A sheet for use in ground works, the sheet having an upper face with an plurality of openings therein, a lower face configured so as to permit liquid to drain through the sheet and a spacing arrangement to separate the upper face from the lower face and define a volume therebetween, where the volume is capable of receiving an infill material via the openings in the upper face. The lower face of the sheet is configured to be interengageably secured to an upper face of a similar further sheet.