A storm surge coinciding with high tides caused the River Tees to rise. It flowed over and eroded the dykes built to protect the local residents. A Seveso-classified port terminal containing chemicals stored in tanks was flooded 1.8 m above ordnance datum.
The terminal’s employees fled to the control room on the top floor of the main building. Most of the firewalls were submerged by the water. The rising water lifted a number of partially full storage tanks, damaging their pipes and supports in the process. A number of fixtures were damaged by mobile equipment carried away by the water. No chemical leaks were reported. Due to the site’s low altitude, the water was unable to drain back by gravity into the river bed. It had to be pumped and piped to the river in order to allow access to strategic portions of the site.
Mobile generator sets were brought in as a temporary source of electricity. The main electrical switching and control systems were damaged. Extensive work was undertaken to replace them. The level alarms, tank gauges, and other operations-essential systems were the first to be repaired. The transfer operations, which until then had been remotely automated, were conducted manually, and temporary operation procedures were implemented. The walls of the retention tanks were inspected for breaches. The storage tanks that had been moved by the water were put back in place and the damaged pipes were either replaced or repaired. The electrical equipment was tested and replaced as necessary.
The Environment Agency had issued multiple flood warnings predicting a rise in the water level to the site up to 5 February. However, the site did not suspend its operations (shipments, loading of road vehicles, pipeline transfers). As the site is located several kilometres inland, the storm’s effects were not felt locally until 5 February. On that day, the site suspended its operations and isolated the electrical power supply. A flood investigation report listing the events that occurred before and during the flood was drafted to draw lessons for the future. The dyke along the river was raised. Work will be conducted to safeguard the rest of the site’s wall at the same level and ultimately give the site a less than 1 in 1000 annual probability of flooding (<0.1%).
A petrochemical site (46146), a cement works (46151), and a petrochemical terminal (46149) were also flooded that day.