METHODS AND EQUIPMENT IN GENERAL , ARTIFICIAL WATER CANALS BARRAGES OR WEIRS , WATER-POWER PLANTS DRAINAGE; IRRIGATION; CLEANING OF SURFACE OF OPEN WATER ; ; ARTIFICIAL ISLANDS MOUNTED ON PILES OR LIKE SUPPORTS This subclass covers underground structures made by foundation engineering, i.e. involving disturbance of the ground surface. This subclass does not cover underground spaces, made by underground mining methods only, i.e. not involving disturbance of the ground surface, which are covered by subclass . INVESTIGATING, IMPROVING OR PRESERVING FOUNDATION SOIL OR ROCK , STRUCTURAL ELEMENTS AND TECHNIQUES THEREFOR Structural elements Placing; removing; placing and removing; accessories ; ; ; HANDLING MATERIALS EXCAVATIONS, MAKING EMBANKMENTS KEEPING DRY FOUNDATION SITES CAISSONS , FOUNDATIONS AS SUBSTRUCTURES; UNDERGROUND OR UNDERWATER STRUCTURES, RETAINING WALLS ; PROTECTING, TESTING, STRAIGHTENING, LIFTING, REPAIRING This subclass covers: primarily equipment for excavating or loosening earth or for moving loose earth; equipment for working similarly on other materials and similar equipment for loading or unloading materials. GENERAL WORKING METHODS HAND-OPERATED MACHINES OR APPARATUS FOR GENERAL USE MECHANICALLY-DRIVEN MACHINES OR APPARATUS FOR GENERAL USE OR THEIR SPECIAL DETAILS MACHINES FOR SPECIAL PURPOSES OR THEIR SPECIAL DETAILS EQUIPMENT FOR CONVEYING OR SEPARATING EXCAVATED MATERIAL GENERAL DETAILS