Prepare the Bed for Pipelaying
Before beginning any pipelaying project, it is essential to ensure that the bed is correctly prepared. This involves creating a level and correctly aligned surface for the pipes to sit on. The bed should be created using pea shingle, which should be spread evenly and compacted to ensure a stable foundation for the pipes. Once the bed is prepared, the pipes can be laid, with the joints lubricated and the pipes connected. It is important to ensure that the pipes are laid to the correct gradient, as this will affect the flow of water. When the pipes are laid and connected, the trench should be backfilled and protected from damage.
Joining Plain-Ended Pipes
Joining plain-ended pipes is a simple process. First, lubricate the end of the pipe or fitting and the coupling, then slide the coupling onto the pipe or fitting. Grease the receiving end of the coupling and the next pipe or fitting and slide them together. Make sure the joint is secure and watertight by tightening the coupling with a spanner. If a ring seal is used, spigot or coupling must be lubricated and the pipes brought together with gentle force. To ensure a good seal, check the pipes are not twisted or misaligned and that the seal is properly seated. Finally, test the joint for any leaks.
Connecting Ring-seal Plasticware
Ring-seal plasticware is a popular choice for connecting pipes in underground drainage systems. To join the pipes, the spigot or coupling must be lubricated and the pipes brought together with gentle force. This type of connection is quick and easy to make and is suitable for most plastic pipes. Before connecting the pipes, it is important to check that the pipes are the correct size and that the ends are chamfered. This will ensure a secure and watertight connection. It is also important to ensure that the pipe is pushed in as far as possible and that the seal is not damaged in any way. Once the pipes have been connected, the joint should be tested for leaks and any necessary adjustments made.
4. Solvent-Weld Connections for Plasticware
Solvent-weld connections are the most reliable way to join plastic pipes. The pipes and fittings must be clean and free from any dust, dirt or debris. Apply a solvent-weld adhesive to the end of the pipe and the socket of the fitting. Push the pipe into the fitting until it is fully seated and hold for a few seconds. The joint will be secure and watertight. Take care when applying solvent-weld adhesive, wear gloves and ensure the area is well ventilated. Make sure to follow the manufacturer’s instructions when using solvent-weld adhesive. Check the joint after a few minutes to ensure it is secure. If not, remove and re-apply the adhesive.
Joining Socketed Clayware
Socketed clayware is joined using either an ‘O’ ring or a mortar joint. An ‘O’ ring joint is made by lubricating the joint and pushing the pipe fully into the socket. A mortar joint is made by packing mortar into the socket and pushing the pipe in. Both methods require the pipe to be pushed in with gentle force. It is important to ensure that the pipe is pushed in evenly so there is a secure joint. If the pipe is not pushed in evenly, it may result in a weak joint or water leakage. It is also important to ensure that the pipe is pushed in far enough so that it is flush with the socket. If the pipe is not pushed in far enough, it may lead to water leakage.
Cutting Pipes for Installation
Cutting pipes is an important step in the installation process, and requires different tools depending on the material. Plastic pipes can be cut with an angle grinder, while clayware requires a power cut-off saw or a pipe-cutting tool. It’s essential that the cut is square to the rest of the pipes or fitting, as an uneven cut may cause a leak. Always take safety precautions when using power tools, such as wearing protective eyewear and gloves. It’s also important to ensure that all swarf, dirt or grit is removed from the end of the pipe after cutting.
7. Safety Considerations When Working in Trenches
Working in trenches can be hazardous, so it’s important to take the necessary safety precautions. Wear protective clothing such as a hard hat, safety glasses, and sturdy boots. Make sure that the trench is properly shored up and that there is a banksman or buddy with you to help with the work. Keep at least one metre away from the edge of the trench at all times. If the trench is deeper than 1.2m, it must be shored up with timber or other materials. Make sure that all tools and equipment are in good working order and that you are familiar with their use. Use ladders or steps to access the trench and avoid standing on the sides of the trench.
Digging the Trench for Underground Drainage
Digging the trench for underground drainage is an important step in the installation process. The trench must be wide enough to accommodate the pipes and must have a gradient of 1:100 for surface water drainage and 1:40 (1:80 if WC connected) for foul water drainage. The trench should also be shored up if it is deeper than 1.2m. A laser level can be used to check levels and gradient. The trench should be dug and prepared before the pipes are laid. It is important to take safety precautions when digging the trench, such as wearing protective clothing and having a banksman/buddy with you. Care should also be taken to avoid damaging any existing underground services.
9. Checking Levels/Gradient
It is important to check levels and gradient when installing underground drainage. A laser level should be used to check levels and gradient, with a minimum gradient required of 1:100 for surface water drainage and 1:40 (or 1:80 if WC connected) for foul water drainage. To ensure good flow, the trench should be dug to the correct depth, width and gradient. It is also important to ensure that the pipes are laid at the correct angle to ensure that the water flows in the right direction. If the gradient is too shallow, the water may not flow correctly and could cause blockages and flooding. If the gradient is too steep, the water may flow too quickly and cause erosion of the pipe.
Lubricating and Connecting Pipes
When connecting pipes, it is important to lubricate the ends to ensure a secure fit. This is especially important for plain-ended pipes, which rely on couplings to join pipes and fittings. Before beginning to joint the pipes, ensure that all ends are chamfered where needed. For Ring-seal plasticware, the spigot or coupling should be lubricated and the pipes brought together with gentle force. For Solvent Weld systems, follow the manufacturer’s jointing instructions and use the correct solvents and adhesives. Socketed clayware may use either an ‘O’ ring or a mortar joint for jointing. Once the pipes and fittings are in place, the joint must be tested for watertightness.
Sealing Joints for Watertightness
When installing underground drainage it is essential to ensure that all joints are watertight. This can be achieved by using sealant or cement. Sealant is usually applied to the joint before the pipes are fitted together and then allowed to dry. Cement is applied after the pipes are fitted together, and the joint is wiped clean of any excess. Both methods should be used in conjunction with lubricant to ensure a good seal. It is also important to make sure that the joint is not over-tightened as this can cause the joint to become brittle and prone to cracking. If the joint is not watertight, it can cause serious damage to the surrounding area and lead to costly repairs.
Installing Gullies to Collect Water
Gullies are an essential part of any drainage system, as they collect water at a low point and divert it into a drain. Installing a gully is a relatively straightforward process, but it must be done correctly to ensure it functions properly. Firstly, the gully should be laid in the trench, ensuring that it is level and that the fall of the pipe is correct. The gully should then be connected to the pipe using either a flexible coupling or a solvent weld connection. Finally, the gully should be backfilled with a layer of granular material and protected with a layer of concrete, paving slabs or similar. Taking the time to properly install a gully will help ensure that your drainage system functions as it should and will help prevent any water from pooling in low areas.
Selecting and Purchasing Materials
When selecting materials for installing a drainage pipe, it’s important to consider the type of pipe needed, the environment it will be used in, and the cost. Clayware pipes and fittings are strong and less likely to deform when buried. Plastic pipes are lighter and easier to handle, but have a smaller range of fittings. For underground drainage, uPVC, concrete, vitrified clay, cast iron, GRP and asbestos pipes are all suitable. It’s also important to purchase the necessary tools and accessories, such as a hacksaw, angle grinder, power cut-off saw, pipe-cutting tool, lubricant, sealant, cement, pea shingle, adjustable bends, and silicone grease. Ensure that all materials are of good quality and fit for purpose, and that any necessary safety equipment is also sourced.
Backfilling and Protecting Pipes
Once the pipes have been laid and connected, the trench must be backfilled with selected fill or granular material. No stones larger than 40mm, no clay clumps larger than 100mm and no frozen material should be used. To protect the pipes from damage, a layer of concrete, paving slabs or similar should be placed over them, with a minimum 75mm cushioning layer of granular material between. The bedding and sidefill should be compacted to ensure the pipes are not displaced by movement. Finally, the surface should be reinstated and the area made safe.
Testing the Drain for Leaks
Leak testing is an important step in the installation of underground drainage pipes. It helps to ensure that the system is watertight and will not cause any damage or disruption to the surrounding area. Leak testing can be done with a variety of methods, such as using water pressure or dye tests. When testing with water pressure, the pipes are filled with water and the pressure is increased to a specified level. If there are any leaks, they will become apparent when the pressure is released. Dye tests involve placing a fluorescent dye into the pipes and then checking for the presence of the dye in the surrounding area. If any dye is found, it indicates a leak. It is important to test all drainage installations for leaks before backfilling the trench.
