Superseded Bench Mark Sheet for 9452437, EXCURSION INLET (SOUTH END) AK

Present Epoch

Printable version

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

                                                   PUBLICATION DATE:  10/23/2000
Station ID: 9452437                                SUPERCEDED DATE:   04/21/2003
Name:       EXCURSION INLET (SOUTH END)                       
            ALASKA
NOAA Chart: 17316                                  Latitude:         58° 25.0' N
USGS Quad:  JUNEAU (B-5)                           Longitude:       135° 26.8' W


To reach the tidal bench marks from Icy Passage, navigate 18 km (11 mi) east of
Gustavus about 1/3 of the way up Excursion Inlet on the eastern shore near the
main cannery building adjacent to the large pier.  The bench marks are located
in the vicinity of the pier along shore.  The tide gauge was located just north
of the main pier. 


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


                 PRIMARY BENCH MARK STAMPING:  EXCURSION INLET SO. END 5 1964
                         DESIGNATION:          945 2437 EXCURSION 5

MONUMENTATION:           Tidal Station disk                        VM#:    15952
AGENCY:                  US Coast & Geodetic Survey (USC&GS)       PID:         
SETTING CLASSIFICATION:  Concrete step


The primary bench mark is a disk set in the third of five concrete steps near
the SW corner of a 30 m x 61 m x 1 m (100 ft x 200 ft x 4 ft) concrete fuel pen,
105 m (345 ft) NE of the east end of the cannery pier, and 10.21 m (33.5 ft)
north of the SW corner of the foundation.



                         BENCH MARK STAMPING:  2437 E 1999
                         DESIGNATION:          945 2437 E

MONUMENTATION:           Tidal Station disk                        VM#:    15953
AGENCY:                  National Ocean Service (NOS)              PID:         
SETTING CLASSIFICATION:  Loading dock


The bench mark is a disk set in the northern corner of a concrete loading dock
for the main building near the pier, 58 m (190 ft) south of bench mark 2437 F
1999, and 15 m (50 ft) NE of the apparent high water line.

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

                                                   PUBLICATION DATE:  10/23/2000
Station ID: 9452437                                SUPERCEDED DATE:   04/21/2003
Name:       EXCURSION INLET (SOUTH END)                       
            ALASKA
NOAA Chart: 17316                                  Latitude:         58° 25.0' N
USGS Quad:  JUNEAU (B-5)                           Longitude:       135° 26.8' W


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


                         BENCH MARK STAMPING:  2437 F 1999
                         DESIGNATION:          945 2437 F

MONUMENTATION:           Tidal Station disk                        VM#:    15954
AGENCY:                  National Ocean Service (NOS)              PID:         
SETTING CLASSIFICATION:  Concrete foundation


The bench mark is a disk set in the NW corner of the concrete foundation for a
garbage pit, located outside of a chain link fence but inside an electric fence,
and 140 m (460 ft) SW of bench mark 2437 G 1999.



                         BENCH MARK STAMPING:  2437 G 1999
                         DESIGNATION:          945 2437 G

MONUMENTATION:           Tidal Station disk                        VM#:    15955
AGENCY:                  National Ocean Service (NOS)              PID:         
SETTING CLASSIFICATION:  Tar deck


The bench mark is a disk set in the tar deck near the NW corner of a 30 m x 61 m
x 1 m (100 ft x 200 ft x 4 ft) concrete fuel pen, just outside of the
chain/barbwire fence near tank D1, and 47 m (155 ft) NW of bench mark EXCURSION
INLET SO. END 5 1964.



                         BENCH MARK STAMPING:  2437 H 1999
                         DESIGNATION:          945 2437 H

MONUMENTATION:           Tidal Station disk                        VM#:    15956
AGENCY:                  National Ocean Service (NOS)              PID:         
SETTING CLASSIFICATION:  Concrete deck


The bench mark is a disk set in the concrete deck along the east side near the
SW corner of a 30 m x 61 m x 1 m (100 ft x 200 ft x 4 ft) concrete fuel pen,
directly across from a fence gate, and 43 m (140 ft) NE of bench mark EXCURSION
INLET SO. END 5 1964.

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

                                                   PUBLICATION DATE:  10/23/2000
Station ID: 9452437                                SUPERCEDED DATE:   04/21/2003
Name:       EXCURSION INLET (SOUTH END)                       
            ALASKA
NOAA Chart: 17316                                  Latitude:         58° 25.0' N
USGS Quad:  JUNEAU (B-5)                           Longitude:       135° 26.8' W


                            T I D A L   D A T U M S 


Tidal datums at EXCURSION INLET (SOUTH END) based on:

     LENGTH OF SERIES:      62 hws and 62 lws
     TIME PERIOD:           May 7,1999 - June 8,1999
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  9452210 JUNEAU, GASTINEAU CHANNEL, STEPHENS PASS


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

     MEAN HIGHER HIGH WATER                     MHHW   =  4.515
     MEAN HIGH WATER                            MHW    =  4.248
     MEAN SEA LEVEL                             MSL    =  2.365
     MEAN TIDE LEVEL                            MTL    =  2.357
     MEAN LOW WATER                             MLW    =  0.467
     MEAN LOWER LOW WATER                       MLLW   =  0.000



Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     EXCURSION INLET SO. END 5 1964              8.459    4.211
     2437 E 1999                                 7.881    3.633
     2437 F 1999                                 7.844    3.596
     2437 G 1999                                 9.002    4.754
     2437 H 1999                                 8.800    4.552


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

                                                   PUBLICATION DATE:  10/23/2000
Station ID: 9452437                                SUPERCEDED DATE:   04/21/2003
Name:       EXCURSION INLET (SOUTH END)                       
            ALASKA
NOAA Chart: 17316                                  Latitude:         58° 25.0' N
USGS Quad:  JUNEAU (B-5)                           Longitude:       135° 26.8' W


Foot Notes:

Portions of SE Alaska in the area of Lynn Canal and Stephens Passage have
anomalous relative sea level trends compared to most other geographic regions in
the United States. This is due to a general uplift of the land in this area,
which has been occurring at a rapid rate. Because of the magnitude of the sea
level trends in these areas, NOAA has adopted a procedure for computing accepted
 tidal datums for the National Water Level Observation Network (NWLON) using the
last several years of sea level data rather than the 19-year tidal epoch. The
tide ranges are still based on the 1960 - 1978 National Tidal Datum Epoch (NTDE)
and are applied to the five year (1994 - 1998) Mean Tide Level (MTL) to compute
other tidal datums. The adoption of this procedure was necessary to ensure that
tidal datums accurately represent the existing stand of sea level.

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

                                                   PUBLICATION DATE:  10/23/2000
Station ID: 9452437                                SUPERCEDED DATE:   04/21/2003
Name:       EXCURSION INLET (SOUTH END)                       
            ALASKA
NOAA Chart: 17316                                  Latitude:         58° 25.0' N
USGS Quad:  JUNEAU (B-5)                           Longitude:       135° 26.8' W


                             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 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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