Challenging Grading Project

[randcdavidson]

I've been assigned to do this grading project and it is becoming a challenge at least for me at this point. What is needed is top of Pond set to OG elevations, down 3.5:1 to a relative elevation of 5' then bottom infill. So far so good.

Now they want the bottom to funnel into a drainage inlet which is set at 368.55. Then they want the remainder of the pond bottom to all slope towards this inlet at about 0.5%.

SO what I figure I'll do is grade down the top the 3.5:1 at 5 feet deep. Explode the grading and take the bottom feature line and insert a low point near the drain inlet at el 368.55. Then I'll use the set grade/slope between points command and slope this featureline out at 0.5 percent to the extreme corners of the pond. Once that is set I'll do an infill and create a surface I'll call "bottom". Next I'll re-grade the top down the 3.5:1 only this time I'll target the bottom surface then do an infill to get one single grading.

Sound like a good way to tackle this? Before you answer take a look at the attached image and see what kind of animal I'm up against.

[randcdavidson]

Reply to Troma. The pond bottom surface was created from the grading group properties. I was unaware that mattered?

[troma]

Sometimes I create a surface from a grading, other times I just create a grading with no surface. When you said you couldn't find it to target it just seemed like the first logical thing to check.
If you have the surface, it shouldn't matter how you got it. I'm not sure why you can't target it.

[Neilw_05]

I thought your objective was to grade from the top down to a relative elevation = -5'. Why do you need a separate bottom surface? All you need to do is add an infill after grading down at -5'.

[randcdavidson]

Well that was before they wanted the bottom to grade to the outfall. My objective is now to create the bottom surface with a set elevation at the outfall then grade out a half percent in all directions. Once that is complete the I must grade the top down at 3.5:1 to hit this newly created bottom surface. Thing is it's not showing up as an option in my target surfaces. I have included a pic of the bottom surface and what I have as a outfall area. What you will not see is the top of bank grading down yet.

[Neilw_05]

Ok, I think it would be better to just add flowlines to get the bottom to drain.

[cwitzel]

Make surde it is in a different grading group.  You may not be able to see the "target" surface, because it is being created by the grading group you are using.  That is another reason to keep them in different sites.

If that still doesn't work, don't have it create the surface automatically add the grading to a different surface.

Conan Witzel

[cwitzel]

Attached is an example drawing with the pond bottom surface and the pond top.

In this case graded at 2% using a feature line at the outfall and a grading object set to 250' @ 2%.  The top of the pond is then graded down to the pond bottom surface.  

In both cases the resultant feature lines are added manually to the surfaces (Pond Bottom and Proposed)  There are also two sites.

[randcdavidson]

Nice I'll try that out and see what kind of result I get. As you may have seen from my last image there is a "wall" where the outfall structure will be placed.  I have that to contend with as well.