Two fires linked to methane from septic tanks

Sunday, May 23, 2004

Most people are aware that decorative candles, left unattended, can be a fire hazard. What is less obvious is that a faulty septic tank system can also cause a fire.

What members of one household found out earlier this month is that a combination of the two can, and did, set a house ablaze.

John Sachen, training officer for the Delta Fire District, said that rural residents should be especially aware that danger could be lurking in their bathroom.

Two such instances happened within a year's time, Sachen said. The most recent was on May 9 on County Road 439. The homeowner noticed an unpleasant odor coming from the bathroom, where the toilet had been removed. The odor came from a leaking pipe leading from the septic tank. The woman lit a scented candle and closed the door.

The candle ignited sewer gas, and a fire erupted.

In April 2003, a motorist noticed a fire in a house on Highway 25 between Delta and Blomeyer. The house was empty because it was being renovated. The owner had pulled out the commode in the bathroom and covered the hole, as he should have, Sachen said, but somehow the covering was dislodged. What fire officials believe happened, he said, is that the pilot light from the water heater kicked on and ignited sewer gas.

The result was not only a fire but an explosion.

"We found a window frame broken out and broken glass about 35 or 40 feet away," Sachen said.

Sewer gas -- methane -- is lighter than air and will rise and collect in a small area like a closed bathroom, Sachen said. In cities where there are building codes, homes are generally built with a vent pipe leading from the septic tank through the roof to let the gas escape.

In rural areas, where building codes are less likely to have been enacted, some houses don't have those vents, Sachen said.

"A lot of people don't think it's important, that it's there just to vent odors," Sachen said. "Sewer gases are as ignitable as liquid petroleum or natural gas."

He advises that anyone building or remodeling a home where there are no building codes hire a plumber to install a vent pipe or learn how to install one. He also suggests that anyone who notices a strong, suspicious odor coming from a septic tank not take any chances -- call the fire department to come investigate.

"It's not uncommon for gases to ignite by an unknown source," he said.

Gases could ignite by someone flipping a light switch. Or lighting a scented candle.

Glass can crack

Sachen also advised that people be cautious with candles, especially those that come in glass containers.

Often, he said, those containers are not made of fireproof glass and can crack from the heat of the candle. He pointed out that the labels on the packaging caution that even those encased in glass should be placed in another container for safety.

Also, candles that are marketed as being able to burn for 30 or 40 hours should not be burned for more than three or four hours at a time. Wax in candles that are burned longer than that can pool and spill over, igniting whatever might be nearby, he said.

In addition, if a candle has burned too long, the wick could flip to one side and the oxygen in the air around it could cause a brief, but large, flame that could set nearby materials on fire.

It's easy, he said, to light a decorative candle and forget about it, allowing it to burn too long. Some people also misuse candles, such as one woman who burned candles for warmth in her oven because the electricity was cut off.

"That created an extremely hot environment," he said. "The wax melted and set fire to the floor and to the house."

335-6611, extension 160

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