Restoring the moisture content of soils by rehydration

The great majority of damage caused to buildings in the southern half of Great Britain is as a result of clay shrinkage caused by desiccation. In cases where damage has already occurred the prevention of further damage and the correction of existing damage can be effected by addressing the moisture content of the soils directly. This is a patented process known as Soil Moisture Management and this company enjoys sole rights to the process throughout Great Britain. In broad terms it ensures that the moisture content of a body of soil is kept within acceptable limits regardless of external influences. If the soil moisture content falls below a predetermined level then the process utilises rehydration of the soil by the introduction of water through a mechanism that will stop when the required moisture content has been achieved. If soil is rehydrated without regard for this equilibrium figure then enormous damage can be caused to any nearby buildings. It should not be attempted without a full understanding of the processes involved.

In cases where the cause of the desiccation is tree root encroachment, the process must be used in conjunction with management of the offending tree. Removal of the tree is not always required, but control of its root arrangement is an essential part of the process.

In broad terms the rehydration process involves the introduction of water into the body of the soil. A network of probes is inserted into the soil and connected to a water supply. Rehydration takes place to a pre-arranged sequence and for a given period. As the various parts of the soil mass come up to their correct level, the uptake of moisture is reduced and when equilibrium has been achieved the system is switched off. In instances where the problem might occur again the system is left live, but in a state where the supply of water will only be restarted if the soil begins to suffer desiccation.

At present the process is only used on particular types of problem, but where it is used the results can be spectacular. In one case where the willow trees which had caused the subsidence were removed, closure of about 20 mm was achieved within 3 months.