Underground installation – Install PVC pipes underground in a trench. Trenches should be excavated to the required size to allow for the size of pipe and enough space for jointing, compaction and inspection. The depth of the trench must be sufficient to allow for the minimum required cover over the PVC pipe. (Refer AS/NZS2032-2006 Installation of Pipe Systems Table 5.1). Note the trench should be kept free of water as much as possible. Narrow trenches can be permitted in cases when access to the trench is not necessary.
Other important considerations are anchorage when it may be required as per AS/NZS2566.2. Encasement in concrete may be required, when this is the case precautionary measure must be taken to prevent movement, flotation or deformation of PVC pipe installs when pouring concrete. The floor of the trench is designed to provide a suitable foundation. engineering advice should be sought on how to provide a suitable foundation.
When excavating the trench, the trench floor should be inspected so that loose debris from rocks or other loose areas so that the PVC pipe or fitting or other structure will not be affected from differential surface settlement. Bedding material shall be placed and raked in to add support for the PVC pipe along the whole length of the barrel. (For further information refer to AS/NZS 2032 5.3.8.) Prevention of flotation of the PVC pipe from groundwater must be prevented. Use of trench stops, filling material sufficiently, or filling the pipeline with water are some methods used to prevent flotation.
PVC Pipe jointed with solvent cements should only be placed into the trench once the joint has ample strength to handle the load required. For our solvent cement application process, click here
PVC Pipe should be placed along the centre of the trench. Install PVC pipe slightly bent to allow a pipeline to go in a curved direction. Where bending the PVC pipe is not suitable, bends, moulded fittings or suitable sockets should be used.
Trench fill material should be laid onto the PVC pipe embedment and compacted appropriately to fill the trench. Marking tape if installed should be placed on the top of the embedment section.
