PERFORATED PIPE
Perforated pipes are available in 53.9mm to 400mm and are supplied in single socketed 6 metre lengths only. Perforated pipes are normally used in French drain applications, draining rainfall from paved or concreted areas such as roads, car parks, airfields etc. The camber of the paved or concreted area runs rainfall into the permeable fill above the perforated pipe. Highway drainage systems for example usually include French drains on both sides of the carriageway and in the central reservation.

PERFORATED RIGID PIPES
INSTALLATION OF PERFORATED RIGID PIPES AS A FRENCH DRAIN

• Install Perforated Pipes as other Brett Martin pipes but use a selected permeable fill as bedding, sidefill and backfill material, Figure 34.
• Do not compact the bedfill.

FIGURE 34
FRENCH DRAIN



SEPTIC TANK LEACH PIPE INSTALLATION USING PERFORATED RIGID PIPES

Brett Martin Perforated Pipes may be used to dispose of septic tank effluent by sub-surface irrigation.

• Lay pipes in trenches with a uniform gradient not steeper than 1:200 from the septic tank outlet.

• Install unperforated Brett Martin pipe with a fall of 1:30 for the first 3 metres. Installing an Inspection Chamber at this point will make it easier to monitor land drainage.

• Lay the pipes on, and surround them with a 150mm layer of clinker, clean gravel or broken stone 20mm - 50mm grade. Consult the septic tank manufacturer for advice on whether to position the perforations upwards or downwards in the trench.

• Place a layer of polythene sheet over the perforated pipe before backfilling.

• Do not use pipes manufactured in accordance with BS4962 for disposing of septic tank effluent.

A herringbone pattern is commonly used (see Figure 35). A percolation test is carried out to determine the area of land needed for effluent disposal.

FIGURE 35
SEPTIC TANK INSTALLATION SHOWING HERRINGBONE LAYOUT OF PIPES



SOLVENT CEMENT JOINTING
To ensure a permanent solvent cement join, the following procedure should be followed:

1. When a solvent joint involves a pipe, the pipe end must be cut square and all burrs and rough edges removed.

2. Clean both surfaces to be joined, making sure they are free from dirt, grease and water.

3. With a clean brush apply Brett Martin solvent cleaner.

4. Again, with a clean brush apply Brett Martin solvent cement to both surfaces to be joined: apply the solvent cement along the surface, not around it.



5. Immediately insert the coated pipe end or fitting spigot into the coated fitting socket, using a slight twist motion to ensure correct spread of adhesive and removal of air bubbles. If cemented surfaces are left unjoined for longer than 90 seconds, bonding will not be totally effective.



6. Hold the joint still for 30 seconds for initial bonding to take place; wipe off excess solvent cement: leave for a further 2 hours to gain strength. Do not test for at least 24 hours.

Do not thin solvent cement or solvent cement filler. As these cements are solvent based it is essential to observe the normal precautions for solvents.


CONNECTION TO UNDERGROUND DRAINAGE
Connection to PVCu drain socket.

It is possible to connect the 110mm Soil Stack to a PVC underground drainage system: where this is of greater diameter, an adaptor must be used.



Connection to PVCu drain spigot.

With no ground floor connection, the socket should be above F.F.L. to help prevent rubbish entering the drain



Connection to cast iron drain socket.