I don't have any ideas but I'm having the same problems this year and it's really bad. Out of 9 plants 2 are on death's doorstep ready to be pulled and 2 more are getting symptoms so whatever it is it might be spreading. I suspect blight. We had tons of rain last month (over 10 inches). When my plants had those yellowing leaves like yours I pruned them off. This was 3 weeks ago. The pretty much dead plants just kept going downhill. I was going to search the tomato forum to figure out what I did wrong and maybe try not to do the same thing next year. BTW: Due to all the rain here in Chicago, I have mushrooms growing out the drainage holes in many containers.

If you know any contractors, you could ask them. How much soil are you looking for? If you want it by the truckload, there's usually "aggregate" places where you can order a truckload of top soil. Glover in Hilo may sell topsoil by the truckload, they have cinders at least. We build raised bed gardens from cinder blocks. About three layers high, then we put down a layer of weed mat to keep any tree roots from coming in from below. Then pile in whatever soil we can get. I'll usually let all the weeds sprout up and then yank them out before they seed. But you can skip this part if you don't mind weeding for the first year or so of your garden. Then the top 10" of soil, especially the top 4" are the best soil I can get. There's usually amendments of oyster shell worked into at least the top ten inches as well as compost and rabbit manure since we have that. Rabbit manure is an excellent fertilizer, you can put it directly on your plants without the need for composting as you'd have to do for chicken manure. For the cinder blocks, we set them so we can reach into the middle of the garden. How long doesn't really matter, but being able to reach the center from the sides is pretty important, IMHO.

I used Miracle Gro Moisture Control Organic Soil (I bought a big bag at Costco and used it for other plants, so it is what I had here). The pot does have some drainage holes on the sides and drains out into a saucer shapped edge. I rarely (if ever) water it to the point where water comes out of the drainage spots though. When I repotted the plant the soil was very moist. The roots didn't look alarming, but to be honest, I don't exactly know what I am looking for. I have been encouraged to see some small new growth on it, but want to be sure I'm doing the right thing to let that new growth have a chance. I also don't want to throw away a viable plant, but if there is no hope, I will move on.

The staining may only be happening in a few boards but the CUPPING of the planks is more wide spread. That's the biggest issue. As for moisture mitigation during install, it would be up to you to contact the original installer to find out what was done. Only they can answer those questions for you. But I will give you a heads up on that one. These OLD slabs (1948 = post war era building boom) are often thought of as DRY when carpet is removed (again, this is why I asked what USED to be on the floor). The slab will 'test' as dry because it has been happily evaporating off moisture THROUGH the carpet for decades. And decades. And decades. Many moisture tests (ie. anhydrous calcium chloride test) will see how much PRESSURE is in the slab on that day. If carpet is removed and there is NO BUILD-UP of moisture/pressure BEFORE that day, it will 'read' as a nice dry-ish slab. Once the slab is CAPPED (solid flooring put over top = nowhere for the water to escape = HIGH moisture content/pressure) it gets MUCH more difficult to deal with. If you test the slab TODAY it will be MUCH HIGHER than the slab was before you put the wood on it. The moisture barrier treatment at the TIME was 'good enough' for the reading (3 years ago before the slab filled with water). But NOW the moisture has overwhelmed the system used. This is why it takes wet-basement specialists to figure out some of these old slabs. The moisture tests done before they were capped probably looked very good (or very promising to be good in the future) but the wood flooring people could not predict the pressure build up over 3 years. That's not their level of expertise. A wet-slab/basement specialist *MIGHT have been able to guestimate the issues...but they too might have guessed wrong. These old slabs are SUPER TRICKY to predict. Please tell us if your floors are glued down to the concrete or if they are floating. Please add more photos of the cupping please. Tell us how much of the 1800sf is having moisture issues (cupping/staining, popping, etc).