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.
No. OG is fairly flat and if anything drops off lower from the inlet at about 0.2%
Yes I need to slope the entire spiderweb of a basin about 0.5% down so that all the water will drain to the discharge at elevation 368.55. Now it does not have to be exactly .5% I kind of figured I'd work out from the discharge a half percent north and south on the first (nearest) legs then continue on the remaining three legs.
Given that geometry I'd create some flowlines down the middle of each finger, all sloping from the outlet at 5%. Then I would apply gradings to the flowlines outward at some slope to make a nice pan for the fingers and make a target surface for the sides of the pond.
Thanks for the feedback Joe.
Thinking about it a bit more I realized that it would be better to not apply any gradings to the flowlines at all. Instead just grade from the top of the pond down to the relative elevation target and add the flowlines and infills for the bottom. That way all the parameters are met. Of course this will result in variable slopes between the bottom edges of the pond and the flowlines. The flowlines can be tweaked to compensate for excessive slopes.
For ponds I almost always use a dummy surface graded in all directions towards the outfall. In other words I set an elevation at my outfall and have a grading object that goes in all directions at the desired grade.
I then grade down to this surface with my pond top.
When we have a trickle channel say at point .5%, I will run a feature along the bottom then grade away from it at 2% well past extents of the pond.
Hope that helps.
Thanks,
Conan Witzel
Conan. I ike that idea. Now how can I grade in all directions as you state. Have you seen my attached image and what I'm being asked to create?
Neil when you say "add the flowlines" Do you mean add featurelines and re-grade them in the infill? I'm asking because all the ponds I have done to date have been simple rectangular with flat bottoms.
Yes, If you use featurelines and have them in the same site they will automatically influence the grading infill and you should see the contours adjust to the flowlines as you change their slopes or elevations. Don't extend the flowlines to touch the bottom of the pond edge or it will create closed areas. Leave a good sized gap from the ends and one infill should cover the entire pond bottom and you'll have a nice pan all around the ends of the flowlines..
Here is a file for you to look at (2013 format)
Also a DWF for those who can't open the file. Rename Pond Model.dwg to .dwfx
Cwitzel. I see. Also yes a circle can be a featureline. Run mapclean and go to cleanup methods and select "circle to polyline" then convert that new polyline into a featureline and there you have it.
Thanks
I didn't know about that function in MapClean. One Kudo for you!
Yep! Same here. Did not know that one!
I will do that once and keep it in a block on tool palette.
Thanks,
Conan Witzel
Ok new problem. I did the graded pond bottom as directed but now as I go to grade the top rim down to the new surface it is not an available surface in my create grading tools set the target surface. Everything is in the same site. My pond bottom surface was created from the grading group.
I'm thinking I have some site issues as I have about a half dozen sites I'm dealing with.
Mark Green
Working on Civil 3D in Canada
I usually have the pond bottom on its own site. You don't want it to interact with the other feature lines.