Sink hole/ land depression forming
I live in Londonderry, NH and 2 weeks ago a sink hole opened up 50 feet on the side of my house. The sink hole is about 5+ feet deep and 2-3 feet round, with water at the bottom. However, where the sink hole is it looks like a 25 foot round section of my lawn is depressing inwards. I don't have town sewarge and the septic tank is a good 50+ feet away from it, So I don't think it could be the issues,or maybe I'm wrong?
I had the town engineer come over to inspect this and he said no sewer or other water main pipe in within this area. He thinks it the sink hole might have been caused by either building debris or tree stumps buried when the neighborhood or house was developed back in 1978. Is it possible that this could be the cause or is there somethink else? I do notice a lot of sand at the bottom of this hole.
Any suggestions on how to repair this?
Re: Sink hole/ land depression forming
You didn't mention if your yard is leveled or sloped. Let's assume it's leveled.
The town engineer is telling you that there are no water or sewer lines near by - he ought to know that for a fact.
He also assumed that when they did construction back in 1978, they buried building materials and tree stumps there and used them as fill. If that is the case, it is very possible to have the whole thing cave in.
What to do now? I would back fill the hole again, using imported dirt from a different area and compact it. Then wait see if it happens again. It could be a long wait...