I dont know if this will work
but when I buried my setup I
bought a bunch of those long mens
socks made of like nylon and
a big container of this blue
chemical cat litter then I filled
several socks with the cat litter
tied them off at the ends then tied
a length of dental floss to each sock
and lowered them all around
the base of the container.
That was a couple years ago
and things are still operational.
I put foam on top of the can to protect
from temp changes of direct sunlight
in the hot summers.
The cat litter is not to stop moisture
just to provide a place for it to go
to and from without coating everything
with dew.
It gets like 140F on the ground here
in summer. Rain of like 2 inches
in a single monsoon storm in july or august
or september (unusual yet does happen
in a short period of time in small areas here).
We get avg of 7 inches (17.78cm per year).
By code our water pipes are to be 18 inches
below ground surface. I did my own water enterance
and was required to do this.
I recommend you use steel pipe on the pvc when
you come above ground and solidly fix the pipe to
some kind of foundation to prevent movement
of the pipe. Pressure testing everything
with a bicycle or tire pump to maybe 50psi
for several hours.

I do not know if any of this has worked since it
has not been uncovered for some time.
I just know I still am getting a signal
from the old HS-10 geophone.
The geophone appeared to have been
exposed to water before i ever purchased it
in the first place. But it still is functional.
Prosit, :-)
geoff

----- Original Message ----- 
From: 
To: 
Sent: Monday, May 17, 2010 2:37 PM
Subject: Re: Mystery to Me


> 
> In a message dated 17/05/2010, icarus@......... writes:
> 
> I called Dr. Haydar Al-Shukri today, and he told me the story of water in  
> the vault.
> _http://www.eas.slu.edu/Earthquake_Center/NM/UALR/ualr.pict.html_ 
> (http://www.eas.slu.edu/Earthquake_Center/NM/UALR/ualr.pict.html)  
> 
> The vault was installed while he was working at St. Louis University, and  
> he is currently at the University of Arkansas at Little Rock. The wires from 
> the vault to the building were encased in PVC pipes.  The seismometer was  
> manufactured by Guralp. One day the instrument stopped working and they  
> investigated as to why. After checking all the instrumentation in the  
> building, they opened up the vault and it was filled with water. It  turned out 
> that a tree had fallen down and they brought in heavy equipment to  remove the 
> tree. Driving over the buried PVC pipe, the heavy vehicle had  fractured the 
> PVC pipe........then, there was a heavy rain, and water leaked  into the 
> broken PVC pipe which filled the vault with water. The vault was  emptied and 
> the instrument forward to Guralp for  repair.
> 
> 
> 
> Hi Bob,
> 
>    One of my previous comments was that the cable pipe  seemed to be 
> buried only about 6" deep. That would agree with the crush  damage. Drains and 
> water pipes are normally ~18" below ground level for several  very good 
> reasons.
>    This suggests cold weather. PVC pipe normally  deforms and then springs 
> back.
> 
>    This is still not very complementary about the  performance of the 
> seismometer. It should be waterproof and floating! Guralp did  have some leakage 
> problems with early seismometers.
>    Quote: The CMG-40T is ''Self-contained in a  waterproof stainless steel 
> case'' Umm?
> 
> 
> If one were to build a similar setup as the U of  Arkansas did, what be the 
> best installation of the connecting pipe  containing cables?  Perhaps 
> V-shape or dip with the pipe,  allowing for drainage? Would some sort of a P-trap 
> be applicable?  How  could one control or prevent condensation etc?
> 
>    On the site photo it looks as if the seismometer  pit is downslope from 
> the buildings. The ground is shale, which is fairly water  resistant. The 
> pit should have been provided with drainage and the cable  extended beyond 
> the seismometer and looped back. 
>    Threading cable through 18ft lengths of tube can be  quite difficult. I 
> hung the tube down a well and fed the cable in from the top.  You can get 
> reels of strip steel for threading electrical conduit. 
>    The concrete being poured looks as if it has stones  in it. It should 
> be cement and sand in equal proportions.
>    You can't seal the vault due to air pressure  changes. 
> 
> I was a little concerned with their installation among  all those trees. 
> Having lived in Arkansas in 2008, I had severe noise  level from the tree 
> motions on windy days. (But, I suppose you have to go with  what you got! Not 
> all installations are ideal.)
> 
>    I would expect the location to be severely effected  by wind noise from 
> the large tall trees. A seismometer needs to be well clear of  any tree 
> roots. This was supposed to be a professional quality installation, but  it 
> seems to be 'a bit short' on both planning and construction. 
>    I note that the seismometer site was moved about  290 x 180 ft back in 
> 2007. 
> 
>    Regards,
> 
>    Chris Chapman
>


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