How to display a surface with very flat slopes?

[civilengineer83]

I have a drawing in which I have a rectangular landfill that goes up at a 3:1 slope for maybe 2-ft max before it turns into a very shallow 0.5% slope for drainage. Now because the site is small enough and the slope is so flat, I show maybe 2 contours for about 6-ft using 1's and 5's contouring and nothing but empty space in between. I took my top feature and graded it up at a 0.5% slope to a relative elevation of 5 just until it closed itself out with grading. In the plan view, it just looks weak and I have nothing in there to be able to represent whats going on. Obviously you know it's there, because you can see it in the cross-section, but nothing is showing up in the plan view and I'm afraid the client will not understand that it's actually there, but you can't see it....sounds shady.

All that being said, is there something anyone here may do to reveal what that plan view might look like to a very non-CAD savvy client? Because all he's going to see is blank space and wonder where the hell the surface is. I could hatch it, but we don't really use hatching to denote a surface unless it's a cartoon and these will eventually go out for permit. Any help in this area would be greatly appreciated!

[Anonymous]

Proposed spot grades in a 50 ft grid could be helpful to reveal a very flat surface.

[Joe-Bouza]

I concur with @Anonymous  

if a grid is more than desired geometric changes and midpoint.  

[cwr-pae · Accepted solution]

I concur with @Joe-Bouza and @Anonymous with the addition using a second surface to show 0.2' contorus over the top. Paste the design surface to a new surface and applying a style showing on 0.2 contours as minor contours and 1' contours as major, freeze the major 1' contours in the new style and plot the minor contours lighter than your minor contours in the main surface style. Add either an outer boundary or an outside mask to the new surface at about the top of slope (based on your general description extract a user contour at elevation 6.1 for this) on the sides to not show the 0.2 contours down the side slopes and label the 0.2 contours  on the crown. Now you have spot elevations and graphic representation.

[rl_jackson]

Here's and option for you, in this particular case I was doing a camber survey on the newly constructed second floor of in a warehouse building. So I did a surface analyses with a range. here I'm only playing with 0.18' of elevation change.

[n_bartholomew]

Perhaps display the break lines with the elevations on the vertices? There can't be that many if it is that flat?

Add supplementary surface slope arrows with the grade/slope shown??

[cwr-pae]

If you have access to a large scale color plotter or will be presenting it on screen, @rl_jackson 's color 'heat map' is great. This past summer I had to do an analysis of a problematic milled surface and produced heat maps with 1/4" elevation differences (0.0208').

[AllenJessup · Accepted solution]

@cwr-pae That beats me. Back in the days before EDMs and CAD. I had to shoot elevations on an asphalt area between buildings in a chemical plant. They wanted tight grading. We laid out a 20' grid with an instrument and tape. Then shot the points with a level. I plotted the elevations on grid paper and hand contoured the area at 0.2' minor and 1' major.

@civilengineer83 You could do something similar. Just keep reducing the contour interval until you think it shows enough contour lines for your client.  You wouldn't be changing the Surface. So you could even have the minor interval at 0.05' or less.

[civilengineer83]

@cwr-paeYes, I did use something like this. I created a copy of my surface and set the contour intervals to 0.2' and 1' minors and majors, respectively and just added a boundary where the tighter contours needed to start, added some slope labels for grade and also copied the break lines that make up the top portion and made them dashed and screened with a label to indicate the grade lines. All in all, hopefully this will work for the client. I mean in the end, they'll certainly tell me if doesn't, right? 😆 Thanks for your input!

[civilengineer83]

@AllenJessupYes, that approach did seem the most legitimate for what I was going for. Heat maps work great, but most of my clients absolutely hate color. Especially red.....red means bad ju-ju. So we don't do colors often, unless it's a cartoon for a proposal or it's needed for illustration purposes. I made a surface with 0.2'-1' contour levels and I think that'll suit the client fine. It gave me at least a couple of contours, which is better than the none I had before. I typically don't like to mix interval levels, but on this occasion I reckon it was merited. Thank you for your input.

[fcernst]

Directional surface slope arrows should always be shown on grading/drainage plans to show adequate drainage slope. That with the all the key grading spot elevations at grade breaks the contractor needs to hit would take care of it.

[Joe-Bouza]

... don't forget to put coordinates on those contours 😂

All Contours are lies...where have I heard this? 🤣