Abstract: An excavation wall retaining assembly for use during repairs of damaged, earth ground-embedded fluid pipes, comprising: a first series of lowermost walls, vertically installed at the periphery of the lower section of an excavation made in the ground about the fluid pipes; feet releasably supporting the first series of walls spacedly above the flooring defined by the excavation; at least a second series of upper walls, vertically installed edgewisely over the first series of walls, supportingly by the latter. Jacks provide releasable, adjustable, compressive biasing forces against the walls so as to retain the latter in vertical position against caving in of surrounding earth. The wall retaining assembly is dismantleable and all of its structural elements are fully retrievable after use, from the bottom up or from top to bottom.