Results of monitoring groundwater above the natural gas underground storage at Stenlille, Denmark

Groundwater in the Stenlille area is regularly analysed for light hydrocarbons after a natural gas underground storage facility was established there in 1989. The monitoring is carried out by the Geological Survey of Denmark and Greenland and is part of the authorities’ requirements for the environmental approval of the natural gas storage run by the state-owned Danish Oil and Gas company DONG A/S. Groundwater from observation wells and water wells in the area was analysed every month during the first year of operation and four times a year in the following years. More frequent analyses are undertaken on special occasions.