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Leaking pipe.  From www.epa.gov OUST siteContents

Why should you be concerned if you have an underground tank?
Could your tank be leaking?

Signs of leakage
What causes leaks?
What is your liability?
How can you avoid problems?
What should you look for when you inspect your tank (whether it is above or underground)
What should you do if you have an aboveground tank?
What should you do if you want to replace your underground tank?
What should you do if your tank has leaked?
Who can you contact for more information?
References and Acknowledgements


Home heating oil (#2 Fuel Oil) is usually stored onsite in a tank that holds about 275 gallons, located in a basement, garage or underground. Note: This information applies to residential tanks used for home heating oil.  Non-residential tanks containing oil or other materials may be subject to additional regulation by the State of Connecticut Department of Environmental Protection, Underground Tank Program at (860) 424-3376 or 4061 for more information.

Why should you be concerned if you have an underground tank?

Fuel oil is a toxic and hazardous substance. Underground tanks can leak, and leaks can go undetected for years. They can contaminate soil, drinking water wells, surface water and groundwater. This is especially a concern in Woodstock, CT, where we depend on groundwater for our drinking water.  Tanks near a drinking water well (within 100-500 feet) pose a threat, especially if they are upslope.  Leaks can also ruin septic systems, cause odor and vapor problems, and enter sumps that can then result in contamination of storm/sanitary sewers, surface water and drainage ditches. 

Could your tank be leaking? 

The CT Department of Environmental Protection and the U.S. Environmental Protection Agency estimate that one out of every four existing bare steel tanks may be leaking. The typical life expectancy of bare steel tanks in Connecticut is only about 10 - 18 years. 

Signs of leakage include:

bullet Unexpected consumption of oil.
bullet Tank taking on water.
bullet Oil-like sheen on streams or on wet places near the tank.
bullet Soil nearby stained with petroleum. 
bullet Constant, strong smell of petroleum near the tank.
bullet Fuel odors near plumbing or sewer line openings or basement.
bullet Smell or taste petroleum in your drinking water.

In one Connecticut town, a leaking underground tank was discovered after people noticed that the maple syrup harvested from trees nearby tasted like oil. If your drinking water smells or tastes of petroleum, the groundwater may already be contaminated.  Contact the local health department immediately

What causes leaks? (DON'Ts)

bullet Overfills.  A study conducted in Alaska estimated that 26% of all household heating oil releases were caused by overfilling the tank.
bullet Corrosion by soil and moisture.  Unlike commercial underground storage tanks, residential tanks are nCorroded tank.  From www.epa.gov OUST siteot subject to strict regulation. Until recently, they were made of steel painted or coated with asphalt, and had a one year warranty for manufacturing defects only. Most older tanks don't have corrosion protection. Acidic or wet soils (e.g., where the water table is near the surface of the ground) can significantly speed up the rate of corrosion of underground metal tanks and piping. Any other underground metal can increase the rate of corrosion.
bullet Improper tank maintenance such as faulty or open valves, non-operable shut-off valves, improper fittings, ruptured fuel lines due to loose tank fittings, damaged fuel lines, and damaged or misused filters/water separators. Even the newer designs must be properly maintained to ensure integrity. Pipes, hoses, valves and fittings connected to a storage tank can be a major source of leaks.
bullet Improper design and installation of tanks and supply lines.  Failure to place clean fill around tanks, or  scratches or dents caused by careless installation (which can increase corrosion and tank deterioration). Installation in an area where heavy vehicles can drive over it. Installation in soils that have a permanent water table less than 10 feet from the ground surface, or in a floodplain. 
bullet Vandalism
bullet Accidents
bullet Weather-related factors such as frost heaving.

What is your liability?

Liability for cleanup of pollution (wherever it may travel) lies with the homeowner.  Few insurance policies cover residential underground storage tanks. Depending on the extent of pollution, clean up costs can be very high.  One study found the average cost to clean up a residential oil release was $15,000, and the cost can be much higher if the groundwater has been polluted.  In addition to being financially responsible for cleaning up petroleum-contaminated soils and groundwater, tank owners can also be held liable for third-party bodily injury and property damages. Litigation is very possible if the oil contaminates a neighbor's well or the vapors invade their basements or crawl spaces, sewers, sumps, utility trenches, and streams.

If you're planning on selling your home, the buyer may want assurances that the tank is not leaking, or may want it removed out of concern about assuming the potential liability.  The process of having a tank tested for leaks can take months, so plan ahead. The value of home can be significantly reduced by a leaking tank. 

How can you avoid problems?


Replace existing USTs with aboveground tanks located in a basement or garage.  For new houses, put tanks for aboveground.
If you must put your tank underground, use a tank that meets State commercial tank integrity standards--e.g., corrosion protected steel or listed fiberglass tanks.  Double-walled tanks and piping are more expensive, but offer greater protection. Install cathodic protection, which uses an electric current to protect the tank from the corrosive effect of soil moisture. (It is expensive to apply corrosion protection to existing tanks,  and may be more cost effective to replace them.) Put supply lines above basement floors, or encased them in a plastic sleeve (larger pipe) before they are cemented over. Slope pipes so they drain back into the tank.  
Understand your tank system and how it works. You should know  tank size, age, construction material (for both the tank and piping), and whom to call if a repair is needed.
Discuss fuel needs, fuel delivery procedures and what to do if a spill occurs during filling with your delivery service.
Keep track of all deliveries and how much fuel you use, and compare it to last season. Check tank levels for unusual losses, and report sudden changes in product levels to a heating repair professional or your oil supplier.
Keep the fill pipe visible and accessible for the delivery company.
Keep the vent line clear of any snow, ice, or insect nests to prevent pressurization.
Protect fuel lines from damage by vehicles or snow from the roof.
Install a shutoff valve at the tank outlet to isolate the fuel line in case it starts to leak.
Don't let children play around the tank.
Don't leave your tank unattended when it is being filled.  Watch deliveries to prevent spills and overfills.
Secure your tank as much as possible to prevent vandalism, and check it periodically.  Consider using a locking cap on the fill pipe to prevent vandalism.
If your tank is over 10 years old, have it tested by a company that uses State-approved methods.
Have your well tested if you suspect fuel contamination.

What should you look for when you inspect your tank? (whether it is above or below ground)

Know the condition of your tank.  A monthly check is recommended. 

bullet Check for spills or overfills around the fill pipe, vent line or tank.  Check the concrete pad under the tank for any indication of fuel leaks.
bullet Ensure that pipe connections are clean and tight. Look for leaks from fittings, valves, filters, tank gauges and pipes. 
bullet Look for rust spots, wet spots, or excessive dents in the tank surface. 
bullet Check for tank instability. Legs for aboveground tanks should be stable and resting on sturdy footing. 
bullet The bottom of the tank should be off the ground, and clear of debris, leaves, snow, etc. 
bullet Check for obstructions (insect nests, ice, snow) in the vent pipe. 
bullet Check for water in the filter and tank.

What should you do if you have an aboveground tank?

bullet To protect against fire and explosion, contact your local building inspector to make sure that that tank meets local fire protection standards. The location must comply with state and local building and fire codes.
bullet Install the tank a safe distance from water bodies, wells and water tables (500 feet is recommended). 
bullet Tanks on hillsides should be properly anchored. Tanks located in floodplains should be secured against floatation by being anchored to a steel dike or encased in concrete.
bullet Install a tank constructed of corrosion resistant materials, double-walled, and with a wall thickness of at least 7/16". 
bullet Put a roof over the tank to protect it from rainwater.
bullet Protect piping from traffic. Posts made of 4" steel pipe filled with concrete provide a good barrier around aboveground tanks.
bullet Consider installing a secondary containment area under the tank. Construct a concrete pad vault around the tank made of concrete or an impermeable liner, with dikes or berms around it to collect spills, and minimize potential runoff if leaks or spills do occur. 
bullet Paint over rust spots.  Repair the coating.
bullet Avoid using the area around or underneath the tank for storage.
bullet Remove nearby trash and weeds.

What should you do if you want to replace your underground tank?

bullet Notify the town building inspector before you have the tank pulled, to ensure that precautions are taken to prevent problems. 
bullet Have the existing tank and fuel lines completely pumped out. Use a reputable, qualified contractor to clean out the tank and remove it from the ground, along with any contaminated soil. (If you left it in place, it could continue to corrode and leak, someone might try to put something in it in the future, and it could also collapse and destabilize the soil above. There is an option to fill it with a concrete slurry, but removal is best.)  If the tank is removed, it must be disposed of properly per DEP regulations. (It can NOT go to the Transfer Station).  Any connecting lines left in place should be disconnected or plugged.
bullet If you find contaminated soil, you must report it to the DEP, Oils & Chemical Spills Division (the contractor will usually do this for you).  
bullet Keep a record (in case there is legal action in the event of groundwater problems, or in case you sell your property) of all agencies contacted, the date tank was filled/removed, the persons or companies who did the work and a copy of the contract, and photographs of the process if possible.  

What do you do if your tank has leaked?

See this fact sheet by the CT Department of Environmental Protection with answers to Frequently Asked Questions.  Report it to the State of Connecticut DEP, Oil & Chemical Spill Response Division and the Local Fire Marshall immediately. If obvious signs of a leak or spill are found (such as petroleum vapors or oil on the property), stop the flow at the source and contain the oil that has spilled. The sooner you stop the leak and begin the cleanup, the cheaper it will be.  If your water has been contaminated, it can be treated.  You will probably need to have a licensed contractor remove the underground tank and piping for proper disposal.  Soil and well sampling and soil excavation may be needed.  

Who can you contact for more information?

All information on this website is intended for your general knowledge.  You should consult with the appropriate regulatory agencies for specific requirements.

bullet State of Connecticut Department of Environmental Protection (DEP), Underground Storage Tank Program, (860) 424-3374.  See their  fact sheet.
bullet DEP, Oil & Chemical Spill Response Emergency Reporting (24 hour) 860-424-3338 or 4062 (to report a spill or leak)
bullet Town of Woodstock Fire Marshall at (860) 963-2347
bullet Town of Woodstock Building Inspector at (860) 928-1388, e-mail: buildingdept@townofwoodstock.com.
bullet DEP Potable Water Program, (860) 434-3705 for advice on well water testing and treatment OR
bullet Northeast District Department of Health, 136 Main Street, Killingly, (860) 774-7350 for advice on well water testing and treatment

More Information, Acknowledgements and References:

  • Citizen's Guide to Ground-Water Protection, EPA 440/6-90-004, April 1990.
  • Heating Oil Tank Guidance, Division of Spill Prevention and Response, http://www.state.ak.us/dec/dspar/stp/heat.htm.
  • National Farm*A*Syst Program, online AG-567, WQWM-173, last updated 1/31/00 by Janet Young, North Carolina Extension Service, http://www.soil.ncsu.edu/assist/homeassist/fuel.
  • Petroleum Product Storage, Agricultural Environmental Management Reference Sheet, Barbara Bellows, Cornell University Department of Agriculture and Biological Engineering.
  • Protecting Connecticut's Groundwater, A Guide for Local Officials, State of Connecticut Department of Environmental Protection, Hartford, CT, April 1997, Supplement C.5, Pages 147-148.
  • Reducing the Risk of Groundwater Contamination by Improving Petroleum-Product Storage, Water Quality Initiative publication WQ678 - New October 15, 1995, http://muextension.missouri.edu/xplor/envqual/wq0678.htm.
Conservation Commission
The civilized people of today look back with horror at their medieval ancestors who wantonly destroyed great works of art or sat slothfully by while they destroyed. We have passed this stage.... Here in the U.S. we turn our rivers and streams into sewers and dumping grounds, we pollute the air, we destroy our forests and exterminate fishes, birds and mammals - not to speak of vulgarizing charming landscapes with hideous advertisements. But at best it looks as if our people were awakening.

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