lateral soil pressure on casing
 

lateral soil pressure on casing
our contractor wants to use a single-wall 48" hdpe pipe for a wet well casing as part of a fire pump system. the pipe will extend vertically to 30 feet below grade. my concern is the lateral earth pressure on the hdpe pipe. is it reasonable to assume that the pipe will see the active earth pressure at 30 feet or is 48" not enough to cause soil failure? i want to tell the contractor to use double-walled corrugated poly pipe but i have to justify it.