I spent today working on the high isolation filters for ETMY, and was able to install them today. However, when I went to tried to turn them on, I found a 30-ish hz peak in my seismometer spectra that seems to be ringing up the ISI. It's there even with the damping off, so something is creating some ground motion out there. RichM and I went down and turned the last 2 cleanrooms off, but the peak is still there. Rich noted the scroll pump was still on but was doubtful that would cause the problem. The peak is clearly visible in the attached plot, this is after we turned everything off.
The building HVAC main fan is a 25 horsepower fan running at ~29.5hz; the exact frequency depending on load. SF01 is currently running, The flow rate can be reduced to lessen the load on the fan and perhaps any vibration, alternately SF02 can be turned on. Ski or I should be able to swap fans if you want to try this.