A system and method for erecting a temporary retainer in a trench

A system and a method for erecting a temporary retainer in a trench comprising: a rigid frame 110 comprising mounting means 120 for mounting rigid sheets 500, 510 for forming the temporary retainer when braced, on opposite edges of the frame so that the sheets extend at least below the frame; hanging means 130 coupled to the frame, for hanging one or more retainer braces 310 below the frame; wherein the one or more retainer braces are configured to be placed in a bracing configuration or a non-bracing configuration, wherein the bracing configuration maintains a determined separation between the rigid sheets when the rigid sheets are braced within a trench; wherein the frame comprises lifting means to enable lifting of the mounted rigid sheets and the one or more retainer braces in the non-bracing configuration together. The braces and frames may be expandable, the braces may press against waler beams 320 and the frame may have legs.