Re: Sewer Odor
Posted by More on December 17, 2001 at 23:01:57:
In response to Re: Sewer Odor
Excellent Questions!!!!!!!

It is not safe to breathe the odor for long periods of time in concentrated unvented areas, and it will not go away without corrections. The gravity sewer house lateral is supposed to be installed with a minimum of 1/4 inch per foot fall from the point of connection to the point of saddle connection in the Main in the street. When plastic sewer lateral is installed with bent swayed low points and stagnation areas in it, which do not adequately drain at 1/4 inch per foot (and therefore do not adequately dry out) then the sewage waste lays in the lateral, breeds bacteria in the dark warm nutrient rich environment, released Hydrogen Sulfide gas into the lateral, and allows it to fester there (because it is heavier than air but lighter than water), captive in the lateral. When the outside air pressure lowers and becomes moisture laden ( and heavier) and therefore doesn't rise with the thermals from the surrounding heated soil, it settles and surrounds the lower portions of the house and seeps into cracks, penetrations, and windows below the roof vent.

When the house is served by a septic tank and disposal field system which does not drain at 1/4 inch per foot and dry out, the bacteriological digestion is exacerbated. The septic system is designed to drain the treated water into the soil, and also to evapotranspirate the warmer gas and vapor through the soil, to allow the plumbing and pipe to stand dry, and therefore allow breathing through the piping through the roof vent, which creates too cool an environment for adequate bacteria breeding. When you breathe in Hydrogen sulfide, you smell the rotten egg smell for the first three breaths, and then it paralyzes the nerve endings in your nostrils which makes you think it has gone away. BUT IT IS STILL PRESENT! It is heavier than air, and therefore builds in your lungs and in a concentrated environment can cause drowning of very small children or weaker elderly folks. BE CAREFUL. Ask the septic tank installer to install an aereator on the end of the septic disposal field (sometimes called a breather) and also to extend the roof vent to a point higher than the roof peak.

: In our new home we've had a sewer gas odor in the
: downstairs bathroom since we moved in a year ago.
: The smell only occurs during and after it rains or
: snows. Our builder, inspector, and septic tank installer are all scratching their heads. Is it safe
: to breathe the odor and will it ever go away?

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