Pneumatic drills were developed in response to the needs of mining, quarrying, excavating, and tunneling. Foreign products have been found at archaeological sites excavating tombs in southern China. As of January 2019, archaeologists working on HS2 are excavating approximately 40,000 burials. Bulldozers, drills, explosives and trucks are all necessary for excavating the land. Common methods of extracting the iron ore consist of blasting, drilling, or general excavating. Dredging is the operation of excavating material from a water environment (sometimes temporarily created). Turkish archaeologists have been excavating Side since 1947 and intermittently continue to do so. The German Archaeological Institute, Cairo is excavating at Buto since the early 1980s. A Polish archaeological team has been excavating the town since 1964. Woolley had finished his work excavating the Royal Tombs of UR in 1934. The team leader, David Krause, had been excavating fossils from the site since 1993. It was discovered by excavating three sinkholes in an extensive project. It spends large amounts of time on the forest floor excavating wasp nests. The University of Pennsylvania began excavating Sumerian Nippur in 1888. His family had owned a contracting and excavating company in Frederick, Maryland.