Ohlman has core drilling contractors. Core drilling is an activity in which a cylindrical portion of metal is removed. Such drills are used for pipes, manholes, and other large-diameter penetrations in concrete or stone. They can also be used to remove and preserve core samples. The power source may differ, such as electric, pneumatic, hydraulic etc. A contractor is a professional responsible for the overseeing of a project on a daily or regular basis. They may specialize in providing particular services, such as core drilling. Core drilling is done for mineral and natural gas exploration, as a study before full-scale drilling is carried out. You should try to pick a reliable, cost-effective service which uses advanced machinery.