Common Household Remedies Request
Herewith, "The Hellmouth in the Crawlspace."
The backstory: The plumber discovered this in the crawlspace, just before I left, the second time the pipes burst. ("Pass me your iPad, I'll take a picture of it.") He was scared to go near it (!!), and didn't want to find out how deep it was; I thought of tying a rock to a ball of garden yarn and asking him to drop the rock in the whole, but I damn dumb forgot. He does say that it widens out, like a cave or cavern.
One thing I don't know is how long The Hellmouth in the Crawlspace has been there, or when the hole opened up. The plumber certainly didn't notice it the first time he was in the crawlspace, and the energy auditor was in the crawlspace too, and didn't say anything about it. And two other plumbers, one for a bathroom, the other for a cracked main waste pipe, have been under there, though five or six years ago.
A second thing I don't have is a theory. I suppose it could be caused by flowing water, either from running water from the first pipe that burst -- it's always a very bad thing when you come home to hear water running without any faucets on, and go down the basement and hear bubbling noises -- or from the main waste pipe that burst long ago. It could also be a groundhog nest; I have heard they dig schoolbus sized residences under houses, and I've definitely had groundhogs, though, at least visibly, only in onesies and twosies (and never lost the garden to them). Or the two theories might combine; the water from the burst pipe could have eroded the ceiling of a groundhog chamber and opened a hole in it. (The pipe that seemingly drains into the hole isn't, AFAIK, connected to anything; it's scrap.)
A third thing I don't know is how much to panic. How can I tell if I need to worry about the foundation? The hole isn't near anything structural, but I dunno if I like the idea of a big open space in the earth under the crawlspace no matter what it's near. The house has settled, but then this house has been settling for years; it's an old house.
So, expert readers?