Sentence:  Looking north towards Moorgate, through the new tunnel being built at Bank for southbound Northern Line services. More than half a mile of new tunnels have been excavated, producing nearly 200,000 tonnes of material which is being <WSD>repurposed</WSD> as building material in Dartford. 
Meaning of the word marked with <WSD> tags:  To reuse for a different purpose, on a long-term basis, without alteration.