I have a 550-gallon tank buried in the front yard of my home. Two years ago my wife and I were in the same dilemma as you are now; considering the purchase of this home, and reading all the horror stories we could find. But this is what we learned:
Point One – Nothing lasts forever, including fuel oil tanks. That goes for any residential tank, including one’s sitting on the side of the home, or in the basement. My tank is about 50 years old. Because it is well above the water table, I could expect to get another 10 years out of it. If the tank was located in soil with a higher water content, the original tank would have failed long before we bought the house, and I would probably be looking at replacing that one by now. Aboveground tanks fail somewhere in the middle, at say, maybe, 30 years. We’re talking steel ones. Some of the new composite types will last 100 years, so they say.
Point Two - .What happens when a tank fails? Well, in the case of an underground unit, moisture will begin to enter the tank and collect at the bottom. The tanks’ shape will cause the water to pool where it can be easily identified. Water is thinner than the fuel oil, so it will begin to seep in before the hole in the tank is big enough to allow an appreciable amount of oil to escape. If enough water accumulates, your heater will sputter when on, and maybe not even light (a sign). Eventually, fuel oil will begin to seep into the surrounding soil, and the type of soil will determine how far it travels and how fast. The point here is that monthly testing can catch the problem before it really becomes a problem. Fuel oil will travel much slower in the ground than gasoline, and will biodegrade faster. On the other hand, an aboveground tank will begin to “sweat” oil when it is beginning to fail, and often this is not really noticeable. When it finally fails, since there is nothing but air supporting the tank, usually the tank simply bursts, and the entire contents are spilled out on the yard or basement floor.
Point Three – Should I worry about buying a home with a buried tank? No. Concerned? Yes. Educated? Definitely!!! So here is what we did; Our attorney advised us to have a clause in the contract to have the agreement subject to a tank test. There are several tests available. One is a pressure test. They pump the tank with air pressure, then see how it holds. We were told that this could also cause the tank to fail from the pressure, so we choose instead to have an ultrasound test. A small robot is lowered inside, and crawls around, bouncing sound waves off the interior. It was a $450 test, but it did not involve digging up the yard. Next, we found out that most all fuel oil suppliers sell tank insurance. Ours cost $129 a year, and covers about $100,000 in soil remediation, plus $1500 towards tank replacement. Replacement can run $3000, but the idea here is to keep the EPA from taking my home cause I cannot afford the environmental cleanup. As a sidebar, the fact that this insurance only costs $129 should tell you something; they know your tank will eventually fail, hence the fact that they do not cover it’s entire replacement, but statistically, the environmental impact is minimal. Now, they (the fuel oil company) will test the tank regularly for leaks. They want to catch the problem as early as possible. Their test consists of dipping a stick with a paste on the tip, which turns color when it comes in contact with water. They measure how much is at the bottom. There’s always some moisture there, they just want to know if the amount is rising rapidly. I have less than ˝”, so considering the age of the tank (and the fact that it was missing its cap for awhile) is extremely good the amount remains consistent to this day.
In Conclusion – We do not think about our tank anymore. We know we’re covered when the inevitable happens. In the beginning we were planning to have the tank replaced right away, with either a new one in the same place, or in the basement or garage. Well, in 15 years I will have spent in insurance premiums the equivalent of half of the tank’s replacement cost, so we left it in. Everything I wrote here is based on a tank that is currently in use. If you are talking about a tank that has not been used for years, then all bets are off. Most places require the tank’s removal when no longer used, but many times people do not follow that law. An unused tank could have been leaking for years unchecked. Now, you really have a problem. Find out how old the tank is, and, if replaced, did it replace one that was located in the same spot, or is there an abandoned one somewhere else in the yard. Many of the horror stories on the web seem to fit this scenario. Insist on knowing everything before you buy.