the problems I had switching from strictly 2-D data to 3-D data.  A certain line needed to be extended until it was of a certain length.  Drew a circle of the desired radius and then attempted to extend the line to the circle.  It couldn't be done.  After too much frustration, I realized why it couldn't be done.  (Slap to forehead)

I'm trying to remember from the pipeline work I'd done years ago.  I know the pipe lengths are recorded, and the pig is run through the pipe and is recording its distance traveled.  So, I'm thinking that might be something that's based on actual length run (slope) vs horz distance