A year ago, Alan and Caroline Millet filled the tank in the crawl-space below their living room floor with 250 gallons of heating oil to keep their Edgewater home warm during the winter months.
Soon the smell of oil began to permeate all the rooms in their house, and they worried that the noxious liquid might have seeped into their water supply. An inspection showed the rusty edge of the steel tank, which was almost four decades old, had ruptured and leaked all of the oil into the ground.
"We had to get under the house, dig out all the dirt and cut up the tank," Caroline Millet said. "Then we had to test the soil, the well water and get a new tank. A nightmare."
Six months, $15,000 and 2 tons of contaminated soil later, the Millets could finally heat their home again.
More and more homeowners are finding similar spills and drips from heating oil storage tanks as they fire up their furnaces. While the winter months are always busy for the state agency that oversees such problems, the past few years have brought an influx of leaks due to old, deteriorating tanks.
The number of incidents reported by homeowners and business owners who have had to remove or replace a storage tank has quintupled in the past five years, according to a Capital News Service analysis of records kept by the Maryland Department of the Environment.
In 1999, glitches with heating oil tanks made up less than 3 percent of the calls to which the agency responded. This year leaks, spills and tank removals made up nearly 49 percent of those calls, according to the database.
The agency oversees the inspection and maintenance of all oil and gasoline storage tanks in the state, including those buried. While commercial storage tanks are subject to more frequent inspections and maintenance by state workers, the agency does not regulate residential tanks unless the owner reports a problem, or unless it holds more than 1,100 gallons.
The rapid rise in the number of faulty storage tanks, particularly on residential property, probably results from people using aging tanks that haven't been maintained or even looked at since their home was built half a century ago, said Herb Meade, who directs the state's oil control program.
"Underground storage tanks can leak for years and years, and you wouldn't know," Meade said. About 350,000 Marylanders rely on oil to heat their homes.
Traditional steel tanks last between 15 and 20 years, he said, but "most people have had their tanks for 35 or 40 years, and when you pull it out of the ground it looks like Swiss cheese."
Cheryl Wells, who owns American Tank and Petroleum services in Anne Arundel County, said 95 percent of the tanks her technicians remove from the ground are leaking because of corrosion.
"Most of the time people have no idea that they should even think about the tank in the backyard that they use to heat their homes," she said. "They just fill it up every year and expect it will be OK."
That out-of-sight, out-of-mind attitude can have dangerous - and expensive - consequences. If heating oil seeps into the groundwater, it can contaminate well water for the whole neighborhood. Such incidents are rare, however, and most leaks are caught before they reach the well.
Oil is also a fire hazard and can cause adverse respiratory and skin reactions if people come in direct contact with it.
Most commonly, Meade said, the oil will trickle into the basement or foundation, and the strong fumes can "drive people right out of their home." He suggests replacing buried tanks with above-ground tanks, which can be inspected more easily. Leaks from an above-ground tank can also be contained more quickly.
Even a few drops of oil can pose a threat, and residents are required to report trouble to the state and have it inspected as soon as possible or risk paying a hefty fine - as much as $10,000 each day the tank goes unreported. Soil and water tests are almost always run to make sure no contamination has occurred.
Bonita Lepore of Towson was doing laundry in her basement when she noticed a tiny pool of oil on the floor beneath her tank. Although the leak was small, she replaced the tank because it was old.
"I've been living here for 37 years, and God knows how long the former owner had it," she said.
The cost of eliminating most leaks doesn't exceed $5,000, which includes removing the old tank, installing a new one and cleaning up any contaminated soil, Wells said. But if a tank has been leaking for several years and oil has crept into the groundwater, the price could be $50,000 or more.
Leaks from larger tanks at gas stations make up the majority of the cases the state deals with, Meade said. If gasoline enters the groundwater supply, four or five water wells can be contaminated with chemicals more harmful than those in heating oil.