
In Lille as in Paris, urban expansion has reached the fields of catiches, ‘bottle’-shaped traditional underground quarries (200 to 350 m3 in general)
grouped in bunches.
These catiches present risks of subsidence at the heart of the Lille conurbation.
Works were completed in autumn 2013, and the assessment is positive: the improvement principles were validated and, although individually the treatment of most of the catiches differed from the initial estimate, the contract quantities were complied with.