Filling a large sinkhole.. ?

johnshenryOctober 21, 2005

The biblical rains in New England a week ago left a surprise sinkhole in my yard, about 4' across, and 5-6' deep. The soil under the grass/loam, is very sandy. I can see timbers well exposed at the bottom of the hole.

While I know trees and stumps were probably buried when my house was built in '97, I know that that is not long ago enough for waste wood underground to rot away and cause the grade to drop. This hole is a cylinder shape, some water flow clearly removed a large mass of sandy soil. The area was "low" prior and water would pool there and weep down into the earth.

Anyway, what is the best way to fill such a hole? I am inclined to get 3-5 yds of fill and just have it dumped on the hole, and give it the winter to settle in. But I vaguely remember reading somewhere that you should fill a hole with gravel up to about 6" then top soil. This would give the water some way to drain through, and not take the fine, sandy soil with it. I do have access to a lot of 3/4" crusher run gravel.

Ideas? Comments, experiences?

Thanks

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ginny12

Might be a good idea to find out what is causing the hole before you fill it. An abandoned well? An old cellar hole? The fill might be a temporary cosmetic job on a more serious problem.

    Bookmark   October 21, 2005 at 10:36PM
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birdgardner(NJ/ 6b)

about ten years back a boy here in NJ fell into a sinkhole in his back yard - it opened up under his weight and closed on him and he died - the sinkhole was caused by buried stumps and so forth.

I believe burying such material has not been permitted for quite some time here - certainly not as recently as 1997. I would definitely talk to your town's building inspector and have an expert come look at the hole.

    Bookmark   October 22, 2005 at 1:53AM
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ginny12

It may not be permitted but a lot of builders do it anyway and the homeowner is left with the sorry results years down the road. It is a widespread practice, especially in parts of the country where there are lots of trees.

    Bookmark   October 22, 2005 at 8:32AM
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nandina(8b)

My familiarity with MA. over the years has allowed me to deal with a number of buried 'surprises'. The sink hole may be more than buried trees/debris. Find out the history of the land around you from the local historical society. Who has owned it through the years? How has it been used? A friend of mine was dealing with a similar situation and discovered that an early former owner had a small animal skin hide tanning business with a dug shaft for the waste products. Also, oak timbers buried in damp/underwater situations generally do not rot away. It is common to find wells and privy holes shored up with oak in sandy soils. Suggest you play detective, then turn the problem over to an experience backhoe operator who will know how to excavate and fill the hole properly. And, then of course there is always the thought of....dare I say it? Did they ever find the Brink's robbery loot?

    Bookmark   October 22, 2005 at 10:18AM
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saypoint(6b CT)

Maybe Jimmy Hoffa's in there.

    Bookmark   October 22, 2005 at 10:43AM
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ginny12

Hey, this is Massachusetts. It's Whitey Bulger, for sure.

    Bookmark   October 22, 2005 at 5:14PM
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laag(z6CapeCod)

I'm reading that the OP was familiar with the site before the trees were buried:
"The area was "low" prior and water would pool there and weep down into the earth."
So, it does not seem to be a hazardous waste site or a mafia burial ground.

I would suggest filling with clean sand. That is what is recommended in our area to fill abandoned cesspools, septic tanks, and the like. The broblem with gravel is that smaler particles can filter into it causing more settling.

Wareham?

    Bookmark   October 22, 2005 at 6:08PM
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johnshenry

The area was mature woods prior to the house being built, in '97. No other homes in the area (and I have several history books from our tiny town, pretty sure of that). As I said, I think it is highly unlikely that it is rotting material. Too soon since lot was built, there is some timber in there that looks like it was just buried, and the hole looks like the sand just got sucked down out of the bottom. It is deeper than it is wide!

No sign of Whitey or Jimmy (Oor gold. Damn.).

Personally I think that the contractors who bury that stuff should be dropped down the holes. In our previous house/neighborhood, you could go down the street, and every time a house hit about 15yrs of age, depressions would start showing up in the yard, but never just dropped out.

Without other recomendations/data, I will probably get load of sandy fill dumped on/in it. I may even rent the small bucket loader I rented last spring and do it myself, I have several acres and can move soild from another area. If it drops again, then no harm done, jsut take another approach...

I'm in Dunstable BTW.

    Bookmark   October 22, 2005 at 8:01PM
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mckenna(Z5 Chicago IL)

Do you have a sewer or drainage pipe anywhere near the sinkhole? In my experience, soil needs somewhere to go for it to disappear in a short time frame. Organic decomposition is a longer time frame issue. Just my 2 cents.

    Bookmark   October 23, 2005 at 10:03PM
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johnshenry

No. Septic on the far other side of the yard.

    Bookmark   October 27, 2005 at 12:02PM
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surfri

I have the same problem, but mine is from a sub-pump. The hole is about 3-4' wide and about 7' deep. What I plan to do is fill it with pebble stone and reroute the the pipe. Filling the hole with stone will act as a leach field and just wash the water through, incase it happens again.

    Bookmark   June 27, 2006 at 9:14PM
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laag(z6CapeCod)

Large stone with water flowing into it has a great capacity to infiltrate with the material next to it and over it. When that material moves into those voids, it is no longer where it used to be. That means the area is going to settle. That is more or less what the original problem was.

Use a filtration textile over it, if you do it.

    Bookmark   June 28, 2006 at 6:55AM
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watergal(z6/7 Westminster, MD)

Here in Maryland, we have limestone underground that dissolves over time and periodically opens up to create huge sinkholes. Years ago, one opened at night and a car drove into it and the driver was killed. Very sad.

    Bookmark   July 4, 2006 at 9:39AM
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staceyptk

We have a sink hole that continues to open up- not too deep, but it drops about 1-2 feet consistently every time it rains. There is also a drainage pipe that runs undr the yard, and I think right under where our hole is. Who can we contact to help? The owner of the "communtiy" we are in has come twice and filled it in with rocks, but, alas... still the same problem. Any suggestions?

    Bookmark   February 17, 2008 at 5:23PM
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shasta_2008(5 NE Ohio)

We have mine shafts around our property. The neighbor across the street had a hole too but no so big, they filled it in. Since then we purchased mining insurance.

    Bookmark   February 26, 2008 at 11:57AM
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jeanbhall(z6 MA (Norwood))

We went out to plant some flowers last weekend, and found a sinkhole about 4 feet deep and 4 feet across. Worried there might be other problems. Who do you call? Is there a MA or US government agency? A private firm? What type?

We are In Norwood, MA and would appreciate any advice.

We have already dumped a ton (literally) of rocks and soil into the hole. It is just about full, but I worry there might be others.

Please e-mail me at JeanBHall@aol.com

I feel this is urgent but don't know how to deal with it.

Thanks.

    Bookmark   July 26, 2009 at 3:32AM
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rosiew(8 GA)

My neighbors just had a sinkhole repaired. The backhoe had to dig down about 7' deep x 20' length, 7'across. Two huge construction dumpsters were filled with the trees that were excavated. Trunks had been cut to about 15' lengths, huge diameters, minimal rot. Subdivision built about 13 years ago. They had a hillside cut back and were able to use that soil to backfill.

The building inspector/planning department personnel can't be on site all the time, of course. I would surmise the pit for all the trees was dug and filled late in the day or on a Saturday to avoid detection. Contractor saved cartage fee with the subsequent HUGE expense my neighbor incurred.

Rosie, Sugar Hill, GA

    Bookmark   July 26, 2009 at 5:04PM
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accordian

I have a client who wanted some bedding plants around their main entryway and while I was out looking at that area I couldn't help but notice this huge hump of dirt about 5' high and about a 1/4 acre in size off to the side and on a slope below their newly built house. It seriously looks like an elephant graveyard.

Since the owners weren't home and I had never seen anything quite like it, I got on top of the gigantic hump to take a closer look (I had to basically rapel down to it from the porch that overhangs the area, the 5' sides of the hump are much too steep to climb up - they are merely planted with sparse grass too (it's a very shady area), with no other means of retaining the slope - though maybe that's fine.

While on top of the hump (not doing the "Humpty Dance" though - whatever happened to Digital Underground anyway, did they fall down a hole or something?) I noticed large branches protruding in areas. It also looked like this was the septic area for the house. I debated saying anything to the owners, but since it just seemed odd and not necessarily unsafe, and since this was not the area I was supposed to be working in I decided against it.

I ran into the builder, however, at a party and asked him about it. He got very aggressive and angry (although I had just been inquisitive, not accusing in any way) and told me that the lot was heavily treed when he got there and also very swampy (still very swampy actually) and that he had cut the trees up and placed them and the stumps there to "fill in" a swampy area, then piled the excavated dirt and rocks from the cellar on top of it. "Where else did they expect me to put those damn trees," was how he phrased it. He also confirmed that the septic was somewhere in this conglamorate of rubble. He seemd very proud of this fact because he said it was the "first septic he'd ever dug."

Now maybe he is right to be proud and he did a good job but it seems odd to me. I just keep pictuing this steep slope collapsing at some point and/or a giant hole opening up under the septic. Again, it is not my problem and maybe I'm wrong to be concerned but do you think it is unsafe? If so, I would definitely alert the owners to contact a civil engineer and/or anyone else you recommend.

Sorry If I'm hijaking a thread, just ignore me and carry on if my question has no relevance to the OP's concern but it seemed possibly related. If it's not I'll start a new thread.

    Bookmark   July 27, 2009 at 11:06AM
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miltonr72

same situation happen with me.its very dificult to sought out thiz kind of problem.

    Bookmark   July 26, 2013 at 5:57AM
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