The essential facts are not disputed. Lansco leases premises bordering the Hackensack River at 275 W. Fort Lee Road, Bogota, New Jersey, where it maintains tanks for the storage of asphaltic oil. Sometime during the night of December 29, 1974 a person or persons unknown opened the valves on two storage tanks, causing some 14,000 gallons of oil to leak from the tanks and onto Lanscos property. Vandalism was suspected and the police were contacted, but to this date investigation of the incident has failed to determine how it was caused. The only testimony in regard to the specifics of the occurrence was that a key required to open the valves, which was usually kept in a locked building overnight, was found on the ground near the tanks on the morning of December 30.