There's one near the permabrig, and another in medbay.
Drat, so near and yet so far!
I did have an educational hour or so earlier - I was the only one on, and started off as engineer. Managed to get the singularity set up (in a stable manner, remembering to actually set the SMESes up first this time!), and wired up the solars. Unfortunately as I was the only one on, I had no way of achieving my (traitorous) objectives - I stole the object I needed to steal (syringe gun), but had no way to call the shuttle!
Someone else (I assume someone public) logged in, joined as captain, and then went AFK. I left them alone for about fifteen minutes, then decided 'sod it' and pickpocketed the captain's ID from their vacant body. Got onto the bridge, got to the comms console...and it wouldn't let me log in or do anything.
I then found that something had blown an almighty hole right through the central tree chamber, the library and the dorms. I assume this was what was causing my problems with the comms console. I repaired everything as best I could, but to no avail. The atmosphere had already mostly gone, and my delayed patch-up job hadn't saved enough of it. I was relegated to the maintenance tunnels to get between areas with air. I closed as many fire doors as I could to preserve what remained.
Then, on opening a door - weeds. Lots and lots of weeds. They'd evidently started off somewhere in medical, and by the time I spotted them they'd taken over most of the starboard (east) side of the station.
I hightailed it to Tool Storage and made myself a flamethrower. Snuck around to engineering and stocked up on plasma tanks. And then went on a fiery rampage through the weeds. Made decent headway, too - cleared out most of the central corridors - but eventually the fiery blaze was too much even for my engie hardsuit, and I collapsed from burns. The weeds wasted no time in growing back over me and, eventually, strangling me.
Thus ended my glorious solo 90 minute maintenance-man shift. It was lonely, but I learned a lot. Namely, don't walk into fire. Fire bad.