The excavatability of an earth (rock and regolith) material is a measure of the material to be excavated (dug) with conventional excavation equipment such as a bulldozer with rippers, backhoe, scraper and other grading equipment. Materials that cannot be excavated with conventional excavation equipment are said to be non-rippable. Such material typically requires pre-blasting or use of percussion hammers or chisels to facilitate excavation. The excavatability or rippability of earth materials is evaluated typically by an engineering geophysicist or geotechnical engineer, often in conjunction with a seismic refraction survey.