I have a split level house with two patios in the back yard against the house. The problem is the grade of my yard flows back to the house. When it rains heavly the lower level floods. My solution to this is to build two retaining walls around these patios and regrade the yard. My questions is: Using the Anchor blocks can i build the retaining wall on top of the patio with the back lip just over the edge of the slab? The walls are only 1'8" high and will be in a horse shoe shape with the open end against the house. I plan to anchor the bottem layer with two rebar stakes in each block.