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HOLMES & NARVER, Ine.
ENGINEERS-CONSTRUCTORS
To:
S. P. Howall
R-23
for
.
408004
__jop:_ 942
FROM:____ue Se Hammond
re:_ LOCAL Fi
— EN
pATe:__August 9, 1957
ASe
M
“Hy
Reference is made to Field Sketches 6267 and 6268 delineating proposed local control
surveys in the Ruby-Sally-Tilda area and in the Yvonne area. These sketches outline
jobsite planning to provide sufficient controls in these areas to perform any
requirements for layout of scientific stations.
I concur in the proposed program
(‘.
S
wee
but submit the following modifications which I believe will reduce the amount of
field work required to provide controls consistant with project requirements.
1.
In the Yvonne area, a traverse is proposed between triangulation station "Runit"
and the new station "North". Intermediate monuments are proposed at approximately
200 meter intervals and all 50 meter chaining bucks are to consist of 4 x 4
posts set in concrete. I recommend that the monuments be set as proposed but
that temporary chaining bucks be used for measurement of the traverse. Control
points 200 meters apart should be sufficient for any needs and the expense of
permanent points 50 meters apart could not be justified.
The measurement of the traverse should be performed to first order traverse
specifications, or within a tolerance of 1:25000, and the resulting measurements
adjusted between the established positions of stations Ronit and North. Any
refinement beyond first order traverge specifications would serve no purpose
or the final values will be based on the established coordinates of the
triangulation stations.
The triangle North-Traverse Station Ynez-Runit should be observed to second
order observing procedure.
2
In the Ruby-Sally-Tilda area, the proposed traversing includes two triangles
and connecting traverses. As in the Yvonne area, it should be sufficient to
establish permanent momments at 200 meter intervals rather than making all
50 meter chaining bucks permanent momments.
Traversing to first order traverse
specifications ahould be satisfactory to meet any requirements in this «rea.
All angles involved in the traverses and including ties to the basic network
should be to second order observing procedures.
The attached sketch indicates the recommended location of permanent monuments
and the angles to be observed.
It should be recognized that this program is based on limited information by the
Jcusite, or Home Office, as to the ultimate requirements for these areas. However,
the proposal to establish these controls early, before a great increase in the survey
work load can certainly be justified.
.
LSH s cw
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