Underground PVC pipe

[haynewp]

I am working on a building with that will have 40" dia schedule 40 PVC pipes running below the slab to bring air in from an outside ahu. The top of these ducts will be 5' below finished floor. Even if I design my slab to span over the ducts, I am still concerned about the weight of the soil on the PVC. Is there a table that is used to indicate allowable placement depths of these types of air ducts?

 

[gerrytt]

Didn't I read this post in "foundation engineering," refer to Asshto, section on pipe culverts