Some 80 tonnes sulphuric acid per hour will be removed from the ship in order to lessen stress to its hull, members of the salvage team told a press conference in St. Goarshausen in the state of Rhineland-Palatinate.
"In the worst-case scenario 1,000 tonnes of acid will have to be directed into the Rhine," a spokesman said, adding the ship had taken a "slight banana shape" after 240 tonnes were pumped into another tanker.
A laboratory vessel will supervise the pumping operation to make certain the concentration does not exceed twelve litres of acid for every 1.6 million litres of river water per second. Experts expect the environmental impact to be minimal.
The wreck of the “Waldhof,” which continues to hinder traffic on one of Europe’s most important waterways, has already leaked some 900 tonnes of acid since tipping over near the fabled Loreley rocky point on January 13, officials said. Some of remaining toxic liquid will be pumped into another ship with stainless steel tanks on Tuesday.
The massive backlog of ships waylaid by the accident is slowly starting to ease – though some 300 vessels are still unable to proceed down the Rhine. On Monday, the first multi-ship barges were allowed to navigate past the wreck.
What caused the “Waldhof” to capsize remains unclear. Two crew members died in the accident.
The narrows near the Loreley have been the bane of sailors for centuries. According to legend, a beautiful siren at the spot calls to those sailing the Rhine, causing them to crash their boats on the rocks.