Home & Garden Columns

About the House: Who’s Buried in the Yard?

By Matt Cantor
Friday March 21, 2008

I crawled out from underneath someone’s house the other day and placed in the hands of a brow-knit homeowner, a pithy black rock. Before she could form the words for what she could not quite specify, I said “Coal … Anthracite, I think” (as though I know anything about coal). Since she continued to bear that befuddled look, I explained that I’d been under the house and that there, near the furnace, I’d found a few of these black shiny artifacts of geophysics. 

“I’m fairly certain that the hulk of a furnace in the crawlspace was once a coal burning device” I said and that it had been converted from this to natural gas at some point, perhaps 90 years ago. But that wasn’t my real concern. A few piece of coal in the crawlspace aren’t particularly dangerous although the converted furnace was long overdue for replacement.  

My concern was related but only as a first cousin removed once or twice. Earlier in the day, I had noticed a pipe running up the side of the house that seemed to stop, think a while, go back down an inch or two and just give up. Oh, I said to myself. Could there be an oil tank on the property. 

In the first two decades of the twentieth century, oil tanks were being used a fair amount in our area. Fuel oil, still commonly used in the East Coast was used to run central heating systems. Some of these systems heated water and some heated air and used ducting. While virtually none of these exist in working form today (I’ve never seen one ‘round these parts) the tanks and piping may still be lurking beneath your soil. 

As regulations regarding safe ground water have developed over the past few decades, this issue has brought with it some financial hazards. As a homeowner, you may be held accountable, should a tank of this kind be found and known to leak.  

Discovery of a tank requires that it be examined to determine if it IS leaking. If a tank is found to be leaking, it will have to be removed along with enough soil to assure that the ground water is safe.  

And water is the issue. Water is an increasingly precious resource and local harvesting of water may be on its way back as the cost of water and water delivery increases in coming decades. 

Tim Hallen of San Francisco’s Golden Gate Tank Removal helped me get some of my facts straight. While most tanks are not leaking, it’s almost impossible to tell if they have, until a tank has been removed. Further, all tanks will eventually leak, so keeping one is a bad idea.  

Once your tank is removed (this may be in the ballpark of ten grand) the soil can then be tested and removed to some extent if needed. Removal of soil is generally in the three to six thousand dollar range including backfilling with clean soil. 

Communities vary in the cleanliness required in the soil around tanks. While an Oakland house may allow as much as one hundred PPM petroleum hydrocarbon, some areas allow no detectable amount and may demand increased soils replacement. 

If you’re living on a property that was used as a residence over eighty years ago, you may want to look for some of the following items as they may indicate the presence of an oil tank: 

Small diameter tubing in the area of the furnace or in an area that previously housed a furnace. This can include a pair of quarter inch copper tubes or a single small diameter galvanized pipe. Other signs are pipes that make a U-turn after they come up out of the ground near the house exterior. This is a breather for the oil tank and is essentially, an open pipe that won’t take on rain water by being turned downward. 

I’m told, but have never seen, a pump and wiring system in the crawlspace for pumping heavy oil. This may go along with the dual tubing I mentioned above. Apparently, when great grandpa bought the oil system, an array of numbered oil grades were available (ranging from Bunker oil, whatever that was, to the more familiar diesel oil). 

Lastly, there may be signs of a tank in the form of a cover, cap or medallion in the driveway or sidewalk. These are fill caps and no different from the one on your car. Remove them (if you can) and you’ll find (or smell) an oil storage system. 

Tim tells me that most tanks aren’t leaking today (his rough guess was 95 percent) but that many tank removal companies will claim higher numbers so beware of those who want to perform further soil removal when it’s not necessary. A second opinion after removal may be your only option. 

If you have a tank, it’s most likely to be near the sidewalk for the simple reason that it was easiest to install. A typical size is about ten feet long and five-feet wide (goodness!) so it’s quite a project taking one out. A backyard tank may be smaller. 

Expect oil to remain inside. The output tubing on these tanks wasn’t at the bottom so they tend to still have some oil, even if they were run to a sputter. 

While it can be a hard call deciding when to have an expert out to check the property, the cost is really quite small. For about $75 you can have an expert check your property for a tank. My feeling is that if the property you’re on is older (including those that bore a previous home), it’s cheap assurance to have this done.  

If you’re in a neighborhood that was likely to have had a large furnace in the aught through the ‘30s (larger houses generally) it’s worth the money. 

Rachel Carson said, “In an age when man has forgotten his origins and is blind even to his most essential needs for survival, water along with other resources has become the victim of his indifference.” 

That indifference may soon become a pressing and intimately personal matter in the coming decades.  

Discovering your own role in tainting that vital resource may, today, seem an irrelevant nuisance but tomorrow may make all the difference. 


Got a question about home repairs and inspections? Send them to Matt Cantor at mgcantor@pacbell.net.