Thank you Krisidious. None of those programs do what I need.

I do have to be exact, it is part of the Building Code.

I am trying to figure out site placement of a home and reduce the amount of retaining walls.

In the picture I attached, the green surface is the existing Topo. i need to slope everything towards the center of the shape, from that black line drawn on the topo. That line isn't on one plane, so it isn't a single contour line.

Manual doesn't work because there are probably a thousand points.

Is there a method or plugin to create a specific slope on a curving, irregular, line?

I have a topographic plan that I've imported into Sketchup.

I drew the lot boundaries with a 10' offset and projected them onto the topo.

I need to create a 2:1 or 3:1 slope towards the center of the site.

The best method would be something like a chamfer where I can specify the angle.

(I've already tried: Follow Me, 1001bit tools slope and it's version of follow-me, extruding and scaling the bottom face, and fredo6 roundcorner.)