Another notable excerpt from the linked state safety agency document ( http://www.michigan.gov/documents/cis_wsh_cet5041_90142_7.do... ): -- Two employees of a fertilizer company in Riga, Michigan, were assigned to install a new float valve in an old 35-foot deep cistern for a new 300-foot well. This cistern was covered with a concrete slab with entry through a covered manhole. The first worker entered the cistern an…
There are too many stories like this where a whole bunch of people die trying to rescue the first victim so it makes total sense but it is kind of weird working in an environment where you know your colleagues will not help you (at least at first) if something goes wrong.
Btw: H2S doesn't really dull your sense of smell because of prolonged exposure. It only becomes odorless at deadly concentrations. So it turns out you don't know if you cannot smell it because it isn't present or it is just about to kill you.