Retaining wall blocks?
I need advice on retaining wall blocks (concrete).
As some of you know, a developer is using part of my backyard temporarily while they install a water retention vault adjacent to it. As part of the deal, they will be redoing my backyard, including installing some terraces with retaining blocks to better deal with a slope in my yard.
He is giving me the choice of 2 different style of block--both of which he has used on other developments in the area. I know nothing about blocks other than, when they are installed, they must be installed "right" so they don't collapse in future years.
How do I get more information? He sent me to go look at them, and asthetically, I like one style more than the other. The first style (my favorite aestetically) is a smaller block with 3 sizes that fit together. They appear to have a ridge in their top so that they interlock to some degree. But, the blocks themselves are not heavy. And, he said they have a maximum stacking height of 3 feet. The other style is heavier, trapezoidal shape about 7" tall and maybe 15" long on the face (didn't measure, just approximating). These are what I think of as typical retaining block. I am unsure the maximum height on these, but I do know they are higher than the tumbled piza (option 1). They don't appear to interlock--just flat tops and bottoms and so I think they stay in place due to their weight.
My soil has a lot of clay. In one area, there is a significant cut in the soil which has been there for 3 years with minimal (no) collapse.
How important is it, given this type of soil, to have a stout block wall? Will the lighter weight blocks work okay, assuming a proper install? Or, will I have trouble years down the line because the clay is heavier than they are?
Thank you in advance!