 Pressure for its completion to coincide with the opening of the new airport resulted in tunnel excavation proceeding at maximum speed, without adequate measures to exclude water, which resulted in leaks.Houses above the route of the tunnel in Hellerud were damaged and the water levels of many lakes in Østmarka were reduced, including lakes Lutvann and Nordre Puttjern.After the damage was discovered on 3 February 1997, legal actions were initiated by the Norwegian Water Resources and Energy Directorate requiring remedial measures to halt the leakage.