TITLE: Example of nonvanishing Waldhausen Nil group
QUESTION [6 upvotes]: In a  remarkable  series  of  papers, both  anticipating  development  in  geometric  topology and algebraic K-theory, specifically  what  we  call  now the  Farrell-Jones conjecture, Waldhausen  introduced  obstructions  to  the  Whitehead  groups  to  satisfy  a  mayer-vietoris  sequence.
See https://mathscinet.ams.org/mathscinet-getitem?mr=498807
These  obstructions  are  related  to  splitting  of  homotopy  equivalences  across  submanifolds  of  high  dimension ( >5) due  to  Sylvain Cappell: https://mathscinet.ams.org/mathscinet-getitem?mr=285010. 
Since  then ,  lots  of  effort  has  been  put  into  showing vanishing  results  for  Waldhausen Nil  groups. I  would  like  to  know  an  easy  example  of  non-vanishing  of  these  groups. It  would  be  interesting  to  know  the  minimal  cohomological  dimension  of  the  groups involved  in  an amalgam  of  such  example. Waldhausen  sorts  out  in  his  original  paper fundamental  groups  of  surfaces, free  groups,  fundamental  groups  of  submanifolds  of  the  three  dimensional  spheres...

REPLY [4 votes]: There are examples of non-vanishing nil groups due to Daniel Juan-Pineda. See Juan-Pineda, Daniel(MEX-NAMMO-IM) On higher nil groups of group rings. Homology Homotopy Appl. 9 (2007), no. 2, 95–100 (MSN).