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Reproduced from the holdings of the National Archives
Pacific Southwest Region
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VERTICAL CONTROL
There has been no requirement for an overall vertical control network
and such a network would involve extensive observations over a conSiderable period of time.
Bench marks for vertical control have
been established independently at each of the project ereas from
tidal observations and the accuracy is considered consistent with
project requirements.
A check was obtained of the datum established
by this method at Eniwetok island when a tide gage was operated at
.
this location for several months during Operation Greenhouse by the
U. S. Coast and Geodetic Survey.
A differential of 0.1) foot was
determined which would be of no consequence in the
to project structures.
tidal relation