L-J parameters can be specified in two ways in CHARMM, but today only one is used. The 0.0 in the first column is not used. Column two is the well-depth and column 3 is 0.5 * Rmin, where Rmin is the distance between two atoms of the same type at which the L-J energy is at its minimum.
See parmfile.doc (or parmfile.info)
I am not so sure about the quality of the hydroxide parameters - these ions are pretty rare (pronunciation 'non-existent') in classical simulations. At pH 7 you would need a fairly large box to have one OH- ... (