I hate to be flipant but it seems like theres a lot of hipe over a simple 2 foot retaining wall going on here. I have bult many retaining walls up to 8 feet high with everything from rock to timbers and 2 feet just isnt that big. You dont need engeneers or anything. The Keystone type blocks that are designed for such a thing would work great. 6X6 tibers would also be great with "Deadmen" every 6 or 8 feet. A deadman is a timber layed under the actual load bearing surface that ties into the wall. Like a T in the wall. You lay down the first course of wall on well compacted gravel atleast 6 inches or more deep with a good drainage direction. Then you rebar that,or the next course with it, in to the ground with 3 or 4 foot rebar.You lay the deadmen perpandicular to the wall and 6 or 8 feet long. You spike rebar them in at the wall and under the parking pad. Add a course and offset the next set of deadmen. Rinse and repeat. Make sure its all well compacted. IF you want you can set each course of the wall bacl a half inch to create a backward lean into the load area. Make sure it drains and your in buisness. Railroad ties are lame and environmentally unsound. If you want to use 3/16 steel put Upright pipes in concrete every 2 feet and 4 to 5 feet deep. You can also create steel or wood deadmen to weld or bolt to the retaining wall. I would think 6x6 treated timbers would be better but if steel is cheaper for you and yop can weld then just make it bomb proof with 2 or 3" Posts in concrete and deadmen to prevent flex. Good luck, hope all goes well.

Can you see where your wall went? What was it made of? if cement blocks they could be cleaned up with chisel & hammer, I did mine after Northridge earthquake, much cheaper than hiring someone to come & haul them away & get a new wall. Of course I mixed cement in wheelbarrow & dad set the blocks. used rebar both in the blocks & across to strengthen it. In your case because it is a retaining wall you have to have a cement base. But if you could retrieve all your blocks you could cut the expense greatly. Might have retaining wall put in with chain link fence on top of it or wood as that would cut cost by probably 2/3 but you need to find out why earth is moving. I know of some swimming pools that have poorly built fences or no fences,just hedge & ground isn't moving just because of the pool. If the fill in your backyard is mostly sand that could cause problems. We have some areas out here in Ca. that are extremely unstable- guess you saw the beachside community that buried number of people few years back. People love a hillside house & every couple of yrs some slide down on top of other houses but they just fill it in & rebuild. Good Luck!

I think you already have a good plan. I wouldn't put fabric in the bottom, because it will be useless in my opinion. You didn't specify how deep your bed will be, and depth will dictate what kinds of perrenials you plant. I'd go at least 16", with the sand/compost/bark mixture. About 50% compost would work pretty good, I think. I recommend planting things so that any time of the year - something is flowering. Maybe...winter jasmine, forsythia (during cold season), and some type of evergreen like juniper, then some type of plants/flowers that will be in bloom during the warm months. Check the local extension office for suggested varieties for your zone, and they should have some free handouts on growing perrenials. EG Here is a link that might be useful: EG's garden blog

Hi Weedy, Thanks for the reply-- We currently don't even walk on the deck, the beams meeting at the outside-left corner have completely rotted away and not supported by the posts... I swear it's inertia and friction holding the thing up this point... I like your idea of having just two retaining walls and leveling out the area, the trouble is that the lowest spot in my yard is not quite as low as I'd like the area under the deck to be, meaning in order to water away from the house I'd have to either build a retaining wall there or build up a small mound to provide grade. This is why I was thinking of building retaining walls on 3 sides to box in the whole area under the deck while incorporating a set of steps into one of the walls (probably right side) to keep access. For the footings, I figured I needed to 4' lower then the lowest point around me, just wanted to hear another opinion... this a lot of digging!! Regarding posts and retaining walls... my idea was that the footprint of the deck is exactly the same as the retaining wall--so are you suggesting making the deck larger then the footprint of the retaining wall, meaning the posts are set "outside" of the retaining wall? or smaller? I wasn't really expecting to gain much by incorporating posts into the retaining wall, just trying to maximize my space under the deck for storage. Currently the deck is about even w/ the window on the right side, and off by only a couple of feet on the other, so expanding the deck parallel w/ the house could only grow by 2-3' before it starts to overhang the windows (I think it's 8' now, so it could grow to maybe 10')... I could certainly grow the deck perpendicular to the house, that might be the best option, that would also allow me have more of the deck in the sun which would be nice. I'm doing a a "hybrid DIY" on the build, I'll be hiring a family friend who is a professional carpenter, so I do have hourly costs associated with the build, but all the same I'd still rather spend more now to get a better build :) Ideally I'll be getting "serious" around July 1st, applying for the permits, taking down the old deck, etc...