Ground leveling, fill material, very hard soil with many rocks. Ideas appreciated.

[Kurt/Shelley]

Hello everyone. In the process of landscaping our back yard and adding a 15' above ground on a slope. The low area needs to come up about 5" to 6", the ground where we are at is very hard red dirt/clay and rocks, and more rocks. In internet researching and discussing with our local landscape material supply yard, they recommended a darker fill material about 4" deep and 2" of a sandy loam on top. Well 4" on the high side is almost 9" on the low. Digging the high area is not really an option, so as seen on this site we would build a retaining wall with wood to level the area. Would using 4"x 4" wood set on some what leveled area held in place with metal rods pounded into the ground be strong enough to hold back the dirt and support the pool? If we went this way, what is the recommended fill material below the sand?
Any ideas / advice / recommendations greatly appreciated.
Thank you, Kurt

 

[ike0069]

Why could a bobcat or small loader not dig down to the low spot? You level with the loader and use 1/2" sand to smooth. Seems like that would be way easier than what you are proposing.

 

[Kurt/Shelley]

We had that done to a certain point, took out about 8" on the high side and were running into to many large rocks and clay. The loader couldn't scrape down any further.

 

[duraleigh]

Yeah, 4x4's should work. There is little lateral load on the backfill.

I would use pea gravel for the fill. Rake it smooth and then put styrofoam boards on top of it. No compacting needed.

 

[Kurt/Shelley]

Thanks. How thick should the pea gravel be on the high side? Would 2" work? That would be about 8" on the low side.

 

[duraleigh]

I think 2" on the high side is just about right. You could pinch it down to less but it will likely be harder to get nice and level.