Abstract: An excavation shoring system comprised of a modular support frame having longitudinal and lateral beam members provided with collar sleeve openings adapted to slidably receive vertical support pipes which in turn are provided with regularly spaced vertical openings for insertably receiving stop pins in setting vertical height adjustment retention of the longitudinal and lateral beam members of the support frame to accommodate an excavation pit depth when assembling the support frame for placement use in vertically holding shoring grids to retain the exposed earthen walls of an open pit, which shoring grids are in turn adapted to receive slidably inserted planks within the grid slot structure thereof in further providing additional retentive support for unstable soils.