I’m going to take a stab at the HVAC stuff. I did commercial HVAC for ~35 years.
“Immediately adjacent to the beach, the water is made turbid by a reddish-brown substance — appearing to be a “Red Algal ‘Bloom’”. Someone (Anon?) posted the theory that the algal bloom was caused by nutrients from engine exhaust from the HVAC building — which emerged underwater just off the beach.”
This would be the foundation of any HVAC system, how is it powered? In my experience it would usually be 480 Volt/3 Phase electrical power. Since it’s an island, you could do that with a diesel engine generator to create the electricity. Generally, those would exhaust through the roof. I don’t know you would go to trouble to pipe the exhaust out underground to the water sine it was not a secret the building was there.
I have seen chillers (very large refrigeration compressors that supply cold water to coils in large fan units to supply cold air through ductwork) that were driven by natural gas engines (they could also be diesel) but they were very high maintenance. They were introduced as a “green” alternative, I suppose in the 1980s and were soon abandoned because they were too high maintenance and expensive. That wouldn’t run any of the fan motors anyway.
Either of those would require large fuel storage and there should be evidence of those.
Providing the HVAC system to make underground spaces comfortable would be fairly complex. you would need to control the temperature, obviously, but also the amount of fresh air, the humidity, and the pressure. You would want keep the underground space at a slightly higher pressure compared to the outside so that air (and germs, etc) would tend to go out of the space, rather than into it.
Long way to wonder, why would they vent any exhaust out to the shore line if the whole thing is pretty obvious anyway?
MileHi,
In previous digs in Chantown, anon pretty much confirmed that there are underwater power and phone cables to Little St James.
Apparently it’s a relatively short haul from the neighboring island. (Tex - is that Greater St James?).
I haven’t seen or heard where the power ultimately comes from though. I imagine a larger power generation plant on a larger island?
I mentioned a couple festivals back there were USTs there, you could see the vent pipes and the fill port in the close up drone aerial...
Algal bloom can be caused by incorrectly treated sewage effluent. I think this is the most likely cause.