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Mount Commonly Used
|
Stability
|
Cost
|
Install Time
|
Labor
|
Substrate
|
Site Impact
|
SCIGN mount |
med |
$800 |
1 d |
2-3 |
U
|
med |
The shallow braced (non-drilled, hand augured or pounnded) monument consists of 4-5 1"-diameter stainless steel legs in a tripod configuration pounded into the substrate up to depths of about 5-6 feet. The legs are welded together at the top. The short braced monument is nearly identical to the shallow drilled braced monument, with the exception that the legs are either pounded into unconsolidated ground or a hand auger is used to create the holes for the legs.
Rather than epoxied into holes drilled in bedrock. Use the SBM (Short Braced Monument) at locations where there is no bedrock available.
l
Site P492 of EarthScope’s Plate Boundary Observatory (PBO) (left); test site NWOT on Niwot Ridge (middle) and ,Costa Rica (right).
installable in unconsolidated substrate
materials relatively inexpensive
drill bits will not get stuck (as in short drilled braced monument)
materials and equipment can be flown to remote locations by helicopter
can be installed in environmentally sensitive sites
relatively quick deployment
site permitting potentially easier than for the deep drilled braced monument
labor and tool intensive
is probably less stable than the deep drilled braced monument
initial cost to purchase required tools potentially expensive
A heavy duty hammer drill with a special chuck is required for installation.
Ed Arnitz of UNAVCO drives the central rod into the ground with a Hilti drill.
The rods can also be pounded into the ground with a sledgehammer.
You first need to make the ends pointed.
Victor Gonzales (OVSICORI) using the hand auger to dig out the holes for the legs.
$800
This cost is for the monumentation only; the antenna mount (e.g. SCIGN mount) is not included.
4 12-foot stainless steel rods (1" diameter) with grooves
3 weld gussets
threaded adapter (if using the SCIGN antenna mount; see below)
welding rod
gas for the generator (if there is no AC hookup)
water (for fire safety while welding)
The materials specific to construction of the SBM are available as a kit which can be purchased from:
McRoberts Machine, Inc. (Judy or Doug McRoberts)
402 Martin St
Longmont, CO 80501
Phone: (303) - 776 - 2397
Fax: (303) - 776 - 0704
When ordering please refer to Part #1090.
AC-powered heavy-duty hammer drill (e.g. Hilti) with bit
generator (if there is no AC hookup)
chop saw or dry cut saw
grinder
vertical and angle level(s)
leg alignment tool
welder
file, pick, brush, gloves, helmet, long-sleeved shirt, hat (for welding)
compass
The SCIGN mount is the antenna mount most commonly used with the shallow braced monument, although it is only required when using the SCIGN radome. Otherwise, any other leveling mount, such as the SECO 2072-series antenna mount, is acceptable.
Send questions or comments to Support (supportunavco.org).
Article ID: 323
Created: April 9, 2014
Last Updated: April 28, 2017
Author: Beth Bartel
Online URL: https://kb.unavco.org/article/shallow-braced-non-drilled-hand-augered-or-pounded-monument-overview-323.html