Building New Retaining Walls
Most competitors advise having a 20 cm wide gravel drainage layer running the full height of the wall behind it (apart from a clay cap on top) In practice this is very tedious, costly, and unnecessary. At most, a 20 cm gravel or coarse sand layer on top of the discharge pipe is recommended if the soil has a high clay content. By placing lengths of Capiphon™ against the wall will pick up any water as it moves towards the wall.
If a serious challenge from water coming, not from the surface but from an underground source, is feared a Capiphon™ pipe can be inserted into the discharge pipe.
The presence of expansive or reactive soils is often quoted as the reason to use a gravel drainage layer. There should not be a problem with the more thorough capillary drainage afforded by Capiphon™ given that
the head pressure of the soil water will exert much more pressure than that exerted by the "reactive soil"
the expansion rate of a reactive soil is approximately proportional to water content of the soil
Hundreds of retaining walls have been drained using Capiphon™. In most cases the trenches have been backfilled only with sand at bottom to cover the collecting pipe as protection before backfilling with existing soil materials.
Draining Existing Retaining Walls
If circumstances allow smaller walls can be excavated by machine or manually to replace blocked conventional drainage with Capiphon™, or to install new Capiphon™ drainage if there is none. Alternatively, Capiphon™ pipe can be inserted into horizontal shafts drilled into the retaining wall. This is a particularly useful technique where the structure of the wall is damaged or would be further compromised by excavation.
Serious Alternative to Ag Pipe
Ag pipe is also called aggie, agricultural pipe, ag line etc. Capiphon also out-performs slotted pipe.