i’m on a job that involves building a deck around a 24′ above ground pool.  BUT because the yard sloped, approx 55″ in that 24′, about half the pool is surrounded by the excavation.  Although tapered, it’s steep.  Aside from having to hand dig 10 holes 10″ from the pool in a trench that is just wide enough to walk sideways through, there are piers that will be on the steep part of the excavation.  Because of a 10′ set back, I was not able to widen the deck surrounding the pool to clear the hole. 

I’m worried about the piers sliding.  , so I’m going to dig and dig and get the part of the pier below virgin soil.  Frost is still an issue.  (Here in Pittsburgh it’s 36″, I usually go 40″ – 42″).    The article on helical piers in FHB sounds like something that would have worked here. 

Any thoughts on lateral stability of piers.  IS depth in undisturbed soil my best bet?  The soil is clay.  I can post pictures tomorrow after work.  Concrete is schedule for Tuesday next week?

Thanks.