Excavation means the mechanical removal of earth material.
Excavation zone means the volume containing the tank system and backfill material bounded by the ground surface, walls, and floor of the pit and trenches into which the UST system is placed at the time of installation.
Excavate or "excavation" means ditching, dredging, or mechanized removal of earth, soil or rock.
Excavation work means the making of any man-made cavity, trench, pit or depression formed by cutting, digging or scooping;
Water surface elevation means the height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929, the North American Vertical Datum (NAVD) of 1988, or other datum, where specified, of floods of various magnitudes and frequencies in the floodplains of riverine areas.