The invention relates to a machine for scraping away sediment or the like deposited on the bottom of a gallery. The machine comprises: a first movable body suitable for moving over the bottom portion of the wall of the gallery; first movement means for moving said first movable body; scraper means for detaching sediment from the bottom; first buffer storage means mounted on said first movable body; first transfer means for transferring detached sediment into said first storage means; second transfer means for transferring sediment stored in said first buffer storage means to the outside of said first movable body; a second movable body; second movement means; and second storage means mounted on said second movable body to collect the transferred sediment.