There are still a few oil burning furnaces. Most of the houses I inspect are heated with natural gas. (I’m seeing more and more geothermal heating systems, but those are still relatively rare.) But natural gas was not always available Many older houses had furnaces and boilers that used fuel oil, which was delivered via tanker truck. The fuel oil was pumped into tanks that were either in the basement of the house or buried next to it. When the furnace or boiler got old and replaced, the tanks were often left behind. And forgotten. Over the years, the tanks slowly corrode, and unused fuel can seep into the ground.
Once free from the tank, petroleum will sink through unsaturated soil and enter the water table. There, much of the chemical will vaporize and eventually bubble up through the ground’s surface. In addition to the risks posed by other petroleum products, leaked fuel oil presents the risk of fire and explosion, especially if the fumes collect in buildings. Any petroleum-contaminated water that is ingested or used to bathe is potentially deadly. Tanks are capable of leaking chemicals for many years, since the corrosion process is typically slow.
Benzene, toluene, ethylbenzene and xylenes, collectively known as the BTEX compounds, are the most hazardous chemicals found in petroleum. Benzene-contaminated water has been proven to cause cancer. Have you ever smelled diesel fumes? Heating oil and diesel fuel are the same product.
So when I inspect an older home, I make a point of looking for signs indicating the presence of a buried oil tank. Two pipes coming from the ground outside the house are a strong indicator. Sometimes snow, bushes or soil make them hard to see. A pipe coming through the basement wall indicates that there was a buried tank, but not whether or not it’s still there.
There are a few companies around that can remove the tank and look for soil contamination. The one I usually recommend is Dean’s Tank Removal. They have been around for a very long time, and have a well-earned reputation for quality work at a good price. (No, I didn’t get paid for saying that. I just really like the company).