Grading created weird spikes

[chlang]

Hello all,

   I am trying to create a grading in Civil3D 2012, for a stormwater pond design.  The sides have a 3:1 slope, and on one side the pond follows natural pre-existing contours, and on the other side there is a construted dam.  When I created the grading, the generated feature line has some crazy spikes that are >10000' high.  The slopes all look fine, it's just the feature line thats wacky, but it won't let me edit it because its part of a grading, and if I delete it, the pond goes too.  In the attached screen shot, the green suface is my existing ground, the blue is my pond, and the white is the problem feature line.  Can anyone tell me how to fix this?

[chlang]

Oh, one other oddity - isn't a grading supposed to actually cut away at an existing surface?  My ground was not cut where the pond is dug into it.

[dgordon]

Chlang,

a grading does not alter the existing surface in any way. 

One can however make a new surface and first paste the existing surface into it using the edit tools for surfaces and then paste the proposed surface into it creating a composite surface.

as for the wacky feature line let me ask you a couple questions.   Are you grading up from the bottom of the pond or down to the bottom of the pond.  

I any case, you might try weeding the initial feature line to see if that helps.

[chlang]

I was grading top down, because I knew the top of the bank contour for the existing ground. I did weeding on the line before I started - took out almost 60% of the points actually.  I don't know how much more I can take out before it starts to be too much.

[bv44com]

I was hoping you might still visit this site, I am grading a compost pad and pond and find that the proposed surface will not match the exisitng, but my alignment is well beyond the proposed edge, I did notice that the grading is off and on around the parameter. It seems the grading did not complete in this area, how do you twick this problem?