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I am involved in a project which consists on a 10 ft excavation to place 3 ft diameter pipe.
Anyone knows if there is an approach of computing the setback so the overexcavated soils do not become a surcharge for the excavation (excavated walls)?. I am not familiar with this.
Do a Culman analysis?
Make sure it’s at least 14 ft away (5 ft plus 10 cos 30). That’d be the active wedge plus 5 ft (phi of 30).
Not sure what else we can say?
Well, you can look at the OSHA stuff too.
fattdad gave a good distance estimate for a sheeted cut. However, if the excavation is not sheeted and you have an OSHA Type C soil, the minimum excavated slope is 1.5H:1V plus the 5’ setback for the spoils pile. 10’ at 1.5:1 = 15’ + 5’ = 20’ to spoils pile.