Its for stabling and light repairs. All the heavy work will still be done at Newton Heath or the other big depots. The train crew will have facilities I believe in the station building at Blackburn and will be taxied to and fromt the depot if needs be.
Last time I looked they were laying the sidings in the depot and sleepers were in place. Its coming along. First staff will be transfering/starting in December.
The new Blackburn depot will cover, the future half hourly Vic - Clitheroe. Blackburn to Vic via Todmorden. Colne line, Blackpool N and S and also the Orsmkirk Branch.