DRR Q4 Lesson 2: Sinkholes

Sinkhole

It is a depression in the ground that has no natural external surface drainage.

Water drains to the subsurface

Underneath soil/rock is dissolved by groundwater flowing through the material.

Human involvement

Causes of sinkholes

Aquifer systems

The soil above the system is balanced by the water pressure in the aquifer. When water is removed from system it destabilizes the pressure, increasing the chance of a sinkhole forming

Higher chance in urban

Karst Terrain

landscape formed from the dissolution of soluble rocks like limestone and gypsum.

characterized by sinkholes, caves, and underground drainage systems

Dissolution sinkholes

ground with little overburden

Water erodes the rock away

deep impression in the ground forming a basin

Cover-collapse sinkhole

Water erodes rock away underneath overburden

Overburden soil loses stability

Rapid and sudden collapse

Human involvement

Leaky pipes

Sewer leakage

Pumping of groundwater

Construction

Water diversion

These are majors in formation of a sinkhole

Proper construction and maintenance of any underground pipes

Proper groundwater usage

Helps keep water table high and supports overburden

When a sinkhole occurs make sure it is kept trash free

Sinkholes usually have a direct link to drinking water which trash thrown into the sinkhole can lead to pollution of drinking water

Human made sinkholes can be avoidable

Guatemala City's Sinkholes, Guatemala

Happened in 2007, 300 ft. down

Devil's Sinkhole, Texas, U.S.A.

40 ft. by 60 ft. opening, 400 ft. down

Keep Away

Leave Your Impacted House Immediately

Fence or Rope Off the Area

Contact Your Insurance Company

Consult with a Soil Testing Firm or Engineering Company

Monitor the Sinkhole for Signs of Growth

Watch for Further Structural Damage

Avoid Dumping Anything into the Sinkhole

8 Actions To Take if You Believe You Have a SINKHOLE

Keep Away

The first step you should always take if you believe a sinkhole exists on your property is to keep away from it. In particular, make sure you keep children away from the possible sinkhole area. Then, locate any animals you may have and keep them away as well.

Leave Your Impacted House Immediately

Determine if the hole is impacting your house in any way. If it is, then leave the home and stay out of it. The most obvious signs that the hole is impacting your house include the following:

1. Sinking, sagging, or cracking walls

2. Difficulty closing doors and/or windows

3. Cracks in floors, pavement, patios, and/or ground surface in or around the house

Fence or Rope Off the Area

Making sure to use materials that are visible in both the daytime and nighttime, block the area of the sinkhole with fencing or rope. The critical point here is to make it clear to anyone that the area is definitely off limits and to block it off as best you can.

Contact Your Insurance Company

You may find that your insurance policy covers both assessment of the situation as well as repair. At the same time, you may find out that your insurance covers neither. It's important to understand what your insurance covers and does not cover so that you can budget for the right course of action.

Consult with a Soil Testing Firm or Engineering Company

To know for sure if you have a sinkhole, you will need to obtain the results of a test by a licensed engineer with a professional geologist on staff or by a geological testing firm, either of whom can perform an evaluation of your property. Pricing can vary widely from such firms.

Monitor the Sinkhole for Signs of Growth

Sinkholes can change in size rapidly. Continuously monitor the size of your sinkhole, making sure to remain at a safe distance from the sinkhole at all times.

Watch for Further Structural Damage

If you originally decided to stay in your home because you saw no signs of damage impact from the sinkhole, continue checking for signs of damage impact. Sinkhole dangers can evolve quickly, and you need to remain vigilant and be ready to evacuate your home at the first sign of damage.

Avoid Dumping Anything into the Sinkhole

Dumping materials into sinkholes could possibly contaminate groundwater. Before putting anything into a sinkhole, await specific instructions from your local government agency and insurance company. You do not want to be liable for any damage.