Drainage, drainage, drainage. Make sure you take run off into consideration. Water pressure builds up behind terrace walls and can destroy all your hard work if you aren't careful. Also remember to leave room at top of walls for mulch and water to pool slightly before draining.

Notice the weep holes(actually one more is just out of frame to right) in this picture which shows how water is removed from upper tiers and released to driveway without erosion. Cheap plastic pipe can be used for this quite easily.
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Are there weep holes on each level? Would you have the plastic pipes for each level to the next level, or could we use the piping to drain off all the way from the top to the bottom (we have a creek at the bottom)? I hope that makes sense.
Thanks Vroomp!

i have dry stacked stone wall terraces. We put the 4" plastic drainage pipe behind the top of the wall and it all goes into a six inch pipe that goes into the creek. As my walls are dry stacked water can seep through if it needs to. Vroomp, beautiful terraces!!!

Pam, love this topic! Could you post some pictures and give more info about this slope - size, degree of slope, what you'd like to use the area for??

Looking forward to hearing more on this.

Rosie in Sugar Hill

No need to weep each upper level as you can pipe excess directly to the lowest level or out to drain field. I like to minimize the amout of hardware actually visible, so lights are hidden behind bushes for backlighting and drains are hidden as well.

I like to put a couple surface drains on each level with sreen type inlets just at mulch level so excess is collected and never overflows to next level down.

Always make sure you have lots of gravel around each pipe and aginst the back of retaining walls to minimize pressure from heavy rains as soil becomes saturated.

Just remember, every gallon of water trapped behind a wall exerts another 8 pounds of force against the wall so keep drains at bottom of all walls and ensure drainage to pipes flows eaily without blockage.

I use landscape fabric on top of the gravel bed I place around drain pipes to keep silt from clogging the gravel over time. And those surface drains come in handy when you have a clog as you can simply shove a garden hose with a high pressure nozzle down them to un-clog pipes below without digging anything up.

Thanks for the great advice! This is sounding like a big project already. We started talking about trying to level out some areas in our backyard for play areas for our kids. I'd also like to have a sitting area/patio, and some gardening beds. It's going to take a lot of planning. We haven't measured the area for slope or anything, yet, so we truly are in the infancy stages. I'll try to do that and post some pictures soon, and maybe y'all can tell me if I'm crazy!
Pam