[ANSS-netops] Trillium Compact installation

[David S. Croker]

Thanks Mark (and others).  All good comments.  Looks like we will 
always have to trade ease and cost of installation and maintenance 
with data quality.  And accessibility (ie, how long does it take to 
uncover the vault when you need to and can you get the lid off after 
its been sitting in the soil for 3 years).

Paul Bodin shared a couple thoughts:
"That said, based on my previous experiences and not ever having used 
a Tcompact, I nevertheless think that direct burial is the most 
likely to be successful. i.e., narrow borehole as deep as you can 
conveniently get (1-2 m?), packed in sand. If you put them in a tube, 
I'd argue for a fairly compliant material - i.e. pvc rather than 
steel---and something with a low coefficient of thermal expansivity."
He also included a rough draft of a paper he wrote and submitted to 
BSSA on "some of the sad facts we've learned about long period 
seismometry and vault design over the past year."  With his 
permission, I can forward it to everyone.

Dave Drobeck chimed in with similar thoughts as Mark and I, and 
similar concerns that maybe our vaults have not been as thoroughly 
tested as they perhaps should be.  Sounds like a perfect task for 
Bob.  Part of the problem is that no one vault is appropriate, or 
even possible, at all locations.

The difficult thing the NCSN is facing for this summer is how to 
install a C-Trill (or is it Tcompact, or Trilco?) in a location where 
metamorphic quartzite bedrock is right on the surface and the Forest 
Service needs us to be as discreet and low-profile as possible 
(forget a backhoe).

Mark, that's a cute little vault you have in the attachments.  Can 
you point me to a link that shows me what it is?  I assume it's water 
tight?  Is the bottom removed?

Thanks again,
Dave

At 09:58 PM 7/19/2011, Mark E. Meremonte wrote:
>Hi Dave,
>
>For 6 months to a year we use the small vault systems we developed 
>for portable systems:  see attachments.  For the portables we try to 
>install insulated vaults at least 6 inches below the 
>surface.   However, for permanent install I would not install less 
>than a foot below the surface; or, if necessary, we mound at least a 
>foot of soil over top of vault if less than a foot below surface.
>
>For permanent I will probably be using a smaller version of our 
>regional vaults with sandblasted glass bases and using 
>insulation.   See 
>ftp://ftpext.usgs.gov/pub/cr/co/golden/hazards/Eq_Effects/Vaults/Regional/5_Vault_CMG3-MEMS.jpg 
>
>
>Yes, I believe some tests should be done on temperature 
>effects.  Similar to other BBs, they should be insulated to 
>stabilize temps.  Sounds like an experiment for Bob Hutt at ASL.
>
>Some thoughts and Regards,
>Mark
>
>At 15:20 7/19/2011, David S. Croker wrote:
>>Hi All,
>>
>>Simple question with a potentially longwinded answer (simple answer 
>>preferred):  What kind of vault installation do you do for 
>>permanent Trillium Compact sites?  Full-blown vaults with lots of 
>>insulation, slightly reduced scale vaults with a little less 
>>insulation, or simple small scale tubes buried a couple feet down 
>>with minor insulation?  How do they respond to temperature changes?
>>
>>Thanks for any insight you might have.
>>
>>Dave
>>
>>__________________________________________________________
>>USGS - Earthquake Science Center - NCSN Field Operations Manager
>>David S. Croker                                         office (650) 329-4697
>>345 Middlefield Rd, MS 977                           fax (650) 329-4732
>>Menlo Park, CA 94025                                 cell (650) 465-4334
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>>
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>
>
>*********************************************************
>Mark E. Meremonte        Geophysicist    USGS/ANSS/NEIC
>
>U.S. Geological Survey        Work: 303-273-8670   Cell: 303-478-5766
>MS 966, Box 25046          Email: meremonte at usgs.gov
>Denver, CO  80225             Web: http://geohazards.cr.usgs.gov
>
>Ship:  U.S. Geological Survey, 1711 Illinois St., Golden, CO 80401
>**********************************************************
>
>
>
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