  We analyse high-resolution VLT+UVES spectra of the low-ionization intrinsic
absorber observed in the BAL QSO SDSS J001130.56+005550.7. Two narrow
absorption systems at velocities -600 km/s and -22000 km/s are detected. The
low-velocity system is part of the broad absorption line (BAL), while the
high-velocity one is well detached. While most narrow absorption components are
only detected in the high-ionization species, the lowest velocity component is
detected in both high- and low-ionization species, including in the excited
SiII* and CII* lines. From the analysis of doublet lines, we find that the
narrow absorption lines at the low-velocity end of the BAL trough are
completely saturated but do not reach zero flux, their profiles being dominated
by a velocity-dependent covering factor. The covering factor is significantly
smaller for MgII than for SiIV and NV, which demonstrates the intrinsic nature
of absorber. From the analysis of the excited SiII* and CII* lines in the
lowest velocity component, we find an electron density ~ 1000 cm^{-3}. Assuming
photoionization equilibrium, we derive a distance ~ 20 kpc between the
low-ionization region and the quasar core. The correspondence in velocity of
the high- and low-ionization features suggests that all these species must be
closely associated, hence formed at the same distance of ~ 20 kpc, much higher
than the distance usually assumed for BAL absorbers.
