In addition to the papers listed at [http://ilog.ligo-wa.caltech.edu:7285/advligo/Seismic_Isolation the AdvLIGO wiki], I found [http://www.iop.org/EJ/abstract/0264-9381/15/11/004/ this VIRGO paper], which contains a section "Effect of the apparatus infrastructure".
[http://www.ligo.caltech.edu/docs/P/P040032-00.pdf Rana's thesis]
[http://www.ligo.caltech.edu/docs/G/G040557-00.pdf Rana's presentation with scale diagram of BSC]