[Greenbuilding] copper pipe and underground propane leak

[Chris Green]

Reuben Deumling wrote:
> Two years ago I buried a 45' copper line from my propane tank through the
> foundation into my crawlspace. The line was two feet below grade. Yesterday
> I discovered 120 gallons of propane missing from the tank, 

> <snip>
> My question is whether anyone on this list has heard of a big leak like this
> (~1gal/hr) developing suddenly underground?
I have: A motel unit in Kamloops, B.C. exploded a few years ago, killing 
two people--a construction worker and his young child--who were renting 
the unit while working in town. The explosion also set the building on 
fire.
It is likely the leak started that day while the man was at work, since 
it's likely he would have known to say something about the odour if it 
had leaked before he left for the day.
As in your case, the copper line ran through the foundation and into a 
crawl space under the motel units.
The authorities investigating this incident came to realize that the 
copper pipes had been corroded by sulfur which is naturally present in 
the soil here: moisture in the ground mixes with the sulfur to create 
sulfuric acid.
Up until that point, no-one realized this was a problem. Now, no-one 
around here uses copper pipes for underground gas lines, but use instead 
the plastic pipes intended for gas lines. Ordinary black plastic pipe is 
slightly porous, by the way, so should also be avoided. Use the plastic  
piping designed for gas lines.
And I would avoid burying any brass clamps/crimps if  these are used.

The sulfuric acid created by the above method is also known to slowly 
weaken concrete and the rebar inside it as moisture containing the acid 
is pulled up through the slabs.  A lot of older buildings--over 30 years 
old--in the area will have to have their slab floors and foundations 
repaired as time passes. Our concrete suppliers now add something to 
prevent this corrosion.

It is reasonable to assume that other acidic soils, such as those found 
in forested areas, will also corrode copper and other metals.


Chris Green.