Showing Areas of cut/fill below a certain elevation

[Anonymous]

Hello. I have two surfaces, a proposed and an existing. What I need to show are the areas where the proposed surface is higher than the existing surface and areas where the proposed surface is lower than the existing surface, but only in areas where the existing surface is already below the base flood elevation. The base flood elevation in the area is 13.00.  For example, if the proposed surface was 14 and the existing surface was 13.5, I would not need to show that area as being fill in the floodplain. But if the existing surface is below 13.00, I need to show that area as being cut if the proposed surface is lower (does not matter how much lower) or fill if the proposed surface is higher (does not matter how much higher). Is there an easy way to do this in Civil 3D without having to hover my mouse over the surface and manually check what the surface elevations are? The end goal is to have two separate hatched areas and call them out in the sheet legend as one hatch pattern being proposed cut in the floodplain and the other hatch pattern to be proposed fill in the floodplain.

Thank you.

[AllenJessup]

I think it can be done by creating a Volume Surface and using Elevation Banding. You may have to set some of the ranges to a No_Plot color.

[ChrisRS]

1. you need to make a base Flood elevation surface (BFE).
   This can be a flat surface at 13, or a sloping surface base on various BFE's or contours.
   It does not need to follow the flood plain delineation, just be wider that your area of interest.
2. Use "MinimumDistanceBetweenSurfaces", selecting EXISTING and BFE surfaces. This will give you 3D polylines alone the edge of the flood plain. Edit as necessary to get a closed polyline.
3. Create a Tin Volume surface (CUT-FILL) using EXISTING and PROPOSED surfaces. Stylize CUT-FILL as desired.
4. Add the polyline created in step 2 as an outer boundary to the CUT-FILL surface. The will trim it the floodway limts.

Good luck!

[rstewartBDDFE]

I'm currently performing the same procedure in Civil 3D in which I created three surfaces

1) EG Surface

2) PG Surface

3) Flood Plain Elevation Surface

My end goal is to determine the cumulative cut & fill volume below the Flood plain surface, and I'm using the method described above. One question that I have is on the tool "Minimum Distance Between Surfaces" I would like to know when I set this as the boundary that the cut and fill volume will not be computed above this boundary, the second question is I would like to know if the "minimum distance between surface" tool represents the floodplain surface?

Thank you!