Yes, subject to the City's height limits for walls and fences, which vary depending on the location of the fence and retaining wall in the property (e.g., front yard, side yard, rear yard). The combined total height of the fence and the retaining wall cannot exceed the allowed maximum height, measured per Richmond Municipal Code Section 15.04.103.050 - Measuring Height Subsection C. Measuring Height of Fences or Walls.