Abandoned Septic Systems

[TomG]

Has anybody heard of methane from old septic systems entering buildings through under-ground electrical conduit?

I made an underground electrical connection to a construction trailer. The underground end of the conduit going to the trailer may be close to an old septic system. Parts of the system are rumored to be a buried car, trenches filled with large rocks and a cement-block cesspool. It would be difficult to find, let alone fill these things in. Small wonder we abandoned the system.

I know that natural gas can enter buildings through under-ground electrical conduit from broken gas mains. I don't know if an old septic system poses a similar risk. I have taken the precaution of sealing the conduit end with electrical putty. I also installed vapour barrier on the trench wall between the conduit and what I think may be part of the old system. I may bury a vent hose near the conduit.

 

[Thomas]

Tom,
Some of the older homes in this area have and septic system before zoning and the state laws were in enforced.
They would have a well drill than the old well was used for septic and cover over with a cement slab.

Does your local sewer department have a meter so you can check to make sure?

Be careful for as you know a spark could be danger.

Take care and stay/w3tcompact/icons/cool.gif

Thomas..NH

 

[Bird]

TomG, I believe the possibility of enough methane to be a danger is very remote; however, the precautions you've taken are not a bad idea (I always believe in overkill for safety). After I retired in Dallas and we spent some time traveling full time in an RV just sightseeing, I spent about two years traveling for a company in Georgia doing gas leakage surveys. Your local gas company should have some very sensitive instruments for locating any hydrocarbons, but I don't know what they would charge to survey your property. Of course, in two years I didn't see everything, but I surveyed a few hundred miles of gas lines, both in towns and cross country, found small amounts of methane in lots of sewer systems, but never enough to be remotely hazardous.

Bird

 

[TomG]

Thanks Bird and Thomas. We live in an area where there is no gas or sewer service. Sort of ironic, since a transcontinental gas pipe line runs within a couple miles of here. A couple of small towns do have gas service, and maybe I can work out a testing deal with them, or I could just take up keeping canaries.

Yikes, old wells for septic tanks? I thought old cars were bad enough. I happy I'm not down-stream from something like that, although there's probably more to the idea than just running sewerage into an old well.

I read recently about a pipeline guy that used Turkey Vultures to check for leaks in new pipelines. The article talked about 'rotten egg' smell, so I'm guessing that new pipeline sections were charged with hydrogen-sulfide gas. The guy just waited to see if any vultures started circling over the pipeline. Apparently, vultures have very sensitive senses of smell, unlike most birds. That is, 'birds,' not 'Bird's.' We may not have gas or sewer service, but Turkey vultures we've got, although the idea is probably more interesting than practical.

Thanks again. I'm happy to hear that I may be over-estimating the risk, but I'll continue to take precautions.

 

[Bird]

TomG, I learned about a number of ways of doing leakage surveys, but Turkey Vultures is a new one on me./w3tcompact/icons/laugh.gif And like you, I live where there is no gas or sewer service, although there is an LPG pipeline only a couple of miles from us. Of course, natural gas is odorless until the odorant is added, and while I don't know about all the pipelines, the biggest one I'm familiar with, running from the Texas coast to New Jersey, has no odorant. That first struck me as odd, since no one would smell even a large leak, but then when I found that it had 950-1000 psi, I guess they figure if it springs a leak, someone will see the rocks and dirt flying./w3tcompact/icons/smile.gif

Bird

 

[TomG]

Yes, no odourant does seem odd. Hope they aren't depending entirely on flying rocks. Maybe pressures at points along the way are compared. That's the way the old under-ground telephone cables worked. The old transcontinental cable lines were charged with nitrogen to keep out moisture etc.

I do know about the odourant. I lived in L.A. when a plant that manufactured the chemical sprung a leak. It caused a major panic in part of the city for awhile. I remember now that the vulture thing came from a recent issue of 'Canadian Geographic,' in an article about the birds.

 

[Bird]

Yeah, TomG, in '93 I was doing a leakage survey in north central Pennsylvania and at the point where the gas company had tapped into the pipeline and was adding the odorant, anyone getting within 50' of the place would have sworn they had a bad gas leak, but there was nothing combustible escaping (and the main pipeline pressure gauge was sitting on 975 psi that day).

Bird