Look for:
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Fill Valves or Fill Pipes: Inspect the yard, garden, or near the foundation of the house for metal pipes sticking up from the ground, usually 2-3 inches in diameter. These were used for filling underground tanks.
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Vent Pipes: Look for a smaller diameter pipe (often capped or with a mushroom-shaped top) near the house foundation or sticking up from the ground. This vent allowed the tank to release pressure.
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Capped or Cut-Off Pipes: Inside basements or crawl spaces, check for pipes that seem to have been sealed off or cut close to the floor or wall, which could have connected to an oil tank in the past.
Additional Evidence:
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Copper Fuel Lines: If visible in the basement or crawlspace, especially if cut off, these often indicate an oil heating system that may have sourced oil from a buried tank.
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Oil Stains or Odors: Unexplained stains or the smell of oil near walls, floors, or in the basement could suggest leaks from a buried tank.
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Old Oil Heating Equipment: Signs of an oil furnace, especially without a current aboveground tank, might mean it was connected to an underground tank.
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Historical Records: Check property paperwork or local records for any mentions of oil heating, tank installations, or removals. Older homes (built before 1970) are more likely to have had tanks installed.
Even if a heating oil tank is unregulated, a leak could be very unfortunate. When an underground tank or pipe leaks, the cleanup can cost tens of thousands of dollars.
One way to address these concerns is to remove the underground tank and replace it with a new underground tank or a new aboveground tank installed in the basement, garage or storage shed.
Underground tank replacement considerations
Like all equipment, tanks have a limited useful life and eventually have to be repaired or replaced. Many underground home heating oil tanks are similar to the 275-gallon steel tanks you have probably seen in basements or garages. These tanks were not designed to be buried and, if left in place, will eventually corrode and leak. Even larger tanks that were specifically designed for underground use will leak if they are not protected from corrosion.
While possible, the odds are that an underground tank 10 or 15 years old probably is not leaking. However, the likelihood of a leak increases as the tank gets older. Even small, slow leaks can pose a serious threat to your family, your neighbors and the environment if they go undiscovered for a long time. And if your tank does leak, you may face a costly cleanup.
Removal costs for an underground tank
Removal can cost from $1000 to $5,000 or more, depending on the size of the tank, its condition, how easily it can be reached, and extent of any soil contamination. To help ensure that you avoid this cost, have the tank condition evaluated by a qualified contractor.
Have a tank tested for leaks
Many underground home heating oil tanks are similar to the 275-gallon steel tanks you have probably seen in basements or garages. These tanks were not designed to be buried and, if left in place, will eventually corrode and leak. Even larger tanks that were specifically designed for underground use will leak if they are not protected from corrosion. If the tank is cracked or rusted through and leaking, it will probably need to be replaced, and contaminated soil will need to be removed and properly disposed of, each of which may be expensive.
Option: emptying oil from a tank and leaving it underground
Depending on jurisdictional regulations, emptying the tank and leaving it underground may be an options... if certain measures are taken.
Regulations may require that aboveground the tank be emptied, cleaned and purged of all vapors. It must be filled with an inert material such as sand, and the vent lines must remain open and intact and the fill line capped or removed.
Removing the tank will make it easier to check for soil contamination. If you decide to sell the home, a bank or the buyer likely will ask for an environmental assessment or the removal of the tank or any contaminated soil. Having the tank and soil inspected when you purchase will allow you to negotiate with the seller for any removal and cleanup costs.
Tank leakage Concerns
Contamination may be indicated by soil that is stained or gives off strong oil odors, a sheen on groundwater, or environmental test results. If the tank is located near any wells, drinking water supplies, wetlands, ponds or streams, or if there are any indications that contamination is present, sampling and analysis is highly recommended .