Cinder Block Retaining Wall Question

Hello Everyone,
I am planning build two successive retaining walls 2' high (4' from bottom of footer to top of the wall), and approximately 38' long. The horizontal distance between the two walls will be approximately three feet, with a step of 2' from the top of the bottom wall to the top of the top wall, thus forming a small 3' planting terrace in between. The total drop from top to bottom will be 4'.
I live in Southern California, so there is no frost line or threat of freezing. The soil at 2' feet below grade is a composite of hard clay/ virgin rotted sandstone. Both walls will be holding back a flat grade. The newly formed terrace was previously a rounded/sloped mass of unsupported earth, which was luckily only 4' high. The area above the top wall runs flat to the back of the lot. Permitting is only required for walls that are greater than 4' in height in my area.
My plan was to dig down to 2' below grade for each wall and pour a concrete footer that is 8" in depth and 2' wide. I was planning on using standard 8x8x16 cinder blocks for the wall itself. Based on this, roughly two courses of cinder block would be below ground, while another three would be above (yielding an exposed height of 2' for each wall).
I am going to use rebar to tie the retaining wall to the footer, as well as to provide lateral support through bond beam block running the length of the wall. I will also fill and cap all blocks with solid concrete. Both walls will be water proofed, be back filled with gravel (covered with filter fabric to prevent clogging) and have a sloped perforated drainage pipe leading water away from the wall.
The reason I have decided to build in this manner, rather than using a pre-cast concrete dry stacking system, is that I plan, for aesthetic reasons, to face the above ground sections of both walls with flagstone veneer.
I have a few questions about this setup.
1.    Do you think the placement of the top wall in proximity the bottom wall would present any structural issues? If so, should I reduce the size and depth of the footer in the top wall, thus reducing overall weight? 2.    Do I have to worry about moisture with regard to the underground courses of cinderblock? If so, should I raise the footer? 3.    Given that I am building a French drain, would I even need any weep holes in the wall?
I am trying to build the most stable structure possible, but am worried that I might be going into overkill mode. Any suggestions on my questions above, or better way to build a similar type wall while still allowing me to face with flagstone veneer would be very much appreciated.
Naveen
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You should be able to find a standard plan for such a wall. Years ago I got one from our city building inspector. It showed details for a walls up to 4 feet high and up to 8 feet high.
Since your 3-foot setback from a 2-foot rise is within the one 1-1/2 to 1 angle of repose of ordinary soils, I would expect no special requirement for either of the two low walls.
Not sure about the details of your french drain but if water can accumulate behind the wall it must have an outlet -- usually weep holes. A pipe drain could work if properly detailed as to slope and outfall point.
SJF
You mention clayey soils which may not permit drainage by normal percolation. A french drain would seem to imply the use of weep holes.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It sounds good to me. You might consider turning back a "dead man" made of block and bond beam at each end and one at mid point to make the structure even stronger.
(top posted for your convenience) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Warning: nitpick ahead.
Cinder blocks haven't been made for years. Concrete blocks are what you're referring to.
-Tim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks for all of the responses.
I thought cinder blocks were the cheaper blocks (the rough sandy surface) pressed into mold forms, available at any big box hardware retailers for about $1 a piece. Whereas concrete blocks were actual concrete poured into a similar form and fully cured - this being stronger and more expensive. I could be mistaken.
Here are are my thoughts to the various responses
1 .Segmental Block Wall - I thought about using something like this at first when planning the project, but cannot find any that meet our aesthetic needs. The house is essentially modern in design, and most of the segmental block wall systems lend themselves to a farm house/country appearance.
2. French Drain - I meant a pipe drain - it's the same thing by a different name. I plan to use this as a means to move water away from the back of the wall, along with backfilled gravel for percolation. The question is whether adding equally spaced weep holes along the bottom of the wall is redundant or still necessary. I suppose since I plan to face the wall with flagtone using mortar, using maximum drainage is the best thing.
3. Dead Man - I thought about this as well. I suppose it couldn't hurt, and since I am planing to do the work myself it should not be too much to ask for. I have seen deadmen discussed for timber retaining walls, but am not quite sure how this would be accomplished using block. Would I flip and build the bond beam blocks perpendicular to the wall, and then mortar succesive blocks to form a line back into the earth?
One other issue I failed to mention is that my property is at the bottom of a hillside. While the grade from the top wall is flat running 40 feet back (20 into the adjacent property behind the line) and then rises to a moderately steep hill, on which my neighbor's house is built upon. During the 40 year flood in Los Angeles we had last year I was told (I just bought this house) that the hillside became saturated. This led to some degree of flooding in all basements and garages along my side of the street. The one thing I am worried about is the shifting and heaving (aside from the hillside actually coming down) of clay under such wet conditions. Should I consider buidling the footing with a key, to help prevent shifting?
In any case, my next door neighbor has two terraced block retaining walls of similar design and greater height that look that they have been standing for 30 odd years. There are no visible cracks or bulges, and are retaining a moderately sloped hillside. If I use this as a guide, I suppose if I design the wall preoperly, there should not be any issues, given my lesser requirements.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
- naveenreddy_la -

- Nehmo - Read This First. Retaining Walls, Means and Methods https://courseware.vt.edu/users/mikev/public/CE5074/qpr/P19part1.pdf
And consider a segmental block wall http://www.versa-lok.com/contractor/cInstallationr.htm
--
|||||||||||||||| Nehmo Sergheyev ||||||||||||||||


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.