HomeMy WebLinkAboutMINUTES - 10231990 - 1.4 TO: BOARD OF SUPERVISORS
FROM: J. MICHAEL WALFORD, PUBLIC WORKS DIRECTOR
DATE: October 23, 1990
SUBJECT: Countywide Survey Control Network
Project No.: 0161-6X5502-90
SPECIFIC REQUEST(S) OR RECOMMENDATION(S) &BACKGROUND AND JUSTIFICATION
I. Recommended Action:
APPROVE Consulting Services Agreement with Sunrise Geodetic, for surveying services in
conjunction with the establishment of a Countywide Survey Control Network based on the new
North American Datum of 1983.
II. Financial Impact:
The maximum cost to the County is $63,000, which is available in the Monument Preservation
fund.
III. Reasons for Recommendations and Background:
The National Ocean Service/National Geodetic Survey has completed the redefinition of the
National Geodetic Horizontal Datum. The readjustment, known as the North American Datum
of 1983 (NAD83), is necessary because recent improvements in positioning technology have
detected discrepancies in horizontal locations based on the currently used reference system,
known as the North American Datum of 1927 (NAD27), sufficient in magnitude to require
readjustment.
The National Geodetic Survey will no longer publish information in support of NAD27. In order
to avoid being left with an obsolete horizontal control datum not supported by the Federal
government or compatible with the datum used in adjacent states, California amended portions
of the Public Resources Code relating to surveying and mapping. This was accomplished in
1986 by SB1680 and became effective January 1, 1987.
Continued on Attachment: X SIGNATURE:
_ RECOMMENDATION OF COUNTY ADMINISTRATOR
_ RECOMMENDATION OF BOARD COMMITTEE
APPROVE OTHER
SIGNATURE(S):
ACTION OF BOARD ON 3 1990 APPROVED AS RECOMMENDED OTHER
OCTv v � N �+ IJ�U
VOTE OF SUPERVISORS
UNANIMOUS (ABSENT )
AYES: NOES:
ABSENT: ABSTAIN:
I hereby eardfy that*.Is 1s a mm and correct copy of
an action taken and entered on the minutes of the
RN:drg Board of Supervisors on the date shown.
c\BO:23.t10 ATTESTED: QST 2 3 1990
PHIL BATCHELOR,Clerk of the Board
Orig. Div: Public Works (Design Division) of Supervlsors and County AdminlRtrator
cc: County Administrator - -
Auditor-Controller a� `�� ���'�='-�`•�p`rt''
PW Accounting
Countywide Survey Control Network
October 23, 1990
Page Two
III. Reasons for Recommendations and Background Cont'd:
The new law specified that, after January 1, 1995, use of State Plane Coordinates for new
surveys and new mapping shall be limited to the California Coordinate System based on NAD83,
known as CCS83. The County has historically used the State Plane Coordinate System and the
new Geographic Information System (GIS) is based on it.
The County's survey control network will tie into the State's control network now underway using
this same technology. We will have five points in common to create an extension of the State
network. This will allow all future surveys and maps to conform to a common, high precision
network.
Although this new law was not yet in effect when we started our GIS project, we knew of it. Our
GIS is fully capable of adjusting to the new system. This adjustment has already been made in
other areas.
IV. Consequences of Negative Action:
Negative action would prevent the County and all surveyors and mappers doing work in the
County from conforming their surveys and maps to a unified NAD 83 datum which has been
adopted by the Federal and State governments.