Home Improv guys: Sinkholes around drywell, and it\'s not draining So I have this drywell we dug 4 or 5 years ago when we bought a washer/dryer... A big ol' precast thing like a mini cesspool, ran some PVC to it, and everything was grand. Recently, the vent pipe seemed to sink a little around it, and then a 1' wide by 1.5' deep hole appeared at the edge of the drywell, and the hole filled up with washer waste water when my wife did laundry. The topmost lid was about 1' below surface, and the hole looked like it was just as deep as the top of the precast, below the lowest lid (there are two lids). I dug it out and opened the service lid last weekend, and it was filled with gray water (which stank like sewage). My wife hadn't done any laundry in about 4 or 5 days, so this thing is not draining, or extremely slow. I pumped it down about halfway, and measured that the bottom was probably 6 inches to 1 foot higher than it was when we closed it up, much more dirt volume than the sinkhole, too. I left it, my wife did 5 or 6 loads of laundry since then, and it has been rainy for 2 days, so I opened it today to find it full again. I pumped the stinking water down to about 6 inches (my neighbors must love that stench in the street), but my pumps are now all clogged with lint, and the water seems to be a gray-blue mud at the bottom. Any suggestions (besides the obvious dig it back out) or ides why it filled itself in so much? BTW, I think it was a 5' deep x 4' wide precast ring. There are no sewage tanks or pipes anywhere near that could be leaking into this one (the cesspools/sewage tanks around here are at least 10 feet down anyway) I had wanted to run some gutter runoff into this thing, but it looks like I'll be digging another one all together to handle gutters and this ones overflow. Did we dig and install this thing wrong? We dug a pit til we hit sand, dropped in the precast, and covered it up. Same way we did my dad's house, and his is fine after 10 years.