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INSTALLATION GUIDE
Omnidrain installation details are concise and are provided as general guidelines only.
Omnico recommend that references should be made to the appropriate Codes of Practice for Underground Drainage Systems.
New European Standards BS EN752: 1997 Drain and sewer systems outside buildings and BS EN 1610: 1998 Construction and testing of drains and sewers, have been introduced. These have replaced British Standards BS8301 (Code of Practice for Building Drainage).
TRENCH DETAIL AND BACKFILL MATERIAL
The trench should be constructed 300mm wider than the outside diameter of the pipe to be installed. Where the as dug material is suitable, the bottom of the trenches may be trimmed to form a pipe bed, this material can also be used as a sidefill and backfill. Imported granular backfill materials, such as pea shingle and used in accordance with the recommendations of BS5955 Part 6: 1980 Appendix A, having a nominal particle size not exceeding 10mm, should be used as required up to and over the crown of the pipe. When this has been achieved, as dug material can be replaced into the trench. Once 300mm of as dug material has been replaced into the trench, mechanical compaction can commence.
TESTING
Testing of all drainage installations should be carried out in accordance with the requirements of the appropriate approving authority, using either air or water testing. References should be made to current editions of Building Regulations (Approved Document'H') BSEN752: 1997 and BSEN 1610: 1998. Where drainage appears inside buildings BSEN12056 should also be consulted.
JOINTING
Pipe End Preparation
When cutting pipes ensure that all ends are chamfered and are free from swarf, grit and dirt.
Ring Seal Joints
The Omnidrain Ring Seal Joint acts as both a seal and expansion joint. The following sequence should be adhered to:
- Check that all ring seal sockets are properly located in their recessed position.
- Ensure spigots and ring seal sockets are dry, clean and free from grit and dirt.
- Lubricate all ring seal fittings. This will allow for a fast and efficient connection.
- Ensure all pipes and fittings are in the correct position.
- Insert pipe fully into the socket, then withdraw pipe by a minimum of 12mm. This will allow for expansion.
ADAPTORS
External rainwater Downpipes can be connected directly to a surface water drain or, depending on the design, via a gully trap to the underground drainage system.
The diameter of The Omnidrain 110mm PVC-U below ground drainage system is the same specification as 110mm above ground systems and therefore direct connection may be achieved without the use of an adaptor. Where rainwater pipes connect directly to a drain, a suitable reducer will be required as follows:
- RA1 110mm x 68mm Rainwater adaptor for Round downpipe.
- FRDS2 used in conjunction with the above adaptor for connection to 65mm Square Downpipe.
Connection to other materials such as Cast Iron, Supersleeve and Hepsleeve, is achieved by the use of a range of rigid and flexible couplings and Adaptors.
ACCESS AND RODDING POINTS
Access is very important on all installations for testing, inspection and removal of any blockage or debris. Rodding in both directions can be achieved by using a Mini-Access Chamber (MAC) or Polypropylene Inspection Chamber (PPIC) in conjunction with access fittings.
Rodding points are more usually used in storm water drainage systems where the rodding point is used at the head of the drain run connection to a chamber, and being no further than 22 metres away from the chamber. The rodding point should be enclosed in a concrete surround to provide support and to ensure that the rodding point does not become mislaid at ground level.
Rodding points are occasionally used on foul water drainage systems where they or sited at the head of a drain connecting for instance gullies to an inspection chamber. In any situation where rodding points are used, a manhole or inspection chamber should be incorporated downstream to allow for the removal of any debris.
INSPECTION CHAMBERS
Mini Access Chamber
A mini access chamber has a relatively narrow riser shaft, and is used for inspecting, clearing, and rodding a drain line.
The narrowness of the riser shaft permits limited clearing and rodding, because of the narrowness these chambers can only be used to a maximum depth to invert of 600mm. Any unused side connections should be sealed with a plain plug. Should bends be required to change direction, these should be sited directly at either the inlet or the outlet to the chamber. Side branches of the chamber should not be used to change direction, as a self-cleansing flow through the chamber cannot be guaranteed. Intermediate depths can be achieved by cutting a riser to the level required. The frame and cover should also be adjusted to suit the level of the adjacent ground and surrounded in a minimum 50mm of concrete.
Inspection Chambers
The larger diameter of the riser shafts of inspection chambers enables them to be installed to a maximum depth to invert of 1000mm. The chamber is installed on a suitable bed dependent on the quality of the trench and backfill material. Intermediate depths can be achieved by cutting a riser to the level required. Backfilling is continued up to approximately 50mm of the finished ground level.
The frame and cover is placed on a bed of concrete around the top of the uppermost shaft, and adjusted to the finished line.
Where an inspection chamber is used at a change of direction, bends should be connected directly to the main channel sockets. Side branches off the chamber should not be used to change direction, as a self cleansing flow through the chamber cannot be guaranteed.
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