Abstract: Disclosed is an extended shaft collar comprising a reinforced concrete collar which extends from the surface to below a groundwater formation, providing an impenetrable barrier between the surrounding groundwater formations and the work area within the shaft. The extended shaft collar of the present invention provides a barrier to the ground and the work area of a shaft, including the prevention of contamination of shallow groundwater of the surrounding formations from the activities of the shaft, and may further be used for emergency shaft purposes. Concrete utilized in the extended collar may be comprised of conventional cements as well as specialty cements. The disclosed extended shaft collar supports a wide variety of scenarios for heavy civil construction projects, oil and gas production and mining, including subterranean oil recovery platforms and related products and services where shallow groundwater reservoirs are located.