How to build a yurt platform - part 5

After the drain rock fiasco, I decided to get some gravel delivered instead. I ordered 5 yards this time, inch-and-a-quarter crushed rock. In this pic, a chunk has already been taken out of the right side:

After the rock was delivered, I tried working it in to a hole:

1. Clean any loose dirt and mud out that has fallen in to the hole.
   
2. Shovel gravel in to wheelbarrow.
   
3. Pour in to hole, but not too much.
   
4. Tamp with a 4" x 4" post.
   
5. Tamp a little more with 10" x 10" tamper.
   
6. Go to #2

The first hole I did was small (18" x 18" x 12"), and dry. The second one had a lot of mud in it and was bigger (2' diameter x 2' deep).  There are 30 holes total.

Muddy hole, needs cleaning.

Clean, with first lift of rock, ready for tamping.

My inlaws came to visit, so we put them to work, too. 4 adults working together, rotating between cleaning holes, loading gravel in to the wheelbarrow, and tamping.

After 2 days, we had rock in 1/2 the holes but not full enough. We were exhausted and our wrists hurt. Everyone was grumpy, and the road ahead looked too long. I decided to find a power tamper.

The rental place I usually go to had 4 small tampers, and 2 big ones. (The other rental places had 0!). It's a heavy beast, and it took 2 of us to move it from hole to hole. But it was amazing at pounding the rock in to the ground. We were able to take bigger lifts, and in the end the gravel was pretty hard and flat on the surface.

The machine wasn't easier than tamping by hand, but it was sure faster, maybe 10x faster. 

The original plan was to excavate to the frost depth (12") or hard, undisturbed soil, whichever was greater (the soft ground was never more than 12" deep). Then fill with 4" of coarse gravel for a stable base, and 4" of finer gravel (3/4" minus) for a smoother surface. But now, with the much bigger holes and the really powerful tamper, we ended up bringing the coarse gravel to 4-6" below grade, tamped smooth.

We used almost the whole 5 yards of gravel. The big pile became a small lump.

Once the coarse gravel was in, we added just a thin layer of the fine gravel to each hole. We figured we didn't need much, since the coarse gravel had tamped to such a smooth surface.

Now we were roughly back where we started, having excavated 30 holes and then filled them in again. Costs to get back to grade level:

- shovel $30
- digging bar $40
- 12" auger rental $60? (forgot)
- 24" auger / Dingo rental $200
- tamper rental $60
- 5 yard load of gravel $125

With all that done, I now believe it was unnecessary. At a minimum, we could have just placed the pier blocks directly on the ground. Topsoil was already gone. For a little more, we could have hand-dug just the looser soil, and only as far as it was easy to dig, and something smaller than 18" square. Not much gravel buying/hauling/tamping required.

Next up, placing pier blocks.