Retaining Wall Against Fence . Starting at the lowest part and working one layer at a time until reaching a full contiguous line. Dust and fallen leaves etc. We like the clean lines of this privacy fence and retaining wall. The from www.pinterest.com The whole garden was lined with a thick black plastic. It may also be placed for the utility of protecting against the collapse of land and as such be placed in a location which most strategically serves this purpose. Some instances where this might be used include: