Visual & Other Clues Indicating the Risk of Sinkholes in New York, New Jersey, & Elsewhere
InspectAPedia® -
What are sinkholes?
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
Directory of geotechnical engineers
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.
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers nor with topics or services discussed at this website.
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.
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, ASHI 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.
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
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]
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"A Hole in the Ground Erupts, to Estonia's Delight", New York Times, 9 December 2008 p. 10.
History of water usage in Estonia: (5.7 MB PDF) jaagupi.parnu.ee/freshwater/doc/the_history_of_water_usage_systems_in_estonia.pdf
Thanks to reader Y.Z., Whitestone, NY for discussing a back yard collapse 4/1/2010
"Flushing road to disaster? Using sinkhole-plagued street is game of chance, locals say", Clare Trapasso, New York NY DAILY NEWS, 8 May 2009
http://www.nydailynews.com/ny_local/2009/05/08/2009-05-08_flushing_road_to_disaster_using_sinkholeplagued_street
_is_game_of_chance_locals_.html#ixzz0jx0mrAmG) in 2009:
"Sinkhole Reported, Buffalo New York" - Wikinews
http://en.wikinews.org/wiki/Sinkhole_reported_in_Buffalo,_New_York
Washington street between E. Eagle and Clinton was closed to vehicle and pedestrian traffic. Wikinews was on scene and obtained exclusive photos and statements.City officials say the sinkhole is located in an area under the road where a tunnel, about 40 feet wide ... portions of the blacktop were seen caving in near the sidewalks. When city engineers examined the holes, they found it to span the entire width of the street and nearly a half the block's length with the hole being nearly 15 feet deep. Officials say the only thing holding up the road, is the thin layer of concrete and asphalt that make up the road's surface. Wikinews reported (anonymously) that the problems began nearly 10 years previously.
Directory of Geotechnical Engineers in the New York / New Jersey Area
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Dynamic Earth, Jeffrey W. Schaumburg P.E., 245 Main Street - Suite 204 Chester, NJ 07930 Tel: 908.879.9229
Whitestone Associates - Mount Bethel Corp. Center 35 Technology Drive Warren, NJ 07059 Tel: 908.668.7777
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
Diagnosing & Repairing House Structure Problems, Edgar O. Seaquist, McGraw Hill, 1980 ISBN 0-07-056013-7 (obsolete, incomplete, missing most diagnosis steps, but very good reading; out of print but used copies are available at Amazon.com, and reprints are available from some inspection tool suppliers). Ed Seaquist was among the first speakers invited to a series of educational conferences organized by D Friedman for ASHI, the American Society of Home Inspectors, where the topic of inspecting the in-service condition of building structures was first addressed.
Design of Wood Structures - ASD, Donald E. Breyer, Kenneth Fridley, Kelly Cob een, David Pollock, McGraw Hill, 2003, ISBN-10: 0071379320, ISBN-13: 978-0071379328 This book is an update of a long-established text dating from at least 1988 (DJF); Quoting: This book is gives a good grasp of seismic design for wood structures. Many of the examples especially near the end are good practice for the Californa PE Special Seismic Exam design questions. It gives a good grasp of how seismic forces move through a building and how to calculate those forces at various locations.THE CLASSIC TEXT ON WOOD DESIGN UPDATED TO INCLUDE THE LATEST CODES AND DATA. Reflects the most recent provisions of the 2003 International Building Code and 2001 National Design Specification for Wood Construction. Continuing the sterling standard set by earlier editions, this indispensable reference clearly explains the best wood design techniques for the safe handling of gravity and lateral loads. Carefully revised and updated to include the new 2003 International Building Code, ASCE 7-02 Minimum Design Loads for Buildings and Other Structures, the 2001 National Design Specification for Wood Construction, and the most recent Allowable Stress Design.
Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting: A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
"Avoiding Foundation Failures," Robert Marshall, Journal of Light Construction, July, 1996 (Highly recommend this article-DF)
"A Foundation for Unstable Soils," Harris Hyman, P.E., Journal of Light Construction, May 1995
"Backfilling Basics," Buck Bartley, Journal of Light Construction, October 1994
"Inspecting Block Foundations," Donald V. Cohen, P.E., ASHI Reporter, December 1998. This article in turn cites the Fine Homebuilding article noted below.
"When Block Foundations go Bad," Fine Homebuilding, June/July 1998
Straw Bale Home Design, U.S. Department of Energy provides information on strawbale home construction - original source at http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10350
More Straw Bale Building: A Complete Guide to Designing and Building with Straw (Mother Earth News Wiser Living Series), Chris Magwood, Peter Mack, New Society Publishers (February 1, 2005), ISBN-10: 0865715181 ISBN-13: 978-0865715189 - Quoting: Straw bale houses are easy to build, affordable, super energy efficient, environmentally friendly, attractive, and can be designed to match the builder’s personal space needs, esthetics and budget. Despite mushrooming interest in the technique, however, most straw bale books focus on “selling” the dream of straw bale building, but don’t adequately address the most critical issues faced by bale house builders. Moreover, since many developments in this field are recent, few books are completely up to date with the latest techniques. More Straw Bale Building is designed to fill this gap. A completely rewritten edition of the 20,000-copy best--selling original, it leads the potential builder through the entire process of building a bale structure, tackling all the practical issues: finding and choosing bales; developing sound building plans; roofing; electrical, plumbing, and heating systems; building code compliance; and special concerns for builders in northern climates.
Sinkholes and Sudden Land Subsidence References, Products, Consultants
"A Hole in the Ground Erupts, to Estonia's Delight", New York Times, 9 December 2008 p. 10.
History of water usage in Estonia: (5.7 MB PDF) jaagupi.parnu.ee/freshwater/doc/the_history_of_water_usage_systems_in_estonia.pdf
"Quebec Family Dies as Home Vanishes Into Crater, in Reminder of Hidden Menace", Ian Austen, New York Times, 13 May 2010 p. A8. See http://www.nytimes.com/
"Quick Clay", Wikipedia search 5/13/2010 - http://en.wikipedia.org/wiki/Quick_clay
Florida DEP - Department of Environmental Protection, & Florida Geological survey (http://www.dep.state.fl.us/geology/default.htm) on Florida sinkholes: Effects of Sinkholes on Water Conditions Hernando County, Florida, Brett Buff, GIS in Water Resources, 2008, Dr. David R. Maidment, Photos - Tom Scott, Florida Geographic Survey - Web Search 06/09/2010 - http://www.dep.state.fl.us/geology/geologictopics/jacksonsink.htm
and - http://www.dep.state.fl.us/geology/geologictopics/sinkhole.htm
also see
Lane, Ed, 1986, Karst in Florida: Florida Geological Survey Special Publication 29, 100 p.
Foundation Engineering Problems and Hazards in Karst Terranes, James P. Reger, Maryland Geological Survey, web search 06/05/2010, original source: http://www.mgs.md.gov/esic/fs/fs11.html Maryland Geological Survey, 2300 St. Paul Street, Baltimore, MD 21218
"Frost Heaving Forces in Leda Clay", Penner, E., Division of Building Research, National Research Council of Canada, Canadian Geotechnical Journal, NRC Research Press, 1970-2, Vol 7, No 1, PP 8-16, National Research Council of Canada, Accession number 1970-023601, Quoting from original source
The frost heaving forces developed under a 1 ft. (30.5 cm) diameter steel plate were measured in the field throughout one winter. The steel plate was fixed at the ground surface with a rock-anchored reaction frame. heave gauges and thermocouples were installed at various depths to determine the position and temperature of the active heaving zone. The general trend was for the surface force to increase as the winter progressed. when the frost line approached the maximum depth the force was in excess of 30,000 lb (13,608 KG). Estimates of the heaving pressure at the frost line ranged from 7 to 12 psi (0.49 to 0.84 KG/cm) square during this period. The variation of surface heaving force was closely associated with weather conditions. Warming trends resulting in a temperature increase of the frozen layer caused the forces to decline.
"Geoscape Ottowa-Gatineau Landslides", Canada Department of Natural Resources, original source http://geoscape.nrcan.gc.ca/ottawa/landslides_e.php - quoting from that source:
Leda clay slopes in the Ottawa valley are vulnerable to catastrophic landslides. More than 250 landslides, historical and ancient, large and small, have been identified within 60 km of Ottawa. Some of these landslides caused deaths, injuries, and property damage, and their impact extended far beyond the site of the original failure. In spectacular flowslides, the sediment underlying large areas of flat land adjacent to unstable slopes liquefies. The debris may flow up to several kilometres, damming rivers and causing flooding, siltation, and water-quality problems or damaging infrastructure. Geologists and geotechnical engineers can identify potential landslide areas, and appropriate land-use zoning and protective engineering works can reduce the risk to property and people.
Deposits of Leda clay, a potentially unstable material, underlie extensive areas of the Ottawa-Gatineau region. Leda clay is composed of clay- and silt-sized particles of bedrock that were finely ground by glaciers and washed into the Champlain Sea. As the particles settled through the salty water, they were attracted to one another and formed loose clusters that fell to the seafloor. The resulting sediment had a loose but strong framework that was capable of retaining a large amount of water. Following the retreat of the sea, the salts that originally contributed to the bonding of the particles were slowly removed (leached) by fresh water filtering through the ground. If sufficiently disturbed, the leached Leda clay, a weak but water-rich sediment, may liquefy and become a 'quick clay'. Trigger disturbances include river erosion, increases in pore-water pressure (especially during periods of high rainfall or rapid snowmelt), earthquakes, and human activities such as excavation
and construction.
After an initial failure removes the stiffer, weathered crust, the sensitive clay liquefies and collapses, flowing away from the scar. Failures continue in a domino-like fashion, rapidly eating back into the flat land lying behind the failed slope. The flowing mud may raft intact pieces of the stiffer surface material for great distances.
Kochanov, W. E., 1999, Sinkholes in Pennsylvania: Pennsylvania
Geological Survey, 4th ser., Educational Series 11,
33 p., 3rd printing April 2005, Pennsylvania Department of Conservation and Natural Resources / Bureau of Topographic and Geologic Survey, DCNR Educational Series 11, Pennsylvania Geological Survey, Fourth Series, Harrisburg,
1999 - web search 06/05/2010, original source: http://www.dcnr.state.pa.us/topogeo/hazards/es11.pdf - Quoting from the document introduction: The first 18 pages of this booklet contain an explanation of how sinkholes
develop. In order to tell the sinkhole story, it is important to discuss
a number of related geologic disciplines. The words used to describe sinkholes
and these disciplines may be a bit unfamiliar. However, general explanations
are given throughout the booklet to help clarify their meanings.
Key words are printed in bold type for emphasis. The more important
ones are defined in a Glossary that begins on page 29.
The remaining sections, starting with “Sinkholes in the Urban Environment”
(page 18), deal with sinkholes and their impact on our environment.
This includes recognition of subsidence features and sinkhole repair.
Thanks to reader Y.Z., Whitestone, NY for discussing a back yard collapse 4/1/2010
[1] Sarah Cervone, [web page] data from the APIRS database, Graphics by Ann Murray, Sara Reinhart and Vic Ramey, Vic Ramey is
the editor. DEP review by Jeff Schardt and Judy Ludlow. The web page is a
collaboration of the Center for Aquatic and Invasive Plants, University of Florida, and the Bureau of Invasive
Plant Management, Florida Department of Environmental Protection contact: varamey@nersp.nerdc.ufl.edu [A primary resource for this article
[2] Center for Cave and Karst Studies or the
Kentucky
Climate
Center, both at
Western
Kentucky
University
Vanity Fair - web search 06/04/2010 http://www.vanityfair.com/online/daily/2010/06/what-caused-the-guatemala-sinkhole-and-why-is-it-so-round.html
Sinkholes, [on file as /vision/Sinkholes_Virginia_DME.pdf ] - , Virginia Division of Mineral Resources,
Virginia Department of Mines, Minerals and Energy, www.dmme.virginia.gov Virginia Department of Mines, Minerals and Energy
Division of Mineral Resources
900 Natural Resources Drive, Suite 500
Charlottesville, VA 22903
Sales Office: (434) 951-6341 FAX : (434) 951-6365
Geologic Information: (434) 951-6342
http://www.dmme.virginia.gov/
divisionmineralresources.shtml - Web search 06/09/2010
Wikipedia - web search 06/04/2010 - http://en.wikipedia.org/wiki/Guatemala_City
Sink Hole & Related Engineering References
Newton, J. G., 1987, Development of sinkholes resulting from man's activities in the eastern United States: US Geological Survey Circular 968, 54 p.
Sinclair, W. C., 1982, Sinkhole development resulting from ground-water withdrawal in the Tampa Area, Florida: U.S. Geological Survey Water-Resources Investigations 81-50, 19 p.
White, W. B., 1988, Geomorphology and Hydrology of Karst Terrains: Oxford University Press, New York, 464 p.
Williams, J. H. and Vineyard, J. D., 1976, Geologic indicators of subsidence and collapse in karst terrain in Missouri: Presentation at the 55th Annual Meeting, Transportation Research Board, Washington, D.C.
Barry F. Beck, A. J. (1999). Hydrogeology and Engineering Geology of Sinkholes and Karst. Rotterdam, Netherlands: A. A. Balkema.
Beck, B. F. (2003). Sinkholes and the Engineering and Environmental Impacts of Karst. Huntsville, Alabama: The American Society of Civil Engineers.
Beck, B. F. (2005). Sinkholes and the Engineering and Envrionmental Impacts of Karst. San Antonio, Texas: The American Society of Civil Engineers.
Tony Waltham, F. B. (2005). Sinkholes and Subsidence, Karst and Cavernous Rocks in Engineering and Construction. Chichester, United Kingdom: Praxis Publishing.
Whitman D., G. T. (1999). Spatial Interrelationships Between Lake Elevations, Water Tables, and Sinkhole Occurence in Central Florida: A GIS Approach. Photogrammetric Engineering and Remote Sensing , 1169-1178.
Mobile View
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.
