The shed itself is a Keter Apex 8x6 (8 feet wide, 6 feet deep). It's a walk-in with floor structure included. Their set up instructions only called for "leveling the dirt" before assembling in place.
So this is about a BETTER ground pad. It's quite standard in construction but often misunderstood or made over-complex. The sloping ground only means that a retaining wall (RW for short) is needed. And if the RW is less than three feet tall, it's considered non-structural as a "garden wall" in most building codes that you can build any way you want. On the other hand, if your RW is three feet or taller, better call an engineer because special reinforcements may be necessary.
Relative Cost (remember this is only about the ground pad, not the shed):
Low to Average
DIY Manpower Needed:
Two strong men (or women! — but just to lift the heavy plate vibrator onto and off of transport)
Special Tools Needed:
Zip Level or water level
Step 1: Plan and Calculate
First thing was calculating the height of the retaining wall. I located the corners of the future shed for a rough visual (in my head, of how it fits). Measure the lowest point with the ZipLevel. Then subtract the highest finish (future) grade at the upslope side. It helps to know (or plan for) the upslope side, too. I'm planning a low-walled raised planter there. So my tiny RW is primarily to protect the side of the shed rather than hold any surcharge of wet dirt.
Step 2: Shed Kit Transportation
Step 3: Prepare for the RW
Step 4: Concrete Footing
Step 5: Crushed Granite
Remove form board (off the concrete) after a few days. It doesn't hurt to compact dry the dirt pad first (with the plate vibrator! why not). Crushed granite is then shoveled in, raked leveled and compacted in thin layers with intermittent water spray. The ZipLevel comes in very handy for quick checks.
This is actually easy work for two guys — one operating the heavy plate vibrator, the other shoveling, raking and checking spots.
Step 6: Flush and Level
Step 7: Retaining Wall
Step 8: Assemble the Shed Floor
Step 9: Ready for Storage
One important next project will be the "landing" area in front because storage stuff needs to roll in and out, and that curb on the left dropping to a sloping ground is still very unresolved — winter rains would cause erosion if unfinished. Gophers or moles also attack the soft soils here.