The Collaborative International Dictionary of English v.0.48:

Stope \Stope\, v. t. [imp. & p. p. Stoped; p. pr. & vb. n.
   Stoping.] (Mining)
   (a) To excavate in the form of stopes.
   (b) To fill in with rubbish, as a space from which the ore
       has been worked out.
       [1913 Webster] Stope