swale grading

[CADmgrMike]

I am building a trail corridor where I need a swale between edge of trail and property line.

I have about 6' to design in, but the issue is the edge of trail profile and existing ground profile at property line are not consistently sloping the same direction.

Along with this, I need the swale needs to create holding areas so the water doesn't go into adjacent property or over the top of the trail.

The only way I've figured out how to try and do this is have a feature line for my swale centerline and target my trail corridor link both horizontally and vertically to this line. I then daylight from there at 2:1 to existing ground.

Designing this way means I have to edit my swale feature line in both horizontal and vertical direction, rebuild the corridor, look at contours, etc and try to figure out if I have holding areas. Mucho time consuming.

Is there a better way that I need to know about and learn??

Thanks

[sboon]

Trying to picture your typical section - you have a proposed elevation at the edge of the trail and an existing elevation at the property line.  You need to project down at 2/1 from both sides to the swale - correct?

I am thinking about LinkSlopesBetweenPoints for this.  It would create a meandering swale alignment to fit your criteria, and where the slopes don't intersect you're going to see it right away.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[CADmgrMike]

Pretty close.

I need 4:1 on the trail side and 2:1 for the daylight side.

Looking at the help for that subassembly, it uses a Mark Point for the outer daylight edge, and the Mark Point doesn't have any targets.

To further clarify, the swale attachment point to the trail and the outside daylight edge where the Mark Point would be are not parallel.

They both meander in and out.

Doesnt' that mean this method won't work, or am I missing something?

[sboon · Accepted solution]

Here's an example, to show how it's done.  From the shoulder of the road I use LinkOffsetOnSurface to place a MarkPoint.  This sub is targeted in the corridor to follow a polyline which represents my boundary.  Then I attach LinkSlopesBetweenPoints to the shoulder so that it can create the two intersecting links that form the swale.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[CADmgrMike]

Exactly what I needed! Thanks.

[Anonymous]

Im not sure if im posting this question in the right place but I'm fairly new to Civil 3D, but i have my existing surface all set up, i wanted to know if anyone can help me create a swale, what would be the detailed steps on doing that. 

thanks in advanced for your help 

[sboon]

The answer to your question is dependent on several design questions that you'll need to answer.  Is your swale attached to another design feature like an edge of road?  Are you grading a site, or just running a swale across an existing surface?  Does your swale have any design constraints - depth, width, minimum or maximum grade?  Do you want to force the flow in one direction, or do you just want a specified depth below existing surface, which might create ponding?

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[Anonymous]

thanks for the response! I have a 2 lot subdivision with a built existing surface. For the erosion control plan I just need to run a swale to the sediment control basin, no specified depth or width, i just need it to flow downhill to reach the sediment basin at the end of the site, I have attached a picture of how it should look per the drainage engineer's mark up but i did it manually by adding polylines with elevations to the surface but i would really appreciate if you told me the correct way to do it. I hope the picture describes what i'm trying to do a little better. thanks again 

[sboon]

Here's an example of how I would probably do it.  I started by drawing in a couple of featurelines to approximate the horizontal geometry.  Then I used the editing tools to set them lower than the existing ground around them, except at the two end points where the swale daylights.  I created two grading objects on either side, sloped at 2/1 to the existing surface. 

If you look closely you'll see that I missed in a few areas; some parts of my swales are above the existing ground and slope the wrong way.  It would be easy enough to tweak them until they flow as they should.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[Anonymous]

Okay so i attached the drawing and if you can just look to see if that looks fine i would really appreciate it. I added the swale as a feature line and made it a foot lower than the EG as you suggested and graded 2:1 to the sides. My last question is if i wanted that to show as my proposed surface, would i make a copy of the Existing Surface and add the grading and feature line to it as breaklines in order for the contours to reflect the 1 foot lower swale?

[sboon]

You can create a surface from the grading group, if you haven't already done that.  Rather than copy EG you're better off to create a new empty surface then paste in the EG and the grading surfaces to that.  Doing it this way will mean that any changes to the two source surfaces will be reflected in the final FG surface.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[Anonymous]

thank you that's perfect!