## Minimum Trench Width Calculation in the US for Various Pipe Materials

# How to Calculate the Minimum Trench Width for Vitrified Clay Pipes?

Trenches for Vitrified Clay Pipe (VCP) installation shall be excavated to a width that will provide adequate working space, but not more than the maximum design width, according to [ASTM C12-07].

There is no single formula that is applicable for __minimum trench__ width calculation for VCP. Trench width is **mainly** one factor to compute loads caused by backfilling to determine the supporting strength of VCP. The factors taken into consideration to determine the vertical external load on a closed conduit due to backfill materials (Marston Equation) are:

• Depth of backfill cover over the top of the pipe.

• __Width of trench__ measured at the level of the top of the pipe.

• Unit weight of backfill.

• Values for frictional characteristics of the backfill material.

Trench Width At Top Of Pipe (in) for GRAVELS (GW, GP, GM, GC) Kμ' = 0.165 | ||||||||||||||||

Diameter VCP [in] | 18 | 24 | 30 | 36 | 42 | 48 | 54 | 60 | 72 | 84 | 96 | 108 | 120 | 132 | 144 | |

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