Buried Pipe Pressure Question

[JohnDH]

As an EE, my CE training was minimal (understatement). That said, I need to have some work done in my front yard where a very heavy bucket truck/man-lifter will need to be parked directly over a buried 4 inch sanitary sewer pipe. I don't remember the truck's exact weight, but I do recall that it's at last 20 tons. The pipe in question is buried roughly 10 feet deep, and it's somewhat fragile due to earlier work where a Fernco rubber coupler was used to convert from old 4 inch cast iron to modern plastic pipe. So the question is.... will the pressure created by the bucket truck be fully dissipated at the depth of 10 feet -- that is, is there no danger to the buried pipe? Or will there still be significant pressure such that I should find another method, one not involving such a heavy truck? I realize that much of this will have to do with the specifics of our soil. I wish I could say more, but all I know is we are not in a rocky area, we don't have much clay -- more or less an average east coast (mid-atlantic) soil condition (if there is such a thing).

Thanks for any opinion on this....

John

 

[cvg]

at ten feet deep, there should be very little effect from live load regardless of the type of east coast soil you have. the truck may create deep ruts in your yard. have them drive onto wood planking if you have it. that will spread the load out even more.

 

[JohnDH]

Thanks for this information -- what you said is certainly good news! I spoke to the contractor about all this just this morning, and he advised me that his truck is lighter than I had recalled -- he said it weighs 9 tons. And even at that weight, he said he takes great care to cover the lawn with wood to avoid ruts from the truck tires as well as from the stabilizing legs, etc. It sounds like we can go ahead with my job..... Thanks again.

 

[Okiryu]

Considering that the pressure's influence depth is a function of the size of the loaded area, you should have problems at 10 feet depth. Tire sizes are small to make huge impact at that depth.