Sinkhole or drywell collapse in New York (C) Daniel Friedman Visual & Other Clues Indicating the Risk of Sinkholes in New York, New Jersey, & Elsewhere

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

This document uses a report of sudden yard collapse in New York as an example of causes of sudden soil subsidence, and discusses safety concerns as well as what sinkholes are and why they occur, describes their effects on buildings, and gives building and site inspection advice useful in identifying areas where there is an increased risk of sink holes at properties.

Green links show where you are. © Copyright 2015, All Rights Reserved.

Sinkholes in New York

Photograph of a sink hole swallowing a house in FloridaQuoting from our topic home page at SINKHOLES & SUBSIDENCES,

The bare minimum that a property owner needs to know about sinkholes or any other sudden subsidence of soils at a property is that these conditions might be very dangerous. Someone falling into a sink hole or into a collapsing septic tank could be seriously injured or even die.

If a suspicious hole, subsidence, or depression appears at a property the owner should rope off and prevent access to the area to prevent anyone from falling into the opening, and then should seek prompt assistance from a qualified expert, geotechnical engineer, septic contractor, excavator, or the like.

If a sinkhole is already visible near an inspected property or if signs of a sinkhole are observed this information should be cited by the inspector as a potential safety concern and significant expense requiring immediate professional action. Synonyms and similar terms for sink holes include: shake hole, swallow hole, swallet, doline, cenote, moulin, and glacier mill.

Article Contents

    • Inspecting a property for signs of sink holes in New York
    • Report of sudden back yard collapse at New York Home
    • Causes of sinkholes and sudden soil subsidence
    • Sink hole damage and risks to buildings
    • When to hire a geotechnical engineer for sinkhole or soil testing
  • SINKHOLE DAMAGE REPAIRS - separate directory of repair contractors or geotechnical engineers to consult for New York sinkholes & subsidences

What to do if a Sinkhole or Soil Subsidence is Observed or Suspected at a property

Safety Warning: Sinkholes or even small soil subsidences can be an immediate potential life-safety concern. For home owners, inspectors, professional and trade association standards, home inspection standards, and in some states, inspector licensing regulations (should) require you make to appropriate notifications.

  • Notify all parties: occupants, owners, real estate agents, buyers
  • Notify the local Water Management District
  • Fence or rope the hole off or arrange for this action to be taken immediately
  • Keep children away!
  • Protect the area from garbage and waste
  • The property owner should be advised to contact their homeowners insurance company
  • You may inform the parties that there are engineering firms specializing in detection and evaluation of potential or evident sinkholes
  • Record in your report the notifications and actions you took
  • Also see SINKHOLES, WARNING SIGNS where we include examples of sinking New York homes that were not caused by sinkholes but by construction on poor or improperly prepared soils.

How to Research an Apparent Sinkhole in Your Neighborhood

  • Dig: Hire a professional contractor experienced with sinkholes to excavate a bit in the hole before it is filled-in, to see what debris is in the opening. You may find components of an old septic tank, cesspool, drywell, dug well, building foundation, or other material that can help explain the cause of this sinkhole.
  • Check with local building officials for reports of other subsidence events in the neighborhood and identify their cause
  • Check with area contractors, excavators, who offer services that cause them to encounter soil subsidences and apparent sinkholes to ask what has been observed in your area.
    All American Water Line & Sink Hole Repair Service‎New Brunswick, NJ 08901(732) 249-2151‎ may have people who can assist.
  • Pay for an initial consult with local geotechnical engineers to ask the same question.
  • Determine the type of sinkhole and its cause. Keep in mind that people use the term "sink holes" more broadly than the classic sinkholes that I discuss at our website.

Classic sinkholes have their origin in earth formations, possibly aggravated by very large scale human-directed operations such as coal mining, oil, gas, or water removal from the earth, etc. Those sinkholes have large-scale underlying conditions.

Local, individualized "sinkholes" may be caused for example by soil wash-out from a burst water main below a city street. Or a sudden collapse of a buried cesspool, or soil subsidence over locally-buried brush and trees.

Local individualized sinkholes may still be dangerous, but once their cause is understood, affected property owners can more reliably and more easily estimate the chances of that sinkhole's spreading, increasing, or suddenly reappearing under a nearby building.

Sinkhole Related to Possible Cesspool Collapse Hazard - question about sudden back yard cave in

Sinkhole or drywell collapse in New York (C) Daniel Friedman

Earlier this evening, after a day of rainfall, our backyard caved in. Currently there is a hole in the ground about 12x10ft and 6-7 feet in depth. After the initial collapse, there was some growth in the diameter but that appears to have stabilized. The closest edge is about 6-7 feet away from the actual house.

[Photo at left shows the New York "sinkhole".]

The area has been perpetually plagued by flooding in the street as well as in the basements. We recently installed a very large dry well 3 years ago to deal with the flooding of the basement. The sinkhole is next to the drywell. Could the drywell have been the trigger? Besides the constant leaking of water into the basement from ?

It is an unclear collapse source, there were no other signs. I contacted our homeowner's insurance policy and they told me that this sort of thing is "water damage" and not covered. Should I request that a claims office assesses the property anyway? I'm not sure what the appropriate next step would be in order to ensure the safety of the backyard and the home.

My husband is convinced that it was a former cesspool. It's hard to look for debris as proof - because the hole is filled with stagnant water/clay right now. At it's deepest it's a little over 10 feet actually. We are planning on having the excavator who put in our drywell take a look. Thank you so much, really. There weren't many people who were able to guide me or even help me understand the problem! -- Y.Z., Whitestone, NY

Answer: what to do about a sudden subsidence or yard collapse

Watch Out: Immediately rope off the area of any soil subsidence or suspected old septic tank or cesspool area, and mark it plainly as unsafe so that a wandering neighbor, adult or child, does not go near nor fall into this hole. It could be quite dangerous. See CESSPOOL SAFETY WARNINGS for examples of potentially fatal cesspool collapse hazards.

We are elated that no one fell in to the hole, and that no one walked-over and fell into what may have been an imminent collapse well before it was so visible - such catastrophes can be fatal.

Better Off if it is Not a Sinkhole

If the back yard cave-in is nowhere near the house itself, and if you can establish that it is not a true sink-hole but rather something local like an old cesspool collapse, it probably is not a risk to the house foundation.

At events such as this one it is proper to ask if the cause was an old septic tank, drywell, or cesspool, long abandoned and not filled in.

Local Flooding and Sinkholes

However the area where this back yard sinkhole was observed has been reported to produce (smaller) soil subsidences and "sinkholes" due to the combination of clay soils, poor drainage, and a history of local flooding in times of heavy rain. See Sinkholes in Whitestone New York Associated with Flooding Conditions.

Signs of Old Septic or Drywell Components

Look at and in the hole itself and at any debris to see if you see pieces of piping (upper right near the drywell in the photo) - identifying these can save you some future worry and maybe geotechnical engineering costs - that is, if we can be sure it was an old tank and not a sinkhole the risk of other sudden collapses and sinkholes is of course less. In this case the piping visible in the photo was identified by the owner as electrical, from an electrical lighting pole that fell into the opening, not septic components.

The light colored material in the hole in our photo above was considered to be due to clay soils, not sewage waste.

Finally, if it was an old septic tank, or cesspool, warn neighbors whose homes are of similar age that they might have the same condition and the same hazards lurking.

What if it Is a Sink Hole?

IF there remains a concern that this is a true sinkhole the risk of other property subsidence that could also threaten buildings could be important.

Your local county and highway or building departments can tell you if sink-holes have been found in your area - you may need the services a local geotechnical engineer to inspect the site, possibly taking soil borings, and then advise you further. Other clues about imminent sink-holes and sink-hole collapses are discussed at SINKHOLES, WARNING SIGNS.

Sinkholes in New York Associated with Flooding Conditions

What causes sinkholes in areas where there is not a karst formation or subsidence associated with mining, oil, gas, or water drilling? A sudden soil subsidence can occur if the water table has dropped, leaving voids - a condition that can occur in some areas.We would expect such voids to be deeper, however, than just 10-12' below the yard surface - the sudden subsidence case discussed above. .

Related but pressing in a different direction, is your report of basement flooding, suggesting that in fact the area does not drain well and had a high water table.

Sinkholes In the Whitestone New York area, area flooding has a long-standing history and a history of causing problems, including occasional and dangerous sinkholes. In 2009 occupants of co-op buildings on 28th Road between 139th St. and the Whitestone Expressway observed small (2' wide x inches deep) sinkholes recurring in the area after periods of heavy rain. - May 2009 the NY Daily News reported sinkholes along the Whitestone Expressway.

The city recognized that improving its storm drainage system was important in alleviating local sink holes related to rainfall and local flooding, and in 2009 a multi-phase area drainage project was being planned.

The sinkholes produced by those conditions were much smaller than the back yard collapse described above. The largest "sink hole" was about 2-feet in width and just inches deep. But the hazard is someone falling through an opening into a larger, hidden cavity, especially if such a "sinkhole" is really just the visible manifestation of soil wash-out and subsidence over buried debris such as trash, trees, stumps.

Sinkholes in New York City streets are common, have been reported for decades, often related to a burst water main or deterioration in the infrastructure.

Sinkholes In the Buffalo New York area, downtown streets were closed after a sinkhole was reported in September 2008. - Wikinews. The sinkhole was discovered to be a large cavity below a paved city street where a tunnel connected two buildings.

Sinkhole Warning - How Much Time Do You Have ?

A rapid sinkhole caused by well drilling or other sudden alterations to the terrain may not give any warning signs. Otherwise, the collapse process usually occurs gradually enough that a person may leave the affected area safely. The final breakthrough can develop over a period of a few minutes to a few hours. [13]

Sinkhole Repair Services for New York

Watch out: Readers trying to diagnose and deal with sudden soil subsidence or yard collapses should see SINKHOLES - IMMEDIATE SAFETY ACTIONS.

Call your local building department for advice on prompt sinkhole assessment as well as for their advice about which excavation contractors or foundation repair contractors in your immediate area have experience with sinkhole diagnosis and repair. In some circumstances you may need to contact an engineering firm who have sinkhole expertise, typically listed under civil engineers or geotechnical engineer.

Companies identify themselves as sinkhole damage repair experts in New York are listed at SINKHOLE DAMAGE REPAIRS

More Reading

Green link shows where you are in this article series.


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

HTML Comment Box is loading comments...

Technical Reviewers & References

Publisher's Google+ Page by Daniel Friedman

Click to Show or Hide Citations & References