It's between the 18th and 3rd (so right side of 18, left side of the 3rd) iirc. I think they are only in play for the 18th, to stop people cutting the dogleg by going via 13.
It's mentioned in the description of the hole in this vid :
(you need to open it in youtube to read the notes).
Having said that, it's a while since I've been there, and I'm not sure how they've been maintained of late.