Hiding behind technobabble, we had an explosive loss of containment in the Marine Sanitation device. Put simply, the shit tank blew up REALLY energetically in a confined space.
How bad was it? There was shrapnel (crapnel? Heh.) out to about 25 ft, and as the MSD is located in a void space underdeck, and that space runs the full width and full depth of the HQ. So, it's 50 by 20 by 20, with closely spaced framing running across all surfaces. Framing that traps liquids and solids to a depth of about 6 inches.
So, the shit tank blew out, unfortunately more or less straight up, and put simply, it contaminated the entire compartment.
I won't lie. I considered sealing the compartment, putting in my notice and finding new employment, but there wasn't much to do but fix the problem. We had to wait 24 hours to get time and space and the equipment necessary to handle it. When it was time, we docked at company HQ on a sunny, hot and humid day.
The technical part, causing the failure, was that an air regulator (MSD's are made to break down the poop a bit using bacterial colonies, so they need air, like a really really awful aquarium) failed, so the tank got...impacted. a Blivvy, in other words.
Before the engineers could come at the problem, though, we had to set up ventilation, using big air horns under compressed air to blow out the space and test the air. After just an hour, the compartment registered perfectly safe.
So, me being unwilling to pass such an awful task to anyone else, I took a solo adventure into the compartment with a high-pressure garden hose and fresh water. No fire hoses for this sort of work. Too much risk of blowback. I put on a Tyvek suit, rubber boots and rubber gloves duct taped to the suit, a bandanna over my head, goggles and a respirator.
And I went down into that 100+ degree dark and drippy hell to the first platform, 10 feet down, opened up the MSD fully, (protip, don't look in the tank. Pretty sure my hair is gonna come in all white now), and fired up the hose, flushing down everything from overhead, the bulkheads, and the grating, down to the bilge. While I was doing this a vacuum truck came in, with a septic tank crew, and put a hose in the bottom of the compartment.
I then lifted the planks separating the platform deck from the tank tops at the bottom and crawled down another 10 feet below into the darkness.
Dodging the water droplets still falling from above, I cleaned up that space, and it took an hour. By the end I was overheated and gasping for air, and just as I finished, the air meter clipped to my suit zipper went off- stirring the shit displaced enough oxygen that it was time to go anyhow. So I headed up, and felt poorly for a while, with minor heat exhaustion and having been breathing mephitic, slightly oxygen poor air for so long.
After about 30 minutes, a half-gallon of water and pouring the sweat out of my boots, I went down with a case of bleach, and sanitized the compartment, then rinsed and vacuumed it out with the hose from the honey wagon on the dock. Took about 45 minutes. Then repeat with a 5 gallon bucket of powerful concentrated soap. And rinse. Only THEN could I approach the MSD and vacuum out the... contents, then rinse, sanitize and rinse again. At that point the engineers came in and fixed the actual problem, and I was so overheated and ill that I jumped in the shower and sat in a chair for an hour, feeling poorly, drinking water slowly.
It was hell. But OTOH, we have a shiny happy crapper tank, so we can do our business in a businesslike manner again, I guess.
I threw away everything I was wearing, right down to my socks and drawers. It all went into a bucket, and after my shower, I put on gloves, closed the bucket, put it into a heavy plastic bag, and that went to the dumpster. At that point I was done. Our shoreside staff didn't ask any more out of me, which is good, as I was done in a literal sense. It took almost 2 days before I felt 100%. Getting older, getting heat-sick is not so easy to snap back from.