Buried Concrete pipe under new concrete pad

[Kom3]

Hi,

I am installing a new concrete pad for heavy industrial equipment. Upon doing exploratory excavation, we discovered two 8" buried pipes at the location that spans across the entire future pad. One is made of plastic and the other is concrete. They are about 1 ft below the bottom of the future pad. My concern is the new concrete pad can surcharge the buried pipes or cause settlement that will shear the pipes below. Any suggestions on how to protect the pipes?

Regards

 

[DoubleStud]

draw 45 degree line from the pipe and span the pad the whole distance where 45 degree intersects. Put form void to make sure the slab spans and will not put pressure under the span.

 

[GC_Hopi]

If you can determine the pipe properties or assume conservative values then check the pipe for the increased pressures. Void forms as DoubleStud mentioned. Last option is to bridge the load over the pipe (encasement or concrete cap). For settlement you can check the pipe for anticipated settlement to see if it will accommodate it or install flexible coupling on the pipe to accommodate it.

 

[WARose]

You won't get much help based on the depth: The last time I looked, AASHTO mandates 2 feet of cover minimum (in most cases) before you can spread the load out via some sort of pressure distribution.

I'd see what kind of pressure you are superimposing on the pipe (and the resulting settlement) and see if the pipe can take it. You may want to get a civil involved. I've found they are typically faster at making those judgements than we are.