In general, the following three types of materials can be used as backfill materials for HDPE Drainage Pipes;
The first category: 5-40mm angular stone, including a large number of locally accessible materials such as coral, crushed slag, gravel and broken shells;
The second category: coarse sand and gravel with a maximum diameter of 40 mm, including different grades of sand or gravel containing a small amount of powder, generally granular and non-sticky, may be wet or dry;
The third category: excellent sand and clay gravel, including fine sand, sticky sand and clay gravel mixture.
Under normal circumstances, the corner and initial backfill requirements should be at least 90%. The tamping layer should be at least 150mm from the top of the Large Diameter HDPE Water Supply Pipe. Direct tamping should be avoided for less than 300mm from the top of the pipe.
