Read this and answer the question. If the question is unanswerable, say "unanswerable".

The Exeter to Plymouth railway of the LSWR needs to be reopened to connect Cornwall and Plymouth to the rest of the UK railway system on an all weather basis. There are proposals to reopen the line from Tavistock to Bere Alston for a through service to Plymouth. On the night of 4 February 2014, amid high winds and extremely rough seas, part of the sea wall at Dawlish was breached washing away around 40 metres (130 ft) of the wall and the ballast under the railway immediately behind. The line was closed. Network Rail began repair work  and the line reopened on 4 April 2014. In the wake of widespread disruption caused by damage to the mainline track at Dawlish by coastal storms in February 2014, Network Rail are considering reopening the Tavistock to Okehampton and Exeter section of the line as an alternative to the coastal route.

In feet, how much of the Dawlish sea wall was destroyed?
130