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Bench Mark Sheet for 9454777, CHENEGA ISLAND (S.W. END) AK

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 9454777                         PUBLICATION DATE:  06/08/2011
Name:       CHENEGA ISLAND (S.W. END)                         
            AK
NOAA Chart: 16701                           Latitude:   60° 17.0' N (  60.28330)
USGS Quad:  Seward B-3                      Longitude: 148°  6.8' W (-148.11300)





                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  NO 1 1957
                         DESIGNATION:          945 4777 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:        14677
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Detached rock                         OPUS PID:        
LATITUDE:   60°  7.0' N (  60.11670)          LONGITUDE: 148°  6.8' W (-148.11300)


The bench mark is a disk set in top of a detached rock on the east side of the
southern-most bight of a small bay about one mile west of Chenega Village, about
40 m (131 ft) north of south end of ight and 10 m (33 ft) west of the
approximate high water line.



                         BENCH MARK STAMPING:  NO 2 1957
                         DESIGNATION:          945 4777 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:        13255
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Boulder                               OPUS PID:        
LATITUDE:   60°  7.0' N (  60.11670)          LONGITUDE: 148°  6.8' W (-148.11300)


The bench mark is a disk set in top of a large boulder at the approximate high
water line on the west side of the bight and about 15 m (49 ft) north of the
south end of the bight.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 9454777                         PUBLICATION DATE:  06/08/2011
Name:       CHENEGA ISLAND (S.W. END)                         
            AK
NOAA Chart: 16701                           Latitude:   60° 17.0' N (  60.28330)
USGS Quad:  Seward B-3                      Longitude: 148°  6.8' W (-148.11300)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  NO 4 1964
                         DESIGNATION:          945 4777 TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:        14678
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Black shale rock                      OPUS PID:        
LATITUDE:   60°  7.0' N (  60.11670)          LONGITUDE: 148°  6.8' W (-148.11300)


The bench mark is a disk set in top of a black shale rock, 2.44 m (8.0 ft)
inside moss line, and 2.44 m (8.0 ft) inshore from the approximate high water
line.



                         BENCH MARK STAMPING:  NO 5 1964
                         DESIGNATION:          945 4777 TIDAL 5

MONUMENTATION:           Tidal Station disk                    VM#:        14679
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Black shale rock ledge                OPUS PID:        
LATITUDE:   60°  7.0' N (  60.11670)          LONGITUDE: 148°  6.8' W (-148.11300)


The bench mark is a disk set in top of a black shale rock ledge 1.22 m (4.0 ft)
outside of a tree line, 22 m (72 ft) ENE of bench mark NO 4 1964, and 3 m (10
ft) inshore of the approximate high water line.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 9454777                         PUBLICATION DATE:  06/08/2011
Name:       CHENEGA ISLAND (S.W. END)                         
            AK
NOAA Chart: 16701                           Latitude:   60° 17.0' N (  60.28330)
USGS Quad:  Seward B-3                      Longitude: 148°  6.8' W (-148.11300)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  NO 6 1964
                         DESIGNATION:          945 4777 TIDAL 6

MONUMENTATION:           Tidal Station disk                    VM#:        14680
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Black shale ledge                     OPUS PID:        
LATITUDE:   60°  7.0' N (  60.11670)          LONGITUDE: 148°  6.8' W (-148.11300)


The bench mark is a disk set in the top of a black shale ledge about 0.61 m (2.0
ft) outside of moss and tree line and 21.64 m (71.0 ft) ENE of bench mark NO 5
1964. 



                         BENCH MARK STAMPING:  NO 7 1964
                         DESIGNATION:          945 4777 TIDAL 7

MONUMENTATION:           Tidal Station disk                    VM#:        14681
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Outcrop of bedrock                    OPUS PID:        
LATITUDE:   60°  7.0' N (  60.11670)          LONGITUDE: 148°  6.8' W (-148.11300)


The bench mark is a disk set in the top of a solid black prominent round outcrop
of bedrock, on the south side of a small tree-topped islet ENE of bench mark NO
1 1957, 3 m (10 ft) outside of tree line and about 4.57 m (15.0 ft) inshore of
approximate high water line.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 9454777                         PUBLICATION DATE:  06/08/2011
Name:       CHENEGA ISLAND (S.W. END)                         
            AK
NOAA Chart: 16701                           Latitude:   60° 17.0' N (  60.28330)
USGS Quad:  Seward B-3                      Longitude: 148°  6.8' W (-148.11300)


                            T I D A L   D A T U M S 


Tidal datums at CHENEGA ISLAND (S.W. END) based on:

     LENGTH OF SERIES:      57 Days
     TIME PERIOD:           September 3 1996 - October 29 1996
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9454240 VALDEZ, PRINCE WILLIAM SOUND


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     MEAN HIGHER HIGH WATER                     MHHW   =  3.601
     MEAN HIGH WATER                            MHW    =  3.327
     MEAN SEA LEVEL                             MSL    =  1.920
     MEAN TIDE LEVEL                            MTL    =  1.891
     MEAN LOW WATER                             MLW    =  0.455
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1957                                   5.158    1.831
     NO 2 1957                                   5.337    2.010
     NO 4 1964                                   5.013    1.686
     NO 5 1964                                   4.855    1.528
     NO 6 1964                                   5.395    2.068
     NO 7 1964                                   5.268    1.941


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 9454777                         PUBLICATION DATE:  06/08/2011
Name:       CHENEGA ISLAND (S.W. END)                         
            AK
NOAA Chart: 16701                           Latitude:   60° 17.0' N (  60.28330)
USGS Quad:  Seward B-3                      Longitude: 148°  6.8' W (-148.11300)


                             D E F I N I T I O N S


Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal
Datum Epoch.  It pertains to local mean sea level and should not be confused
with the fixed datums of North American Vertical Datum of 1988 (NAVD88).

NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum
constraint adjustment of Canadian/Mexican/United States leveling observations.
Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as
the single initial constraint.  NAVD88 replaces NGVD29 as the national
standard geodetic reference for heights.  Bench mark elevations relative to
NAVD88 are available from NGS through the World Wide Web at 
National Geodetic Survey.

NGVD29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded.  NGVD29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads.  NGVD29 was originally derived from a general
adjustment of the first-order leveling networks of the U.S. and Canada after
holding mean sea level observed at 26 long term tide stations as fixed.
Numerous local and wide-spread adjustments have been made since establishment in
1929.  Bench mark elevations relative to NGVD29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at 
National Geodetic Survey.

NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to
local MSL and other tidal datums may not be consistent from one location to
another.

The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique
identifiers for bench marks in the tidal and geodetic databases, respectively.
Each bench mark in either database has a single, unique VM# and/or PID# assigned.
Where both VM# and PID# are indicated, both tidal and geodetic elevations are
available for the bench mark listed. The NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.

The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD88 elevations.
The NAVD88 elevation relationship shown in the table is derived from an average
of several bench mark elevations relative to tide station datum.  As a result of
this averaging, NAVD88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD88 elevations listed for
each bench mark in the NGS database.

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Products available at 9454777 CHENEGA ISLAND (S.W. END), AK

Revised: 10/15/2013
NOAA / National Ocean Service
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