Re: Trench depth
0" IF UNDER A BUILDING
4" IF UNDER 4" OR MORE OF CONCRETE (NOT A ROADWAY)
12" IF BELOW 2" OF CONCRETE OR EQUIVALANT
24" UNDER SREETS ETC.
18" IF UNDER 1 OR 2 FAMILY DRIVEWAY
18" UNDER AIRPORT RUNWAYS
18" IF NOTHING ABOVE APPLIES (ACROSS A LAWN ETC.)