[ANSS-netops] Net-Ops: Small/Remote Style Vault
Mark E Meremonte
meremonte at usgs.gov
Sat Feb 21 01:08:39 GMT 2009
Hi all,
At the last February 2008 ANSS Net-Ops meeting we discussed a bit about
vault systems used by various institutions/agencies. And, I understood
there was interest in a smaller, versatile, robust, water tight, and
easily transportable vault system that could be utilized by all, i.e., a
standardized system. If I remember correctly, there are several goals of
the Net-Ops meetings:
- promote cooperation
- encourage ideas
- exchange best practices on instrumentation, communications, power,
grounding, installation techniques, inventory, and monitoring tools
- promote standardization especially for broadband and strong motion
stations
In an effort to move toward these goals, I present information here to
promote vault standardization of small/remote style vaults which use
minimum resources to produce maximum response results to obtain
high-quality data. At meeting Greg Steiner discussed the CERI vault,
there was discussion on several types of vault used by Pasadena from small
to large with their largest being similar to the TA (Transportable Array)
style vault, a small style vault (by whom I do not remember) that was made
out of a PVC tube with a PVC lid, which had a conduit connection
protruding from the top, and a small/remote style vault (which also
doubled as a tabletop at the meeting) shown by myself. The primary
differences from USGS's investigations between good structurally designed
and insulated small vaults and large vaults such as the McMillan, CERI, or
TA vaults are poorer response in the low frequency range below 30 seconds
and more excited by microseisms in the range between 4-10 seconds by about
10 db. See ANSS Vault Design Test results below:
Vault types annotated in plots are:
ALQM - McMillan style to specs except using a gabled roof rather than lean
type; soil mounded up to edge of lid.
ALTA - TA style to specs; soil mounded up to edge and over lid.
ALQT - TA style w/ concrete poured from base all the way up to surface
around outside of corrugated conduit; soil mounded up to edge and over
lid.
ALCE - CERI style vault to specs; soil mounded to edge and over lid.
ALQO - Small/remote style vault composed of 16" O.D. fiberglass tube
embedded 2" into 10"x18" of concrete with tile base; buried under 20" of
soil.
ALQI - Same as for ALQO except the entire vault was isolated by an outer
shell using an overpack barrel; all buried under 14" of soil
For vault test photos and a powerpoint presentation on vault responses
see: ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/VaultTests/ .
Since the meeting I have made a few improvements on the vault and
installed the first one at station MOOW in the IW Network near Moose Ponds
below Teewinot Mtn in the Grand Teton National Park (see photos of the
MOOW installation at
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/StationMOOW). The vault,
itself, is made from a standard 18" inner diameter (ID) fiberglass tube
with a 1" wide fiberglass flange attached around the base, and a
polyurethane lid with a silicone seal embedded in the lid to fit over the
1/4" thick wall of the tube.
The standard vault design specifications are:
Vault -- 18" ID x 18" H x 1/4" T fiberglass tube with a 1" wide flange:
see
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/CurrentPhotos/Vault2_Lid-Opened.jpg
-- fiberglass tube is strong and resilient,
-- flange helps anchor vault in concrete,
see vault installed at station MOOW:
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/StationMOOW/MOOW_Vault-in-Concrete.jpg
-- Because the vault is made from a tube, the height of the vault can be
changed to accommodate taller instrument configurations.
Base -- 1/2" T x 20" D glass plate, sand blasted on both sides, and bonded
to 1" wide flange on base:
see
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/CurrentPhotos/Vault5-Tilted_GlassBase.jpg
-- rough surface helps bond concrete,
-- provides electrical isolation with the Earth,
-- provides a nice flat, even surface for seismometer,
-- sand blasted surface minimizes seismometer slippage,
-- it is a water tight seal.
Lid -- a 2" thick polyurethane lid with embedded U-shaped silicone seal:
see
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/CurrentPhotos/Vault3_Lid-SilconeSeal.jpg
-- the polyurethane makes the lid lightweight and strong,
-- the U-shaped seals against both sides of the vault as well as along the
top of the rim providing a water tight seal.
Cable Access -- vault engineered with two approx. 4" square fiberglass,
flat-based mounting plates built into the vault wall:
see
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/CurrentPhotos/Vault12_Shelf_SeisTemplate.jpg
-- mounting plates provide a flat base to attach conduit fittings for
cable access,
-- the fittings are PVC bulkhead water-tight fittings w/ EPDM gaskets (
http://www.plumbingsupply.com/bulkhead.html) and provide a water-tight
seal,
-- the mounting plates are 180 deg from each other and just below the lid;
and will allow side by side vaults to be installed w/ conduit installed in
between,
-- one of the plates is initially drilled to accept a 3-1/8" bulkhead
fitting which will accept 2" ID PVC or liquidtight conduit,
Note: we used liquidtight conduit at station MOOW:
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/StationMOOW/MOOW_LiquidtightConduit.jpg
-- reducers can be used to accept smaller 1.5" PVC or liquidtight conduit
or other.
Latch system -- the lid is clamped to the vault using three EPDM rubber
latches:
see
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/CurrentPhotos/Vault9_Latch-system-closeup-closed.JPG
-- EPDM is a strong, weather resistant rubber,
-- keeper of the latch is galvanized steel mounted/bonded on edge of the
2" wide lid,
-- base of the latch will be made of fiberglass bonded to side of the
vault with a stainless steel bolt instead of the metal base as seen in the
photo.
Note: the vault installed at station MOOW has latches that will be
replaced with the ones described above.
Inner shelf system -- a shelf has been engineered inside the vault
see
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/CurrentPhotos/Vault12_Shelf_SeisTemplate.jpg
-- shelf is 7" Wide and can be removed to access seismometer,
-- shelf resides about 11" up from the base and below cable access
mounting plates,
-- shelf can be used to rest/anchor other components such as surge
protector,
-- optional: add another opposite shelf to possibly allow datalogger to
reside inside vault; may also need to increase height of vault depending
datalogger; Note: some CMG systems have a digitizer cap which will fit
inside vault too.
Broadbands -- The design can accommodate any number of seismometers:
-- Currently we install both a CMG3T- ESP and a MEMS seismometer in the
vault for our remote regional stations,
-- a STS-2 with room to adjust the legs,
-- a CMG-40T or CMG-40TD w/ digitizer cap
-- Trillium 120
Strong Motion Mount -- a type of elevator bolt which can be bonded to
glass plate:
see
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/CurrentPhotos/Vault16_SM-ElavatorBolt-Closeup.jpg
-- nominally a 1/4" x 20 elevator bolt.
-- it's base is flat, wide and circular with a number of holes that allow
bonding material to envelop it and hold fast,
-- the bolt fits both an Episensor and a MEMS mounts.
Note: Currently the bolt is not included in vault manufacture but I can
provide info where to purchase and bonding agent if interest.
Well that is the best I can do to describe the vault and show its response
characteristics in an email. Most of you have seen its main design at the
last meeting and some have seen it installed at the vault test site in
Albuquerque. My interest is to promote its adoption and use.
Since the meeting several members have expressed interest and I have sent
them some info already. Currently, I am interested in manufacturing about
6-8 of these. The cost of each is estimated to be somewhere between
$500-600. I know this may sound expensive to some or if not most of the
regional networks. But if you add up the costs of each of us visiting
different stores by vehicle or searching on-line for appropriate
materials, talking to reps on the phone, shipping the hardware bought (if
it is the correct hardware), and the effort, time, and salary to build our
individual style vaults, then you will discover that much expense and
personal time were incurred. This system will be essentially
off-of-the-shelf and ready to be deployed with little to no tinkering.
However, in part because of these economic times, in part due to the
creation of some fiberglass templates, and in part to devoting some custom
labor, the manufacture is hard pressed to produce less than 20-30 vaults
to make it worthwhile; and, of course, the more systems to be produced the
cheaper an individual system will cost.
Thus, I am asking everyone to please evaluate what I have proposed and
respond with your interests or comments especially in light of the Net-Ops
goals and cooperation amongst ANSS regional networks. I make no bones
that I have a personal, professional interest to encourage others to join
in the manufacture and purchasing of these vaults. Currently, I have one
major interest -- Bureau of Reclamation to replace about 6-8 vaults in the
Paradox Valley Seismic Network in western Colorado which monitors the
Delores/Colorado Rivers desalination project which the USGS is a
cooperator. Also, currently, I am planning to install two new IW stations
where these type of vaults would be beneficial to the remote, quiet
locations they will be installed.
Finally, sure some may want a different type of bulkhead fitting possibly
or some other small change; but in my 26 years of installing vaults for
regional network monitoring and for teleseismic monitoring where I have
used CERI vaults, McMillan vaults, TA vault style, numerous irrigation
style vaults, electronic pedestal type vaults, quick PVC tube style
vaults, upside down garbage can vaults, small salad bowl style vaults,
etc., this style vault satisfies all requirements I have encountered thus
far. And, I have noticed these days, there is more interest to not only
install the seismometers in the vault but the datalogger too. Guralp's
systems with digitizer caps makes it simple for others who use the RT-130
or Q330 systems, the option to increase height tube makes it possible. Of
course, my interest is to install the vault at least 1 foot below the
Earth's surface or more. Hence, why I rather have an above ground
electronic shelter for regional network installations especially remote
installations like we have in IW network and two more (McCall and Fox
Creek, ID) are planned for this summer.
see:
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/StationMOOW/MOOW_BelowSurface1.jpg
ftp://hazards.cr.usgs.gov/meremonte/VaultDesign/StationMOOW/MOOW_BelowSurface2.jpg
I have tried to include all parties that may have an interest. If you are
on the Net-Ops list already and receive a duplicate copy, I apologize.
Thank you for your time,
Mark
******************************************************************************
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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