Sven -
The Olmsted drawings (1932) show a c/l bunker on 11. Yes, they were suggested by Jones (as I recall Jones wanted to replicate c/l bunkers he had seen at English inland courses) when MacK was still alive and were installed early on. They should be included in a 1934 vs. 2012 course comparison.
The bunkers survived the RTJ changes in'48. My guess is they were removed in the early '50's, though I've never read anything about why or who carried out their removal.
As you note, you have to see the 11th to appreciate the size of the mounding twenty or so yards short and right of the green. They would have been very much in play from the original tee.
Bob