07:21 Jan 9 

I agree with Tony that "chantier" is likely to be "project". The extra context provided by the asker (lean, OEE, etc.) confirms that 5S is referring to the 5S continual improvement-oriented approach. Marco has provided a good link in his answer.

22:29 Jan 8 

Organisation rigoureuse basée sur les standards des grandes entreprises industrielles (5S, Lean manufacturing, TRS, système management intégré QSE).

22:08 Jan 8 

Sounds very like it must be company-specific. (No, I'm wrong, standard management abbreviation, see useful ref. provided by Marco)

Depending on just what it is, I suspect 'chantier' here is probably going to be something long the lines of 'project' (perhaps 'programme'?)

In the light of that information provided by Marco, I now feel more convinced than ever that they are probably talking about some kind of 'project' — the term 'chantier' is very often used for this sort of thing in e.g. IT.

However, it would be wise to see if you can get confirmation of this from your wider context, as it just might be referring to e.g. "roll-out on different sites / in new locations"!