We present multiobject spectroscopy of galaxies in the immediate (Mpc-scale) environments of four low-power (L_1.4GHz_~<10^25^W/Hz) radio galaxies at z~0.5, selected from the Subaru/XMM-Newton Deep Field. We use the spectra to calculate velocity dispersions and central redshifts of the groups the radio galaxies inhabit, and combined with XMM-Newton (0.3-10keV) X-ray observations investigate the L_X_-{sigma}_v_ and T_X_-{sigma}_v_ scaling relationships. All the radio galaxies reside in moderately rich groups - intermediate environments between poor groups and rich clusters, with remarkably similar X-ray properties.