Structural modular interconnectable subsoil drainage cell

A structural module comprising:

• a first and a second substantially parallel generally planar member retained in a fixed spaced relationship from each other by a plurality of spacers extending between the first and second planar members, the module having side edges extending between perimeters of the first and second planar members and wherein each planar member defines an ordered array of apertures;
• male interlocking means which are integral with the module projecting from at least a first one of the side edges;
• female interlocking means defined in at least a second of the side edges adapted to receive a male interlocking means so that two modules can be secured together in side edge to side edge relation;
• characterised in that the size and configuration of the male locking means relative to the size and configuration of the apertures, is such that a first module may also be inter-engaged with a second module, with the first module oriented generally normally to the second module with a side edge of the first module abutting a planar member of the second module and with each male locking means defined along said side edge of the first member extending into one of the apertures defined in one of the planar members in a close or interference type fit with the aperture.