Surface Contour Issue After Applying Hide Boundary

[Hatam_Nazem]

Hello,

I’ve created a proposed site surface starting at elevation 50 m with a 1V:2.5H slope down to elevation 30 m (see Figure 1). The lower area is flat at El. 30 m, and the contours display correctly (Figure 2). However, after applying a hide boundary (Figure 3), the contour lines appear distorted or irregular where the boundary affects the surface (Figure 4).

My question is:
Is there a way to ignore or exclude the influence of those triangle-shaped areas caused by the hide boundary, especially in specific regions?

Thank you for your help.

Best regards,

Figure 1

figure 2

Figure 3

figure 4

    

[ChrisRS · Accepted solution]

Civil 3D has difficulty stylizing contours on level areas that are at a contour elevation.

The troublesome lines you see are contour lines at 30.000 or 50.000 
They are in an ambiguous area.

I would use a workaround to eliminate the totally level areas 

Raising the elevation of the central 30.00 feature line creates a slight vertical arch, eliminating the totally flat area.  Adding a slightly elevated feature line to the 50 area does the same thing.

Contours are displayed as expected for these slightly sloped areas.

(A modified drawing file is attached.)

Good Luck. 

[Hatam_Nazem]

Thank you Chris for your help