Question of compaction...........

Greetings to all....

First off, what a wonderful board!

OK, here is my situation:
We are placing an 12x24x54 AG into the ground. The earth will be tapered, so no side contact or back filling will exist...free standing within the hole. We had the excavator come out and we requested the hole be 3 feet deep, allowing us two feet exposed for tiered decking. Well, the dig ended up hitting the 4 foot mark at one end and the other is about 3'6". That sucks for me.

OK, back up and punt...not a giant issue with respect to deck, we can make changes at this point easily. I do not however care to have my finished floor at 4 feet of depth but, if we have to...well then we have to.

Using a plate compactor, can I reasonably compact the earth enough on my low side. My ground is heavy clay (west coast) and I would at least like to bring the low side up 4 inches and cut the high side down to come to a happy medium. If the risk is too much, then we shall deal with this depth but, we want to exhaust our options.

Bob-

Bob,

A plate compactor may not be the best option. A "jumping jack" type compactor will compact pretty thoroughly especially if you fill in layers....about 4" per layer. Much deeper than that and it loses some effectiveness as well.

Thank You. I actually imagined the Jumping Jack but called it a plate...duh. Another question:
I have thoroughly wetted the existing bottom, shall each new compaction be wetted thoroughly also and how long should I wait between compactions?

Bob-

Question(s):
1. How will you be dealing with the water buildup around the outside of your pool that will collect there every rainfall? (mosquito breeding ground and probably not very good for the life of the pool)
2. Where on the east coast - will you incurr freezing/frost? If so, your pool WILL heave because the saturated clay from above will expand drastically.

Now back to your questions...

You should not have any issues compacting the filled in clay, I had my grade for the pool raised 2 feet, let that sit over the winter to settle, then got final grading done in spring. I also used about 4" of screenings as a sub base for the wall, compacted these screenings with a gas plate compactor and it never moved or settled at all.
The compactor will do a good enough job, remember that the pressure a full pool exerts on one square inch is less than 2 pounds or about 270lbs/sq foot, that's less than a person standing on the same ground/sq ft.

Quote:

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Originally Posted by matt4x4

Question(s):
1. How will you be dealing with the water buildup around the outside of your pool that will collect there every rainfall? (mosquito breeding ground and probably not very good for the life of the pool)
2. Where on the east coast - will you incurr freezing/frost? If so, your pool WILL heave because the saturated clay from above will expand drastically.

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With respect to water buildup around the pool, I am grading the dirt away from the pool edge at the base and placing speed drains around the perimeter and feeding into a collection box. The bare earth will be treated with mortar to reduce errosion. The water will be removed via pump and sent into my seasonal creek. Yes, this is somewhat of a hassle but, for where the pool is being placed, worth it.

Living where we do, we have no frost heave. The temperature here on the central coast of Caliornia today is 101. Nice temperature to be working in a hot hole.

Bob-

Thanks Bob, just wanted to be sure all caveats are covered!

Thank You Matt, I do appreciate your concerns....this is why I love this board.

Bob-