• FINAL BACKFILL          : SDecompressed area of soil
                                     (cross-sections are excluded)

• INITIAL BACKFILL : Sall solid materials are removed. Decompressed area of soil.

• BEDDING LAYER     : Decompressed area of sand

Ho    : Distance between the ground to the top of the pipe
b         : Width of the trench (mm)
Y         : Height of the bedding layer (mm)
DN      : Pipe outside diameter (mm)

* Ho has to be minimum 50 cm.

The Width of the Trench: taking the ground properties into the consideration, the amount of material used for filling and assembling can not be larger than the area that needs to be filling.

<200                           for       600MM
200<D<600                for       D+400 MM
600<D<1200              for       D+500 MM

Base of Trench: The pipe has to be placed into the ground neatly and in a stable position. The base of trench has to be cleaned from any sharp materials, if it is necessary the ground can be filled with small soft particles such as soil and sand. When the ground requisites are appropriate in order to lay the pipes a 120° degrees bedding is recommended. The material that is going to cover the pipe the 10cm of it should not contain any hard or sharp particles.