Latest update...
Well guys came by... they were really nice, but also over-booked with work.
They told me to put 2 gallons of muriatic acid down the well... wait 2 to 4 hours, then back flush with a garden hose for 1 hr, and try it.
They admitted it might do nothing, or could clear the well, or could clear it only to have the well pipe fail shortly afterwards, or it could eat through the pipe at the bottom near the screen -- many of those options would require a new well. They also said they've seen it clear up a well and have it be fine for another decade.
They suggested the same as
@Reach4, which was to bring the PVC up to my level, so that I'm not in the pit, and carefully pour the acid in that way, then cap the well.
I opened windows, put on lots of fans, had on full protective gear, and went for it. I also rigged up a t-fitting with two female hose thread adapters and shut off valves. One of them went to a neighbor's garden hose to allow easy back-flushing. The other went to 3/4" ID clear tubing that was connected to some fancy, over-priced gas can that includes an outlet hose and a lever to dispense the gas...
and I clamped all of the hoses to their connections using stainless steel hose clamps. I also capped off the line at the output from the pump, so that all water, acid, etc will be forced down into the well.
The result was that i suited up will full protective gear, poured 2 gallons of acid into the gas can and then had levers and valves to carefully dispense the acid into the well, and flush some of it down with water in the process while not facing much risk of exposure to the acid, even if it were to react or bubble back up out of the well. Nonetheless, I cleared the house, had the windows open, fans running and blowing so that the acid fumes and other vapors would go away from me and out the window, and I had the kitchen door open with a clear escape path so that I could exit immediately if anything seemed like it was going wrong.
I've left the house open and airing out, and just now started the back-flush after 4 hrs of allowing the acid to work.
I'll back flush for a full hour, and then turn off the water, reconnect everything and see how we do...
(finger's crossed).
If the well doesn't hold up, the well guys will put a new one in this fall or winter. They plan on using some type of air-driven hammer, and 10 ft pipe sections, since my location doesn't allow access by heavy equipment. With a 6 foot well pit in the kitchen and a 7 or 8 foot kitchen ceiling height, the 10 foot pipe sections sound like a good plan to me.
In the meantime, our neighbor is kind enough to let us pressurize our house and draw water using a garden hose running from his home.... that will get us through the rest of the season just fine if need be.
More to come....
Oh... and the well guys warned me not to get any muriatic acid that claims to have reduced fumes, or similar claims. Some products make that claim, and whatever they do to the acid, it apparently doesn't work as well in terms of cleaning rust out of a galvanized well pipe. Sure enough, the HD had this reduced fume stuff, and my local Lowes had both the regular muriatic acid, and a reduced fume version too.
-Phil